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1da177e4 LT |
1 | /* |
2 | * linux/arch/frv/mm/extable.c | |
3 | */ | |
4 | ||
5 | #include <linux/config.h> | |
6 | #include <linux/module.h> | |
7 | #include <linux/spinlock.h> | |
8 | #include <asm/uaccess.h> | |
9 | ||
10 | extern const struct exception_table_entry __attribute__((aligned(8))) __start___ex_table[]; | |
11 | extern const struct exception_table_entry __attribute__((aligned(8))) __stop___ex_table[]; | |
12 | extern const void __memset_end, __memset_user_error_lr, __memset_user_error_handler; | |
13 | extern const void __memcpy_end, __memcpy_user_error_lr, __memcpy_user_error_handler; | |
14 | extern spinlock_t modlist_lock; | |
15 | ||
16 | /*****************************************************************************/ | |
17 | /* | |
18 | * | |
19 | */ | |
20 | static inline unsigned long search_one_table(const struct exception_table_entry *first, | |
21 | const struct exception_table_entry *last, | |
22 | unsigned long value) | |
23 | { | |
24 | while (first <= last) { | |
25 | const struct exception_table_entry __attribute__((aligned(8))) *mid; | |
26 | long diff; | |
27 | ||
28 | mid = (last - first) / 2 + first; | |
29 | diff = mid->insn - value; | |
30 | if (diff == 0) | |
31 | return mid->fixup; | |
32 | else if (diff < 0) | |
33 | first = mid + 1; | |
34 | else | |
35 | last = mid - 1; | |
36 | } | |
37 | return 0; | |
38 | } /* end search_one_table() */ | |
39 | ||
40 | /*****************************************************************************/ | |
41 | /* | |
42 | * see if there's a fixup handler available to deal with a kernel fault | |
43 | */ | |
44 | unsigned long search_exception_table(unsigned long pc) | |
45 | { | |
46 | unsigned long ret = 0; | |
47 | ||
48 | /* determine if the fault lay during a memcpy_user or a memset_user */ | |
49 | if (__frame->lr == (unsigned long) &__memset_user_error_lr && | |
50 | (unsigned long) &memset <= pc && pc < (unsigned long) &__memset_end | |
51 | ) { | |
52 | /* the fault occurred in a protected memset | |
53 | * - we search for the return address (in LR) instead of the program counter | |
54 | * - it was probably during a clear_user() | |
55 | */ | |
56 | return (unsigned long) &__memset_user_error_handler; | |
57 | } | |
58 | else if (__frame->lr == (unsigned long) &__memcpy_user_error_lr && | |
59 | (unsigned long) &memcpy <= pc && pc < (unsigned long) &__memcpy_end | |
60 | ) { | |
61 | /* the fault occurred in a protected memset | |
62 | * - we search for the return address (in LR) instead of the program counter | |
63 | * - it was probably during a copy_to/from_user() | |
64 | */ | |
65 | return (unsigned long) &__memcpy_user_error_handler; | |
66 | } | |
67 | ||
68 | #ifndef CONFIG_MODULES | |
69 | /* there is only the kernel to search. */ | |
70 | ret = search_one_table(__start___ex_table, __stop___ex_table - 1, pc); | |
71 | return ret; | |
72 | ||
73 | #else | |
74 | /* the kernel is the last "module" -- no need to treat it special */ | |
75 | unsigned long flags; | |
76 | struct module *mp; | |
77 | ||
78 | spin_lock_irqsave(&modlist_lock, flags); | |
79 | ||
80 | for (mp = module_list; mp != NULL; mp = mp->next) { | |
81 | if (mp->ex_table_start == NULL || !(mp->flags & (MOD_RUNNING | MOD_INITIALIZING))) | |
82 | continue; | |
83 | ret = search_one_table(mp->ex_table_start, mp->ex_table_end - 1, pc); | |
84 | if (ret) | |
85 | break; | |
86 | } | |
87 | ||
88 | spin_unlock_irqrestore(&modlist_lock, flags); | |
89 | return ret; | |
90 | #endif | |
91 | } /* end search_exception_table() */ |