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 __init trap_init(void)
  24{
  25        return;
  26}
  27
  28void 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 */
  41static noinline int
  42unhandled_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) \
  64int 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 */
  73DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
  74DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
  75DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
  76DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)
  77DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
  78DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
  79DO_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 */
  84int 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 */
  98void 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 */
 115void 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 */
 146void 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 */
 161void abort(void)
 162{
 163        __asm__ __volatile__("trap_s  5\n");
 164}
 165