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(sig: signo, code: 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(val: DIE_IERR, str: "kprobe_ierr", regs, err: address, trap: 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}
160

source code of linux/arch/arc/kernel/traps.c