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