1 /* 2 * Kernel exception handling table support. Derived from arch/alpha/mm/extable.c. 3 * 4 * Copyright (C) 1998, 1999, 2001-2002, 2004 Hewlett-Packard Co 5 * David Mosberger-Tang <davidm@hpl.hp.com> 6 */ 7 8 #include <linux/sort.h> 9 10 #include <asm/uaccess.h> 11 #include <linux/module.h> 12 13 static int cmp_ex(const void *a, const void *b) 14 { 15 const struct exception_table_entry *l = a, *r = b; 16 u64 lip = (u64) &l->addr + l->addr; 17 u64 rip = (u64) &r->addr + r->addr; 18 19 /* avoid overflow */ 20 if (lip > rip) 21 return 1; 22 if (lip < rip) 23 return -1; 24 return 0; 25 } 26 27 static void swap_ex(void *a, void *b, int size) 28 { 29 struct exception_table_entry *l = a, *r = b, tmp; 30 u64 delta = (u64) r - (u64) l; 31 32 tmp = *l; 33 l->addr = r->addr + delta; 34 l->cont = r->cont + delta; 35 r->addr = tmp.addr - delta; 36 r->cont = tmp.cont - delta; 37 } 38 39 /* 40 * Sort the exception table. It's usually already sorted, but there 41 * may be unordered entries due to multiple text sections (such as the 42 * .init text section). Note that the exception-table-entries contain 43 * location-relative addresses, which requires a bit of care during 44 * sorting to avoid overflows in the offset members (e.g., it would 45 * not be safe to make a temporary copy of an exception-table entry on 46 * the stack, because the stack may be more than 2GB away from the 47 * exception-table). 48 */ 49 void sort_extable (struct exception_table_entry *start, 50 struct exception_table_entry *finish) 51 { 52 sort(start, finish - start, sizeof(struct exception_table_entry), 53 cmp_ex, swap_ex); 54 } 55 56 static inline unsigned long ex_to_addr(const struct exception_table_entry *x) 57 { 58 return (unsigned long)&x->addr + x->addr; 59 } 60 61 #ifdef CONFIG_MODULES 62 /* 63 * Any entry referring to the module init will be at the beginning or 64 * the end. 65 */ 66 void trim_init_extable(struct module *m) 67 { 68 /*trim the beginning*/ 69 while (m->num_exentries && 70 within_module_init(ex_to_addr(&m->extable[0]), m)) { 71 m->extable++; 72 m->num_exentries--; 73 } 74 /*trim the end*/ 75 while (m->num_exentries && 76 within_module_init(ex_to_addr(&m->extable[m->num_exentries-1]), 77 m)) 78 m->num_exentries--; 79 } 80 #endif /* CONFIG_MODULES */ 81 82 const struct exception_table_entry * 83 search_extable (const struct exception_table_entry *first, 84 const struct exception_table_entry *last, 85 unsigned long ip) 86 { 87 const struct exception_table_entry *mid; 88 unsigned long mid_ip; 89 long diff; 90 91 while (first <= last) { 92 mid = &first[(last - first)/2]; 93 mid_ip = (u64) &mid->addr + mid->addr; 94 diff = mid_ip - ip; 95 if (diff == 0) 96 return mid; 97 else if (diff < 0) 98 first = mid + 1; 99 else 100 last = mid - 1; 101 } 102 return NULL; 103 } 104 105 void 106 ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e) 107 { 108 long fix = (u64) &e->cont + e->cont; 109 110 regs->r8 = -EFAULT; 111 if (fix & 4) 112 regs->r9 = 0; 113 regs->cr_iip = fix & ~0xf; 114 ia64_psr(regs)->ri = fix & 0x3; /* set continuation slot number */ 115 } 116