1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_TEXT_PATCHING_H
3 #define _ASM_X86_TEXT_PATCHING_H
4
5 #include <linux/types.h>
6 #include <linux/stddef.h>
7 #include <asm/ptrace.h>
8
9 struct paravirt_patch_site;
10 #ifdef CONFIG_PARAVIRT
11 void apply_paravirt(struct paravirt_patch_site *start,
12 struct paravirt_patch_site *end);
13 #else
apply_paravirt(struct paravirt_patch_site * start,struct paravirt_patch_site * end)14 static inline void apply_paravirt(struct paravirt_patch_site *start,
15 struct paravirt_patch_site *end)
16 {}
17 #define __parainstructions NULL
18 #define __parainstructions_end NULL
19 #endif
20
21 extern void *text_poke_early(void *addr, const void *opcode, size_t len);
22
23 /*
24 * Clear and restore the kernel write-protection flag on the local CPU.
25 * Allows the kernel to edit read-only pages.
26 * Side-effect: any interrupt handler running between save and restore will have
27 * the ability to write to read-only pages.
28 *
29 * Warning:
30 * Code patching in the UP case is safe if NMIs and MCE handlers are stopped and
31 * no thread can be preempted in the instructions being modified (no iret to an
32 * invalid instruction possible) or if the instructions are changed from a
33 * consistent state to another consistent state atomically.
34 * On the local CPU you need to be protected again NMI or MCE handlers seeing an
35 * inconsistent instruction while you patch.
36 */
37 extern void *text_poke(void *addr, const void *opcode, size_t len);
38 extern int poke_int3_handler(struct pt_regs *regs);
39 extern void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler);
40
41 #ifndef CONFIG_UML_X86
int3_emulate_jmp(struct pt_regs * regs,unsigned long ip)42 static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
43 {
44 regs->ip = ip;
45 }
46
47 #define INT3_INSN_SIZE 1
48 #define CALL_INSN_SIZE 5
49
50 #ifdef CONFIG_X86_64
int3_emulate_push(struct pt_regs * regs,unsigned long val)51 static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
52 {
53 /*
54 * The int3 handler in entry_64.S adds a gap between the
55 * stack where the break point happened, and the saving of
56 * pt_regs. We can extend the original stack because of
57 * this gap. See the idtentry macro's create_gap option.
58 */
59 regs->sp -= sizeof(unsigned long);
60 *(unsigned long *)regs->sp = val;
61 }
62
int3_emulate_call(struct pt_regs * regs,unsigned long func)63 static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func)
64 {
65 int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
66 int3_emulate_jmp(regs, func);
67 }
68 #endif /* CONFIG_X86_64 */
69 #endif /* !CONFIG_UML_X86 */
70
71 #endif /* _ASM_X86_TEXT_PATCHING_H */
72