blob: 0f90cc218d04644b9ca5f109cb754c6b3b7e611c [file] [log] [blame]
Harvey Harrison6d485832008-01-30 13:31:41 +01001#include <linux/module.h>
Harvey Harrison6d485832008-01-30 13:31:41 +01002#include <asm/uaccess.h>
Andy Lutomirski0d0efc02016-04-02 07:01:33 -07003#include <asm/traps.h>
Harvey Harrison6d485832008-01-30 13:31:41 +01004
Tony Luck548acf12016-02-17 10:20:12 -08005typedef bool (*ex_handler_t)(const struct exception_table_entry *,
6 struct pt_regs *, int);
7
H. Peter Anvin70627652012-04-20 17:12:48 -07008static inline unsigned long
H. Peter Anvin70627652012-04-20 17:12:48 -07009ex_fixup_addr(const struct exception_table_entry *x)
10{
11 return (unsigned long)&x->fixup + x->fixup;
12}
Tony Luck548acf12016-02-17 10:20:12 -080013static inline ex_handler_t
14ex_fixup_handler(const struct exception_table_entry *x)
Harvey Harrison6d485832008-01-30 13:31:41 +010015{
Tony Luck548acf12016-02-17 10:20:12 -080016 return (ex_handler_t)((unsigned long)&x->handler + x->handler);
17}
18
19bool ex_handler_default(const struct exception_table_entry *fixup,
20 struct pt_regs *regs, int trapnr)
21{
22 regs->ip = ex_fixup_addr(fixup);
23 return true;
24}
25EXPORT_SYMBOL(ex_handler_default);
26
27bool 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}
34EXPORT_SYMBOL_GPL(ex_handler_fault);
35
36bool ex_handler_ext(const struct exception_table_entry *fixup,
37 struct pt_regs *regs, int trapnr)
38{
39 /* Special hack for uaccess_err */
Andy Lutomirskidfa9a942016-07-14 13:22:56 -070040 current->thread.uaccess_err = 1;
Tony Luck548acf12016-02-17 10:20:12 -080041 regs->ip = ex_fixup_addr(fixup);
42 return true;
43}
44EXPORT_SYMBOL(ex_handler_ext);
45
Andy Lutomirskifbd70432016-04-02 07:01:37 -070046bool 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}
58EXPORT_SYMBOL(ex_handler_rdmsr_unsafe);
59
60bool 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}
71EXPORT_SYMBOL(ex_handler_wrmsr_unsafe);
72
Andy Lutomirski45e876f2016-04-26 12:23:26 -070073bool 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}
81EXPORT_SYMBOL(ex_handler_clear_fs);
82
Tony Luck548acf12016-02-17 10:20:12 -080083bool 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
96int fixup_exception(struct pt_regs *regs, int trapnr)
97{
98 const struct exception_table_entry *e;
99 ex_handler_t handler;
Harvey Harrison6d485832008-01-30 13:31:41 +0100100
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
Tony Luck548acf12016-02-17 10:20:12 -0800115 e = search_exception_tables(regs->ip);
116 if (!e)
117 return 0;
H. Peter Anvin70627652012-04-20 17:12:48 -0700118
Tony Luck548acf12016-02-17 10:20:12 -0800119 handler = ex_fixup_handler(e);
120 return handler(e, regs, trapnr);
Harvey Harrison6d485832008-01-30 13:31:41 +0100121}
H. Peter Anvin6a1ea272012-04-19 15:24:20 -0700122
Andy Lutomirski0e861fb2016-04-02 07:01:34 -0700123extern unsigned int early_recursion_flag;
124
H. Peter Anvin6a1ea272012-04-19 15:24:20 -0700125/* Restricted version used during very early boot */
Andy Lutomirski0e861fb2016-04-02 07:01:34 -0700126void __init early_fixup_exception(struct pt_regs *regs, int trapnr)
H. Peter Anvin6a1ea272012-04-19 15:24:20 -0700127{
Andy Lutomirski0d0efc02016-04-02 07:01:33 -0700128 /* Ignore early NMIs. */
129 if (trapnr == X86_TRAP_NMI)
Andy Lutomirski0e861fb2016-04-02 07:01:34 -0700130 return;
131
132 if (early_recursion_flag > 2)
133 goto halt_loop;
134
135 if (regs->cs != __KERNEL_CS)
136 goto fail;
Andy Lutomirski0d0efc02016-04-02 07:01:33 -0700137
Andy Lutomirski60a0e202016-04-04 08:46:22 -0700138 /*
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 */
Andy Lutomirskiae7ef452016-04-02 07:01:35 -0700152 if (fixup_exception(regs, trapnr))
153 return;
Andy Lutomirski0e861fb2016-04-02 07:01:34 -0700154
155fail:
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
162halt_loop:
163 while (true)
164 halt();
H. Peter Anvin6a1ea272012-04-19 15:24:20 -0700165}