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

INCLUDED FROM

DEFINITIONS

1. apply_paravirt
2. int3_emulate_jmp
3. int3_emulate_push
4. int3_emulate_call

   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 /*
  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 
  28 struct text_poke_loc {
  29         void *detour;
  30         void *addr;
  31         size_t len;
  32         const char opcode[POKE_MAX_OPCODE_SIZE];
  33 };
  34 
  35 extern void text_poke_early(void *addr, const void *opcode, size_t len);
  36 
  37 /*
  38  * Clear and restore the kernel write-protection flag on the local CPU.
  39  * Allows the kernel to edit read-only pages.
  40  * Side-effect: any interrupt handler running between save and restore will have
  41  * the ability to write to read-only pages.
  42  *
  43  * Warning:
  44  * Code patching in the UP case is safe if NMIs and MCE handlers are stopped and
  45  * no thread can be preempted in the instructions being modified (no iret to an
  46  * invalid instruction possible) or if the instructions are changed from a
  47  * consistent state to another consistent state atomically.
  48  * On the local CPU you need to be protected against NMI or MCE handlers seeing
  49  * an inconsistent instruction while you patch.
  50  */
  51 extern void *text_poke(void *addr, const void *opcode, size_t len);
  52 extern void *text_poke_kgdb(void *addr, const void *opcode, size_t len);
  53 extern int poke_int3_handler(struct pt_regs *regs);
  54 extern void text_poke_bp(void *addr, const void *opcode, size_t len, void *handler);
  55 extern void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries);
  56 extern int after_bootmem;
  57 extern __ro_after_init struct mm_struct *poking_mm;
  58 extern __ro_after_init unsigned long poking_addr;
  59 
  60 #ifndef CONFIG_UML_X86
  61 static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
  62 {
  63         regs->ip = ip;
  64 }
  65 
  66 #define INT3_INSN_SIZE 1
  67 #define CALL_INSN_SIZE 5
  68 
  69 static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
  70 {
  71         /*
  72          * The int3 handler in entry_64.S adds a gap between the
  73          * stack where the break point happened, and the saving of
  74          * pt_regs. We can extend the original stack because of
  75          * this gap. See the idtentry macro's create_gap option.
  76          */
  77         regs->sp -= sizeof(unsigned long);
  78         *(unsigned long *)regs->sp = val;
  79 }
  80 
  81 static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func)
  82 {
  83         int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
  84         int3_emulate_jmp(regs, func);
  85 }
  86 #endif /* !CONFIG_UML_X86 */
  87 
  88 #endif /* _ASM_X86_TEXT_PATCHING_H */