1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __PARISC_EXTABLE_H 3 #define __PARISC_EXTABLE_H 4 5 #include <asm/ptrace.h> 6 #include <linux/compiler.h> 7 8 /* 9 * The exception table consists of three addresses: 10 * 11 * - A relative address to the instruction that is allowed to fault. 12 * - A relative address at which the program should continue (fixup routine) 13 * - An asm statement which specifies which CPU register will 14 * receive -EFAULT when an exception happens if the lowest bit in 15 * the fixup address is set. 16 * 17 * Note: The register specified in the err_opcode instruction will be 18 * modified at runtime if a fault happens. Register %r0 will be ignored. 19 * 20 * Since relative addresses are used, 32bit values are sufficient even on 21 * 64bit kernel. 22 */ 23 24 struct pt_regs; 25 int fixup_exception(struct pt_regs *regs); 26 27 #define ARCH_HAS_RELATIVE_EXTABLE 28 struct exception_table_entry { 29 int insn; /* relative address of insn that is allowed to fault. */ 30 int fixup; /* relative address of fixup routine */ 31 int err_opcode; /* sample opcode with register which holds error code */ 32 }; 33 34 #define ASM_EXCEPTIONTABLE_ENTRY( fault_addr, except_addr, opcode )\ 35 ".section __ex_table,\"aw\"\n" \ 36 ".align 4\n" \ 37 ".word (" #fault_addr " - .), (" #except_addr " - .)\n" \ 38 opcode "\n" \ 39 ".previous\n" 40 41 /* 42 * ASM_EXCEPTIONTABLE_ENTRY_EFAULT() creates a special exception table entry 43 * (with lowest bit set) for which the fault handler in fixup_exception() will 44 * load -EFAULT on fault into the register specified by the err_opcode instruction, 45 * and zeroes the target register in case of a read fault in get_user(). 46 */ 47 #define ASM_EXCEPTIONTABLE_VAR(__err_var) \ 48 int __err_var = 0 49 #define ASM_EXCEPTIONTABLE_ENTRY_EFAULT( fault_addr, except_addr, register )\ 50 ASM_EXCEPTIONTABLE_ENTRY( fault_addr, except_addr + 1, "or %%r0,%%r0," register) 51 52 static inline void swap_ex_entry_fixup(struct exception_table_entry *a, 53 struct exception_table_entry *b, 54 struct exception_table_entry tmp, 55 int delta) 56 { 57 a->fixup = b->fixup + delta; 58 b->fixup = tmp.fixup - delta; 59 a->err_opcode = b->err_opcode; 60 b->err_opcode = tmp.err_opcode; 61 } 62 #define swap_ex_entry_fixup swap_ex_entry_fixup 63 64 #endif 65