arch/arc/kernel/traps.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Traps/Non-MMU Exception handling for ARC
   4  *
   5  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   6  *
   7  * vineetg: May 2011
   8  *  -user-space unaligned access emulation
   9  *
  10  * Rahul Trivedi: Codito Technologies 2004
  11  */
  12
  13 #include <linux/sched/signal.h>
  14 #include <linux/kdebug.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/ptrace.h>
  17 #include <linux/kprobes.h>
  18 #include <linux/kgdb.h>
  19 #include <asm/entry.h>
  20 #include <asm/setup.h>
  21 #include <linux/unaligned.h>
  22 #include <asm/kprobes.h>
  23 #include "unaligned.h"
  24
  25 void die(const char *str, struct pt_regs *regs, unsigned long address)
  26 {
  27         show_kernel_fault_diag(str, regs, address);
  28
  29         /* DEAD END */
  30         __asm__("flag 1");
  31 }
  32
  33 /*
  34  * Helper called for bulk of exceptions NOT needing specific handling
  35  *  -for user faults enqueues requested signal
  36  *  -for kernel, chk if due to copy_(to|from)_user, otherwise die()
  37  */
  38 static noinline int
  39 unhandled_exception(const char *str, struct pt_regs *regs,
  40                     int signo, int si_code, void __user *addr)
  41 {
  42         if (user_mode(regs)) {
  43                 struct task_struct *tsk = current;
  44
  45                 tsk->thread.fault_address = (__force unsigned int)addr;
  46
  47                 force_sig_fault(signo, si_code, addr);
  48
  49         } else {
  50                 /* If not due to copy_(to|from)_user, we are doomed */
  51                 if (fixup_exception(regs))
  52                         return 0;
  53
  54                 die(str, regs, (unsigned long)addr);
  55         }
  56
  57         return 1;
  58 }
  59
  60 #define DO_ERROR_INFO(signr, str, name, sicode) \
  61 int name(unsigned long address, struct pt_regs *regs) \
  62 {                                                               \
  63         return unhandled_exception(str, regs, signr, sicode,    \
  64                                    (void __user *)address);     \
  65 }
  66
  67 /*
  68  * Entry points for exceptions NOT needing specific handling
  69  */
  70 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
  71 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
  72 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
  73 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)
  74 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
  75 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
  76 DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0)
  77
  78 /*
  79  * Entry Point for Misaligned Data access Exception, for emulating in software
  80  */
  81 int do_misaligned_access(unsigned long address, struct pt_regs *regs,
  82                          struct callee_regs *cregs)
  83 {
  84         /* If emulation not enabled, or failed, kill the task */
  85         if (misaligned_fixup(address, regs, cregs) != 0)
  86                 return do_misaligned_error(address, regs);
  87
  88         return 0;
  89 }
  90
  91 /*
  92  * Entry point for miscll errors such as Nested Exceptions
  93  *  -Duplicate TLB entry is handled separately though
  94  */
  95 void do_machine_check_fault(unsigned long address, struct pt_regs *regs)
  96 {
  97         die("Unhandled Machine Check Exception", regs, address);
  98 }
  99
 100
 101 /*
 102  * Entry point for traps induced by ARCompact TRAP_S <n> insn
 103  * This is same family as TRAP0/SWI insn (use the same vector).
 104  * The only difference being SWI insn take no operand, while TRAP_S does
 105  * which reflects in ECR Reg as 8 bit param.
 106  * Thus TRAP_S <n> can be used for specific purpose
 107  *  -1 used for software breakpointing (gdb)
 108  *  -2 used by kprobes
 109  *  -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as
 110  *     -fno-isolate-erroneous-paths-dereference
 111  */
 112 void do_non_swi_trap(unsigned long address, struct pt_regs *regs)
 113 {
 114         switch (regs->ecr.param) {
 115         case 1:
 116                 trap_is_brkpt(address, regs);
 117                 break;
 118
 119         case 2:
 120                 trap_is_kprobe(address, regs);
 121                 break;
 122
 123         case 3:
 124         case 4:
 125                 kgdb_trap(regs);
 126                 break;
 127
 128         case 5:
 129                 do_trap5_error(address, regs);
 130                 break;
 131         default:
 132                 break;
 133         }
 134 }
 135
 136 /*
 137  * Entry point for Instruction Error Exception
 138  *  -For a corner case, ARC kprobes implementation resorts to using
 139  *   this exception, hence the check
 140  */
 141 void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs)
 142 {
 143         int rc;
 144
 145         /* Check if this exception is caused by kprobes */
 146         rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL);
 147         if (rc == NOTIFY_STOP)
 148                 return;
 149
 150         insterror_is_error(address, regs);
 151 }
 152
 153 /*
 154  * abort() call generated by older gcc for __builtin_trap()
 155  */
 156 void abort(void)
 157 {
 158         __asm__ __volatile__("trap_s  5\n");
 159 }