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