Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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
9struct paravirt_patch_site;
10#ifdef CONFIG_PARAVIRT
11void apply_paravirt(struct paravirt_patch_site *start,
12 struct paravirt_patch_site *end);
13#else
14static 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/*
22 * Currently, the max observed size in the kernel code is
23 * JUMP_LABEL_NOP_SIZE/RELATIVEJUMP_SIZE, which are 5.
24 * Raise it if needed.
25 */
26#define POKE_MAX_OPCODE_SIZE 5
27
28struct text_poke_loc {
29 void *addr;
30 int len;
31 s32 rel32;
32 u8 opcode;
33 const u8 text[POKE_MAX_OPCODE_SIZE];
34};
35
36extern void text_poke_early(void *addr, const void *opcode, size_t len);
37
38/*
39 * Clear and restore the kernel write-protection flag on the local CPU.
40 * Allows the kernel to edit read-only pages.
41 * Side-effect: any interrupt handler running between save and restore will have
42 * the ability to write to read-only pages.
43 *
44 * Warning:
45 * Code patching in the UP case is safe if NMIs and MCE handlers are stopped and
46 * no thread can be preempted in the instructions being modified (no iret to an
47 * invalid instruction possible) or if the instructions are changed from a
48 * consistent state to another consistent state atomically.
49 * On the local CPU you need to be protected against NMI or MCE handlers seeing
50 * an inconsistent instruction while you patch.
51 */
52extern void *text_poke(void *addr, const void *opcode, size_t len);
53extern void *text_poke_kgdb(void *addr, const void *opcode, size_t len);
54extern int poke_int3_handler(struct pt_regs *regs);
55extern void text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate);
56extern void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries);
57extern void text_poke_loc_init(struct text_poke_loc *tp, void *addr,
58 const void *opcode, size_t len, const void *emulate);
59extern int after_bootmem;
60extern __ro_after_init struct mm_struct *poking_mm;
61extern __ro_after_init unsigned long poking_addr;
62
63#ifndef CONFIG_UML_X86
64static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
65{
66 regs->ip = ip;
67}
68
69#define INT3_INSN_SIZE 1
70#define INT3_INSN_OPCODE 0xCC
71
72#define CALL_INSN_SIZE 5
73#define CALL_INSN_OPCODE 0xE8
74
75#define JMP32_INSN_SIZE 5
76#define JMP32_INSN_OPCODE 0xE9
77
78#define JMP8_INSN_SIZE 2
79#define JMP8_INSN_OPCODE 0xEB
80
81static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
82{
83 /*
84 * The int3 handler in entry_64.S adds a gap between the
85 * stack where the break point happened, and the saving of
86 * pt_regs. We can extend the original stack because of
87 * this gap. See the idtentry macro's create_gap option.
88 */
89 regs->sp -= sizeof(unsigned long);
90 *(unsigned long *)regs->sp = val;
91}
92
93static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func)
94{
95 int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
96 int3_emulate_jmp(regs, func);
97}
98#endif /* !CONFIG_UML_X86 */
99
100#endif /* _ASM_X86_TEXT_PATCHING_H */