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 void *text_poke_kgdb(void *addr, const void *opcode, size_t len); 39 extern int poke_int3_handler(struct pt_regs *regs); 40 extern void text_poke_bp(void *addr, const void *opcode, size_t len, void *handler); 41 extern int after_bootmem; 42 extern __ro_after_init struct mm_struct *poking_mm; 43 extern __ro_after_init unsigned long poking_addr; 44 45 #ifndef CONFIG_UML_X86 46 static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip) 47 { 48 regs->ip = ip; 49 } 50 51 #define INT3_INSN_SIZE 1 52 #define CALL_INSN_SIZE 5 53 54 #ifdef CONFIG_X86_64 55 static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val) 56 { 57 /* 58 * The int3 handler in entry_64.S adds a gap between the 59 * stack where the break point happened, and the saving of 60 * pt_regs. We can extend the original stack because of 61 * this gap. See the idtentry macro's create_gap option. 62 */ 63 regs->sp -= sizeof(unsigned long); 64 *(unsigned long *)regs->sp = val; 65 } 66 67 static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func) 68 { 69 int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE); 70 int3_emulate_jmp(regs, func); 71 } 72 #endif /* CONFIG_X86_64 */ 73 #endif /* !CONFIG_UML_X86 */ 74 75 #endif /* _ASM_X86_TEXT_PATCHING_H */ 76