Commit | Line | Data |
---|---|---|
6d48583b | 1 | #include <linux/module.h> |
6d48583b | 2 | #include <asm/uaccess.h> |
0d0efc07 | 3 | #include <asm/traps.h> |
6d48583b | 4 | |
548acf19 TL |
5 | typedef bool (*ex_handler_t)(const struct exception_table_entry *, |
6 | struct pt_regs *, int); | |
7 | ||
70627654 PA |
8 | static inline unsigned long |
9 | ex_fixup_addr(const struct exception_table_entry *x) | |
10 | { | |
11 | return (unsigned long)&x->fixup + x->fixup; | |
12 | } | |
548acf19 TL |
13 | static inline ex_handler_t |
14 | ex_fixup_handler(const struct exception_table_entry *x) | |
15 | { | |
16 | return (ex_handler_t)((unsigned long)&x->handler + x->handler); | |
17 | } | |
6d48583b | 18 | |
548acf19 TL |
19 | bool ex_handler_default(const struct exception_table_entry *fixup, |
20 | struct pt_regs *regs, int trapnr) | |
6d48583b | 21 | { |
548acf19 TL |
22 | regs->ip = ex_fixup_addr(fixup); |
23 | return true; | |
24 | } | |
25 | EXPORT_SYMBOL(ex_handler_default); | |
26 | ||
27 | bool ex_handler_fault(const struct exception_table_entry *fixup, | |
28 | struct pt_regs *regs, int trapnr) | |
29 | { | |
30 | regs->ip = ex_fixup_addr(fixup); | |
31 | regs->ax = trapnr; | |
32 | return true; | |
33 | } | |
34 | EXPORT_SYMBOL_GPL(ex_handler_fault); | |
35 | ||
36 | bool ex_handler_ext(const struct exception_table_entry *fixup, | |
37 | struct pt_regs *regs, int trapnr) | |
38 | { | |
39 | /* Special hack for uaccess_err */ | |
40 | current_thread_info()->uaccess_err = 1; | |
41 | regs->ip = ex_fixup_addr(fixup); | |
42 | return true; | |
43 | } | |
44 | EXPORT_SYMBOL(ex_handler_ext); | |
45 | ||
fbd70437 AL |
46 | bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup, |
47 | struct pt_regs *regs, int trapnr) | |
48 | { | |
49 | WARN_ONCE(1, "unchecked MSR access error: RDMSR from 0x%x\n", | |
50 | (unsigned int)regs->cx); | |
51 | ||
52 | /* Pretend that the read succeeded and returned 0. */ | |
53 | regs->ip = ex_fixup_addr(fixup); | |
54 | regs->ax = 0; | |
55 | regs->dx = 0; | |
56 | return true; | |
57 | } | |
58 | EXPORT_SYMBOL(ex_handler_rdmsr_unsafe); | |
59 | ||
60 | bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup, | |
61 | struct pt_regs *regs, int trapnr) | |
62 | { | |
63 | WARN_ONCE(1, "unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x)\n", | |
64 | (unsigned int)regs->cx, | |
65 | (unsigned int)regs->dx, (unsigned int)regs->ax); | |
66 | ||
67 | /* Pretend that the write succeeded. */ | |
68 | regs->ip = ex_fixup_addr(fixup); | |
69 | return true; | |
70 | } | |
71 | EXPORT_SYMBOL(ex_handler_wrmsr_unsafe); | |
72 | ||
45e876f7 AL |
73 | bool ex_handler_clear_fs(const struct exception_table_entry *fixup, |
74 | struct pt_regs *regs, int trapnr) | |
75 | { | |
76 | if (static_cpu_has(X86_BUG_NULL_SEG)) | |
77 | asm volatile ("mov %0, %%fs" : : "rm" (__USER_DS)); | |
78 | asm volatile ("mov %0, %%fs" : : "rm" (0)); | |
79 | return ex_handler_default(fixup, regs, trapnr); | |
80 | } | |
81 | EXPORT_SYMBOL(ex_handler_clear_fs); | |
82 | ||
548acf19 TL |
83 | bool ex_has_fault_handler(unsigned long ip) |
84 | { | |
85 | const struct exception_table_entry *e; | |
86 | ex_handler_t handler; | |
87 | ||
88 | e = search_exception_tables(ip); | |
89 | if (!e) | |
90 | return false; | |
91 | handler = ex_fixup_handler(e); | |
92 | ||
93 | return handler == ex_handler_fault; | |
94 | } | |
95 | ||
96 | int fixup_exception(struct pt_regs *regs, int trapnr) | |
97 | { | |
98 | const struct exception_table_entry *e; | |
99 | ex_handler_t handler; | |
6d48583b HH |
100 | |
101 | #ifdef CONFIG_PNPBIOS | |
102 | if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) { | |
103 | extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp; | |
104 | extern u32 pnp_bios_is_utter_crap; | |
105 | pnp_bios_is_utter_crap = 1; | |
106 | printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n"); | |
107 | __asm__ volatile( | |
108 | "movl %0, %%esp\n\t" | |
109 | "jmp *%1\n\t" | |
110 | : : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip)); | |
111 | panic("do_trap: can't hit this"); | |
112 | } | |
113 | #endif | |
114 | ||
548acf19 TL |
115 | e = search_exception_tables(regs->ip); |
116 | if (!e) | |
117 | return 0; | |
6d48583b | 118 | |
548acf19 TL |
119 | handler = ex_fixup_handler(e); |
120 | return handler(e, regs, trapnr); | |
6d48583b | 121 | } |
6a1ea279 | 122 | |
0e861fbb AL |
123 | extern unsigned int early_recursion_flag; |
124 | ||
6a1ea279 | 125 | /* Restricted version used during very early boot */ |
0e861fbb | 126 | void __init early_fixup_exception(struct pt_regs *regs, int trapnr) |
6a1ea279 | 127 | { |
0d0efc07 AL |
128 | /* Ignore early NMIs. */ |
129 | if (trapnr == X86_TRAP_NMI) | |
0e861fbb AL |
130 | return; |
131 | ||
132 | if (early_recursion_flag > 2) | |
133 | goto halt_loop; | |
134 | ||
135 | if (regs->cs != __KERNEL_CS) | |
136 | goto fail; | |
0d0efc07 | 137 | |
60a0e203 AL |
138 | /* |
139 | * The full exception fixup machinery is available as soon as | |
140 | * the early IDT is loaded. This means that it is the | |
141 | * responsibility of extable users to either function correctly | |
142 | * when handlers are invoked early or to simply avoid causing | |
143 | * exceptions before they're ready to handle them. | |
144 | * | |
145 | * This is better than filtering which handlers can be used, | |
146 | * because refusing to call a handler here is guaranteed to | |
147 | * result in a hard-to-debug panic. | |
148 | * | |
149 | * Keep in mind that not all vectors actually get here. Early | |
150 | * fage faults, for example, are special. | |
151 | */ | |
ae7ef45e AL |
152 | if (fixup_exception(regs, trapnr)) |
153 | return; | |
0e861fbb AL |
154 | |
155 | fail: | |
156 | early_printk("PANIC: early exception 0x%02x IP %lx:%lx error %lx cr2 0x%lx\n", | |
157 | (unsigned)trapnr, (unsigned long)regs->cs, regs->ip, | |
158 | regs->orig_ax, read_cr2()); | |
159 | ||
160 | show_regs(regs); | |
161 | ||
162 | halt_loop: | |
163 | while (true) | |
164 | halt(); | |
6a1ea279 | 165 | } |