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
die(const char * str,struct pt_regs * regs,unsigned long address)24 void 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 */
37 static noinline int
unhandled_exception(const char * str,struct pt_regs * regs,int signo,int si_code,void __user * addr)38 unhandled_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) \
60 int 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 */
69 DO_ERROR_INFO(SIGILL, "Priv Op/Disabled Extn", do_privilege_fault, ILL_PRVOPC)
70 DO_ERROR_INFO(SIGILL, "Invalid Extn Insn", do_extension_fault, ILL_ILLOPC)
71 DO_ERROR_INFO(SIGILL, "Illegal Insn (or Seq)", insterror_is_error, ILL_ILLOPC)
72 DO_ERROR_INFO(SIGBUS, "Invalid Mem Access", __weak do_memory_error, BUS_ADRERR)
73 DO_ERROR_INFO(SIGTRAP, "Breakpoint Set", trap_is_brkpt, TRAP_BRKPT)
74 DO_ERROR_INFO(SIGBUS, "Misaligned Access", do_misaligned_error, BUS_ADRALN)
75 DO_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 */
do_misaligned_access(unsigned long address,struct pt_regs * regs,struct callee_regs * cregs)80 int 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 */
do_machine_check_fault(unsigned long address,struct pt_regs * regs)94 void 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 */
do_non_swi_trap(unsigned long address,struct pt_regs * regs)111 void 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 */
do_insterror_or_kprobe(unsigned long address,struct pt_regs * regs)140 void 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 */
abort(void)155 void abort(void)
156 {
157 __asm__ __volatile__("trap_s 5\n");
158 }
159