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/config.h> 9 #include <linux/sort.h> 10 11 #include <asm/uaccess.h> 12 #include <asm/module.h> 13 14 static int cmp_ex(const void *a, const void *b) 15 { 16 const struct exception_table_entry *l = a, *r = b; 17 u64 lip = (u64) &l->addr + l->addr; 18 u64 rip = (u64) &r->addr + r->addr; 19 20 /* avoid overflow */ 21 if (lip > rip) 22 return 1; 23 if (lip < rip) 24 return -1; 25 return 0; 26 } 27 28 static void swap_ex(void *a, void *b, int size) 29 { 30 struct exception_table_entry *l = a, *r = b, tmp; 31 u64 delta = (u64) r - (u64) l; 32 33 tmp = *l; 34 l->addr = r->addr + delta; 35 l->cont = r->cont + delta; 36 r->addr = tmp.addr - delta; 37 r->cont = tmp.cont - delta; 38 } 39 40 /* 41 * Sort the exception table. It's usually already sorted, but there 42 * may be unordered entries due to multiple text sections (such as the 43 * .init text section). Note that the exception-table-entries contain 44 * location-relative addresses, which requires a bit of care during 45 * sorting to avoid overflows in the offset members (e.g., it would 46 * not be safe to make a temporary copy of an exception-table entry on 47 * the stack, because the stack may be more than 2GB away from the 48 * exception-table). 49 */ 50 void sort_extable (struct exception_table_entry *start, 51 struct exception_table_entry *finish) 52 { 53 sort(start, finish - start, sizeof(struct exception_table_entry), 54 cmp_ex, swap_ex); 55 } 56 57 const struct exception_table_entry * 58 search_extable (const struct exception_table_entry *first, 59 const struct exception_table_entry *last, 60 unsigned long ip) 61 { 62 const struct exception_table_entry *mid; 63 unsigned long mid_ip; 64 long diff; 65 66 while (first <= last) { 67 mid = &first[(last - first)/2]; 68 mid_ip = (u64) &mid->addr + mid->addr; 69 diff = mid_ip - ip; 70 if (diff == 0) 71 return mid; 72 else if (diff < 0) 73 first = mid + 1; 74 else 75 last = mid - 1; 76 } 77 return NULL; 78 } 79 80 void 81 ia64_handle_exception (struct pt_regs *regs, const struct exception_table_entry *e) 82 { 83 long fix = (u64) &e->cont + e->cont; 84 85 regs->r8 = -EFAULT; 86 if (fix & 4) 87 regs->r9 = 0; 88 regs->cr_iip = fix & ~0xf; 89 ia64_psr(regs)->ri = fix & 0x3; /* set continuation slot number */ 90 } 91