1 /* 2 * Copyright (C) 1999 Magnus Damm <kieraypc01.p.y.kie.era.ericsson.se> 3 * 4 * (C) Copyright 2000 5 * Wolfgang Denk, DENX Software Engineering, wd@denx.de. 6 * 7 * SPDX-License-Identifier: GPL-2.0+ 8 */ 9 #include <common.h> 10 11 /* 12 * The exception table consists of pairs of addresses: the first is the 13 * address of an instruction that is allowed to fault, and the second is 14 * the address at which the program should continue. No registers are 15 * modified, so it is entirely up to the continuation code to figure out 16 * what to do. 17 * 18 * All the routines below use bits of fixup code that are out of line 19 * with the main instruction path. This means when everything is well, 20 * we don't even have to jump over them. Further, they do not intrude 21 * on our cache or tlb entries. 22 */ 23 24 struct exception_table_entry 25 { 26 unsigned long insn, fixup; 27 }; 28 29 extern const struct exception_table_entry __start___ex_table[]; 30 extern const struct exception_table_entry __stop___ex_table[]; 31 32 static inline unsigned long 33 search_one_table(const struct exception_table_entry *first, 34 const struct exception_table_entry *last, 35 unsigned long value) 36 { 37 long diff; 38 while (first <= last) { 39 diff = first->insn - value; 40 if (diff == 0) 41 return first->fixup; 42 first++; 43 } 44 45 return 0; 46 } 47 48 unsigned long 49 search_exception_table(unsigned long addr) 50 { 51 unsigned long ret; 52 53 /* There is only the kernel to search. */ 54 ret = search_one_table(__start___ex_table, __stop___ex_table-1, addr); 55 /* if the serial port does not hang in exception, printf can be used */ 56 #if !defined(CONFIG_SYS_SERIAL_HANG_IN_EXCEPTION) 57 debug("Bus Fault @ 0x%08lx, fixup 0x%08lx\n", addr, ret); 58 #endif 59 if (ret) return ret; 60 61 return 0; 62 } 63