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Commit | Line | Data |
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744c193e | 1 | #include <linux/extable.h> |
7c0f6ba6 | 2 | #include <linux/uaccess.h> |
b17b0153 IM |
3 | #include <linux/sched/debug.h> |
4 | ||
0d0efc07 | 5 | #include <asm/traps.h> |
81c2949f | 6 | #include <asm/kdebug.h> |
6d48583b | 7 | |
548acf19 TL |
8 | typedef bool (*ex_handler_t)(const struct exception_table_entry *, |
9 | struct pt_regs *, int); | |
10 | ||
70627654 PA |
11 | static inline unsigned long |
12 | ex_fixup_addr(const struct exception_table_entry *x) | |
13 | { | |
14 | return (unsigned long)&x->fixup + x->fixup; | |
15 | } | |
548acf19 TL |
16 | static inline ex_handler_t |
17 | ex_fixup_handler(const struct exception_table_entry *x) | |
18 | { | |
19 | return (ex_handler_t)((unsigned long)&x->handler + x->handler); | |
20 | } | |
6d48583b | 21 | |
548acf19 TL |
22 | bool ex_handler_default(const struct exception_table_entry *fixup, |
23 | struct pt_regs *regs, int trapnr) | |
6d48583b | 24 | { |
548acf19 TL |
25 | regs->ip = ex_fixup_addr(fixup); |
26 | return true; | |
27 | } | |
28 | EXPORT_SYMBOL(ex_handler_default); | |
29 | ||
30 | bool ex_handler_fault(const struct exception_table_entry *fixup, | |
31 | struct pt_regs *regs, int trapnr) | |
32 | { | |
33 | regs->ip = ex_fixup_addr(fixup); | |
34 | regs->ax = trapnr; | |
35 | return true; | |
36 | } | |
37 | EXPORT_SYMBOL_GPL(ex_handler_fault); | |
38 | ||
39 | bool ex_handler_ext(const struct exception_table_entry *fixup, | |
40 | struct pt_regs *regs, int trapnr) | |
41 | { | |
42 | /* Special hack for uaccess_err */ | |
dfa9a942 | 43 | current->thread.uaccess_err = 1; |
548acf19 TL |
44 | regs->ip = ex_fixup_addr(fixup); |
45 | return true; | |
46 | } | |
47 | EXPORT_SYMBOL(ex_handler_ext); | |
48 | ||
fbd70437 AL |
49 | bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup, |
50 | struct pt_regs *regs, int trapnr) | |
51 | { | |
81c2949f BP |
52 | if (pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pF)\n", |
53 | (unsigned int)regs->cx, regs->ip, (void *)regs->ip)) | |
54 | show_stack_regs(regs); | |
fbd70437 AL |
55 | |
56 | /* Pretend that the read succeeded and returned 0. */ | |
57 | regs->ip = ex_fixup_addr(fixup); | |
58 | regs->ax = 0; | |
59 | regs->dx = 0; | |
60 | return true; | |
61 | } | |
62 | EXPORT_SYMBOL(ex_handler_rdmsr_unsafe); | |
63 | ||
64 | bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup, | |
65 | struct pt_regs *regs, int trapnr) | |
66 | { | |
81c2949f BP |
67 | if (pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pF)\n", |
68 | (unsigned int)regs->cx, (unsigned int)regs->dx, | |
69 | (unsigned int)regs->ax, regs->ip, (void *)regs->ip)) | |
70 | show_stack_regs(regs); | |
fbd70437 AL |
71 | |
72 | /* Pretend that the write succeeded. */ | |
73 | regs->ip = ex_fixup_addr(fixup); | |
74 | return true; | |
75 | } | |
76 | EXPORT_SYMBOL(ex_handler_wrmsr_unsafe); | |
77 | ||
45e876f7 AL |
78 | bool ex_handler_clear_fs(const struct exception_table_entry *fixup, |
79 | struct pt_regs *regs, int trapnr) | |
80 | { | |
81 | if (static_cpu_has(X86_BUG_NULL_SEG)) | |
82 | asm volatile ("mov %0, %%fs" : : "rm" (__USER_DS)); | |
83 | asm volatile ("mov %0, %%fs" : : "rm" (0)); | |
84 | return ex_handler_default(fixup, regs, trapnr); | |
85 | } | |
86 | EXPORT_SYMBOL(ex_handler_clear_fs); | |
87 | ||
548acf19 TL |
88 | bool ex_has_fault_handler(unsigned long ip) |
89 | { | |
90 | const struct exception_table_entry *e; | |
91 | ex_handler_t handler; | |
92 | ||
93 | e = search_exception_tables(ip); | |
94 | if (!e) | |
95 | return false; | |
96 | handler = ex_fixup_handler(e); | |
97 | ||
98 | return handler == ex_handler_fault; | |
99 | } | |
100 | ||
101 | int fixup_exception(struct pt_regs *regs, int trapnr) | |
102 | { | |
103 | const struct exception_table_entry *e; | |
104 | ex_handler_t handler; | |
6d48583b HH |
105 | |
106 | #ifdef CONFIG_PNPBIOS | |
107 | if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) { | |
108 | extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp; | |
109 | extern u32 pnp_bios_is_utter_crap; | |
110 | pnp_bios_is_utter_crap = 1; | |
111 | printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n"); | |
112 | __asm__ volatile( | |
113 | "movl %0, %%esp\n\t" | |
114 | "jmp *%1\n\t" | |
115 | : : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip)); | |
116 | panic("do_trap: can't hit this"); | |
117 | } | |
118 | #endif | |
119 | ||
548acf19 TL |
120 | e = search_exception_tables(regs->ip); |
121 | if (!e) | |
122 | return 0; | |
6d48583b | 123 | |
548acf19 TL |
124 | handler = ex_fixup_handler(e); |
125 | return handler(e, regs, trapnr); | |
6d48583b | 126 | } |
6a1ea279 | 127 | |
0e861fbb AL |
128 | extern unsigned int early_recursion_flag; |
129 | ||
6a1ea279 | 130 | /* Restricted version used during very early boot */ |
0e861fbb | 131 | void __init early_fixup_exception(struct pt_regs *regs, int trapnr) |
6a1ea279 | 132 | { |
0d0efc07 AL |
133 | /* Ignore early NMIs. */ |
134 | if (trapnr == X86_TRAP_NMI) | |
0e861fbb AL |
135 | return; |
136 | ||
137 | if (early_recursion_flag > 2) | |
138 | goto halt_loop; | |
139 | ||
fc0e81b2 AL |
140 | /* |
141 | * Old CPUs leave the high bits of CS on the stack | |
142 | * undefined. I'm not sure which CPUs do this, but at least | |
143 | * the 486 DX works this way. | |
144 | */ | |
145 | if ((regs->cs & 0xFFFF) != __KERNEL_CS) | |
0e861fbb | 146 | goto fail; |
0d0efc07 | 147 | |
60a0e203 AL |
148 | /* |
149 | * The full exception fixup machinery is available as soon as | |
150 | * the early IDT is loaded. This means that it is the | |
151 | * responsibility of extable users to either function correctly | |
152 | * when handlers are invoked early or to simply avoid causing | |
153 | * exceptions before they're ready to handle them. | |
154 | * | |
155 | * This is better than filtering which handlers can be used, | |
156 | * because refusing to call a handler here is guaranteed to | |
157 | * result in a hard-to-debug panic. | |
158 | * | |
159 | * Keep in mind that not all vectors actually get here. Early | |
160 | * fage faults, for example, are special. | |
161 | */ | |
ae7ef45e AL |
162 | if (fixup_exception(regs, trapnr)) |
163 | return; | |
0e861fbb AL |
164 | |
165 | fail: | |
166 | early_printk("PANIC: early exception 0x%02x IP %lx:%lx error %lx cr2 0x%lx\n", | |
167 | (unsigned)trapnr, (unsigned long)regs->cs, regs->ip, | |
168 | regs->orig_ax, read_cr2()); | |
169 | ||
170 | show_regs(regs); | |
171 | ||
172 | halt_loop: | |
173 | while (true) | |
174 | halt(); | |
6a1ea279 | 175 | } |