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