arch/arc/kernel/traps.c

   1 /*
   2  * Traps/Non-MMU Exception handling for ARC
   3  *
   4  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * vineetg: May 2011
  11  *  -user-space unaligned access emulation
  12  *
  13  * Rahul Trivedi: Codito Technologies 2004
  14  */
  15
  16 #include <linux/sched/signal.h>
  17 #include <linux/kdebug.h>
  18 #include <linux/uaccess.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/kprobes.h>
  21 #include <linux/kgdb.h>
  22 #include <asm/setup.h>
  23 #include <asm/unaligned.h>
  24 #include <asm/kprobes.h>
  25
  26 void __init trap_init(void)
  27 {
  28         return;
  29 }
  30
  31 void die(const char *str, struct pt_regs *regs, unsigned long address)
  32 {
  33         show_kernel_fault_diag(str, regs, address);
  34
  35         /* DEAD END */
  36         __asm__("flag 1");
  37 }
  38
  39 /*
  40  * Helper called for bulk of exceptions NOT needing specific handling
  41  *  -for user faults enqueues requested signal
  42  *  -for kernel, chk if due to copy_(to|from)_user, otherwise die()
  43  */
  44 static noinline int
  45 unhandled_exception(const char *str, struct pt_regs *regs, siginfo_t *info)
  46 {
  47         if (user_mode(regs)) {
  48                 struct task_struct *tsk = current;
  49
  50                 tsk->thread.fault_address = (__force unsigned int)info->si_addr;
  51
  52                 force_sig_info(info->si_signo, info, tsk);
  53
  54         } else {
  55                 /* If not due to copy_(to|from)_user, we are doomed */
  56                 if (fixup_exception(regs))
  57                         return 0;
  58
  59                 die(str, regs, (unsigned long)info->si_addr);
  60         }
  61
  62         return 1;
  63 }
  64
  65 #define DO_ERROR_INFO(signr, str, name, sicode) \
  66 int name(unsigned long address, struct pt_regs *regs) \
  67 {                                               \
  68         siginfo_t info;                         \
  69                                                 \
  70         clear_siginfo(&info);                   \
  71         info.si_signo = signr;                  \
  72         info.si_errno = 0;                      \
  73         info.si_code  = sicode;                 \
  74         info.si_addr = (void __user *)address;  \
  75                                                 \
  76         return unhandled_exception(str, regs, &info);\
  77 }
  78
  79 /*
  80  * Entry points for exceptions NOT needing specific handling
  81  */
  82 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
  83 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
  84 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
  85 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)
  86 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
  87 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
  88 DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0)
  89
  90 /*
  91  * Entry Point for Misaligned Data access Exception, for emulating in software
  92  */
  93 int do_misaligned_access(unsigned long address, struct pt_regs *regs,
  94                          struct callee_regs *cregs)
  95 {
  96         /* If emulation not enabled, or failed, kill the task */
  97         if (misaligned_fixup(address, regs, cregs) != 0)
  98                 return do_misaligned_error(address, regs);
  99
 100         return 0;
 101 }
 102
 103 /*
 104  * Entry point for miscll errors such as Nested Exceptions
 105  *  -Duplicate TLB entry is handled seperately though
 106  */
 107 void do_machine_check_fault(unsigned long address, struct pt_regs *regs)
 108 {
 109         die("Unhandled Machine Check Exception", regs, address);
 110 }
 111
 112
 113 /*
 114  * Entry point for traps induced by ARCompact TRAP_S <n> insn
 115  * This is same family as TRAP0/SWI insn (use the same vector).
 116  * The only difference being SWI insn take no operand, while TRAP_S does
 117  * which reflects in ECR Reg as 8 bit param.
 118  * Thus TRAP_S <n> can be used for specific purpose
 119  *  -1 used for software breakpointing (gdb)
 120  *  -2 used by kprobes
 121  *  -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as
 122  *     -fno-isolate-erroneous-paths-dereference
 123  */
 124 void do_non_swi_trap(unsigned long address, struct pt_regs *regs)
 125 {
 126         unsigned int param = regs->ecr_param;
 127
 128         switch (param) {
 129         case 1:
 130                 trap_is_brkpt(address, regs);
 131                 break;
 132
 133         case 2:
 134                 trap_is_kprobe(address, regs);
 135                 break;
 136
 137         case 3:
 138         case 4:
 139                 kgdb_trap(regs);
 140                 break;
 141
 142         case 5:
 143                 do_trap5_error(address, regs);
 144                 break;
 145         default:
 146                 break;
 147         }
 148 }
 149
 150 /*
 151  * Entry point for Instruction Error Exception
 152  *  -For a corner case, ARC kprobes implementation resorts to using
 153  *   this exception, hence the check
 154  */
 155 void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs)
 156 {
 157         int rc;
 158
 159         /* Check if this exception is caused by kprobes */
 160         rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL);
 161         if (rc == NOTIFY_STOP)
 162                 return;
 163
 164         insterror_is_error(address, regs);
 165 }
 166
 167 /*
 168  * abort() call generated by older gcc for __builtin_trap()
 169  */
 170 void abort(void)
 171 {
 172         __asm__ __volatile__("trap_s  5\n");
 173 }