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
swap_ex_entry_fixup(struct exception_table_entry * a,struct exception_table_entry * b,struct exception_table_entry tmp,int delta)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