perf/tests/vmlinux-kallsyms.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <linux/compiler.h>
0003 #include <linux/rbtree.h>
0004 #include <inttypes.h>
0005 #include <string.h>
0006 #include <ctype.h>
0007 #include <stdlib.h>
0008 #include "dso.h"
0009 #include "map.h"
0010 #include "symbol.h"
0011 #include <internal/lib.h> // page_size
0012 #include "tests.h"
0013 #include "debug.h"
0014 #include "machine.h"
0015
0016 #define UM(x) kallsyms_map->unmap_ip(kallsyms_map, (x))
0017
0018 static bool is_ignored_symbol(const char *name, char type)
0019 {
0020     /* Symbol names that exactly match to the following are ignored.*/
0021     static const char * const ignored_symbols[] = {
0022         /*
0023          * Symbols which vary between passes. Passes 1 and 2 must have
0024          * identical symbol lists. The kallsyms_* symbols below are
0025          * only added after pass 1, they would be included in pass 2
0026          * when --all-symbols is specified so exclude them to get a
0027          * stable symbol list.
0028          */
0029         "kallsyms_addresses",
0030         "kallsyms_offsets",
0031         "kallsyms_relative_base",
0032         "kallsyms_num_syms",
0033         "kallsyms_names",
0034         "kallsyms_markers",
0035         "kallsyms_token_table",
0036         "kallsyms_token_index",
0037         /* Exclude linker generated symbols which vary between passes */
0038         "_SDA_BASE_",       /* ppc */
0039         "_SDA2_BASE_",      /* ppc */
0040         NULL
0041     };
0042
0043     /* Symbol names that begin with the following are ignored.*/
0044     static const char * const ignored_prefixes[] = {
0045         "$",            /* local symbols for ARM, MIPS, etc. */
0046         ".L",           /* local labels, .LBB,.Ltmpxxx,.L__unnamed_xx,.LASANPC, etc. */
0047         "__crc_",       /* modversions */
0048         "__efistub_",       /* arm64 EFI stub namespace */
0049         "__kvm_nvhe_$",     /* arm64 local symbols in non-VHE KVM namespace */
0050         "__kvm_nvhe_.L",    /* arm64 local symbols in non-VHE KVM namespace */
0051         "__AArch64ADRPThunk_",  /* arm64 lld */
0052         "__ARMV5PILongThunk_",  /* arm lld */
0053         "__ARMV7PILongThunk_",
0054         "__ThumbV7PILongThunk_",
0055         "__LA25Thunk_",     /* mips lld */
0056         "__microLA25Thunk_",
0057         NULL
0058     };
0059
0060     /* Symbol names that end with the following are ignored.*/
0061     static const char * const ignored_suffixes[] = {
0062         "_from_arm",        /* arm */
0063         "_from_thumb",      /* arm */
0064         "_veneer",      /* arm */
0065         NULL
0066     };
0067
0068     /* Symbol names that contain the following are ignored.*/
0069     static const char * const ignored_matches[] = {
0070         ".long_branch.",    /* ppc stub */
0071         ".plt_branch.",     /* ppc stub */
0072         NULL
0073     };
0074
0075     const char * const *p;
0076
0077     for (p = ignored_symbols; *p; p++)
0078         if (!strcmp(name, *p))
0079             return true;
0080
0081     for (p = ignored_prefixes; *p; p++)
0082         if (!strncmp(name, *p, strlen(*p)))
0083             return true;
0084
0085     for (p = ignored_suffixes; *p; p++) {
0086         int l = strlen(name) - strlen(*p);
0087
0088         if (l >= 0 && !strcmp(name + l, *p))
0089             return true;
0090     }
0091
0092     for (p = ignored_matches; *p; p++) {
0093         if (strstr(name, *p))
0094             return true;
0095     }
0096
0097     if (type == 'U' || type == 'u')
0098         return true;
0099     /* exclude debugging symbols */
0100     if (type == 'N' || type == 'n')
0101         return true;
0102
0103     if (toupper(type) == 'A') {
0104         /* Keep these useful absolute symbols */
0105         if (strcmp(name, "__kernel_syscall_via_break") &&
0106             strcmp(name, "__kernel_syscall_via_epc") &&
0107             strcmp(name, "__kernel_sigtramp") &&
0108             strcmp(name, "__gp"))
0109             return true;
0110     }
0111
0112     return false;
0113 }
0114
0115 static int test__vmlinux_matches_kallsyms(struct test_suite *test __maybe_unused,
0116                     int subtest __maybe_unused)
0117 {
0118     int err = TEST_FAIL;
0119     struct rb_node *nd;
0120     struct symbol *sym;
0121     struct map *kallsyms_map, *vmlinux_map, *map;
0122     struct machine kallsyms, vmlinux;
0123     struct maps *maps;
0124     u64 mem_start, mem_end;
0125     bool header_printed;
0126
0127     /*
0128      * Step 1:
0129      *
0130      * Init the machines that will hold kernel, modules obtained from
0131      * both vmlinux + .ko files and from /proc/kallsyms split by modules.
0132      */
0133     machine__init(&kallsyms, "", HOST_KERNEL_ID);
0134     machine__init(&vmlinux, "", HOST_KERNEL_ID);
0135
0136     maps = machine__kernel_maps(&vmlinux);
0137
0138     /*
0139      * Step 2:
0140      *
0141      * Create the kernel maps for kallsyms and the DSO where we will then
0142      * load /proc/kallsyms. Also create the modules maps from /proc/modules
0143      * and find the .ko files that match them in /lib/modules/`uname -r`/.
0144      */
0145     if (machine__create_kernel_maps(&kallsyms) < 0) {
0146         pr_debug("machine__create_kernel_maps failed");
0147         err = TEST_SKIP;
0148         goto out;
0149     }
0150
0151     /*
0152      * Step 3:
0153      *
0154      * Load and split /proc/kallsyms into multiple maps, one per module.
0155      * Do not use kcore, as this test was designed before kcore support
0156      * and has parts that only make sense if using the non-kcore code.
0157      * XXX: extend it to stress the kcorre code as well, hint: the list
0158      * of modules extracted from /proc/kcore, in its current form, can't
0159      * be compacted against the list of modules found in the "vmlinux"
0160      * code and with the one got from /proc/modules from the "kallsyms" code.
0161      */
0162     if (machine__load_kallsyms(&kallsyms, "/proc/kallsyms") <= 0) {
0163         pr_debug("machine__load_kallsyms failed");
0164         err = TEST_SKIP;
0165         goto out;
0166     }
0167
0168     /*
0169      * Step 4:
0170      *
0171      * kallsyms will be internally on demand sorted by name so that we can
0172      * find the reference relocation * symbol, i.e. the symbol we will use
0173      * to see if the running kernel was relocated by checking if it has the
0174      * same value in the vmlinux file we load.
0175      */
0176     kallsyms_map = machine__kernel_map(&kallsyms);
0177
0178     /*
0179      * Step 5:
0180      *
0181      * Now repeat step 2, this time for the vmlinux file we'll auto-locate.
0182      */
0183     if (machine__create_kernel_maps(&vmlinux) < 0) {
0184         pr_info("machine__create_kernel_maps failed");
0185         goto out;
0186     }
0187
0188     vmlinux_map = machine__kernel_map(&vmlinux);
0189
0190     /*
0191      * Step 6:
0192      *
0193      * Locate a vmlinux file in the vmlinux path that has a buildid that
0194      * matches the one of the running kernel.
0195      *
0196      * While doing that look if we find the ref reloc symbol, if we find it
0197      * we'll have its ref_reloc_symbol.unrelocated_addr and then
0198      * maps__reloc_vmlinux will notice and set proper ->[un]map_ip routines
0199      * to fixup the symbols.
0200      */
0201     if (machine__load_vmlinux_path(&vmlinux) <= 0) {
0202         pr_info("Couldn't find a vmlinux that matches the kernel running on this machine, skipping test\n");
0203         err = TEST_SKIP;
0204         goto out;
0205     }
0206
0207     err = 0;
0208     /*
0209      * Step 7:
0210      *
0211      * Now look at the symbols in the vmlinux DSO and check if we find all of them
0212      * in the kallsyms dso. For the ones that are in both, check its names and
0213      * end addresses too.
0214      */
0215     map__for_each_symbol(vmlinux_map, sym, nd) {
0216         struct symbol *pair, *first_pair;
0217
0218         sym  = rb_entry(nd, struct symbol, rb_node);
0219
0220         if (sym->start == sym->end)
0221             continue;
0222
0223         mem_start = vmlinux_map->unmap_ip(vmlinux_map, sym->start);
0224         mem_end = vmlinux_map->unmap_ip(vmlinux_map, sym->end);
0225
0226         first_pair = machine__find_kernel_symbol(&kallsyms, mem_start, NULL);
0227         pair = first_pair;
0228
0229         if (pair && UM(pair->start) == mem_start) {
0230 next_pair:
0231             if (arch__compare_symbol_names(sym->name, pair->name) == 0) {
0232                 /*
0233                  * kallsyms don't have the symbol end, so we
0234                  * set that by using the next symbol start - 1,
0235                  * in some cases we get this up to a page
0236                  * wrong, trace_kmalloc when I was developing
0237                  * this code was one such example, 2106 bytes
0238                  * off the real size. More than that and we
0239                  * _really_ have a problem.
0240                  */
0241                 s64 skew = mem_end - UM(pair->end);
0242                 if (llabs(skew) >= page_size)
0243                     pr_debug("WARN: %#" PRIx64 ": diff end addr for %s v: %#" PRIx64 " k: %#" PRIx64 "\n",
0244                          mem_start, sym->name, mem_end,
0245                          UM(pair->end));
0246
0247                 /*
0248                  * Do not count this as a failure, because we
0249                  * could really find a case where it's not
0250                  * possible to get proper function end from
0251                  * kallsyms.
0252                  */
0253                 continue;
0254             } else {
0255                 pair = machine__find_kernel_symbol_by_name(&kallsyms, sym->name, NULL);
0256                 if (pair) {
0257                     if (UM(pair->start) == mem_start)
0258                         goto next_pair;
0259
0260                     pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
0261                          mem_start, sym->name, pair->name);
0262                 } else {
0263                     pr_debug("WARN: %#" PRIx64 ": diff name v: %s k: %s\n",
0264                          mem_start, sym->name, first_pair->name);
0265                 }
0266
0267                 continue;
0268             }
0269         } else if (mem_start == kallsyms.vmlinux_map->end) {
0270             /*
0271              * Ignore aliases to _etext, i.e. to the end of the kernel text area,
0272              * such as __indirect_thunk_end.
0273              */
0274             continue;
0275         } else if (is_ignored_symbol(sym->name, sym->type)) {
0276             /*
0277              * Ignore hidden symbols, see scripts/kallsyms.c for the details
0278              */
0279             continue;
0280         } else {
0281             pr_debug("ERR : %#" PRIx64 ": %s not on kallsyms\n",
0282                  mem_start, sym->name);
0283         }
0284
0285         err = -1;
0286     }
0287
0288     if (verbose <= 0)
0289         goto out;
0290
0291     header_printed = false;
0292
0293     maps__for_each_entry(maps, map) {
0294         struct map *
0295         /*
0296          * If it is the kernel, kallsyms is always "[kernel.kallsyms]", while
0297          * the kernel will have the path for the vmlinux file being used,
0298          * so use the short name, less descriptive but the same ("[kernel]" in
0299          * both cases.
0300          */
0301         pair = maps__find_by_name(kallsyms.kmaps, (map->dso->kernel ?
0302                                 map->dso->short_name :
0303                                 map->dso->name));
0304         if (pair) {
0305             pair->priv = 1;
0306         } else {
0307             if (!header_printed) {
0308                 pr_info("WARN: Maps only in vmlinux:\n");
0309                 header_printed = true;
0310             }
0311             map__fprintf(map, stderr);
0312         }
0313     }
0314
0315     header_printed = false;
0316
0317     maps__for_each_entry(maps, map) {
0318         struct map *pair;
0319
0320         mem_start = vmlinux_map->unmap_ip(vmlinux_map, map->start);
0321         mem_end = vmlinux_map->unmap_ip(vmlinux_map, map->end);
0322
0323         pair = maps__find(kallsyms.kmaps, mem_start);
0324         if (pair == NULL || pair->priv)
0325             continue;
0326
0327         if (pair->start == mem_start) {
0328             if (!header_printed) {
0329                 pr_info("WARN: Maps in vmlinux with a different name in kallsyms:\n");
0330                 header_printed = true;
0331             }
0332
0333             pr_info("WARN: %" PRIx64 "-%" PRIx64 " %" PRIx64 " %s in kallsyms as",
0334                 map->start, map->end, map->pgoff, map->dso->name);
0335             if (mem_end != pair->end)
0336                 pr_info(":\nWARN: *%" PRIx64 "-%" PRIx64 " %" PRIx64,
0337                     pair->start, pair->end, pair->pgoff);
0338             pr_info(" %s\n", pair->dso->name);
0339             pair->priv = 1;
0340         }
0341     }
0342
0343     header_printed = false;
0344
0345     maps = machine__kernel_maps(&kallsyms);
0346
0347     maps__for_each_entry(maps, map) {
0348         if (!map->priv) {
0349             if (!header_printed) {
0350                 pr_info("WARN: Maps only in kallsyms:\n");
0351                 header_printed = true;
0352             }
0353             map__fprintf(map, stderr);
0354         }
0355     }
0356 out:
0357     machine__exit(&kallsyms);
0358     machine__exit(&vmlinux);
0359     return err;
0360 }
0361
0362 DEFINE_SUITE("vmlinux symtab matches kallsyms", vmlinux_matches_kallsyms);