arch/x86/include/asm/text-patching.h

   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
  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
  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
  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
  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 */