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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
  */
 
 #include <string.h>
 #include <stdlib.h>
 #include <inttypes.h>
 #include <sys/mman.h>
 
 #include <arch/elf.h>
 #include <objtool/builtin.h>
 #include <objtool/cfi.h>
 #include <objtool/arch.h>
 #include <objtool/check.h>
 #include <objtool/special.h>
 #include <objtool/warn.h>
 #include <objtool/endianness.h>
 
 #include <linux/objtool.h>
 #include <linux/hashtable.h>
 #include <linux/kernel.h>
 #include <linux/static_call_types.h>
 
 struct alternative {
     struct list_head list;
     struct instruction *insn;
     bool skip_orig;
 };
 
 static unsigned long nr_cfi, nr_cfi_reused, nr_cfi_cache;
 
 static struct cfi_init_state initial_func_cfi;
 static struct cfi_state init_cfi;
 static struct cfi_state func_cfi;
 
 struct instruction *find_insn(struct objtool_file *file,
                   struct section *sec, unsigned long offset)
 {
     struct instruction *insn;
 
     hash_for_each_possible(file->insn_hash, insn, hash, sec_offset_hash(sec, offset)) {
         if (insn->sec == sec && insn->offset == offset)
             return insn;
     }
 
     return NULL;
 }
 
 static struct instruction *next_insn_same_sec(struct objtool_file *file,
                           struct instruction *insn)
 {
     struct instruction *next = list_next_entry(insn, list);
 
     if (!next || &next->list == &file->insn_list || next->sec != insn->sec)
         return NULL;
 
     return next;
 }
 
 static struct instruction *next_insn_same_func(struct objtool_file *file,
                            struct instruction *insn)
 {
     struct instruction *next = list_next_entry(insn, list);
     struct symbol *func = insn->func;
 
     if (!func)
         return NULL;
 
     if (&next->list != &file->insn_list && next->func == func)
         return next;
 
     /* Check if we're already in the subfunction: */
     if (func == func->cfunc)
         return NULL;
 
     /* Move to the subfunction: */
     return find_insn(file, func->cfunc->sec, func->cfunc->offset);
 }
 
 static struct instruction *prev_insn_same_sym(struct objtool_file *file,
                            struct instruction *insn)
 {
     struct instruction *prev = list_prev_entry(insn, list);
 
     if (&prev->list != &file->insn_list && prev->func == insn->func)
         return prev;
 
     return NULL;
 }
 
 #define func_for_each_insn(file, func, insn)                \
     for (insn = find_insn(file, func->sec, func->offset);       \
          insn;                          \
          insn = next_insn_same_func(file, insn))
 
 #define sym_for_each_insn(file, sym, insn)              \
     for (insn = find_insn(file, sym->sec, sym->offset);     \
          insn && &insn->list != &file->insn_list &&         \
         insn->sec == sym->sec &&                \
         insn->offset < sym->offset + sym->len;          \
          insn = list_next_entry(insn, list))
 
 #define sym_for_each_insn_continue_reverse(file, sym, insn)     \
     for (insn = list_prev_entry(insn, list);            \
          &insn->list != &file->insn_list &&             \
         insn->sec == sym->sec && insn->offset >= sym->offset;   \
          insn = list_prev_entry(insn, list))
 
 #define sec_for_each_insn_from(file, insn)              \
     for (; insn; insn = next_insn_same_sec(file, insn))
 
 #define sec_for_each_insn_continue(file, insn)              \
     for (insn = next_insn_same_sec(file, insn); insn;       \
          insn = next_insn_same_sec(file, insn))
 
 static bool is_jump_table_jump(struct instruction *insn)
 {
     struct alt_group *alt_group = insn->alt_group;
 
     if (insn->jump_table)
         return true;
 
     /* Retpoline alternative for a jump table? */
     return alt_group && alt_group->orig_group &&
            alt_group->orig_group->first_insn->jump_table;
 }
 
 static bool is_sibling_call(struct instruction *insn)
 {
     /*
      * Assume only ELF functions can make sibling calls.  This ensures
      * sibling call detection consistency between vmlinux.o and individual
      * objects.
      */
     if (!insn->func)
         return false;
 
     /* An indirect jump is either a sibling call or a jump to a table. */
     if (insn->type == INSN_JUMP_DYNAMIC)
         return !is_jump_table_jump(insn);
 
     /* add_jump_destinations() sets insn->call_dest for sibling calls. */
     return (is_static_jump(insn) && insn->call_dest);
 }
 
 /*
  * This checks to see if the given function is a "noreturn" function.
  *
  * For global functions which are outside the scope of this object file, we
  * have to keep a manual list of them.
  *
  * For local functions, we have to detect them manually by simply looking for
  * the lack of a return instruction.
  */
 static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
                 int recursion)
 {
     int i;
     struct instruction *insn;
     bool empty = true;
 
     /*
      * Unfortunately these have to be hard coded because the noreturn
      * attribute isn't provided in ELF data. Keep 'em sorted.
      */
     static const char * const global_noreturns[] = {
         "__invalid_creds",
         "__module_put_and_kthread_exit",
         "__reiserfs_panic",
         "__stack_chk_fail",
         "__ubsan_handle_builtin_unreachable",
         "cpu_bringup_and_idle",
         "cpu_startup_entry",
         "do_exit",
         "do_group_exit",
         "do_task_dead",
         "ex_handler_msr_mce",
         "fortify_panic",
         "kthread_complete_and_exit",
         "kthread_exit",
         "kunit_try_catch_throw",
         "lbug_with_loc",
         "machine_real_restart",
         "make_task_dead",
         "panic",
         "rewind_stack_and_make_dead",
         "sev_es_terminate",
         "snp_abort",
         "stop_this_cpu",
         "usercopy_abort",
         "xen_start_kernel",
     };
 
     if (!func)
         return false;
 
     if (func->bind == STB_WEAK)
         return false;
 
     if (func->bind == STB_GLOBAL)
         for (i = 0; i < ARRAY_SIZE(global_noreturns); i++)
             if (!strcmp(func->name, global_noreturns[i]))
                 return true;
 
     if (!func->len)
         return false;
 
     insn = find_insn(file, func->sec, func->offset);
     if (!insn->func)
         return false;
 
     func_for_each_insn(file, func, insn) {
         empty = false;
 
         if (insn->type == INSN_RETURN)
             return false;
     }
 
     if (empty)
         return false;
 
     /*
      * A function can have a sibling call instead of a return.  In that
      * case, the function's dead-end status depends on whether the target
      * of the sibling call returns.
      */
     func_for_each_insn(file, func, insn) {
         if (is_sibling_call(insn)) {
             struct instruction *dest = insn->jump_dest;
 
             if (!dest)
                 /* sibling call to another file */
                 return false;
 
             /* local sibling call */
             if (recursion == 5) {
                 /*
                  * Infinite recursion: two functions have
                  * sibling calls to each other.  This is a very
                  * rare case.  It means they aren't dead ends.
                  */
                 return false;
             }
 
             return __dead_end_function(file, dest->func, recursion+1);
         }
     }
 
     return true;
 }
 
 static bool dead_end_function(struct objtool_file *file, struct symbol *func)
 {
     return __dead_end_function(file, func, 0);
 }
 
 static void init_cfi_state(struct cfi_state *cfi)
 {
     int i;
 
     for (i = 0; i < CFI_NUM_REGS; i++) {
         cfi->regs[i].base = CFI_UNDEFINED;
         cfi->vals[i].base = CFI_UNDEFINED;
     }
     cfi->cfa.base = CFI_UNDEFINED;
     cfi->drap_reg = CFI_UNDEFINED;
     cfi->drap_offset = -1;
 }
 
 static void init_insn_state(struct objtool_file *file, struct insn_state *state,
                 struct section *sec)
 {
     memset(state, 0, sizeof(*state));
     init_cfi_state(&state->cfi);
 
     /*
      * We need the full vmlinux for noinstr validation, otherwise we can
      * not correctly determine insn->call_dest->sec (external symbols do
      * not have a section).
      */
     if (opts.link && opts.noinstr && sec)
         state->noinstr = sec->noinstr;
 }
 
 static struct cfi_state *cfi_alloc(void)
 {
     struct cfi_state *cfi = calloc(sizeof(struct cfi_state), 1);
     if (!cfi) {
         WARN("calloc failed");
         exit(1);
     }
     nr_cfi++;
     return cfi;
 }
 
 static int cfi_bits;
 static struct hlist_head *cfi_hash;
 
 static inline bool cficmp(struct cfi_state *cfi1, struct cfi_state *cfi2)
 {
     return memcmp((void *)cfi1 + sizeof(cfi1->hash),
               (void *)cfi2 + sizeof(cfi2->hash),
               sizeof(struct cfi_state) - sizeof(struct hlist_node));
 }
 
 static inline u32 cfi_key(struct cfi_state *cfi)
 {
     return jhash((void *)cfi + sizeof(cfi->hash),
              sizeof(*cfi) - sizeof(cfi->hash), 0);
 }
 
 static struct cfi_state *cfi_hash_find_or_add(struct cfi_state *cfi)
 {
     struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
     struct cfi_state *obj;
 
     hlist_for_each_entry(obj, head, hash) {
         if (!cficmp(cfi, obj)) {
             nr_cfi_cache++;
             return obj;
         }
     }
 
     obj = cfi_alloc();
     *obj = *cfi;
     hlist_add_head(&obj->hash, head);
 
     return obj;
 }
 
 static void cfi_hash_add(struct cfi_state *cfi)
 {
     struct hlist_head *head = &cfi_hash[hash_min(cfi_key(cfi), cfi_bits)];
 
     hlist_add_head(&cfi->hash, head);
 }
 
 static void *cfi_hash_alloc(unsigned long size)
 {
     cfi_bits = max(10, ilog2(size));
     cfi_hash = mmap(NULL, sizeof(struct hlist_head) << cfi_bits,
             PROT_READ|PROT_WRITE,
             MAP_PRIVATE|MAP_ANON, -1, 0);
     if (cfi_hash == (void *)-1L) {
         WARN("mmap fail cfi_hash");
         cfi_hash = NULL;
     }  else if (opts.stats) {
         printf("cfi_bits: %d\n", cfi_bits);
     }
 
     return cfi_hash;
 }
 
 static unsigned long nr_insns;
 static unsigned long nr_insns_visited;
 
 /*
  * Call the arch-specific instruction decoder for all the instructions and add
  * them to the global instruction list.
  */
 static int decode_instructions(struct objtool_file *file)
 {
     struct section *sec;
     struct symbol *func;
     unsigned long offset;
     struct instruction *insn;
     int ret;
 
     for_each_sec(file, sec) {
 
         if (!(sec->sh.sh_flags & SHF_EXECINSTR))
             continue;
 
         if (strcmp(sec->name, ".altinstr_replacement") &&
             strcmp(sec->name, ".altinstr_aux") &&
             strncmp(sec->name, ".discard.", 9))
             sec->text = true;
 
         if (!strcmp(sec->name, ".noinstr.text") ||
             !strcmp(sec->name, ".entry.text") ||
             !strncmp(sec->name, ".text.__x86.", 12))
             sec->noinstr = true;
 
         for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
             insn = malloc(sizeof(*insn));
             if (!insn) {
                 WARN("malloc failed");
                 return -1;
             }
             memset(insn, 0, sizeof(*insn));
             INIT_LIST_HEAD(&insn->alts);
             INIT_LIST_HEAD(&insn->stack_ops);
             INIT_LIST_HEAD(&insn->call_node);
 
             insn->sec = sec;
             insn->offset = offset;
 
             ret = arch_decode_instruction(file, sec, offset,
                               sec->sh.sh_size - offset,
                               &insn->len, &insn->type,
                               &insn->immediate,
                               &insn->stack_ops);
             if (ret)
                 goto err;
 
             /*
              * By default, "ud2" is a dead end unless otherwise
              * annotated, because GCC 7 inserts it for certain
              * divide-by-zero cases.
              */
             if (insn->type == INSN_BUG)
                 insn->dead_end = true;
 
             hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset));
             list_add_tail(&insn->list, &file->insn_list);
             nr_insns++;
         }
 
         list_for_each_entry(func, &sec->symbol_list, list) {
             if (func->type != STT_FUNC || func->alias != func)
                 continue;
 
             if (!find_insn(file, sec, func->offset)) {
                 WARN("%s(): can't find starting instruction",
                      func->name);
                 return -1;
             }
 
             sym_for_each_insn(file, func, insn) {
                 insn->func = func;
                 if (insn->type == INSN_ENDBR && list_empty(&insn->call_node)) {
                     if (insn->offset == insn->func->offset) {
                         list_add_tail(&insn->call_node, &file->endbr_list);
                         file->nr_endbr++;
                     } else {
                         file->nr_endbr_int++;
                     }
                 }
             }
         }
     }
 
     if (opts.stats)
         printf("nr_insns: %lu\n", nr_insns);
 
     return 0;
 
 err:
     free(insn);
     return ret;
 }
 
 /*
  * Read the pv_ops[] .data table to find the static initialized values.
  */
 static int add_pv_ops(struct objtool_file *file, const char *symname)
 {
     struct symbol *sym, *func;
     unsigned long off, end;
     struct reloc *rel;
     int idx;
 
     sym = find_symbol_by_name(file->elf, symname);
     if (!sym)
         return 0;
 
     off = sym->offset;
     end = off + sym->len;
     for (;;) {
         rel = find_reloc_by_dest_range(file->elf, sym->sec, off, end - off);
         if (!rel)
             break;
 
         func = rel->sym;
         if (func->type == STT_SECTION)
             func = find_symbol_by_offset(rel->sym->sec, rel->addend);
 
         idx = (rel->offset - sym->offset) / sizeof(unsigned long);
 
         objtool_pv_add(file, idx, func);
 
         off = rel->offset + 1;
         if (off > end)
             break;
     }
 
     return 0;
 }
 
 /*
  * Allocate and initialize file->pv_ops[].
  */
 static int init_pv_ops(struct objtool_file *file)
 {
     static const char *pv_ops_tables[] = {
         "pv_ops",
         "xen_cpu_ops",
         "xen_irq_ops",
         "xen_mmu_ops",
         NULL,
     };
     const char *pv_ops;
     struct symbol *sym;
     int idx, nr;
 
     if (!opts.noinstr)
         return 0;
 
     file->pv_ops = NULL;
 
     sym = find_symbol_by_name(file->elf, "pv_ops");
     if (!sym)
         return 0;
 
     nr = sym->len / sizeof(unsigned long);
     file->pv_ops = calloc(sizeof(struct pv_state), nr);
     if (!file->pv_ops)
         return -1;
 
     for (idx = 0; idx < nr; idx++)
         INIT_LIST_HEAD(&file->pv_ops[idx].targets);
 
     for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++)
         add_pv_ops(file, pv_ops);
 
     return 0;
 }
 
 static struct instruction *find_last_insn(struct objtool_file *file,
                       struct section *sec)
 {
     struct instruction *insn = NULL;
     unsigned int offset;
     unsigned int end = (sec->sh.sh_size > 10) ? sec->sh.sh_size - 10 : 0;
 
     for (offset = sec->sh.sh_size - 1; offset >= end && !insn; offset--)
         insn = find_insn(file, sec, offset);
 
     return insn;
 }
 
 /*
  * Mark "ud2" instructions and manually annotated dead ends.
  */
 static int add_dead_ends(struct objtool_file *file)
 {
     struct section *sec;
     struct reloc *reloc;
     struct instruction *insn;
 
     /*
      * Check for manually annotated dead ends.
      */
     sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
     if (!sec)
         goto reachable;
 
     list_for_each_entry(reloc, &sec->reloc_list, list) {
         if (reloc->sym->type != STT_SECTION) {
             WARN("unexpected relocation symbol type in %s", sec->name);
             return -1;
         }
         insn = find_insn(file, reloc->sym->sec, reloc->addend);
         if (insn)
             insn = list_prev_entry(insn, list);
         else if (reloc->addend == reloc->sym->sec->sh.sh_size) {
             insn = find_last_insn(file, reloc->sym->sec);
             if (!insn) {
                 WARN("can't find unreachable insn at %s+0x%" PRIx64,
                      reloc->sym->sec->name, reloc->addend);
                 return -1;
             }
         } else {
             WARN("can't find unreachable insn at %s+0x%" PRIx64,
                  reloc->sym->sec->name, reloc->addend);
             return -1;
         }
 
         insn->dead_end = true;
     }
 
 reachable:
     /*
      * These manually annotated reachable checks are needed for GCC 4.4,
      * where the Linux unreachable() macro isn't supported.  In that case
      * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
      * not a dead end.
      */
     sec = find_section_by_name(file->elf, ".rela.discard.reachable");
     if (!sec)
         return 0;
 
     list_for_each_entry(reloc, &sec->reloc_list, list) {
         if (reloc->sym->type != STT_SECTION) {
             WARN("unexpected relocation symbol type in %s", sec->name);
             return -1;
         }
         insn = find_insn(file, reloc->sym->sec, reloc->addend);
         if (insn)
             insn = list_prev_entry(insn, list);
         else if (reloc->addend == reloc->sym->sec->sh.sh_size) {
             insn = find_last_insn(file, reloc->sym->sec);
             if (!insn) {
                 WARN("can't find reachable insn at %s+0x%" PRIx64,
                      reloc->sym->sec->name, reloc->addend);
                 return -1;
             }
         } else {
             WARN("can't find reachable insn at %s+0x%" PRIx64,
                  reloc->sym->sec->name, reloc->addend);
             return -1;
         }
 
         insn->dead_end = false;
     }
 
     return 0;
 }
 
 static int create_static_call_sections(struct objtool_file *file)
 {
     struct section *sec;
     struct static_call_site *site;
     struct instruction *insn;
     struct symbol *key_sym;
     char *key_name, *tmp;
     int idx;
 
     sec = find_section_by_name(file->elf, ".static_call_sites");
     if (sec) {
         INIT_LIST_HEAD(&file->static_call_list);
         WARN("file already has .static_call_sites section, skipping");
         return 0;
     }
 
     if (list_empty(&file->static_call_list))
         return 0;
 
     idx = 0;
     list_for_each_entry(insn, &file->static_call_list, call_node)
         idx++;
 
     sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE,
                  sizeof(struct static_call_site), idx);
     if (!sec)
         return -1;
 
     idx = 0;
     list_for_each_entry(insn, &file->static_call_list, call_node) {
 
         site = (struct static_call_site *)sec->data->d_buf + idx;
         memset(site, 0, sizeof(struct static_call_site));
 
         /* populate reloc for 'addr' */
         if (elf_add_reloc_to_insn(file->elf, sec,
                       idx * sizeof(struct static_call_site),
                       R_X86_64_PC32,
                       insn->sec, insn->offset))
             return -1;
 
         /* find key symbol */
         key_name = strdup(insn->call_dest->name);
         if (!key_name) {
             perror("strdup");
             return -1;
         }
         if (strncmp(key_name, STATIC_CALL_TRAMP_PREFIX_STR,
                 STATIC_CALL_TRAMP_PREFIX_LEN)) {
             WARN("static_call: trampoline name malformed: %s", key_name);
             return -1;
         }
         tmp = key_name + STATIC_CALL_TRAMP_PREFIX_LEN - STATIC_CALL_KEY_PREFIX_LEN;
         memcpy(tmp, STATIC_CALL_KEY_PREFIX_STR, STATIC_CALL_KEY_PREFIX_LEN);
 
         key_sym = find_symbol_by_name(file->elf, tmp);
         if (!key_sym) {
             if (!opts.module) {
                 WARN("static_call: can't find static_call_key symbol: %s", tmp);
                 return -1;
             }
 
             /*
              * For modules(), the key might not be exported, which
              * means the module can make static calls but isn't
              * allowed to change them.
              *
              * In that case we temporarily set the key to be the
              * trampoline address.  This is fixed up in
              * static_call_add_module().
              */
             key_sym = insn->call_dest;
         }
         free(key_name);
 
         /* populate reloc for 'key' */
         if (elf_add_reloc(file->elf, sec,
                   idx * sizeof(struct static_call_site) + 4,
                   R_X86_64_PC32, key_sym,
                   is_sibling_call(insn) * STATIC_CALL_SITE_TAIL))
             return -1;
 
         idx++;
     }
 
     return 0;
 }
 
 static int create_retpoline_sites_sections(struct objtool_file *file)
 {
     struct instruction *insn;
     struct section *sec;
     int idx;
 
     sec = find_section_by_name(file->elf, ".retpoline_sites");
     if (sec) {
         WARN("file already has .retpoline_sites, skipping");
         return 0;
     }
 
     idx = 0;
     list_for_each_entry(insn, &file->retpoline_call_list, call_node)
         idx++;
 
     if (!idx)
         return 0;
 
     sec = elf_create_section(file->elf, ".retpoline_sites", 0,
                  sizeof(int), idx);
     if (!sec) {
         WARN("elf_create_section: .retpoline_sites");
         return -1;
     }
 
     idx = 0;
     list_for_each_entry(insn, &file->retpoline_call_list, call_node) {
 
         int *site = (int *)sec->data->d_buf + idx;
         *site = 0;
 
         if (elf_add_reloc_to_insn(file->elf, sec,
                       idx * sizeof(int),
                       R_X86_64_PC32,
                       insn->sec, insn->offset)) {
             WARN("elf_add_reloc_to_insn: .retpoline_sites");
             return -1;
         }
 
         idx++;
     }
 
     return 0;
 }
 
 static int create_return_sites_sections(struct objtool_file *file)
 {
     struct instruction *insn;
     struct section *sec;
     int idx;
 
     sec = find_section_by_name(file->elf, ".return_sites");
     if (sec) {
         WARN("file already has .return_sites, skipping");
         return 0;
     }
 
     idx = 0;
     list_for_each_entry(insn, &file->return_thunk_list, call_node)
         idx++;
 
     if (!idx)
         return 0;
 
     sec = elf_create_section(file->elf, ".return_sites", 0,
                  sizeof(int), idx);
     if (!sec) {
         WARN("elf_create_section: .return_sites");
         return -1;
     }
 
     idx = 0;
     list_for_each_entry(insn, &file->return_thunk_list, call_node) {
 
         int *site = (int *)sec->data->d_buf + idx;
         *site = 0;
 
         if (elf_add_reloc_to_insn(file->elf, sec,
                       idx * sizeof(int),
                       R_X86_64_PC32,
                       insn->sec, insn->offset)) {
             WARN("elf_add_reloc_to_insn: .return_sites");
             return -1;
         }
 
         idx++;
     }
 
     return 0;
 }
 
 static int create_ibt_endbr_seal_sections(struct objtool_file *file)
 {
     struct instruction *insn;
     struct section *sec;
     int idx;
 
     sec = find_section_by_name(file->elf, ".ibt_endbr_seal");
     if (sec) {
         WARN("file already has .ibt_endbr_seal, skipping");
         return 0;
     }
 
     idx = 0;
     list_for_each_entry(insn, &file->endbr_list, call_node)
         idx++;
 
     if (opts.stats) {
         printf("ibt: ENDBR at function start: %d\n", file->nr_endbr);
         printf("ibt: ENDBR inside functions:  %d\n", file->nr_endbr_int);
         printf("ibt: superfluous ENDBR:       %d\n", idx);
     }
 
     if (!idx)
         return 0;
 
     sec = elf_create_section(file->elf, ".ibt_endbr_seal", 0,
                  sizeof(int), idx);
     if (!sec) {
         WARN("elf_create_section: .ibt_endbr_seal");
         return -1;
     }
 
     idx = 0;
     list_for_each_entry(insn, &file->endbr_list, call_node) {
 
         int *site = (int *)sec->data->d_buf + idx;
         *site = 0;
 
         if (elf_add_reloc_to_insn(file->elf, sec,
                       idx * sizeof(int),
                       R_X86_64_PC32,
                       insn->sec, insn->offset)) {
             WARN("elf_add_reloc_to_insn: .ibt_endbr_seal");
             return -1;
         }
 
         idx++;
     }
 
     return 0;
 }
 
 static int create_mcount_loc_sections(struct objtool_file *file)
 {
     struct section *sec;
     unsigned long *loc;
     struct instruction *insn;
     int idx;
 
     sec = find_section_by_name(file->elf, "__mcount_loc");
     if (sec) {
         INIT_LIST_HEAD(&file->mcount_loc_list);
         WARN("file already has __mcount_loc section, skipping");
         return 0;
     }
 
     if (list_empty(&file->mcount_loc_list))
         return 0;
 
     idx = 0;
     list_for_each_entry(insn, &file->mcount_loc_list, call_node)
         idx++;
 
     sec = elf_create_section(file->elf, "__mcount_loc", 0, sizeof(unsigned long), idx);
     if (!sec)
         return -1;
 
     idx = 0;
     list_for_each_entry(insn, &file->mcount_loc_list, call_node) {
 
         loc = (unsigned long *)sec->data->d_buf + idx;
         memset(loc, 0, sizeof(unsigned long));
 
         if (elf_add_reloc_to_insn(file->elf, sec,
                       idx * sizeof(unsigned long),
                       R_X86_64_64,
                       insn->sec, insn->offset))
             return -1;
 
         idx++;
     }
 
     return 0;
 }
 
 /*
  * Warnings shouldn't be reported for ignored functions.
  */
 static void add_ignores(struct objtool_file *file)
 {
     struct instruction *insn;
     struct section *sec;
     struct symbol *func;
     struct reloc *reloc;
 
     sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
     if (!sec)
         return;
 
     list_for_each_entry(reloc, &sec->reloc_list, list) {
         switch (reloc->sym->type) {
         case STT_FUNC:
             func = reloc->sym;
             break;
 
         case STT_SECTION:
             func = find_func_by_offset(reloc->sym->sec, reloc->addend);
             if (!func)
                 continue;
             break;
 
         default:
             WARN("unexpected relocation symbol type in %s: %d", sec->name, reloc->sym->type);
             continue;
         }
 
         func_for_each_insn(file, func, insn)
             insn->ignore = true;
     }
 }
 
 /*
  * This is a whitelist of functions that is allowed to be called with AC set.
  * The list is meant to be minimal and only contains compiler instrumentation
  * ABI and a few functions used to implement *_{to,from}_user() functions.
  *
  * These functions must not directly change AC, but may PUSHF/POPF.
  */
 static const char *uaccess_safe_builtin[] = {
     /* KASAN */
     "kasan_report",
     "kasan_check_range",
     /* KASAN out-of-line */
     "__asan_loadN_noabort",
     "__asan_load1_noabort",
     "__asan_load2_noabort",
     "__asan_load4_noabort",
     "__asan_load8_noabort",
     "__asan_load16_noabort",
     "__asan_storeN_noabort",
     "__asan_store1_noabort",
     "__asan_store2_noabort",
     "__asan_store4_noabort",
     "__asan_store8_noabort",
     "__asan_store16_noabort",
     "__kasan_check_read",
     "__kasan_check_write",
     /* KASAN in-line */
     "__asan_report_load_n_noabort",
     "__asan_report_load1_noabort",
     "__asan_report_load2_noabort",
     "__asan_report_load4_noabort",
     "__asan_report_load8_noabort",
     "__asan_report_load16_noabort",
     "__asan_report_store_n_noabort",
     "__asan_report_store1_noabort",
     "__asan_report_store2_noabort",
     "__asan_report_store4_noabort",
     "__asan_report_store8_noabort",
     "__asan_report_store16_noabort",
     /* KCSAN */
     "__kcsan_check_access",
     "__kcsan_mb",
     "__kcsan_wmb",
     "__kcsan_rmb",
     "__kcsan_release",
     "kcsan_found_watchpoint",
     "kcsan_setup_watchpoint",
     "kcsan_check_scoped_accesses",
     "kcsan_disable_current",
     "kcsan_enable_current_nowarn",
     /* KCSAN/TSAN */
     "__tsan_func_entry",
     "__tsan_func_exit",
     "__tsan_read_range",
     "__tsan_write_range",
     "__tsan_read1",
     "__tsan_read2",
     "__tsan_read4",
     "__tsan_read8",
     "__tsan_read16",
     "__tsan_write1",
     "__tsan_write2",
     "__tsan_write4",
     "__tsan_write8",
     "__tsan_write16",
     "__tsan_read_write1",
     "__tsan_read_write2",
     "__tsan_read_write4",
     "__tsan_read_write8",
     "__tsan_read_write16",
     "__tsan_atomic8_load",
     "__tsan_atomic16_load",
     "__tsan_atomic32_load",
     "__tsan_atomic64_load",
     "__tsan_atomic8_store",
     "__tsan_atomic16_store",
     "__tsan_atomic32_store",
     "__tsan_atomic64_store",
     "__tsan_atomic8_exchange",
     "__tsan_atomic16_exchange",
     "__tsan_atomic32_exchange",
     "__tsan_atomic64_exchange",
     "__tsan_atomic8_fetch_add",
     "__tsan_atomic16_fetch_add",
     "__tsan_atomic32_fetch_add",
     "__tsan_atomic64_fetch_add",
     "__tsan_atomic8_fetch_sub",
     "__tsan_atomic16_fetch_sub",
     "__tsan_atomic32_fetch_sub",
     "__tsan_atomic64_fetch_sub",
     "__tsan_atomic8_fetch_and",
     "__tsan_atomic16_fetch_and",
     "__tsan_atomic32_fetch_and",
     "__tsan_atomic64_fetch_and",
     "__tsan_atomic8_fetch_or",
     "__tsan_atomic16_fetch_or",
     "__tsan_atomic32_fetch_or",
     "__tsan_atomic64_fetch_or",
     "__tsan_atomic8_fetch_xor",
     "__tsan_atomic16_fetch_xor",
     "__tsan_atomic32_fetch_xor",
     "__tsan_atomic64_fetch_xor",
     "__tsan_atomic8_fetch_nand",
     "__tsan_atomic16_fetch_nand",
     "__tsan_atomic32_fetch_nand",
     "__tsan_atomic64_fetch_nand",
     "__tsan_atomic8_compare_exchange_strong",
     "__tsan_atomic16_compare_exchange_strong",
     "__tsan_atomic32_compare_exchange_strong",
     "__tsan_atomic64_compare_exchange_strong",
     "__tsan_atomic8_compare_exchange_weak",
     "__tsan_atomic16_compare_exchange_weak",
     "__tsan_atomic32_compare_exchange_weak",
     "__tsan_atomic64_compare_exchange_weak",
     "__tsan_atomic8_compare_exchange_val",
     "__tsan_atomic16_compare_exchange_val",
     "__tsan_atomic32_compare_exchange_val",
     "__tsan_atomic64_compare_exchange_val",
     "__tsan_atomic_thread_fence",
     "__tsan_atomic_signal_fence",
     /* KCOV */
     "write_comp_data",
     "check_kcov_mode",
     "__sanitizer_cov_trace_pc",
     "__sanitizer_cov_trace_const_cmp1",
     "__sanitizer_cov_trace_const_cmp2",
     "__sanitizer_cov_trace_const_cmp4",
     "__sanitizer_cov_trace_const_cmp8",
     "__sanitizer_cov_trace_cmp1",
     "__sanitizer_cov_trace_cmp2",
     "__sanitizer_cov_trace_cmp4",
     "__sanitizer_cov_trace_cmp8",
     "__sanitizer_cov_trace_switch",
     /* UBSAN */
     "ubsan_type_mismatch_common",
     "__ubsan_handle_type_mismatch",
     "__ubsan_handle_type_mismatch_v1",
     "__ubsan_handle_shift_out_of_bounds",
     /* misc */
     "csum_partial_copy_generic",
     "copy_mc_fragile",
     "copy_mc_fragile_handle_tail",
     "copy_mc_enhanced_fast_string",
     "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
     NULL
 };
 
 static void add_uaccess_safe(struct objtool_file *file)
 {
     struct symbol *func;
     const char **name;
 
     if (!opts.uaccess)
         return;
 
     for (name = uaccess_safe_builtin; *name; name++) {
         func = find_symbol_by_name(file->elf, *name);
         if (!func)
             continue;
 
         func->uaccess_safe = true;
     }
 }
 
 /*
  * FIXME: For now, just ignore any alternatives which add retpolines.  This is
  * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
  * But it at least allows objtool to understand the control flow *around* the
  * retpoline.
  */
 static int add_ignore_alternatives(struct objtool_file *file)
 {
     struct section *sec;
     struct reloc *reloc;
     struct instruction *insn;
 
     sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
     if (!sec)
         return 0;
 
     list_for_each_entry(reloc, &sec->reloc_list, list) {
         if (reloc->sym->type != STT_SECTION) {
             WARN("unexpected relocation symbol type in %s", sec->name);
             return -1;
         }
 
         insn = find_insn(file, reloc->sym->sec, reloc->addend);
         if (!insn) {
             WARN("bad .discard.ignore_alts entry");
             return -1;
         }
 
         insn->ignore_alts = true;
     }
 
     return 0;
 }
 
 __weak bool arch_is_retpoline(struct symbol *sym)
 {
     return false;
 }
 
 __weak bool arch_is_rethunk(struct symbol *sym)
 {
     return false;
 }
 
 #define NEGATIVE_RELOC  ((void *)-1L)
 
 static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
 {
     if (insn->reloc == NEGATIVE_RELOC)
         return NULL;
 
     if (!insn->reloc) {
         if (!file)
             return NULL;
 
         insn->reloc = find_reloc_by_dest_range(file->elf, insn->sec,
                                insn->offset, insn->len);
         if (!insn->reloc) {
             insn->reloc = NEGATIVE_RELOC;
             return NULL;
         }
     }
 
     return insn->reloc;
 }
 
 static void remove_insn_ops(struct instruction *insn)
 {
     struct stack_op *op, *tmp;
 
     list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
         list_del(&op->list);
         free(op);
     }
 }
 
 static void annotate_call_site(struct objtool_file *file,
                    struct instruction *insn, bool sibling)
 {
     struct reloc *reloc = insn_reloc(file, insn);
     struct symbol *sym = insn->call_dest;
 
     if (!sym)
         sym = reloc->sym;
 
     /*
      * Alternative replacement code is just template code which is
      * sometimes copied to the original instruction. For now, don't
      * annotate it. (In the future we might consider annotating the
      * original instruction if/when it ever makes sense to do so.)
      */
     if (!strcmp(insn->sec->name, ".altinstr_replacement"))
         return;
 
     if (sym->static_call_tramp) {
         list_add_tail(&insn->call_node, &file->static_call_list);
         return;
     }
 
     if (sym->retpoline_thunk) {
         list_add_tail(&insn->call_node, &file->retpoline_call_list);
         return;
     }
 
     /*
      * Many compilers cannot disable KCOV or sanitizer calls with a function
      * attribute so they need a little help, NOP out any such calls from
      * noinstr text.
      */
     if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) {
         if (reloc) {
             reloc->type = R_NONE;
             elf_write_reloc(file->elf, reloc);
         }
 
         elf_write_insn(file->elf, insn->sec,
                    insn->offset, insn->len,
                    sibling ? arch_ret_insn(insn->len)
                            : arch_nop_insn(insn->len));
 
         insn->type = sibling ? INSN_RETURN : INSN_NOP;
 
         if (sibling) {
             /*
              * We've replaced the tail-call JMP insn by two new
              * insn: RET; INT3, except we only have a single struct
              * insn here. Mark it retpoline_safe to avoid the SLS
              * warning, instead of adding another insn.
              */
             insn->retpoline_safe = true;
         }
 
         return;
     }
 
     if (opts.mcount && sym->fentry) {
         if (sibling)
             WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset);
 
         if (reloc) {
             reloc->type = R_NONE;
             elf_write_reloc(file->elf, reloc);
         }
 
         elf_write_insn(file->elf, insn->sec,
                    insn->offset, insn->len,
                    arch_nop_insn(insn->len));
 
         insn->type = INSN_NOP;
 
         list_add_tail(&insn->call_node, &file->mcount_loc_list);
         return;
     }
 
     if (!sibling && dead_end_function(file, sym))
         insn->dead_end = true;
 }
 
 static void add_call_dest(struct objtool_file *file, struct instruction *insn,
               struct symbol *dest, bool sibling)
 {
     insn->call_dest = dest;
     if (!dest)
         return;
 
     /*
      * Whatever stack impact regular CALLs have, should be undone
      * by the RETURN of the called function.
      *
      * Annotated intra-function calls retain the stack_ops but
      * are converted to JUMP, see read_intra_function_calls().
      */
     remove_insn_ops(insn);
 
     annotate_call_site(file, insn, sibling);
 }
 
 static void add_retpoline_call(struct objtool_file *file, struct instruction *insn)
 {
     /*
      * Retpoline calls/jumps are really dynamic calls/jumps in disguise,
      * so convert them accordingly.
      */
     switch (insn->type) {
     case INSN_CALL:
         insn->type = INSN_CALL_DYNAMIC;
         break;
     case INSN_JUMP_UNCONDITIONAL:
         insn->type = INSN_JUMP_DYNAMIC;
         break;
     case INSN_JUMP_CONDITIONAL:
         insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
         break;
     default:
         return;
     }
 
     insn->retpoline_safe = true;
 
     /*
      * Whatever stack impact regular CALLs have, should be undone
      * by the RETURN of the called function.
      *
      * Annotated intra-function calls retain the stack_ops but
      * are converted to JUMP, see read_intra_function_calls().
      */
     remove_insn_ops(insn);
 
     annotate_call_site(file, insn, false);
 }
 
 static void add_return_call(struct objtool_file *file, struct instruction *insn, bool add)
 {
     /*
      * Return thunk tail calls are really just returns in disguise,
      * so convert them accordingly.
      */
     insn->type = INSN_RETURN;
     insn->retpoline_safe = true;
 
     if (add)
         list_add_tail(&insn->call_node, &file->return_thunk_list);
 }
 
 static bool same_function(struct instruction *insn1, struct instruction *insn2)
 {
     return insn1->func->pfunc == insn2->func->pfunc;
 }
 
 static bool is_first_func_insn(struct objtool_file *file, struct instruction *insn)
 {
     if (insn->offset == insn->func->offset)
         return true;
 
     if (opts.ibt) {
         struct instruction *prev = prev_insn_same_sym(file, insn);
 
         if (prev && prev->type == INSN_ENDBR &&
             insn->offset == insn->func->offset + prev->len)
             return true;
     }
 
     return false;
 }
 
 /*
  * Find the destination instructions for all jumps.
  */
 static int add_jump_destinations(struct objtool_file *file)
 {
     struct instruction *insn, *jump_dest;
     struct reloc *reloc;
     struct section *dest_sec;
     unsigned long dest_off;
 
     for_each_insn(file, insn) {
         if (insn->jump_dest) {
             /*
              * handle_group_alt() may have previously set
              * 'jump_dest' for some alternatives.
              */
             continue;
         }
         if (!is_static_jump(insn))
             continue;
 
         reloc = insn_reloc(file, insn);
         if (!reloc) {
             dest_sec = insn->sec;
             dest_off = arch_jump_destination(insn);
         } else if (reloc->sym->type == STT_SECTION) {
             dest_sec = reloc->sym->sec;
             dest_off = arch_dest_reloc_offset(reloc->addend);
         } else if (reloc->sym->retpoline_thunk) {
             add_retpoline_call(file, insn);
             continue;
         } else if (reloc->sym->return_thunk) {
             add_return_call(file, insn, true);
             continue;
         } else if (insn->func) {
             /*
              * External sibling call or internal sibling call with
              * STT_FUNC reloc.
              */
             add_call_dest(file, insn, reloc->sym, true);
             continue;
         } else if (reloc->sym->sec->idx) {
             dest_sec = reloc->sym->sec;
             dest_off = reloc->sym->sym.st_value +
                    arch_dest_reloc_offset(reloc->addend);
         } else {
             /* non-func asm code jumping to another file */
             continue;
         }
 
         jump_dest = find_insn(file, dest_sec, dest_off);
         if (!jump_dest) {
             struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
 
             /*
              * This is a special case for zen_untrain_ret().
              * It jumps to __x86_return_thunk(), but objtool
              * can't find the thunk's starting RET
              * instruction, because the RET is also in the
              * middle of another instruction.  Objtool only
              * knows about the outer instruction.
              */
             if (sym && sym->return_thunk) {
                 add_return_call(file, insn, false);
                 continue;
             }
 
             WARN_FUNC("can't find jump dest instruction at %s+0x%lx",
                   insn->sec, insn->offset, dest_sec->name,
                   dest_off);
             return -1;
         }
 
         /*
          * Cross-function jump.
          */
         if (insn->func && jump_dest->func &&
             insn->func != jump_dest->func) {
 
             /*
              * For GCC 8+, create parent/child links for any cold
              * subfunctions.  This is _mostly_ redundant with a
              * similar initialization in read_symbols().
              *
              * If a function has aliases, we want the *first* such
              * function in the symbol table to be the subfunction's
              * parent.  In that case we overwrite the
              * initialization done in read_symbols().
              *
              * However this code can't completely replace the
              * read_symbols() code because this doesn't detect the
              * case where the parent function's only reference to a
              * subfunction is through a jump table.
              */
             if (!strstr(insn->func->name, ".cold") &&
                 strstr(jump_dest->func->name, ".cold")) {
                 insn->func->cfunc = jump_dest->func;
                 jump_dest->func->pfunc = insn->func;
 
             } else if (!same_function(insn, jump_dest) &&
                    is_first_func_insn(file, jump_dest)) {
                 /*
                  * Internal sibling call without reloc or with
                  * STT_SECTION reloc.
                  */
                 add_call_dest(file, insn, jump_dest->func, true);
                 continue;
             }
         }
 
         insn->jump_dest = jump_dest;
     }
 
     return 0;
 }
 
 static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
 {
     struct symbol *call_dest;
 
     call_dest = find_func_by_offset(sec, offset);
     if (!call_dest)
         call_dest = find_symbol_by_offset(sec, offset);
 
     return call_dest;
 }
 
 /*
  * Find the destination instructions for all calls.
  */
 static int add_call_destinations(struct objtool_file *file)
 {
     struct instruction *insn;
     unsigned long dest_off;
     struct symbol *dest;
     struct reloc *reloc;
 
     for_each_insn(file, insn) {
         if (insn->type != INSN_CALL)
             continue;
 
         reloc = insn_reloc(file, insn);
         if (!reloc) {
             dest_off = arch_jump_destination(insn);
             dest = find_call_destination(insn->sec, dest_off);
 
             add_call_dest(file, insn, dest, false);
 
             if (insn->ignore)
                 continue;
 
             if (!insn->call_dest) {
                 WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset);
                 return -1;
             }
 
             if (insn->func && insn->call_dest->type != STT_FUNC) {
                 WARN_FUNC("unsupported call to non-function",
                       insn->sec, insn->offset);
                 return -1;
             }
 
         } else if (reloc->sym->type == STT_SECTION) {
             dest_off = arch_dest_reloc_offset(reloc->addend);
             dest = find_call_destination(reloc->sym->sec, dest_off);
             if (!dest) {
                 WARN_FUNC("can't find call dest symbol at %s+0x%lx",
                       insn->sec, insn->offset,
                       reloc->sym->sec->name,
                       dest_off);
                 return -1;
             }
 
             add_call_dest(file, insn, dest, false);
 
         } else if (reloc->sym->retpoline_thunk) {
             add_retpoline_call(file, insn);
 
         } else
             add_call_dest(file, insn, reloc->sym, false);
     }
 
     return 0;
 }
 
 /*
  * The .alternatives section requires some extra special care over and above
  * other special sections because alternatives are patched in place.
  */
 static int handle_group_alt(struct objtool_file *file,
                 struct special_alt *special_alt,
                 struct instruction *orig_insn,
                 struct instruction **new_insn)
 {
     struct instruction *last_orig_insn, *last_new_insn = NULL, *insn, *nop = NULL;
     struct alt_group *orig_alt_group, *new_alt_group;
     unsigned long dest_off;
 
 
     orig_alt_group = malloc(sizeof(*orig_alt_group));
     if (!orig_alt_group) {
         WARN("malloc failed");
         return -1;
     }
     orig_alt_group->cfi = calloc(special_alt->orig_len,
                      sizeof(struct cfi_state *));
     if (!orig_alt_group->cfi) {
         WARN("calloc failed");
         return -1;
     }
 
     last_orig_insn = NULL;
     insn = orig_insn;
     sec_for_each_insn_from(file, insn) {
         if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
             break;
 
         insn->alt_group = orig_alt_group;
         last_orig_insn = insn;
     }
     orig_alt_group->orig_group = NULL;
     orig_alt_group->first_insn = orig_insn;
     orig_alt_group->last_insn = last_orig_insn;
 
 
     new_alt_group = malloc(sizeof(*new_alt_group));
     if (!new_alt_group) {
         WARN("malloc failed");
         return -1;
     }
 
     if (special_alt->new_len < special_alt->orig_len) {
         /*
          * Insert a fake nop at the end to make the replacement
          * alt_group the same size as the original.  This is needed to
          * allow propagate_alt_cfi() to do its magic.  When the last
          * instruction affects the stack, the instruction after it (the
          * nop) will propagate the new state to the shared CFI array.
          */
         nop = malloc(sizeof(*nop));
         if (!nop) {
             WARN("malloc failed");
             return -1;
         }
         memset(nop, 0, sizeof(*nop));
         INIT_LIST_HEAD(&nop->alts);
         INIT_LIST_HEAD(&nop->stack_ops);
 
         nop->sec = special_alt->new_sec;
         nop->offset = special_alt->new_off + special_alt->new_len;
         nop->len = special_alt->orig_len - special_alt->new_len;
         nop->type = INSN_NOP;
         nop->func = orig_insn->func;
         nop->alt_group = new_alt_group;
         nop->ignore = orig_insn->ignore_alts;
     }
 
     if (!special_alt->new_len) {
         *new_insn = nop;
         goto end;
     }
 
     insn = *new_insn;
     sec_for_each_insn_from(file, insn) {
         struct reloc *alt_reloc;
 
         if (insn->offset >= special_alt->new_off + special_alt->new_len)
             break;
 
         last_new_insn = insn;
 
         insn->ignore = orig_insn->ignore_alts;
         insn->func = orig_insn->func;
         insn->alt_group = new_alt_group;
 
         /*
          * Since alternative replacement code is copy/pasted by the
          * kernel after applying relocations, generally such code can't
          * have relative-address relocation references to outside the
          * .altinstr_replacement section, unless the arch's
          * alternatives code can adjust the relative offsets
          * accordingly.
          */
         alt_reloc = insn_reloc(file, insn);
         if (alt_reloc &&
             !arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
 
             WARN_FUNC("unsupported relocation in alternatives section",
                   insn->sec, insn->offset);
             return -1;
         }
 
         if (!is_static_jump(insn))
             continue;
 
         if (!insn->immediate)
             continue;
 
         dest_off = arch_jump_destination(insn);
         if (dest_off == special_alt->new_off + special_alt->new_len) {
             insn->jump_dest = next_insn_same_sec(file, last_orig_insn);
             if (!insn->jump_dest) {
                 WARN_FUNC("can't find alternative jump destination",
                       insn->sec, insn->offset);
                 return -1;
             }
         }
     }
 
     if (!last_new_insn) {
         WARN_FUNC("can't find last new alternative instruction",
               special_alt->new_sec, special_alt->new_off);
         return -1;
     }
 
     if (nop)
         list_add(&nop->list, &last_new_insn->list);
 end:
     new_alt_group->orig_group = orig_alt_group;
     new_alt_group->first_insn = *new_insn;
     new_alt_group->last_insn = nop ? : last_new_insn;
     new_alt_group->cfi = orig_alt_group->cfi;
     return 0;
 }
 
 /*
  * A jump table entry can either convert a nop to a jump or a jump to a nop.
  * If the original instruction is a jump, make the alt entry an effective nop
  * by just skipping the original instruction.
  */
 static int handle_jump_alt(struct objtool_file *file,
                struct special_alt *special_alt,
                struct instruction *orig_insn,
                struct instruction **new_insn)
 {
     if (orig_insn->type != INSN_JUMP_UNCONDITIONAL &&
         orig_insn->type != INSN_NOP) {
 
         WARN_FUNC("unsupported instruction at jump label",
               orig_insn->sec, orig_insn->offset);
         return -1;
     }
 
     if (opts.hack_jump_label && special_alt->key_addend & 2) {
         struct reloc *reloc = insn_reloc(file, orig_insn);
 
         if (reloc) {
             reloc->type = R_NONE;
             elf_write_reloc(file->elf, reloc);
         }
         elf_write_insn(file->elf, orig_insn->sec,
                    orig_insn->offset, orig_insn->len,
                    arch_nop_insn(orig_insn->len));
         orig_insn->type = INSN_NOP;
     }
 
     if (orig_insn->type == INSN_NOP) {
         if (orig_insn->len == 2)
             file->jl_nop_short++;
         else
             file->jl_nop_long++;
 
         return 0;
     }
 
     if (orig_insn->len == 2)
         file->jl_short++;
     else
         file->jl_long++;
 
     *new_insn = list_next_entry(orig_insn, list);
     return 0;
 }
 
 /*
  * Read all the special sections which have alternate instructions which can be
  * patched in or redirected to at runtime.  Each instruction having alternate
  * instruction(s) has them added to its insn->alts list, which will be
  * traversed in validate_branch().
  */
 static int add_special_section_alts(struct objtool_file *file)
 {
     struct list_head special_alts;
     struct instruction *orig_insn, *new_insn;
     struct special_alt *special_alt, *tmp;
     struct alternative *alt;
     int ret;
 
     ret = special_get_alts(file->elf, &special_alts);
     if (ret)
         return ret;
 
     list_for_each_entry_safe(special_alt, tmp, &special_alts, list) {
 
         orig_insn = find_insn(file, special_alt->orig_sec,
                       special_alt->orig_off);
         if (!orig_insn) {
             WARN_FUNC("special: can't find orig instruction",
                   special_alt->orig_sec, special_alt->orig_off);
             ret = -1;
             goto out;
         }
 
         new_insn = NULL;
         if (!special_alt->group || special_alt->new_len) {
             new_insn = find_insn(file, special_alt->new_sec,
                          special_alt->new_off);
             if (!new_insn) {
                 WARN_FUNC("special: can't find new instruction",
                       special_alt->new_sec,
                       special_alt->new_off);
                 ret = -1;
                 goto out;
             }
         }
 
         if (special_alt->group) {
             if (!special_alt->orig_len) {
                 WARN_FUNC("empty alternative entry",
                       orig_insn->sec, orig_insn->offset);
                 continue;
             }
 
             ret = handle_group_alt(file, special_alt, orig_insn,
                            &new_insn);
             if (ret)
                 goto out;
         } else if (special_alt->jump_or_nop) {
             ret = handle_jump_alt(file, special_alt, orig_insn,
                           &new_insn);
             if (ret)
                 goto out;
         }
 
         alt = malloc(sizeof(*alt));
         if (!alt) {
             WARN("malloc failed");
             ret = -1;
             goto out;
         }
 
         alt->insn = new_insn;
         alt->skip_orig = special_alt->skip_orig;
         orig_insn->ignore_alts |= special_alt->skip_alt;
         list_add_tail(&alt->list, &orig_insn->alts);
 
         list_del(&special_alt->list);
         free(special_alt);
     }
 
     if (opts.stats) {
         printf("jl\\\tNOP\tJMP\n");
         printf("short:\t%ld\t%ld\n", file->jl_nop_short, file->jl_short);
         printf("long:\t%ld\t%ld\n", file->jl_nop_long, file->jl_long);
     }
 
 out:
     return ret;
 }
 
 static int add_jump_table(struct objtool_file *file, struct instruction *insn,
                 struct reloc *table)
 {
     struct reloc *reloc = table;
     struct instruction *dest_insn;
     struct alternative *alt;
     struct symbol *pfunc = insn->func->pfunc;
     unsigned int prev_offset = 0;
 
     /*
      * Each @reloc is a switch table relocation which points to the target
      * instruction.
      */
     list_for_each_entry_from(reloc, &table->sec->reloc_list, list) {
 
         /* Check for the end of the table: */
         if (reloc != table && reloc->jump_table_start)
             break;
 
         /* Make sure the table entries are consecutive: */
         if (prev_offset && reloc->offset != prev_offset + 8)
             break;
 
         /* Detect function pointers from contiguous objects: */
         if (reloc->sym->sec == pfunc->sec &&
             reloc->addend == pfunc->offset)
             break;
 
         dest_insn = find_insn(file, reloc->sym->sec, reloc->addend);
         if (!dest_insn)
             break;
 
         /* Make sure the destination is in the same function: */
         if (!dest_insn->func || dest_insn->func->pfunc != pfunc)
             break;
 
         alt = malloc(sizeof(*alt));
         if (!alt) {
             WARN("malloc failed");
             return -1;
         }
 
         alt->insn = dest_insn;
         list_add_tail(&alt->list, &insn->alts);
         prev_offset = reloc->offset;
     }
 
     if (!prev_offset) {
         WARN_FUNC("can't find switch jump table",
               insn->sec, insn->offset);
         return -1;
     }
 
     return 0;
 }
 
 /*
  * find_jump_table() - Given a dynamic jump, find the switch jump table
  * associated with it.
  */
 static struct reloc *find_jump_table(struct objtool_file *file,
                       struct symbol *func,
                       struct instruction *insn)
 {
     struct reloc *table_reloc;
     struct instruction *dest_insn, *orig_insn = insn;
 
     /*
      * Backward search using the @first_jump_src links, these help avoid
      * much of the 'in between' code. Which avoids us getting confused by
      * it.
      */
     for (;
          insn && insn->func && insn->func->pfunc == func;
          insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {
 
         if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
             break;
 
         /* allow small jumps within the range */
         if (insn->type == INSN_JUMP_UNCONDITIONAL &&
             insn->jump_dest &&
             (insn->jump_dest->offset <= insn->offset ||
              insn->jump_dest->offset > orig_insn->offset))
             break;
 
         table_reloc = arch_find_switch_table(file, insn);
         if (!table_reloc)
             continue;
         dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);
         if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func)
             continue;
 
         return table_reloc;
     }
 
     return NULL;
 }
 
 /*
  * First pass: Mark the head of each jump table so that in the next pass,
  * we know when a given jump table ends and the next one starts.
  */
 static void mark_func_jump_tables(struct objtool_file *file,
                     struct symbol *func)
 {
     struct instruction *insn, *last = NULL;
     struct reloc *reloc;
 
     func_for_each_insn(file, func, insn) {
         if (!last)
             last = insn;
 
         /*
          * Store back-pointers for unconditional forward jumps such
          * that find_jump_table() can back-track using those and
          * avoid some potentially confusing code.
          */
         if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
             insn->offset > last->offset &&
             insn->jump_dest->offset > insn->offset &&
             !insn->jump_dest->first_jump_src) {
 
             insn->jump_dest->first_jump_src = insn;
             last = insn->jump_dest;
         }
 
         if (insn->type != INSN_JUMP_DYNAMIC)
             continue;
 
         reloc = find_jump_table(file, func, insn);
         if (reloc) {
             reloc->jump_table_start = true;
             insn->jump_table = reloc;
         }
     }
 }
 
 static int add_func_jump_tables(struct objtool_file *file,
                   struct symbol *func)
 {
     struct instruction *insn;
     int ret;
 
     func_for_each_insn(file, func, insn) {
         if (!insn->jump_table)
             continue;
 
         ret = add_jump_table(file, insn, insn->jump_table);
         if (ret)
             return ret;
     }
 
     return 0;
 }
 
 /*
  * For some switch statements, gcc generates a jump table in the .rodata
  * section which contains a list of addresses within the function to jump to.
  * This finds these jump tables and adds them to the insn->alts lists.
  */
 static int add_jump_table_alts(struct objtool_file *file)
 {
     struct section *sec;
     struct symbol *func;
     int ret;
 
     if (!file->rodata)
         return 0;
 
     for_each_sec(file, sec) {
         list_for_each_entry(func, &sec->symbol_list, list) {
             if (func->type != STT_FUNC)
                 continue;
 
             mark_func_jump_tables(file, func);
             ret = add_func_jump_tables(file, func);
             if (ret)
                 return ret;
         }
     }
 
     return 0;
 }
 
 static void set_func_state(struct cfi_state *state)
 {
     state->cfa = initial_func_cfi.cfa;
     memcpy(&state->regs, &initial_func_cfi.regs,
            CFI_NUM_REGS * sizeof(struct cfi_reg));
     state->stack_size = initial_func_cfi.cfa.offset;
 }
 
 static int read_unwind_hints(struct objtool_file *file)
 {
     struct cfi_state cfi = init_cfi;
     struct section *sec, *relocsec;
     struct unwind_hint *hint;
     struct instruction *insn;
     struct reloc *reloc;
     int i;
 
     sec = find_section_by_name(file->elf, ".discard.unwind_hints");
     if (!sec)
         return 0;
 
     relocsec = sec->reloc;
     if (!relocsec) {
         WARN("missing .rela.discard.unwind_hints section");
         return -1;
     }
 
     if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
         WARN("struct unwind_hint size mismatch");
         return -1;
     }
 
     file->hints = true;
 
     for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
         hint = (struct unwind_hint *)sec->data->d_buf + i;
 
         reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
         if (!reloc) {
             WARN("can't find reloc for unwind_hints[%d]", i);
             return -1;
         }
 
         insn = find_insn(file, reloc->sym->sec, reloc->addend);
         if (!insn) {
             WARN("can't find insn for unwind_hints[%d]", i);
             return -1;
         }
 
         insn->hint = true;
 
         if (hint->type == UNWIND_HINT_TYPE_SAVE) {
             insn->hint = false;
             insn->save = true;
             continue;
         }
 
         if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
             insn->restore = true;
             continue;
         }
 
         if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
             struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
 
             if (sym && sym->bind == STB_GLOBAL) {
                 if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
                     WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR",
                           insn->sec, insn->offset);
                 }
 
                 insn->entry = 1;
             }
         }
 
         if (hint->type == UNWIND_HINT_TYPE_ENTRY) {
             hint->type = UNWIND_HINT_TYPE_CALL;
             insn->entry = 1;
         }
 
         if (hint->type == UNWIND_HINT_TYPE_FUNC) {
             insn->cfi = &func_cfi;
             continue;
         }
 
         if (insn->cfi)
             cfi = *(insn->cfi);
 
         if (arch_decode_hint_reg(hint->sp_reg, &cfi.cfa.base)) {
             WARN_FUNC("unsupported unwind_hint sp base reg %d",
                   insn->sec, insn->offset, hint->sp_reg);
             return -1;
         }
 
         cfi.cfa.offset = bswap_if_needed(hint->sp_offset);
         cfi.type = hint->type;
         cfi.end = hint->end;
 
         insn->cfi = cfi_hash_find_or_add(&cfi);
     }
 
     return 0;
 }
 
 static int read_noendbr_hints(struct objtool_file *file)
 {
     struct section *sec;
     struct instruction *insn;
     struct reloc *reloc;
 
     sec = find_section_by_name(file->elf, ".rela.discard.noendbr");
     if (!sec)
         return 0;
 
     list_for_each_entry(reloc, &sec->reloc_list, list) {
         insn = find_insn(file, reloc->sym->sec, reloc->sym->offset + reloc->addend);
         if (!insn) {
             WARN("bad .discard.noendbr entry");
             return -1;
         }
 
         if (insn->type == INSN_ENDBR)
             WARN_FUNC("ANNOTATE_NOENDBR on ENDBR", insn->sec, insn->offset);
 
         insn->noendbr = 1;
     }
 
     return 0;
 }
 
 static int read_retpoline_hints(struct objtool_file *file)
 {
     struct section *sec;
     struct instruction *insn;
     struct reloc *reloc;
 
     sec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
     if (!sec)
         return 0;
 
     list_for_each_entry(reloc, &sec->reloc_list, list) {
         if (reloc->sym->type != STT_SECTION) {
             WARN("unexpected relocation symbol type in %s", sec->name);
             return -1;
         }
 
         insn = find_insn(file, reloc->sym->sec, reloc->addend);
         if (!insn) {
             WARN("bad .discard.retpoline_safe entry");
             return -1;
         }
 
         if (insn->type != INSN_JUMP_DYNAMIC &&
             insn->type != INSN_CALL_DYNAMIC &&
             insn->type != INSN_RETURN &&
             insn->type != INSN_NOP) {
             WARN_FUNC("retpoline_safe hint not an indirect jump/call/ret/nop",
                   insn->sec, insn->offset);
             return -1;
         }
 
         insn->retpoline_safe = true;
     }
 
     return 0;
 }
 
 static int read_instr_hints(struct objtool_file *file)
 {
     struct section *sec;
     struct instruction *insn;
     struct reloc *reloc;
 
     sec = find_section_by_name(file->elf, ".rela.discard.instr_end");
     if (!sec)
         return 0;
 
     list_for_each_entry(reloc, &sec->reloc_list, list) {
         if (reloc->sym->type != STT_SECTION) {
             WARN("unexpected relocation symbol type in %s", sec->name);
             return -1;
         }
 
         insn = find_insn(file, reloc->sym->sec, reloc->addend);
         if (!insn) {
             WARN("bad .discard.instr_end entry");
             return -1;
         }
 
         insn->instr--;
     }
 
     sec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
     if (!sec)
         return 0;
 
     list_for_each_entry(reloc, &sec->reloc_list, list) {
         if (reloc->sym->type != STT_SECTION) {
             WARN("unexpected relocation symbol type in %s", sec->name);
             return -1;
         }
 
         insn = find_insn(file, reloc->sym->sec, reloc->addend);
         if (!insn) {
             WARN("bad .discard.instr_begin entry");
             return -1;
         }
 
         insn->instr++;
     }
 
     return 0;
 }
 
 static int read_intra_function_calls(struct objtool_file *file)
 {
     struct instruction *insn;
     struct section *sec;
     struct reloc *reloc;
 
     sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
     if (!sec)
         return 0;
 
     list_for_each_entry(reloc, &sec->reloc_list, list) {
         unsigned long dest_off;
 
         if (reloc->sym->type != STT_SECTION) {
             WARN("unexpected relocation symbol type in %s",
                  sec->name);
             return -1;
         }
 
         insn = find_insn(file, reloc->sym->sec, reloc->addend);
         if (!insn) {
             WARN("bad .discard.intra_function_call entry");
             return -1;
         }
 
         if (insn->type != INSN_CALL) {
             WARN_FUNC("intra_function_call not a direct call",
                   insn->sec, insn->offset);
             return -1;
         }
 
         /*
          * Treat intra-function CALLs as JMPs, but with a stack_op.
          * See add_call_destinations(), which strips stack_ops from
          * normal CALLs.
          */
         insn->type = INSN_JUMP_UNCONDITIONAL;
 
         dest_off = insn->offset + insn->len + insn->immediate;
         insn->jump_dest = find_insn(file, insn->sec, dest_off);
         if (!insn->jump_dest) {
             WARN_FUNC("can't find call dest at %s+0x%lx",
                   insn->sec, insn->offset,
                   insn->sec->name, dest_off);
             return -1;
         }
     }
 
     return 0;
 }
 
 /*
  * Return true if name matches an instrumentation function, where calls to that
  * function from noinstr code can safely be removed, but compilers won't do so.
  */
 static bool is_profiling_func(const char *name)
 {
     /*
      * Many compilers cannot disable KCOV with a function attribute.
      */
     if (!strncmp(name, "__sanitizer_cov_", 16))
         return true;
 
     /*
      * Some compilers currently do not remove __tsan_func_entry/exit nor
      * __tsan_atomic_signal_fence (used for barrier instrumentation) with
      * the __no_sanitize_thread attribute, remove them. Once the kernel's
      * minimum Clang version is 14.0, this can be removed.
      */
     if (!strncmp(name, "__tsan_func_", 12) ||
         !strcmp(name, "__tsan_atomic_signal_fence"))
         return true;
 
     return false;
 }
 
 static int classify_symbols(struct objtool_file *file)
 {
     struct section *sec;
     struct symbol *func;
 
     for_each_sec(file, sec) {
         list_for_each_entry(func, &sec->symbol_list, list) {
             if (func->bind != STB_GLOBAL)
                 continue;
 
             if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
                      strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
                 func->static_call_tramp = true;
 
             if (arch_is_retpoline(func))
                 func->retpoline_thunk = true;
 
             if (arch_is_rethunk(func))
                 func->return_thunk = true;
 
             if (!strcmp(func->name, "__fentry__"))
                 func->fentry = true;
 
             if (is_profiling_func(func->name))
                 func->profiling_func = true;
         }
     }
 
     return 0;
 }
 
 static void mark_rodata(struct objtool_file *file)
 {
     struct section *sec;
     bool found = false;
 
     /*
      * Search for the following rodata sections, each of which can
      * potentially contain jump tables:
      *
      * - .rodata: can contain GCC switch tables
      * - .rodata.<func>: same, if -fdata-sections is being used
      * - .rodata..c_jump_table: contains C annotated jump tables
      *
      * .rodata.str1.* sections are ignored; they don't contain jump tables.
      */
     for_each_sec(file, sec) {
         if (!strncmp(sec->name, ".rodata", 7) &&
             !strstr(sec->name, ".str1.")) {
             sec->rodata = true;
             found = true;
         }
     }
 
     file->rodata = found;
 }
 
 static int decode_sections(struct objtool_file *file)
 {
     int ret;
 
     mark_rodata(file);
 
     ret = init_pv_ops(file);
     if (ret)
         return ret;
 
     ret = decode_instructions(file);
     if (ret)
         return ret;
 
     add_ignores(file);
     add_uaccess_safe(file);
 
     ret = add_ignore_alternatives(file);
     if (ret)
         return ret;
 
     /*
      * Must be before read_unwind_hints() since that needs insn->noendbr.
      */
     ret = read_noendbr_hints(file);
     if (ret)
         return ret;
 
     /*
      * Must be before add_{jump_call}_destination.
      */
     ret = classify_symbols(file);
     if (ret)
         return ret;
 
     /*
      * Must be before add_jump_destinations(), which depends on 'func'
      * being set for alternatives, to enable proper sibling call detection.
      */
     ret = add_special_section_alts(file);
     if (ret)
         return ret;
 
     ret = add_jump_destinations(file);
     if (ret)
         return ret;
 
     /*
      * Must be before add_call_destination(); it changes INSN_CALL to
      * INSN_JUMP.
      */
     ret = read_intra_function_calls(file);
     if (ret)
         return ret;
 
     ret = add_call_destinations(file);
     if (ret)
         return ret;
 
     /*
      * Must be after add_call_destinations() such that it can override
      * dead_end_function() marks.
      */
     ret = add_dead_ends(file);
     if (ret)
         return ret;
 
     ret = add_jump_table_alts(file);
     if (ret)
         return ret;
 
     ret = read_unwind_hints(file);
     if (ret)
         return ret;
 
     ret = read_retpoline_hints(file);
     if (ret)
         return ret;
 
     ret = read_instr_hints(file);
     if (ret)
         return ret;
 
     return 0;
 }
 
 static bool is_fentry_call(struct instruction *insn)
 {
     if (insn->type == INSN_CALL &&
         insn->call_dest &&
         insn->call_dest->fentry)
         return true;
 
     return false;
 }
 
 static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
 {
     struct cfi_state *cfi = &state->cfi;
     int i;
 
     if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
         return true;
 
     if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
         return true;
 
     if (cfi->stack_size != initial_func_cfi.cfa.offset)
         return true;
 
     for (i = 0; i < CFI_NUM_REGS; i++) {
         if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
             cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
             return true;
     }
 
     return false;
 }
 
 static bool check_reg_frame_pos(const struct cfi_reg *reg,
                 int expected_offset)
 {
     return reg->base == CFI_CFA &&
            reg->offset == expected_offset;
 }
 
 static bool has_valid_stack_frame(struct insn_state *state)
 {
     struct cfi_state *cfi = &state->cfi;
 
     if (cfi->cfa.base == CFI_BP &&
         check_reg_frame_pos(&cfi->regs[CFI_BP], -cfi->cfa.offset) &&
         check_reg_frame_pos(&cfi->regs[CFI_RA], -cfi->cfa.offset + 8))
         return true;
 
     if (cfi->drap && cfi->regs[CFI_BP].base == CFI_BP)
         return true;
 
     return false;
 }
 
 static int update_cfi_state_regs(struct instruction *insn,
                   struct cfi_state *cfi,
                   struct stack_op *op)
 {
     struct cfi_reg *cfa = &cfi->cfa;
 
     if (cfa->base != CFI_SP && cfa->base != CFI_SP_INDIRECT)
         return 0;
 
     /* push */
     if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
         cfa->offset += 8;
 
     /* pop */
     if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
         cfa->offset -= 8;
 
     /* add immediate to sp */
     if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
         op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
         cfa->offset -= op->src.offset;
 
     return 0;
 }
 
 static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
 {
     if (arch_callee_saved_reg(reg) &&
         cfi->regs[reg].base == CFI_UNDEFINED) {
         cfi->regs[reg].base = base;
         cfi->regs[reg].offset = offset;
     }
 }
 
 static void restore_reg(struct cfi_state *cfi, unsigned char reg)
 {
     cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
     cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
 }
 
 /*
  * A note about DRAP stack alignment:
  *
  * GCC has the concept of a DRAP register, which is used to help keep track of
  * the stack pointer when aligning the stack.  r10 or r13 is used as the DRAP
  * register.  The typical DRAP pattern is:
  *
  *   4c 8d 54 24 08     lea    0x8(%rsp),%r10
  *   48 83 e4 c0        and    $0xffffffffffffffc0,%rsp
  *   41 ff 72 f8        pushq  -0x8(%r10)
  *   55             push   %rbp
  *   48 89 e5           mov    %rsp,%rbp
  *              (more pushes)
  *   41 52          push   %r10
  *              ...
  *   41 5a          pop    %r10
  *              (more pops)
  *   5d             pop    %rbp
  *   49 8d 62 f8        lea    -0x8(%r10),%rsp
  *   c3             retq
  *
  * There are some variations in the epilogues, like:
  *
  *   5b             pop    %rbx
  *   41 5a          pop    %r10
  *   41 5c          pop    %r12
  *   41 5d          pop    %r13
  *   41 5e          pop    %r14
  *   c9             leaveq
  *   49 8d 62 f8        lea    -0x8(%r10),%rsp
  *   c3             retq
  *
  * and:
  *
  *   4c 8b 55 e8        mov    -0x18(%rbp),%r10
  *   48 8b 5d e0        mov    -0x20(%rbp),%rbx
  *   4c 8b 65 f0        mov    -0x10(%rbp),%r12
  *   4c 8b 6d f8        mov    -0x8(%rbp),%r13
  *   c9             leaveq
  *   49 8d 62 f8        lea    -0x8(%r10),%rsp
  *   c3             retq
  *
  * Sometimes r13 is used as the DRAP register, in which case it's saved and
  * restored beforehand:
  *
  *   41 55          push   %r13
  *   4c 8d 6c 24 10     lea    0x10(%rsp),%r13
  *   48 83 e4 f0        and    $0xfffffffffffffff0,%rsp
  *              ...
  *   49 8d 65 f0        lea    -0x10(%r13),%rsp
  *   41 5d          pop    %r13
  *   c3             retq
  */
 static int update_cfi_state(struct instruction *insn,
                 struct instruction *next_insn,
                 struct cfi_state *cfi, struct stack_op *op)
 {
     struct cfi_reg *cfa = &cfi->cfa;
     struct cfi_reg *regs = cfi->regs;
 
     /* stack operations don't make sense with an undefined CFA */
     if (cfa->base == CFI_UNDEFINED) {
         if (insn->func) {
             WARN_FUNC("undefined stack state", insn->sec, insn->offset);
             return -1;
         }
         return 0;
     }
 
     if (cfi->type == UNWIND_HINT_TYPE_REGS ||
         cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
         return update_cfi_state_regs(insn, cfi, op);
 
     switch (op->dest.type) {
 
     case OP_DEST_REG:
         switch (op->src.type) {
 
         case OP_SRC_REG:
             if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
                 cfa->base == CFI_SP &&
                 check_reg_frame_pos(&regs[CFI_BP], -cfa->offset)) {
 
                 /* mov %rsp, %rbp */
                 cfa->base = op->dest.reg;
                 cfi->bp_scratch = false;
             }
 
             else if (op->src.reg == CFI_SP &&
                  op->dest.reg == CFI_BP && cfi->drap) {
 
                 /* drap: mov %rsp, %rbp */
                 regs[CFI_BP].base = CFI_BP;
                 regs[CFI_BP].offset = -cfi->stack_size;
                 cfi->bp_scratch = false;
             }
 
             else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
 
                 /*
                  * mov %rsp, %reg
                  *
                  * This is needed for the rare case where GCC
                  * does:
                  *
                  *   mov    %rsp, %rax
                  *   ...
                  *   mov    %rax, %rsp
                  */
                 cfi->vals[op->dest.reg].base = CFI_CFA;
                 cfi->vals[op->dest.reg].offset = -cfi->stack_size;
             }
 
             else if (op->src.reg == CFI_BP && op->dest.reg == CFI_SP &&
                  (cfa->base == CFI_BP || cfa->base == cfi->drap_reg)) {
 
                 /*
                  * mov %rbp, %rsp
                  *
                  * Restore the original stack pointer (Clang).
                  */
                 cfi->stack_size = -cfi->regs[CFI_BP].offset;
             }
 
             else if (op->dest.reg == cfa->base) {
 
                 /* mov %reg, %rsp */
                 if (cfa->base == CFI_SP &&
                     cfi->vals[op->src.reg].base == CFI_CFA) {
 
                     /*
                      * This is needed for the rare case
                      * where GCC does something dumb like:
                      *
                      *   lea    0x8(%rsp), %rcx
                      *   ...
                      *   mov    %rcx, %rsp
                      */
                     cfa->offset = -cfi->vals[op->src.reg].offset;
                     cfi->stack_size = cfa->offset;
 
                 } else if (cfa->base == CFI_SP &&
                        cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
                        cfi->vals[op->src.reg].offset == cfa->offset) {
 
                     /*
                      * Stack swizzle:
                      *
                      * 1: mov %rsp, (%[tos])
                      * 2: mov %[tos], %rsp
                      *    ...
                      * 3: pop %rsp
                      *
                      * Where:
                      *
                      * 1 - places a pointer to the previous
                      *     stack at the Top-of-Stack of the
                      *     new stack.
                      *
                      * 2 - switches to the new stack.
                      *
                      * 3 - pops the Top-of-Stack to restore
                      *     the original stack.
                      *
                      * Note: we set base to SP_INDIRECT
                      * here and preserve offset. Therefore
                      * when the unwinder reaches ToS it
                      * will dereference SP and then add the
                      * offset to find the next frame, IOW:
                      * (%rsp) + offset.
                      */
                     cfa->base = CFI_SP_INDIRECT;
 
                 } else {
                     cfa->base = CFI_UNDEFINED;
                     cfa->offset = 0;
                 }
             }
 
             else if (op->dest.reg == CFI_SP &&
                  cfi->vals[op->src.reg].base == CFI_SP_INDIRECT &&
                  cfi->vals[op->src.reg].offset == cfa->offset) {
 
                 /*
                  * The same stack swizzle case 2) as above. But
                  * because we can't change cfa->base, case 3)
                  * will become a regular POP. Pretend we're a
                  * PUSH so things don't go unbalanced.
                  */
                 cfi->stack_size += 8;
             }
 
 
             break;
 
         case OP_SRC_ADD:
             if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
 
                 /* add imm, %rsp */
                 cfi->stack_size -= op->src.offset;
                 if (cfa->base == CFI_SP)
                     cfa->offset -= op->src.offset;
                 break;
             }
 
             if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
 
                 /* lea disp(%rbp), %rsp */
                 cfi->stack_size = -(op->src.offset + regs[CFI_BP].offset);
                 break;
             }
 
             if (!cfi->drap && op->src.reg == CFI_SP &&
                 op->dest.reg == CFI_BP && cfa->base == CFI_SP &&
                 check_reg_frame_pos(&regs[CFI_BP], -cfa->offset + op->src.offset)) {
 
                 /* lea disp(%rsp), %rbp */
                 cfa->base = CFI_BP;
                 cfa->offset -= op->src.offset;
                 cfi->bp_scratch = false;
                 break;
             }
 
             if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
 
                 /* drap: lea disp(%rsp), %drap */
                 cfi->drap_reg = op->dest.reg;
 
                 /*
                  * lea disp(%rsp), %reg
                  *
                  * This is needed for the rare case where GCC
                  * does something dumb like:
                  *
                  *   lea    0x8(%rsp), %rcx
                  *   ...
                  *   mov    %rcx, %rsp
                  */
                 cfi->vals[op->dest.reg].base = CFI_CFA;
                 cfi->vals[op->dest.reg].offset = \
                     -cfi->stack_size + op->src.offset;
 
                 break;
             }
 
             if (cfi->drap && op->dest.reg == CFI_SP &&
                 op->src.reg == cfi->drap_reg) {
 
                  /* drap: lea disp(%drap), %rsp */
                 cfa->base = CFI_SP;
                 cfa->offset = cfi->stack_size = -op->src.offset;
                 cfi->drap_reg = CFI_UNDEFINED;
                 cfi->drap = false;
                 break;
             }
 
             if (op->dest.reg == cfi->cfa.base && !(next_insn && next_insn->hint)) {
                 WARN_FUNC("unsupported stack register modification",
                       insn->sec, insn->offset);
                 return -1;
             }
 
             break;
 
         case OP_SRC_AND:
             if (op->dest.reg != CFI_SP ||
                 (cfi->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
                 (cfi->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
                 WARN_FUNC("unsupported stack pointer realignment",
                       insn->sec, insn->offset);
                 return -1;
             }
 
             if (cfi->drap_reg != CFI_UNDEFINED) {
                 /* drap: and imm, %rsp */
                 cfa->base = cfi->drap_reg;
                 cfa->offset = cfi->stack_size = 0;
                 cfi->drap = true;
             }
 
             /*
              * Older versions of GCC (4.8ish) realign the stack
              * without DRAP, with a frame pointer.
              */
 
             break;
 
         case OP_SRC_POP:
         case OP_SRC_POPF:
             if (op->dest.reg == CFI_SP && cfa->base == CFI_SP_INDIRECT) {
 
                 /* pop %rsp; # restore from a stack swizzle */
                 cfa->base = CFI_SP;
                 break;
             }
 
             if (!cfi->drap && op->dest.reg == cfa->base) {
 
                 /* pop %rbp */
                 cfa->base = CFI_SP;
             }
 
             if (cfi->drap && cfa->base == CFI_BP_INDIRECT &&
                 op->dest.reg == cfi->drap_reg &&
                 cfi->drap_offset == -cfi->stack_size) {
 
                 /* drap: pop %drap */
                 cfa->base = cfi->drap_reg;
                 cfa->offset = 0;
                 cfi->drap_offset = -1;
 
             } else if (cfi->stack_size == -regs[op->dest.reg].offset) {
 
                 /* pop %reg */
                 restore_reg(cfi, op->dest.reg);
             }
 
             cfi->stack_size -= 8;
             if (cfa->base == CFI_SP)
                 cfa->offset -= 8;
 
             break;
 
         case OP_SRC_REG_INDIRECT:
             if (!cfi->drap && op->dest.reg == cfa->base &&
                 op->dest.reg == CFI_BP) {
 
                 /* mov disp(%rsp), %rbp */
                 cfa->base = CFI_SP;
                 cfa->offset = cfi->stack_size;
             }
 
             if (cfi->drap && op->src.reg == CFI_BP &&
                 op->src.offset == cfi->drap_offset) {
 
                 /* drap: mov disp(%rbp), %drap */
                 cfa->base = cfi->drap_reg;
                 cfa->offset = 0;
                 cfi->drap_offset = -1;
             }
 
             if (cfi->drap && op->src.reg == CFI_BP &&
                 op->src.offset == regs[op->dest.reg].offset) {
 
                 /* drap: mov disp(%rbp), %reg */
                 restore_reg(cfi, op->dest.reg);
 
             } else if (op->src.reg == cfa->base &&
                 op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
 
                 /* mov disp(%rbp), %reg */
                 /* mov disp(%rsp), %reg */
                 restore_reg(cfi, op->dest.reg);
 
             } else if (op->src.reg == CFI_SP &&
                    op->src.offset == regs[op->dest.reg].offset + cfi->stack_size) {
 
                 /* mov disp(%rsp), %reg */
                 restore_reg(cfi, op->dest.reg);
             }
 
             break;
 
         default:
             WARN_FUNC("unknown stack-related instruction",
                   insn->sec, insn->offset);
             return -1;
         }
 
         break;
 
     case OP_DEST_PUSH:
     case OP_DEST_PUSHF:
         cfi->stack_size += 8;
         if (cfa->base == CFI_SP)
             cfa->offset += 8;
 
         if (op->src.type != OP_SRC_REG)
             break;
 
         if (cfi->drap) {
             if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
 
                 /* drap: push %drap */
                 cfa->base = CFI_BP_INDIRECT;
                 cfa->offset = -cfi->stack_size;
 
                 /* save drap so we know when to restore it */
                 cfi->drap_offset = -cfi->stack_size;
 
             } else if (op->src.reg == CFI_BP && cfa->base == cfi->drap_reg) {
 
                 /* drap: push %rbp */
                 cfi->stack_size = 0;
 
             } else {
 
                 /* drap: push %reg */
                 save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
             }
 
         } else {
 
             /* push %reg */
             save_reg(cfi, op->src.reg, CFI_CFA, -cfi->stack_size);
         }
 
         /* detect when asm code uses rbp as a scratch register */
         if (opts.stackval && insn->func && op->src.reg == CFI_BP &&
             cfa->base != CFI_BP)
             cfi->bp_scratch = true;
         break;
 
     case OP_DEST_REG_INDIRECT:
 
         if (cfi->drap) {
             if (op->src.reg == cfa->base && op->src.reg == cfi->drap_reg) {
 
                 /* drap: mov %drap, disp(%rbp) */
                 cfa->base = CFI_BP_INDIRECT;
                 cfa->offset = op->dest.offset;
 
                 /* save drap offset so we know when to restore it */
                 cfi->drap_offset = op->dest.offset;
             } else {
 
                 /* drap: mov reg, disp(%rbp) */
                 save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
             }
 
         } else if (op->dest.reg == cfa->base) {
 
             /* mov reg, disp(%rbp) */
             /* mov reg, disp(%rsp) */
             save_reg(cfi, op->src.reg, CFI_CFA,
                  op->dest.offset - cfi->cfa.offset);
 
         } else if (op->dest.reg == CFI_SP) {
 
             /* mov reg, disp(%rsp) */
             save_reg(cfi, op->src.reg, CFI_CFA,
                  op->dest.offset - cfi->stack_size);
 
         } else if (op->src.reg == CFI_SP && op->dest.offset == 0) {
 
             /* mov %rsp, (%reg); # setup a stack swizzle. */
             cfi->vals[op->dest.reg].base = CFI_SP_INDIRECT;
             cfi->vals[op->dest.reg].offset = cfa->offset;
         }
 
         break;
 
     case OP_DEST_MEM:
         if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
             WARN_FUNC("unknown stack-related memory operation",
                   insn->sec, insn->offset);
             return -1;
         }
 
         /* pop mem */
         cfi->stack_size -= 8;
         if (cfa->base == CFI_SP)
             cfa->offset -= 8;
 
         break;
 
     default:
         WARN_FUNC("unknown stack-related instruction",
               insn->sec, insn->offset);
         return -1;
     }
 
     return 0;
 }
 
 /*
  * The stack layouts of alternatives instructions can sometimes diverge when
  * they have stack modifications.  That's fine as long as the potential stack
  * layouts don't conflict at any given potential instruction boundary.
  *
  * Flatten the CFIs of the different alternative code streams (both original
  * and replacement) into a single shared CFI array which can be used to detect
  * conflicts and nicely feed a linear array of ORC entries to the unwinder.
  */
 static int propagate_alt_cfi(struct objtool_file *file, struct instruction *insn)
 {
     struct cfi_state **alt_cfi;
     int group_off;
 
     if (!insn->alt_group)
         return 0;
 
     if (!insn->cfi) {
         WARN("CFI missing");
         return -1;
     }
 
     alt_cfi = insn->alt_group->cfi;
     group_off = insn->offset - insn->alt_group->first_insn->offset;
 
     if (!alt_cfi[group_off]) {
         alt_cfi[group_off] = insn->cfi;
     } else {
         if (cficmp(alt_cfi[group_off], insn->cfi)) {
             WARN_FUNC("stack layout conflict in alternatives",
                   insn->sec, insn->offset);
             return -1;
         }
     }
 
     return 0;
 }
 
 static int handle_insn_ops(struct instruction *insn,
                struct instruction *next_insn,
                struct insn_state *state)
 {
     struct stack_op *op;
 
     list_for_each_entry(op, &insn->stack_ops, list) {
 
         if (update_cfi_state(insn, next_insn, &state->cfi, op))
             return 1;
 
         if (!insn->alt_group)
             continue;
 
         if (op->dest.type == OP_DEST_PUSHF) {
             if (!state->uaccess_stack) {
                 state->uaccess_stack = 1;
             } else if (state->uaccess_stack >> 31) {
                 WARN_FUNC("PUSHF stack exhausted",
                       insn->sec, insn->offset);
                 return 1;
             }
             state->uaccess_stack <<= 1;
             state->uaccess_stack  |= state->uaccess;
         }
 
         if (op->src.type == OP_SRC_POPF) {
             if (state->uaccess_stack) {
                 state->uaccess = state->uaccess_stack & 1;
                 state->uaccess_stack >>= 1;
                 if (state->uaccess_stack == 1)
                     state->uaccess_stack = 0;
             }
         }
     }
 
     return 0;
 }
 
 static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
 {
     struct cfi_state *cfi1 = insn->cfi;
     int i;
 
     if (!cfi1) {
         WARN("CFI missing");
         return false;
     }
 
     if (memcmp(&cfi1->cfa, &cfi2->cfa, sizeof(cfi1->cfa))) {
 
         WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
               insn->sec, insn->offset,
               cfi1->cfa.base, cfi1->cfa.offset,
               cfi2->cfa.base, cfi2->cfa.offset);
 
     } else if (memcmp(&cfi1->regs, &cfi2->regs, sizeof(cfi1->regs))) {
         for (i = 0; i < CFI_NUM_REGS; i++) {
             if (!memcmp(&cfi1->regs[i], &cfi2->regs[i],
                     sizeof(struct cfi_reg)))
                 continue;
 
             WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
                   insn->sec, insn->offset,
                   i, cfi1->regs[i].base, cfi1->regs[i].offset,
                   i, cfi2->regs[i].base, cfi2->regs[i].offset);
             break;
         }
 
     } else if (cfi1->type != cfi2->type) {
 
         WARN_FUNC("stack state mismatch: type1=%d type2=%d",
               insn->sec, insn->offset, cfi1->type, cfi2->type);
 
     } else if (cfi1->drap != cfi2->drap ||
            (cfi1->drap && cfi1->drap_reg != cfi2->drap_reg) ||
            (cfi1->drap && cfi1->drap_offset != cfi2->drap_offset)) {
 
         WARN_FUNC("stack state mismatch: drap1=%d(%d,%d) drap2=%d(%d,%d)",
               insn->sec, insn->offset,
               cfi1->drap, cfi1->drap_reg, cfi1->drap_offset,
               cfi2->drap, cfi2->drap_reg, cfi2->drap_offset);
 
     } else
         return true;
 
     return false;
 }
 
 static inline bool func_uaccess_safe(struct symbol *func)
 {
     if (func)
         return func->uaccess_safe;
 
     return false;
 }
 
 static inline const char *call_dest_name(struct instruction *insn)
 {
     static char pvname[19];
     struct reloc *rel;
     int idx;
 
     if (insn->call_dest)
         return insn->call_dest->name;
 
     rel = insn_reloc(NULL, insn);
     if (rel && !strcmp(rel->sym->name, "pv_ops")) {
         idx = (rel->addend / sizeof(void *));
         snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
         return pvname;
     }
 
     return "{dynamic}";
 }
 
 static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
 {
     struct symbol *target;
     struct reloc *rel;
     int idx;
 
     rel = insn_reloc(file, insn);
     if (!rel || strcmp(rel->sym->name, "pv_ops"))
         return false;
 
     idx = (arch_dest_reloc_offset(rel->addend) / sizeof(void *));
 
     if (file->pv_ops[idx].clean)
         return true;
 
     file->pv_ops[idx].clean = true;
 
     list_for_each_entry(target, &file->pv_ops[idx].targets, pv_target) {
         if (!target->sec->noinstr) {
             WARN("pv_ops[%d]: %s", idx, target->name);
             file->pv_ops[idx].clean = false;
         }
     }
 
     return file->pv_ops[idx].clean;
 }
 
 static inline bool noinstr_call_dest(struct objtool_file *file,
                      struct instruction *insn,
                      struct symbol *func)
 {
     /*
      * We can't deal with indirect function calls at present;
      * assume they're instrumented.
      */
     if (!func) {
         if (file->pv_ops)
             return pv_call_dest(file, insn);
 
         return false;
     }
 
     /*
      * If the symbol is from a noinstr section; we good.
      */
     if (func->sec->noinstr)
         return true;
 
     /*
      * The __ubsan_handle_*() calls are like WARN(), they only happen when
      * something 'BAD' happened. At the risk of taking the machine down,
      * let them proceed to get the message out.
      */
     if (!strncmp(func->name, "__ubsan_handle_", 15))
         return true;
 
     return false;
 }
 
 static int validate_call(struct objtool_file *file,
              struct instruction *insn,
              struct insn_state *state)
 {
     if (state->noinstr && state->instr <= 0 &&
         !noinstr_call_dest(file, insn, insn->call_dest)) {
         WARN_FUNC("call to %s() leaves .noinstr.text section",
                 insn->sec, insn->offset, call_dest_name(insn));
         return 1;
     }
 
     if (state->uaccess && !func_uaccess_safe(insn->call_dest)) {
         WARN_FUNC("call to %s() with UACCESS enabled",
                 insn->sec, insn->offset, call_dest_name(insn));
         return 1;
     }
 
     if (state->df) {
         WARN_FUNC("call to %s() with DF set",
                 insn->sec, insn->offset, call_dest_name(insn));
         return 1;
     }
 
     return 0;
 }
 
 static int validate_sibling_call(struct objtool_file *file,
                  struct instruction *insn,
                  struct insn_state *state)
 {
     if (has_modified_stack_frame(insn, state)) {
         WARN_FUNC("sibling call from callable instruction with modified stack frame",
                 insn->sec, insn->offset);
         return 1;
     }
 
     return validate_call(file, insn, state);
 }
 
 static int validate_return(struct symbol *func, struct instruction *insn, struct insn_state *state)
 {
     if (state->noinstr && state->instr > 0) {
         WARN_FUNC("return with instrumentation enabled",
               insn->sec, insn->offset);
         return 1;
     }
 
     if (state->uaccess && !func_uaccess_safe(func)) {
         WARN_FUNC("return with UACCESS enabled",
               insn->sec, insn->offset);
         return 1;
     }
 
     if (!state->uaccess && func_uaccess_safe(func)) {
         WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function",
               insn->sec, insn->offset);
         return 1;
     }
 
     if (state->df) {
         WARN_FUNC("return with DF set",
               insn->sec, insn->offset);
         return 1;
     }
 
     if (func && has_modified_stack_frame(insn, state)) {
         WARN_FUNC("return with modified stack frame",
               insn->sec, insn->offset);
         return 1;
     }
 
     if (state->cfi.bp_scratch) {
         WARN_FUNC("BP used as a scratch register",
               insn->sec, insn->offset);
         return 1;
     }
 
     return 0;
 }
 
 static struct instruction *next_insn_to_validate(struct objtool_file *file,
                          struct instruction *insn)
 {
     struct alt_group *alt_group = insn->alt_group;
 
     /*
      * Simulate the fact that alternatives are patched in-place.  When the
      * end of a replacement alt_group is reached, redirect objtool flow to
      * the end of the original alt_group.
      */
     if (alt_group && insn == alt_group->last_insn && alt_group->orig_group)
         return next_insn_same_sec(file, alt_group->orig_group->last_insn);
 
     return next_insn_same_sec(file, insn);
 }
 
 /*
  * Follow the branch starting at the given instruction, and recursively follow
  * any other branches (jumps).  Meanwhile, track the frame pointer state at
  * each instruction and validate all the rules described in
  * tools/objtool/Documentation/objtool.txt.
  */
 static int validate_branch(struct objtool_file *file, struct symbol *func,
                struct instruction *insn, struct insn_state state)
 {
     struct alternative *alt;
     struct instruction *next_insn, *prev_insn = NULL;
     struct section *sec;
     u8 visited;
     int ret;
 
     sec = insn->sec;
 
     while (1) {
         next_insn = next_insn_to_validate(file, insn);
 
         if (func && insn->func && func != insn->func->pfunc) {
             WARN("%s() falls through to next function %s()",
                  func->name, insn->func->name);
             return 1;
         }
 
         if (func && insn->ignore) {
             WARN_FUNC("BUG: why am I validating an ignored function?",
                   sec, insn->offset);
             return 1;
         }
 
         visited = VISITED_BRANCH << state.uaccess;
         if (insn->visited & VISITED_BRANCH_MASK) {
             if (!insn->hint && !insn_cfi_match(insn, &state.cfi))
                 return 1;
 
             if (insn->visited & visited)
                 return 0;
         } else {
             nr_insns_visited++;
         }
 
         if (state.noinstr)
             state.instr += insn->instr;
 
         if (insn->hint) {
             if (insn->restore) {
                 struct instruction *save_insn, *i;
 
                 i = insn;
                 save_insn = NULL;
 
                 sym_for_each_insn_continue_reverse(file, func, i) {
                     if (i->save) {
                         save_insn = i;
                         break;
                     }
                 }
 
                 if (!save_insn) {
                     WARN_FUNC("no corresponding CFI save for CFI restore",
                           sec, insn->offset);
                     return 1;
                 }
 
                 if (!save_insn->visited) {
                     WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
                           sec, insn->offset);
                     return 1;
                 }
 
                 insn->cfi = save_insn->cfi;
                 nr_cfi_reused++;
             }
 
             state.cfi = *insn->cfi;
         } else {
             /* XXX track if we actually changed state.cfi */
 
             if (prev_insn && !cficmp(prev_insn->cfi, &state.cfi)) {
                 insn->cfi = prev_insn->cfi;
                 nr_cfi_reused++;
             } else {
                 insn->cfi = cfi_hash_find_or_add(&state.cfi);
             }
         }
 
         insn->visited |= visited;
 
         if (propagate_alt_cfi(file, insn))
             return 1;
 
         if (!insn->ignore_alts && !list_empty(&insn->alts)) {
             bool skip_orig = false;
 
             list_for_each_entry(alt, &insn->alts, list) {
                 if (alt->skip_orig)
                     skip_orig = true;
 
                 ret = validate_branch(file, func, alt->insn, state);
                 if (ret) {
                     if (opts.backtrace)
                         BT_FUNC("(alt)", insn);
                     return ret;
                 }
             }
 
             if (skip_orig)
                 return 0;
         }
 
         if (handle_insn_ops(insn, next_insn, &state))
             return 1;
 
         switch (insn->type) {
 
         case INSN_RETURN:
             return validate_return(func, insn, &state);
 
         case INSN_CALL:
         case INSN_CALL_DYNAMIC:
             ret = validate_call(file, insn, &state);
             if (ret)
                 return ret;
 
             if (opts.stackval && func && !is_fentry_call(insn) &&
                 !has_valid_stack_frame(&state)) {
                 WARN_FUNC("call without frame pointer save/setup",
                       sec, insn->offset);
                 return 1;
             }
 
             if (insn->dead_end)
                 return 0;
 
             break;
 
         case INSN_JUMP_CONDITIONAL:
         case INSN_JUMP_UNCONDITIONAL:
             if (is_sibling_call(insn)) {
                 ret = validate_sibling_call(file, insn, &state);
                 if (ret)
                     return ret;
 
             } else if (insn->jump_dest) {
                 ret = validate_branch(file, func,
                               insn->jump_dest, state);
                 if (ret) {
                     if (opts.backtrace)
                         BT_FUNC("(branch)", insn);
                     return ret;
                 }
             }
 
             if (insn->type == INSN_JUMP_UNCONDITIONAL)
                 return 0;
 
             break;
 
         case INSN_JUMP_DYNAMIC:
         case INSN_JUMP_DYNAMIC_CONDITIONAL:
             if (is_sibling_call(insn)) {
                 ret = validate_sibling_call(file, insn, &state);
                 if (ret)
                     return ret;
             }
 
             if (insn->type == INSN_JUMP_DYNAMIC)
                 return 0;
 
             break;
 
         case INSN_CONTEXT_SWITCH:
             if (func && (!next_insn || !next_insn->hint)) {
                 WARN_FUNC("unsupported instruction in callable function",
                       sec, insn->offset);
                 return 1;
             }
             return 0;
 
         case INSN_STAC:
             if (state.uaccess) {
                 WARN_FUNC("recursive UACCESS enable", sec, insn->offset);
                 return 1;
             }
 
             state.uaccess = true;
             break;
 
         case INSN_CLAC:
             if (!state.uaccess && func) {
                 WARN_FUNC("redundant UACCESS disable", sec, insn->offset);
                 return 1;
             }
 
             if (func_uaccess_safe(func) && !state.uaccess_stack) {
                 WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset);
                 return 1;
             }
 
             state.uaccess = false;
             break;
 
         case INSN_STD:
             if (state.df) {
                 WARN_FUNC("recursive STD", sec, insn->offset);
                 return 1;
             }
 
             state.df = true;
             break;
 
         case INSN_CLD:
             if (!state.df && func) {
                 WARN_FUNC("redundant CLD", sec, insn->offset);
                 return 1;
             }
 
             state.df = false;
             break;
 
         default:
             break;
         }
 
         if (insn->dead_end)
             return 0;
 
         if (!next_insn) {
             if (state.cfi.cfa.base == CFI_UNDEFINED)
                 return 0;
             WARN("%s: unexpected end of section", sec->name);
             return 1;
         }
 
         prev_insn = insn;
         insn = next_insn;
     }
 
     return 0;
 }
 
 static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
 {
     struct instruction *insn;
     struct insn_state state;
     int ret, warnings = 0;
 
     if (!file->hints)
         return 0;
 
     init_insn_state(file, &state, sec);
 
     if (sec) {
         insn = find_insn(file, sec, 0);
         if (!insn)
             return 0;
     } else {
         insn = list_first_entry(&file->insn_list, typeof(*insn), list);
     }
 
     while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {
         if (insn->hint && !insn->visited && !insn->ignore) {
             ret = validate_branch(file, insn->func, insn, state);
             if (ret && opts.backtrace)
                 BT_FUNC("<=== (hint)", insn);
             warnings += ret;
         }
 
         insn = list_next_entry(insn, list);
     }
 
     return warnings;
 }
 
 /*
  * Validate rethunk entry constraint: must untrain RET before the first RET.
  *
  * Follow every branch (intra-function) and ensure ANNOTATE_UNRET_END comes
  * before an actual RET instruction.
  */
 static int validate_entry(struct objtool_file *file, struct instruction *insn)
 {
     struct instruction *next, *dest;
     int ret, warnings = 0;
 
     for (;;) {
         next = next_insn_to_validate(file, insn);
 
         if (insn->visited & VISITED_ENTRY)
             return 0;
 
         insn->visited |= VISITED_ENTRY;
 
         if (!insn->ignore_alts && !list_empty(&insn->alts)) {
             struct alternative *alt;
             bool skip_orig = false;
 
             list_for_each_entry(alt, &insn->alts, list) {
                 if (alt->skip_orig)
                     skip_orig = true;
 
                 ret = validate_entry(file, alt->insn);
                 if (ret) {
                         if (opts.backtrace)
                         BT_FUNC("(alt)", insn);
                     return ret;
                 }
             }
 
             if (skip_orig)
                 return 0;
         }
 
         switch (insn->type) {
 
         case INSN_CALL_DYNAMIC:
         case INSN_JUMP_DYNAMIC:
         case INSN_JUMP_DYNAMIC_CONDITIONAL:
             WARN_FUNC("early indirect call", insn->sec, insn->offset);
             return 1;
 
         case INSN_JUMP_UNCONDITIONAL:
         case INSN_JUMP_CONDITIONAL:
             if (!is_sibling_call(insn)) {
                 if (!insn->jump_dest) {
                     WARN_FUNC("unresolved jump target after linking?!?",
                           insn->sec, insn->offset);
                     return -1;
                 }
                 ret = validate_entry(file, insn->jump_dest);
                 if (ret) {
                     if (opts.backtrace) {
                         BT_FUNC("(branch%s)", insn,
                             insn->type == INSN_JUMP_CONDITIONAL ? "-cond" : "");
                     }
                     return ret;
                 }
 
                 if (insn->type == INSN_JUMP_UNCONDITIONAL)
                     return 0;
 
                 break;
             }
 
             /* fallthrough */
         case INSN_CALL:
             dest = find_insn(file, insn->call_dest->sec,
                      insn->call_dest->offset);
             if (!dest) {
                 WARN("Unresolved function after linking!?: %s",
                      insn->call_dest->name);
                 return -1;
             }
 
             ret = validate_entry(file, dest);
             if (ret) {
                 if (opts.backtrace)
                     BT_FUNC("(call)", insn);
                 return ret;
             }
             /*
              * If a call returns without error, it must have seen UNTRAIN_RET.
              * Therefore any non-error return is a success.
              */
             return 0;
 
         case INSN_RETURN:
             WARN_FUNC("RET before UNTRAIN", insn->sec, insn->offset);
             return 1;
 
         case INSN_NOP:
             if (insn->retpoline_safe)
                 return 0;
             break;
 
         default:
             break;
         }
 
         if (!next) {
             WARN_FUNC("teh end!", insn->sec, insn->offset);
             return -1;
         }
         insn = next;
     }
 
     return warnings;
 }
 
 /*
  * Validate that all branches starting at 'insn->entry' encounter UNRET_END
  * before RET.
  */
 static int validate_unret(struct objtool_file *file)
 {
     struct instruction *insn;
     int ret, warnings = 0;
 
     for_each_insn(file, insn) {
         if (!insn->entry)
             continue;
 
         ret = validate_entry(file, insn);
         if (ret < 0) {
             WARN_FUNC("Failed UNRET validation", insn->sec, insn->offset);
             return ret;
         }
         warnings += ret;
     }
 
     return warnings;
 }
 
 static int validate_retpoline(struct objtool_file *file)
 {
     struct instruction *insn;
     int warnings = 0;
 
     for_each_insn(file, insn) {
         if (insn->type != INSN_JUMP_DYNAMIC &&
             insn->type != INSN_CALL_DYNAMIC &&
             insn->type != INSN_RETURN)
             continue;
 
         if (insn->retpoline_safe)
             continue;
 
         /*
          * .init.text code is ran before userspace and thus doesn't
          * strictly need retpolines, except for modules which are
          * loaded late, they very much do need retpoline in their
          * .init.text
          */
         if (!strcmp(insn->sec->name, ".init.text") && !opts.module)
             continue;
 
         if (insn->type == INSN_RETURN) {
             if (opts.rethunk) {
                 WARN_FUNC("'naked' return found in RETHUNK build",
                       insn->sec, insn->offset);
             } else
                 continue;
         } else {
             WARN_FUNC("indirect %s found in RETPOLINE build",
                   insn->sec, insn->offset,
                   insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
         }
 
         warnings++;
     }
 
     return warnings;
 }
 
 static bool is_kasan_insn(struct instruction *insn)
 {
     return (insn->type == INSN_CALL &&
         !strcmp(insn->call_dest->name, "__asan_handle_no_return"));
 }
 
 static bool is_ubsan_insn(struct instruction *insn)
 {
     return (insn->type == INSN_CALL &&
         !strcmp(insn->call_dest->name,
             "__ubsan_handle_builtin_unreachable"));
 }
 
 static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
 {
     int i;
     struct instruction *prev_insn;
 
     if (insn->ignore || insn->type == INSN_NOP || insn->type == INSN_TRAP)
         return true;
 
     /*
      * Ignore alternative replacement instructions.  This can happen
      * when a whitelisted function uses one of the ALTERNATIVE macros.
      */
     if (!strcmp(insn->sec->name, ".altinstr_replacement") ||
         !strcmp(insn->sec->name, ".altinstr_aux"))
         return true;
 
     /*
      * Whole archive runs might encounter dead code from weak symbols.
      * This is where the linker will have dropped the weak symbol in
      * favour of a regular symbol, but leaves the code in place.
      *
      * In this case we'll find a piece of code (whole function) that is not
      * covered by a !section symbol. Ignore them.
      */
     if (opts.link && !insn->func) {
         int size = find_symbol_hole_containing(insn->sec, insn->offset);
         unsigned long end = insn->offset + size;
 
         if (!size) /* not a hole */
             return false;
 
         if (size < 0) /* hole until the end */
             return true;
 
         sec_for_each_insn_continue(file, insn) {
             /*
              * If we reach a visited instruction at or before the
              * end of the hole, ignore the unreachable.
              */
             if (insn->visited)
                 return true;
 
             if (insn->offset >= end)
                 break;
 
             /*
              * If this hole jumps to a .cold function, mark it ignore too.
              */
             if (insn->jump_dest && insn->jump_dest->func &&
                 strstr(insn->jump_dest->func->name, ".cold")) {
                 struct instruction *dest = insn->jump_dest;
                 func_for_each_insn(file, dest->func, dest)
                     dest->ignore = true;
             }
         }
 
         return false;
     }
 
     if (!insn->func)
         return false;
 
     if (insn->func->static_call_tramp)
         return true;
 
     /*
      * CONFIG_UBSAN_TRAP inserts a UD2 when it sees
      * __builtin_unreachable().  The BUG() macro has an unreachable() after
      * the UD2, which causes GCC's undefined trap logic to emit another UD2
      * (or occasionally a JMP to UD2).
      *
      * It may also insert a UD2 after calling a __noreturn function.
      */
     prev_insn = list_prev_entry(insn, list);
     if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) &&
         (insn->type == INSN_BUG ||
          (insn->type == INSN_JUMP_UNCONDITIONAL &&
           insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
         return true;
 
     /*
      * Check if this (or a subsequent) instruction is related to
      * CONFIG_UBSAN or CONFIG_KASAN.
      *
      * End the search at 5 instructions to avoid going into the weeds.
      */
     for (i = 0; i < 5; i++) {
 
         if (is_kasan_insn(insn) || is_ubsan_insn(insn))
             return true;
 
         if (insn->type == INSN_JUMP_UNCONDITIONAL) {
             if (insn->jump_dest &&
                 insn->jump_dest->func == insn->func) {
                 insn = insn->jump_dest;
                 continue;
             }
 
             break;
         }
 
         if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
             break;
 
         insn = list_next_entry(insn, list);
     }
 
     return false;
 }
 
 static int validate_symbol(struct objtool_file *file, struct section *sec,
                struct symbol *sym, struct insn_state *state)
 {
     struct instruction *insn;
     int ret;
 
     if (!sym->len) {
         WARN("%s() is missing an ELF size annotation", sym->name);
         return 1;
     }
 
     if (sym->pfunc != sym || sym->alias != sym)
         return 0;
 
     insn = find_insn(file, sec, sym->offset);
     if (!insn || insn->ignore || insn->visited)
         return 0;
 
     state->uaccess = sym->uaccess_safe;
 
     ret = validate_branch(file, insn->func, insn, *state);
     if (ret && opts.backtrace)
         BT_FUNC("<=== (sym)", insn);
     return ret;
 }
 
 static int validate_section(struct objtool_file *file, struct section *sec)
 {
     struct insn_state state;
     struct symbol *func;
     int warnings = 0;
 
     list_for_each_entry(func, &sec->symbol_list, list) {
         if (func->type != STT_FUNC)
             continue;
 
         init_insn_state(file, &state, sec);
         set_func_state(&state.cfi);
 
         warnings += validate_symbol(file, sec, func, &state);
     }
 
     return warnings;
 }
 
 static int validate_noinstr_sections(struct objtool_file *file)
 {
     struct section *sec;
     int warnings = 0;
 
     sec = find_section_by_name(file->elf, ".noinstr.text");
     if (sec) {
         warnings += validate_section(file, sec);
         warnings += validate_unwind_hints(file, sec);
     }
 
     sec = find_section_by_name(file->elf, ".entry.text");
     if (sec) {
         warnings += validate_section(file, sec);
         warnings += validate_unwind_hints(file, sec);
     }
 
     return warnings;
 }
 
 static int validate_functions(struct objtool_file *file)
 {
     struct section *sec;
     int warnings = 0;
 
     for_each_sec(file, sec) {
         if (!(sec->sh.sh_flags & SHF_EXECINSTR))
             continue;
 
         warnings += validate_section(file, sec);
     }
 
     return warnings;
 }
 
 static void mark_endbr_used(struct instruction *insn)
 {
     if (!list_empty(&insn->call_node))
         list_del_init(&insn->call_node);
 }
 
 static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn)
 {
     struct instruction *dest;
     struct reloc *reloc;
     unsigned long off;
     int warnings = 0;
 
     /*
      * Looking for function pointer load relocations.  Ignore
      * direct/indirect branches:
      */
     switch (insn->type) {
     case INSN_CALL:
     case INSN_CALL_DYNAMIC:
     case INSN_JUMP_CONDITIONAL:
     case INSN_JUMP_UNCONDITIONAL:
     case INSN_JUMP_DYNAMIC:
     case INSN_JUMP_DYNAMIC_CONDITIONAL:
     case INSN_RETURN:
     case INSN_NOP:
         return 0;
     default:
         break;
     }
 
     for (reloc = insn_reloc(file, insn);
          reloc;
          reloc = find_reloc_by_dest_range(file->elf, insn->sec,
                           reloc->offset + 1,
                           (insn->offset + insn->len) - (reloc->offset + 1))) {
 
         /*
          * static_call_update() references the trampoline, which
          * doesn't have (or need) ENDBR.  Skip warning in that case.
          */
         if (reloc->sym->static_call_tramp)
             continue;
 
         off = reloc->sym->offset;
         if (reloc->type == R_X86_64_PC32 || reloc->type == R_X86_64_PLT32)
             off += arch_dest_reloc_offset(reloc->addend);
         else
             off += reloc->addend;
 
         dest = find_insn(file, reloc->sym->sec, off);
         if (!dest)
             continue;
 
         if (dest->type == INSN_ENDBR) {
             mark_endbr_used(dest);
             continue;
         }
 
         if (dest->func && dest->func == insn->func) {
             /*
              * Anything from->to self is either _THIS_IP_ or
              * IRET-to-self.
              *
              * There is no sane way to annotate _THIS_IP_ since the
              * compiler treats the relocation as a constant and is
              * happy to fold in offsets, skewing any annotation we
              * do, leading to vast amounts of false-positives.
              *
              * There's also compiler generated _THIS_IP_ through
              * KCOV and such which we have no hope of annotating.
              *
              * As such, blanket accept self-references without
              * issue.
              */
             continue;
         }
 
         if (dest->noendbr)
             continue;
 
         WARN_FUNC("relocation to !ENDBR: %s",
               insn->sec, insn->offset,
               offstr(dest->sec, dest->offset));
 
         warnings++;
     }
 
     return warnings;
 }
 
 static int validate_ibt_data_reloc(struct objtool_file *file,
                    struct reloc *reloc)
 {
     struct instruction *dest;
 
     dest = find_insn(file, reloc->sym->sec,
              reloc->sym->offset + reloc->addend);
     if (!dest)
         return 0;
 
     if (dest->type == INSN_ENDBR) {
         mark_endbr_used(dest);
         return 0;
     }
 
     if (dest->noendbr)
         return 0;
 
     WARN_FUNC("data relocation to !ENDBR: %s",
           reloc->sec->base, reloc->offset,
           offstr(dest->sec, dest->offset));
 
     return 1;
 }
 
 /*
  * Validate IBT rules and remove used ENDBR instructions from the seal list.
  * Unused ENDBR instructions will be annotated for sealing (i.e., replaced with
  * NOPs) later, in create_ibt_endbr_seal_sections().
  */
 static int validate_ibt(struct objtool_file *file)
 {
     struct section *sec;
     struct reloc *reloc;
     struct instruction *insn;
     int warnings = 0;
 
     for_each_insn(file, insn)
         warnings += validate_ibt_insn(file, insn);
 
     for_each_sec(file, sec) {
 
         /* Already done by validate_ibt_insn() */
         if (sec->sh.sh_flags & SHF_EXECINSTR)
             continue;
 
         if (!sec->reloc)
             continue;
 
         /*
          * These sections can reference text addresses, but not with
          * the intent to indirect branch to them.
          */
         if ((!strncmp(sec->name, ".discard", 8) &&
              strcmp(sec->name, ".discard.ibt_endbr_noseal"))    ||
             !strncmp(sec->name, ".debug", 6)            ||
             !strcmp(sec->name, ".altinstructions")      ||
             !strcmp(sec->name, ".ibt_endbr_seal")       ||
             !strcmp(sec->name, ".orc_unwind_ip")        ||
             !strcmp(sec->name, ".parainstructions")     ||
             !strcmp(sec->name, ".retpoline_sites")      ||
             !strcmp(sec->name, ".smp_locks")            ||
             !strcmp(sec->name, ".static_call_sites")        ||
             !strcmp(sec->name, "_error_injection_whitelist")    ||
             !strcmp(sec->name, "_kprobe_blacklist")     ||
             !strcmp(sec->name, "__bug_table")           ||
             !strcmp(sec->name, "__ex_table")            ||
             !strcmp(sec->name, "__jump_table")          ||
             !strcmp(sec->name, "__mcount_loc"))
             continue;
 
         list_for_each_entry(reloc, &sec->reloc->reloc_list, list)
             warnings += validate_ibt_data_reloc(file, reloc);
     }
 
     return warnings;
 }
 
 static int validate_sls(struct objtool_file *file)
 {
     struct instruction *insn, *next_insn;
     int warnings = 0;
 
     for_each_insn(file, insn) {
         next_insn = next_insn_same_sec(file, insn);
 
         if (insn->retpoline_safe)
             continue;
 
         switch (insn->type) {
         case INSN_RETURN:
             if (!next_insn || next_insn->type != INSN_TRAP) {
                 WARN_FUNC("missing int3 after ret",
                       insn->sec, insn->offset);
                 warnings++;
             }
 
             break;
         case INSN_JUMP_DYNAMIC:
             if (!next_insn || next_insn->type != INSN_TRAP) {
                 WARN_FUNC("missing int3 after indirect jump",
                       insn->sec, insn->offset);
                 warnings++;
             }
             break;
         default:
             break;
         }
     }
 
     return warnings;
 }
 
 static int validate_reachable_instructions(struct objtool_file *file)
 {
     struct instruction *insn;
 
     if (file->ignore_unreachables)
         return 0;
 
     for_each_insn(file, insn) {
         if (insn->visited || ignore_unreachable_insn(file, insn))
             continue;
 
         WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
         return 1;
     }
 
     return 0;
 }
 
 int check(struct objtool_file *file)
 {
     int ret, warnings = 0;
 
     arch_initial_func_cfi_state(&initial_func_cfi);
     init_cfi_state(&init_cfi);
     init_cfi_state(&func_cfi);
     set_func_state(&func_cfi);
 
     if (!cfi_hash_alloc(1UL << (file->elf->symbol_bits - 3)))
         goto out;
 
     cfi_hash_add(&init_cfi);
     cfi_hash_add(&func_cfi);
 
     ret = decode_sections(file);
     if (ret < 0)
         goto out;
 
     warnings += ret;
 
     if (list_empty(&file->insn_list))
         goto out;
 
     if (opts.retpoline) {
         ret = validate_retpoline(file);
         if (ret < 0)
             return ret;
         warnings += ret;
     }
 
     if (opts.stackval || opts.orc || opts.uaccess) {
         ret = validate_functions(file);
         if (ret < 0)
             goto out;
         warnings += ret;
 
         ret = validate_unwind_hints(file, NULL);
         if (ret < 0)
             goto out;
         warnings += ret;
 
         if (!warnings) {
             ret = validate_reachable_instructions(file);
             if (ret < 0)
                 goto out;
             warnings += ret;
         }
 
     } else if (opts.noinstr) {
         ret = validate_noinstr_sections(file);
         if (ret < 0)
             goto out;
         warnings += ret;
     }
 
     if (opts.unret) {
         /*
          * Must be after validate_branch() and friends, it plays
          * further games with insn->visited.
          */
         ret = validate_unret(file);
         if (ret < 0)
             return ret;
         warnings += ret;
     }
 
     if (opts.ibt) {
         ret = validate_ibt(file);
         if (ret < 0)
             goto out;
         warnings += ret;
     }
 
     if (opts.sls) {
         ret = validate_sls(file);
         if (ret < 0)
             goto out;
         warnings += ret;
     }
 
     if (opts.static_call) {
         ret = create_static_call_sections(file);
         if (ret < 0)
             goto out;
         warnings += ret;
     }
 
     if (opts.retpoline) {
         ret = create_retpoline_sites_sections(file);
         if (ret < 0)
             goto out;
         warnings += ret;
     }
 
     if (opts.rethunk) {
         ret = create_return_sites_sections(file);
         if (ret < 0)
             goto out;
         warnings += ret;
     }
 
     if (opts.mcount) {
         ret = create_mcount_loc_sections(file);
         if (ret < 0)
             goto out;
         warnings += ret;
     }
 
     if (opts.ibt) {
         ret = create_ibt_endbr_seal_sections(file);
         if (ret < 0)
             goto out;
         warnings += ret;
     }
 
     if (opts.orc && !list_empty(&file->insn_list)) {
         ret = orc_create(file);
         if (ret < 0)
             goto out;
         warnings += ret;
     }
 
 
     if (opts.stats) {
         printf("nr_insns_visited: %ld\n", nr_insns_visited);
         printf("nr_cfi: %ld\n", nr_cfi);
         printf("nr_cfi_reused: %ld\n", nr_cfi_reused);
         printf("nr_cfi_cache: %ld\n", nr_cfi_cache);
     }
 
 out:
     /*
      *  For now, don't fail the kernel build on fatal warnings.  These
      *  errors are still fairly common due to the growing matrix of
      *  supported toolchains and their recent pace of change.
      */
     return 0;
 }