Heiko Carstens | eb608fb | 2012-09-05 13:26:11 +0200 | [diff] [blame] | 1 | #include <linux/module.h> |
| 2 | #include <linux/sort.h> |
| 3 | #include <asm/uaccess.h> |
| 4 | |
| 5 | /* |
| 6 | * Search one exception table for an entry corresponding to the |
| 7 | * given instruction address, and return the address of the entry, |
| 8 | * or NULL if none is found. |
| 9 | * We use a binary search, and thus we assume that the table is |
| 10 | * already sorted. |
| 11 | */ |
| 12 | const struct exception_table_entry * |
| 13 | search_extable(const struct exception_table_entry *first, |
| 14 | const struct exception_table_entry *last, |
| 15 | unsigned long value) |
| 16 | { |
| 17 | const struct exception_table_entry *mid; |
| 18 | unsigned long addr; |
| 19 | |
| 20 | while (first <= last) { |
| 21 | mid = ((last - first) >> 1) + first; |
| 22 | addr = extable_insn(mid); |
| 23 | if (addr < value) |
| 24 | first = mid + 1; |
| 25 | else if (addr > value) |
| 26 | last = mid - 1; |
| 27 | else |
| 28 | return mid; |
| 29 | } |
| 30 | return NULL; |
| 31 | } |
| 32 | |
| 33 | /* |
| 34 | * The exception table needs to be sorted so that the binary |
| 35 | * search that we use to find entries in it works properly. |
| 36 | * This is used both for the kernel exception table and for |
| 37 | * the exception tables of modules that get loaded. |
| 38 | * |
| 39 | */ |
| 40 | static int cmp_ex(const void *a, const void *b) |
| 41 | { |
| 42 | const struct exception_table_entry *x = a, *y = b; |
| 43 | |
| 44 | /* This compare is only valid after normalization. */ |
| 45 | return x->insn - y->insn; |
| 46 | } |
| 47 | |
| 48 | void sort_extable(struct exception_table_entry *start, |
| 49 | struct exception_table_entry *finish) |
| 50 | { |
| 51 | struct exception_table_entry *p; |
| 52 | int i; |
| 53 | |
| 54 | /* Normalize entries to being relative to the start of the section */ |
Ard Biesheuvel | bcb7825 | 2016-01-01 13:39:22 +0100 | [diff] [blame] | 55 | for (p = start, i = 0; p < finish; p++, i += 8) { |
Heiko Carstens | eb608fb | 2012-09-05 13:26:11 +0200 | [diff] [blame] | 56 | p->insn += i; |
Ard Biesheuvel | bcb7825 | 2016-01-01 13:39:22 +0100 | [diff] [blame] | 57 | p->fixup += i + 4; |
| 58 | } |
Heiko Carstens | eb608fb | 2012-09-05 13:26:11 +0200 | [diff] [blame] | 59 | sort(start, finish - start, sizeof(*start), cmp_ex, NULL); |
| 60 | /* Denormalize all entries */ |
Ard Biesheuvel | bcb7825 | 2016-01-01 13:39:22 +0100 | [diff] [blame] | 61 | for (p = start, i = 0; p < finish; p++, i += 8) { |
Heiko Carstens | eb608fb | 2012-09-05 13:26:11 +0200 | [diff] [blame] | 62 | p->insn -= i; |
Ard Biesheuvel | bcb7825 | 2016-01-01 13:39:22 +0100 | [diff] [blame] | 63 | p->fixup -= i + 4; |
| 64 | } |
Heiko Carstens | eb608fb | 2012-09-05 13:26:11 +0200 | [diff] [blame] | 65 | } |
| 66 | |
| 67 | #ifdef CONFIG_MODULES |
| 68 | /* |
| 69 | * If the exception table is sorted, any referring to the module init |
| 70 | * will be at the beginning or the end. |
| 71 | */ |
| 72 | void trim_init_extable(struct module *m) |
| 73 | { |
| 74 | /* Trim the beginning */ |
| 75 | while (m->num_exentries && |
| 76 | within_module_init(extable_insn(&m->extable[0]), m)) { |
| 77 | m->extable++; |
| 78 | m->num_exentries--; |
| 79 | } |
| 80 | /* Trim the end */ |
| 81 | while (m->num_exentries && |
| 82 | within_module_init(extable_insn(&m->extable[m->num_exentries-1]), m)) |
| 83 | m->num_exentries--; |
| 84 | } |
| 85 | #endif /* CONFIG_MODULES */ |