arc/kernel/traps.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Traps/Non-MMU Exception handling for ARC
0004  *
0005  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
0006  *
0007  * vineetg: May 2011
0008  *  -user-space unaligned access emulation
0009  *
0010  * Rahul Trivedi: Codito Technologies 2004
0011  */
0012
0013 #include <linux/sched/signal.h>
0014 #include <linux/kdebug.h>
0015 #include <linux/uaccess.h>
0016 #include <linux/ptrace.h>
0017 #include <linux/kprobes.h>
0018 #include <linux/kgdb.h>
0019 #include <asm/setup.h>
0020 #include <asm/unaligned.h>
0021 #include <asm/kprobes.h>
0022
0023 void die(const char *str, struct pt_regs *regs, unsigned long address)
0024 {
0025     show_kernel_fault_diag(str, regs, address);
0026
0027     /* DEAD END */
0028     __asm__("flag 1");
0029 }
0030
0031 /*
0032  * Helper called for bulk of exceptions NOT needing specific handling
0033  *  -for user faults enqueues requested signal
0034  *  -for kernel, chk if due to copy_(to|from)_user, otherwise die()
0035  */
0036 static noinline int
0037 unhandled_exception(const char *str, struct pt_regs *regs,
0038             int signo, int si_code, void __user *addr)
0039 {
0040     if (user_mode(regs)) {
0041         struct task_struct *tsk = current;
0042
0043         tsk->thread.fault_address = (__force unsigned int)addr;
0044
0045         force_sig_fault(signo, si_code, addr);
0046
0047     } else {
0048         /* If not due to copy_(to|from)_user, we are doomed */
0049         if (fixup_exception(regs))
0050             return 0;
0051
0052         die(str, regs, (unsigned long)addr);
0053     }
0054
0055     return 1;
0056 }
0057
0058 #define DO_ERROR_INFO(signr, str, name, sicode) \
0059 int name(unsigned long address, struct pt_regs *regs) \
0060 {                               \
0061     return unhandled_exception(str, regs, signr, sicode,    \
0062                    (void __user *)address); \
0063 }
0064
0065 /*
0066  * Entry points for exceptions NOT needing specific handling
0067  */
0068 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
0069 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
0070 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
0071 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)
0072 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
0073 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
0074 DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0)
0075
0076 /*
0077  * Entry Point for Misaligned Data access Exception, for emulating in software
0078  */
0079 int do_misaligned_access(unsigned long address, struct pt_regs *regs,
0080              struct callee_regs *cregs)
0081 {
0082     /* If emulation not enabled, or failed, kill the task */
0083     if (misaligned_fixup(address, regs, cregs) != 0)
0084         return do_misaligned_error(address, regs);
0085
0086     return 0;
0087 }
0088
0089 /*
0090  * Entry point for miscll errors such as Nested Exceptions
0091  *  -Duplicate TLB entry is handled seperately though
0092  */
0093 void do_machine_check_fault(unsigned long address, struct pt_regs *regs)
0094 {
0095     die("Unhandled Machine Check Exception", regs, address);
0096 }
0097
0098
0099 /*
0100  * Entry point for traps induced by ARCompact TRAP_S <n> insn
0101  * This is same family as TRAP0/SWI insn (use the same vector).
0102  * The only difference being SWI insn take no operand, while TRAP_S does
0103  * which reflects in ECR Reg as 8 bit param.
0104  * Thus TRAP_S <n> can be used for specific purpose
0105  *  -1 used for software breakpointing (gdb)
0106  *  -2 used by kprobes
0107  *  -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as
0108  *     -fno-isolate-erroneous-paths-dereference
0109  */
0110 void do_non_swi_trap(unsigned long address, struct pt_regs *regs)
0111 {
0112     unsigned int param = regs->ecr_param;
0113
0114     switch (param) {
0115     case 1:
0116         trap_is_brkpt(address, regs);
0117         break;
0118
0119     case 2:
0120         trap_is_kprobe(address, regs);
0121         break;
0122
0123     case 3:
0124     case 4:
0125         kgdb_trap(regs);
0126         break;
0127
0128     case 5:
0129         do_trap5_error(address, regs);
0130         break;
0131     default:
0132         break;
0133     }
0134 }
0135
0136 /*
0137  * Entry point for Instruction Error Exception
0138  *  -For a corner case, ARC kprobes implementation resorts to using
0139  *   this exception, hence the check
0140  */
0141 void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs)
0142 {
0143     int rc;
0144
0145     /* Check if this exception is caused by kprobes */
0146     rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL);
0147     if (rc == NOTIFY_STOP)
0148         return;
0149
0150     insterror_is_error(address, regs);
0151 }
0152
0153 /*
0154  * abort() call generated by older gcc for __builtin_trap()
0155  */
0156 void abort(void)
0157 {
0158     __asm__ __volatile__("trap_s  5\n");
0159 }