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                 .si_signo = signr,              \
  70                 .si_errno = 0,                  \
  71                 .si_code  = sicode,             \
  72                 .si_addr = (void __user *)address,      \
  73         };                                      \
  74         return unhandled_exception(str, regs, &info);\
  75 }
  76
  77 /*
  78  * Entry points for exceptions NOT needing specific handling
  79  */
  80 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
  81 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
  82 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
  83 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", do_memory_error, BUS_ADRERR)
  84 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
  85 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
  86
  87 /*
  88  * Entry Point for Misaligned Data access Exception, for emulating in software
  89  */
  90 int do_misaligned_access(unsigned long address, struct pt_regs *regs,
  91                          struct callee_regs *cregs)
  92 {
  93         /* If emulation not enabled, or failed, kill the task */
  94         if (misaligned_fixup(address, regs, cregs) != 0)
  95                 return do_misaligned_error(address, regs);
  96
  97         return 0;
  98 }
  99
 100 /*
 101  * Entry point for miscll errors such as Nested Exceptions
 102  *  -Duplicate TLB entry is handled seperately though
 103  */
 104 void do_machine_check_fault(unsigned long address, struct pt_regs *regs)
 105 {
 106         die("Machine Check Exception", regs, address);
 107 }
 108
 109
 110 /*
 111  * Entry point for traps induced by ARCompact TRAP_S <n> insn
 112  * This is same family as TRAP0/SWI insn (use the same vector).
 113  * The only difference being SWI insn take no operand, while TRAP_S does
 114  * which reflects in ECR Reg as 8 bit param.
 115  * Thus TRAP_S <n> can be used for specific purpose
 116  *  -1 used for software breakpointing (gdb)
 117  *  -2 used by kprobes
 118  */
 119 void do_non_swi_trap(unsigned long address, struct pt_regs *regs)
 120 {
 121         unsigned int param = regs->ecr_param;
 122
 123         switch (param) {
 124         case 1:
 125                 trap_is_brkpt(address, regs);
 126                 break;
 127
 128         case 2:
 129                 trap_is_kprobe(address, regs);
 130                 break;
 131
 132         case 3:
 133         case 4:
 134                 kgdb_trap(regs);
 135                 break;
 136
 137         default:
 138                 break;
 139         }
 140 }
 141
 142 /*
 143  * Entry point for Instruction Error Exception
 144  *  -For a corner case, ARC kprobes implementation resorts to using
 145  *   this exception, hence the check
 146  */
 147 void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs)
 148 {
 149         int rc;
 150
 151         /* Check if this exception is caused by kprobes */
 152         rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL);
 153         if (rc == NOTIFY_STOP)
 154                 return;
 155
 156         insterror_is_error(address, regs);
 157 }