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}
158