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 <asm/unaligned.h>
22#include <asm/kprobes.h>
23
24void die(const char *str, struct pt_regs *regs, unsigned long address)
25{
26	show_kernel_fault_diag(str, regs, address);
27
28	/* DEAD END */
29	__asm__("flag 1");
30}
31
32/*
33 * Helper called for bulk of exceptions NOT needing specific handling
34 *  -for user faults enqueues requested signal
35 *  -for kernel, chk if due to copy_(to|from)_user, otherwise die()
36 */
37static noinline int
38unhandled_exception(const char *str, struct pt_regs *regs,
39		    int signo, int si_code, void __user *addr)
40{
41	if (user_mode(regs)) {
42		struct task_struct *tsk = current;
43
44		tsk->thread.fault_address = (__force unsigned int)addr;
45
46		force_sig_fault(signo, si_code, addr);
47
48	} else {
49		/* If not due to copy_(to|from)_user, we are doomed */
50		if (fixup_exception(regs))
51			return 0;
52
53		die(str, regs, (unsigned long)addr);
54	}
55
56	return 1;
57}
58
59#define DO_ERROR_INFO(signr, str, name, sicode) \
60int name(unsigned long address, struct pt_regs *regs) \
61{								\
62	return unhandled_exception(str, regs, signr, sicode,	\
63				   (void __user *)address);	\
64}
65
66/*
67 * Entry points for exceptions NOT needing specific handling
68 */
69DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
70DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
71DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
72DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)
73DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
74DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
75DO_ERROR_INFO(SIGSEGV, "gcc generated __builtin_trap", do_trap5_error, 0)
76
77/*
78 * Entry Point for Misaligned Data access Exception, for emulating in software
79 */
80int do_misaligned_access(unsigned long address, struct pt_regs *regs,
81			 struct callee_regs *cregs)
82{
83	/* If emulation not enabled, or failed, kill the task */
84	if (misaligned_fixup(address, regs, cregs) != 0)
85		return do_misaligned_error(address, regs);
86
87	return 0;
88}
89
90/*
91 * Entry point for miscll errors such as Nested Exceptions
92 *  -Duplicate TLB entry is handled seperately though
93 */
94void do_machine_check_fault(unsigned long address, struct pt_regs *regs)
95{
96	die("Unhandled Machine Check Exception", regs, address);
97}
98
99
100/*
101 * Entry point for traps induced by ARCompact TRAP_S <n> insn
102 * This is same family as TRAP0/SWI insn (use the same vector).
103 * The only difference being SWI insn take no operand, while TRAP_S does
104 * which reflects in ECR Reg as 8 bit param.
105 * Thus TRAP_S <n> can be used for specific purpose
106 *  -1 used for software breakpointing (gdb)
107 *  -2 used by kprobes
108 *  -5 __builtin_trap() generated by gcc (2018.03 onwards) for toggle such as
109 *     -fno-isolate-erroneous-paths-dereference
110 */
111void do_non_swi_trap(unsigned long address, struct pt_regs *regs)
112{
113	switch (regs->ecr.param) {
114	case 1:
115		trap_is_brkpt(address, regs);
116		break;
117
118	case 2:
119		trap_is_kprobe(address, regs);
120		break;
121
122	case 3:
123	case 4:
124		kgdb_trap(regs);
125		break;
126
127	case 5:
128		do_trap5_error(address, regs);
129		break;
130	default:
131		break;
132	}
133}
134
135/*
136 * Entry point for Instruction Error Exception
137 *  -For a corner case, ARC kprobes implementation resorts to using
138 *   this exception, hence the check
139 */
140void do_insterror_or_kprobe(unsigned long address, struct pt_regs *regs)
141{
142	int rc;
143
144	/* Check if this exception is caused by kprobes */
145	rc = notify_die(DIE_IERR, "kprobe_ierr", regs, address, 0, SIGILL);
146	if (rc == NOTIFY_STOP)
147		return;
148
149	insterror_is_error(address, regs);
150}
151
152/*
153 * abort() call generated by older gcc for __builtin_trap()
154 */
155void abort(void)
156{
157	__asm__ __volatile__("trap_s  5\n");
158}
159