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  * Rahul Trivedi: Codito Technologies 2004
  11  */
  12
  13 #include <linux/sched.h>
  14 #include <linux/kdebug.h>
  15 #include <linux/uaccess.h>
  16 #include <asm/ptrace.h>
  17 #include <asm/setup.h>
  18 #include <asm/kprobes.h>
  19
  20 void __init trap_init(void)
  21 {
  22         return;
  23 }
  24
  25 void die(const char *str, struct pt_regs *regs, unsigned long address,
  26          unsigned long cause_reg)
  27 {
  28         show_kernel_fault_diag(str, regs, address, cause_reg);
  29
  30         /* DEAD END */
  31         __asm__("flag 1");
  32 }
  33
  34 /*
  35  * Helper called for bulk of exceptions NOT needing specific handling
  36  *  -for user faults enqueues requested signal
  37  *  -for kernel, chk if due to copy_(to|from)_user, otherwise die()
  38  */
  39 static noinline int handle_exception(unsigned long cause, char *str,
  40                                      struct pt_regs *regs, siginfo_t *info)
  41 {
  42         if (user_mode(regs)) {
  43                 struct task_struct *tsk = current;
  44
  45                 tsk->thread.fault_address = (__force unsigned int)info->si_addr;
  46                 tsk->thread.cause_code = cause;
  47
  48                 force_sig_info(info->si_signo, info, tsk);
  49
  50         } else {
  51                 /* If not due to copy_(to|from)_user, we are doomed */
  52                 if (fixup_exception(regs))
  53                         return 0;
  54
  55                 die(str, regs, (unsigned long)info->si_addr, cause);
  56         }
  57
  58         return 1;
  59 }
  60
  61 #define DO_ERROR_INFO(signr, str, name, sicode) \
  62 int name(unsigned long cause, unsigned long address, struct pt_regs *regs) \
  63 {                                               \
  64         siginfo_t info = {                      \
  65                 .si_signo = signr,              \
  66                 .si_errno = 0,                  \
  67                 .si_code  = sicode,             \
  68                 .si_addr = (void __user *)address,      \
  69         };                                      \
  70         return handle_exception(cause, str, regs, &info);\
  71 }
  72
  73 /*
  74  * Entry points for exceptions NOT needing specific handling
  75  */
  76 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
  77 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
  78 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
  79 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", do_memory_error, BUS_ADRERR)
  80 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
  81
  82 DO_ERROR_INFO(SIGSEGV, "Misaligned Access", do_misaligned_access, SEGV_ACCERR)
  83
  84 /*
  85  * Entry point for miscll errors such as Nested Exceptions
  86  *  -Duplicate TLB entry is handled seperately though
  87  */
  88 void do_machine_check_fault(unsigned long cause, unsigned long address,
  89                             struct pt_regs *regs)
  90 {
  91         die("Machine Check Exception", regs, address, cause);
  92 }
  93
  94
  95 /*
  96  * Entry point for traps induced by ARCompact TRAP_S <n> insn
  97  * This is same family as TRAP0/SWI insn (use the same vector).
  98  * The only difference being SWI insn take no operand, while TRAP_S does
  99  * which reflects in ECR Reg as 8 bit param.
 100  * Thus TRAP_S <n> can be used for specific purpose
 101  *  -1 used for software breakpointing (gdb)
 102  *  -2 used by kprobes
 103  */
 104 void do_non_swi_trap(unsigned long cause, unsigned long address,
 105                         struct pt_regs *regs)
 106 {
 107         unsigned int param = cause & 0xff;
 108
 109         switch (param) {
 110         case 1:
 111                 trap_is_brkpt(cause, address, regs);
 112                 break;
 113
 114         case 2:
 115                 trap_is_kprobe(param, address, regs);
 116                 break;
 117
 118         default:
 119                 break;
 120         }
 121 }
 122
 123 /*
 124  * Entry point for Instruction Error Exception
 125  *  -For a corner case, ARC kprobes implementation resorts to using
 126  *   this exception, hence the check
 127  */
 128 void do_insterror_or_kprobe(unsigned long cause,
 129                                        unsigned long address,
 130                                        struct pt_regs *regs)
 131 {
 132         /* Check if this exception is caused by kprobes */
 133         if (notify_die(DIE_IERR, "kprobe_ierr", regs, address,
 134                        cause, SIGILL) == NOTIFY_STOP)
 135                 return;
 136
 137         insterror_is_error(cause, address, regs);
 138 }