1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/bug.h>
3 #include <linux/io.h>
4 #include <linux/types.h>
5 #include <linux/kdebug.h>
6 #include <linux/signal.h>
7 #include <linux/sched.h>
8 #include <linux/sched/debug.h>
9 #include <linux/sched/task_stack.h>
10 #include <linux/uaccess.h>
11 #include <linux/hardirq.h>
12 #include <linux/kernel.h>
13 #include <linux/kexec.h>
14 #include <linux/sched/signal.h>
15
16 #include <linux/extable.h>
17 #include <linux/module.h> /* print_modules */
18 #include <asm/unwinder.h>
19 #include <asm/traps.h>
20
21 static DEFINE_SPINLOCK(die_lock);
22
die(const char * str,struct pt_regs * regs,long err)23 void __noreturn die(const char *str, struct pt_regs *regs, long err)
24 {
25 static int die_counter;
26
27 oops_enter();
28
29 spin_lock_irq(&die_lock);
30 console_verbose();
31 bust_spinlocks(1);
32
33 printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
34 print_modules();
35 show_regs(regs);
36
37 printk("Process: %s (pid: %d, stack limit = %p)\n", current->comm,
38 task_pid_nr(current), task_stack_page(current) + 1);
39
40 if (!user_mode(regs) || in_interrupt())
41 dump_mem("Stack: ", KERN_DEFAULT, regs->regs[15],
42 THREAD_SIZE + (unsigned long)task_stack_page(current));
43
44 notify_die(DIE_OOPS, str, regs, err, 255, SIGSEGV);
45
46 bust_spinlocks(0);
47 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
48 spin_unlock_irq(&die_lock);
49 oops_exit();
50
51 if (kexec_should_crash(current))
52 crash_kexec(regs);
53
54 if (in_interrupt())
55 panic("Fatal exception in interrupt");
56
57 if (panic_on_oops)
58 panic("Fatal exception");
59
60 make_task_dead(SIGSEGV);
61 }
62
die_if_kernel(const char * str,struct pt_regs * regs,long err)63 void die_if_kernel(const char *str, struct pt_regs *regs, long err)
64 {
65 if (!user_mode(regs))
66 die(str, regs, err);
67 }
68
69 /*
70 * try and fix up kernelspace address errors
71 * - userspace errors just cause EFAULT to be returned, resulting in SEGV
72 * - kernel/userspace interfaces cause a jump to an appropriate handler
73 * - other kernel errors are bad
74 */
die_if_no_fixup(const char * str,struct pt_regs * regs,long err)75 void die_if_no_fixup(const char *str, struct pt_regs *regs, long err)
76 {
77 if (!user_mode(regs)) {
78 const struct exception_table_entry *fixup;
79 fixup = search_exception_tables(regs->pc);
80 if (fixup) {
81 regs->pc = fixup->fixup;
82 return;
83 }
84
85 die(str, regs, err);
86 }
87 }
88
89 #ifdef CONFIG_GENERIC_BUG
handle_BUG(struct pt_regs * regs)90 static void handle_BUG(struct pt_regs *regs)
91 {
92 const struct bug_entry *bug;
93 unsigned long bugaddr = regs->pc;
94 enum bug_trap_type tt;
95
96 if (!is_valid_bugaddr(bugaddr))
97 goto invalid;
98
99 bug = find_bug(bugaddr);
100
101 /* Switch unwinders when unwind_stack() is called */
102 if (bug->flags & BUGFLAG_UNWINDER)
103 unwinder_faulted = 1;
104
105 tt = report_bug(bugaddr, regs);
106 if (tt == BUG_TRAP_TYPE_WARN) {
107 regs->pc += instruction_size(bugaddr);
108 return;
109 }
110
111 invalid:
112 die("Kernel BUG", regs, TRAPA_BUG_OPCODE & 0xff);
113 }
114
is_valid_bugaddr(unsigned long addr)115 int is_valid_bugaddr(unsigned long addr)
116 {
117 insn_size_t opcode;
118
119 if (addr < PAGE_OFFSET)
120 return 0;
121 if (get_kernel_nofault(opcode, (insn_size_t *)addr))
122 return 0;
123 if (opcode == TRAPA_BUG_OPCODE)
124 return 1;
125
126 return 0;
127 }
128 #endif
129
130 /*
131 * Generic trap handler.
132 */
BUILD_TRAP_HANDLER(debug)133 BUILD_TRAP_HANDLER(debug)
134 {
135 TRAP_HANDLER_DECL;
136
137 /* Rewind */
138 regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
139
140 if (notify_die(DIE_TRAP, "debug trap", regs, 0, vec & 0xff,
141 SIGTRAP) == NOTIFY_STOP)
142 return;
143
144 force_sig(SIGTRAP);
145 }
146
147 /*
148 * Special handler for BUG() traps.
149 */
BUILD_TRAP_HANDLER(bug)150 BUILD_TRAP_HANDLER(bug)
151 {
152 TRAP_HANDLER_DECL;
153
154 /* Rewind */
155 regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
156
157 if (notify_die(DIE_TRAP, "bug trap", regs, 0, TRAPA_BUG_OPCODE & 0xff,
158 SIGTRAP) == NOTIFY_STOP)
159 return;
160
161 #ifdef CONFIG_GENERIC_BUG
162 if (__kernel_text_address(instruction_pointer(regs))) {
163 insn_size_t insn = *(insn_size_t *)instruction_pointer(regs);
164 if (insn == TRAPA_BUG_OPCODE)
165 handle_BUG(regs);
166 return;
167 }
168 #endif
169
170 force_sig(SIGTRAP);
171 }
172
173 #ifdef CONFIG_DYNAMIC_FTRACE
174 extern void arch_ftrace_nmi_enter(void);
175 extern void arch_ftrace_nmi_exit(void);
176 #else
arch_ftrace_nmi_enter(void)177 static inline void arch_ftrace_nmi_enter(void) { }
arch_ftrace_nmi_exit(void)178 static inline void arch_ftrace_nmi_exit(void) { }
179 #endif
180
BUILD_TRAP_HANDLER(nmi)181 BUILD_TRAP_HANDLER(nmi)
182 {
183 TRAP_HANDLER_DECL;
184
185 arch_ftrace_nmi_enter();
186
187 nmi_enter();
188 this_cpu_inc(irq_stat.__nmi_count);
189
190 switch (notify_die(DIE_NMI, "NMI", regs, 0, vec & 0xff, SIGINT)) {
191 case NOTIFY_OK:
192 case NOTIFY_STOP:
193 break;
194 case NOTIFY_BAD:
195 die("Fatal Non-Maskable Interrupt", regs, SIGINT);
196 default:
197 printk(KERN_ALERT "Got NMI, but nobody cared. Ignoring...\n");
198 break;
199 }
200
201 nmi_exit();
202
203 arch_ftrace_nmi_exit();
204 }
205