root/arch/arc/kernel/traps.c

DEFINITIONS

1. trap_init
2. die
3. unhandled_exception
4. DO_ERROR_INFO
5. do_machine_check_fault
6. do_non_swi_trap
7. do_insterror_or_kprobe
8. abort

   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/setup.h>
  20 #include <asm/unaligned.h>
  21 #include <asm/kprobes.h>
  22 
  23 void __init trap_init(void)
  24 {
  25         return;
  26 }
  27 
  28 void die(const char *str, struct pt_regs *regs, unsigned long address)
  29 {
  30         show_kernel_fault_diag(str, regs, address);
  31 
  32         /* DEAD END */
  33         __asm__("flag 1");
  34 }
  35 
  36 /*
  37  * Helper called for bulk of exceptions NOT needing specific handling
  38  *  -for user faults enqueues requested signal
  39  *  -for kernel, chk if due to copy_(to|from)_user, otherwise die()
  40  */
  41 static noinline int
  42 unhandled_exception(const char *str, struct pt_regs *regs,
  43                     int signo, int si_code, void __user *addr)
  44 {
  45         if (user_mode(regs)) {
  46                 struct task_struct *tsk = current;
  47 
  48                 tsk->thread.fault_address = (__force unsigned int)addr;
  49 
  50                 force_sig_fault(signo, si_code, addr);
  51 
  52         } else {
  53                 /* If not due to copy_(to|from)_user, we are doomed */
  54                 if (fixup_exception(regs))
  55                         return 0;
  56 
  57                 die(str, regs, (unsigned long)addr);
  58         }
  59 
  60         return 1;
  61 }
  62 
  63 #define DO_ERROR_INFO(signr, str, name, sicode) \
  64 int name(unsigned long address, struct pt_regs *regs) \
  65 {                                                               \
  66         return unhandled_exception(str, regs, signr, sicode,    \
  67                                    (void __user *)address);     \
  68 }
  69 
  70 /*
  71  * Entry points for exceptions NOT needing specific handling
  72  */
  73 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
  74 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
  75 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
  76 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)
  77 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
  78 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
  79 DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0)
  80 
  81 /*
  82  * Entry Point for Misaligned Data access Exception, for emulating in software
  83  */
  84 int do_misaligned_access(unsigned long address, struct pt_regs *regs,
  85                          struct callee_regs *cregs)
  86 {
  87         /* If emulation not enabled, or failed, kill the task */
  88         if (misaligned_fixup(address, regs, cregs) != 0)
  89                 return do_misaligned_error(address, regs);
  90 
  91         return 0;
  92 }
  93 
  94 /*
  95  * Entry point for miscll errors such as Nested Exceptions
  96  *  -Duplicate TLB entry is handled seperately though
  97  */
  98 void do_machine_check_fault(unsigned long address, struct pt_regs *regs)
  99 {
 100         die("Unhandled Machine Check Exception", regs, address);
 101 }
 102 
 103 
 104 /*
 105  * Entry point for traps induced by ARCompact TRAP_S <n> insn
 106  * This is same family as TRAP0/SWI insn (use the same vector).
 107  * The only difference being SWI insn take no operand, while TRAP_S does
 108  * which reflects in ECR Reg as 8 bit param.
 109  * Thus TRAP_S <n> can be used for specific purpose
 110  *  -1 used for software breakpointing (gdb)
 111  *  -2 used by kprobes
 112  *  -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as
 113  *     -fno-isolate-erroneous-paths-dereference
 114  */
 115 void do_non_swi_trap(unsigned long address, struct pt_regs *regs)
 116 {
 117         unsigned int param = regs->ecr_param;
 118 
 119         switch (param) {
 120         case 1:
 121                 trap_is_brkpt(address, regs);
 122                 break;
 123 
 124         case 2:
 125                 trap_is_kprobe(address, regs);
 126                 break;
 127 
 128         case 3:
 129         case 4:
 130                 kgdb_trap(regs);
 131                 break;
 132 
 133         case 5:
 134                 do_trap5_error(address, regs);
 135                 break;
 136         default:
 137                 break;
 138         }
 139 }
 140 
 141 /*
 142  * Entry point for Instruction Error Exception
 143  *  -For a corner case, ARC kprobes implementation resorts to using
 144  *   this exception, hence the check
 145  */
 146 void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs)
 147 {
 148         int rc;
 149 
 150         /* Check if this exception is caused by kprobes */
 151         rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL);
 152         if (rc == NOTIFY_STOP)
 153                 return;
 154 
 155         insterror_is_error(address, regs);
 156 }
 157 
 158 /*
 159  * abort() call generated by older gcc for __builtin_trap()
 160  */
 161 void abort(void)
 162 {
 163         __asm__ __volatile__("trap_s  5\n");
 164 }