1 #include <linux/module.h>
2 #include <asm/uaccess.h>
4 #include <asm/kdebug.h>
6 typedef bool (*ex_handler_t)(const struct exception_table_entry *,
7 struct pt_regs *, int);
9 static inline unsigned long
10 ex_fixup_addr(const struct exception_table_entry *x)
12 return (unsigned long)&x->fixup + x->fixup;
14 static inline ex_handler_t
15 ex_fixup_handler(const struct exception_table_entry *x)
17 return (ex_handler_t)((unsigned long)&x->handler + x->handler);
20 bool ex_handler_default(const struct exception_table_entry *fixup,
21 struct pt_regs *regs, int trapnr)
23 regs->ip = ex_fixup_addr(fixup);
26 EXPORT_SYMBOL(ex_handler_default);
28 bool ex_handler_fault(const struct exception_table_entry *fixup,
29 struct pt_regs *regs, int trapnr)
31 regs->ip = ex_fixup_addr(fixup);
35 EXPORT_SYMBOL_GPL(ex_handler_fault);
37 bool ex_handler_ext(const struct exception_table_entry *fixup,
38 struct pt_regs *regs, int trapnr)
40 /* Special hack for uaccess_err */
41 current->thread.uaccess_err = 1;
42 regs->ip = ex_fixup_addr(fixup);
45 EXPORT_SYMBOL(ex_handler_ext);
47 bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
48 struct pt_regs *regs, int trapnr)
50 if (pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pF)\n",
51 (unsigned int)regs->cx, regs->ip, (void *)regs->ip))
52 show_stack_regs(regs);
54 /* Pretend that the read succeeded and returned 0. */
55 regs->ip = ex_fixup_addr(fixup);
60 EXPORT_SYMBOL(ex_handler_rdmsr_unsafe);
62 bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup,
63 struct pt_regs *regs, int trapnr)
65 if (pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pF)\n",
66 (unsigned int)regs->cx, (unsigned int)regs->dx,
67 (unsigned int)regs->ax, regs->ip, (void *)regs->ip))
68 show_stack_regs(regs);
70 /* Pretend that the write succeeded. */
71 regs->ip = ex_fixup_addr(fixup);
74 EXPORT_SYMBOL(ex_handler_wrmsr_unsafe);
76 bool ex_handler_clear_fs(const struct exception_table_entry *fixup,
77 struct pt_regs *regs, int trapnr)
79 if (static_cpu_has(X86_BUG_NULL_SEG))
80 asm volatile ("mov %0, %%fs" : : "rm" (__USER_DS));
81 asm volatile ("mov %0, %%fs" : : "rm" (0));
82 return ex_handler_default(fixup, regs, trapnr);
84 EXPORT_SYMBOL(ex_handler_clear_fs);
86 bool ex_has_fault_handler(unsigned long ip)
88 const struct exception_table_entry *e;
91 e = search_exception_tables(ip);
94 handler = ex_fixup_handler(e);
96 return handler == ex_handler_fault;
99 int fixup_exception(struct pt_regs *regs, int trapnr)
101 const struct exception_table_entry *e;
102 ex_handler_t handler;
104 #ifdef CONFIG_PNPBIOS
105 if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) {
106 extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp;
107 extern u32 pnp_bios_is_utter_crap;
108 pnp_bios_is_utter_crap = 1;
109 printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n");
113 : : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
114 panic("do_trap: can't hit this");
118 e = search_exception_tables(regs->ip);
122 handler = ex_fixup_handler(e);
123 return handler(e, regs, trapnr);
126 extern unsigned int early_recursion_flag;
128 /* Restricted version used during very early boot */
129 void __init early_fixup_exception(struct pt_regs *regs, int trapnr)
131 /* Ignore early NMIs. */
132 if (trapnr == X86_TRAP_NMI)
135 if (early_recursion_flag > 2)
138 if (regs->cs != __KERNEL_CS)
142 * The full exception fixup machinery is available as soon as
143 * the early IDT is loaded. This means that it is the
144 * responsibility of extable users to either function correctly
145 * when handlers are invoked early or to simply avoid causing
146 * exceptions before they're ready to handle them.
148 * This is better than filtering which handlers can be used,
149 * because refusing to call a handler here is guaranteed to
150 * result in a hard-to-debug panic.
152 * Keep in mind that not all vectors actually get here. Early
153 * fage faults, for example, are special.
155 if (fixup_exception(regs, trapnr))
159 early_printk("PANIC: early exception 0x%02x IP %lx:%lx error %lx cr2 0x%lx\n",
160 (unsigned)trapnr, (unsigned long)regs->cs, regs->ip,
161 regs->orig_ax, read_cr2());