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.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
 26void __init trap_init(void)
 27{
 28	return;
 29}
 30
 31void 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 */
 44static noinline int
 45unhandled_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) \
 66int 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 */
 80DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
 81DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
 82DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
 83DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", do_memory_error, BUS_ADRERR)
 84DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
 85DO_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 */
 90int 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 */
104void 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 */
119void 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 */
147void 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}