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 <asm/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 const struct exception_table_entry * 57 search_extable (const struct exception_table_entry *first, 58 const struct exception_table_entry *last, 59 unsigned long ip) 60 { 61 const struct exception_table_entry *mid; 62 unsigned long mid_ip; 63 long diff; 64 65 while (first <= last) { 66 mid = &first[(last - first)/2]; 67 mid_ip = (u64) &mid->addr + mid->addr; 68 diff = mid_ip - ip; 69 if (diff == 0) 70 return mid; 71 else if (diff < 0) 72 first = mid + 1; 73 else 74 last = mid - 1; 75 } 76 return NULL; 77 } 78 79 void 80 ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e) 81 { 82 long fix = (u64) &e->cont + e->cont; 83 84 regs->r8 = -EFAULT; 85 if (fix & 4) 86 regs->r9 = 0; 87 regs->cr_iip = fix & ~0xf; 88 ia64_psr(regs)->ri = fix & 0x3; /* set continuation slot number */ 89 } 90