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170 lines
4.4 KiB
170 lines
4.4 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef _ASM_X86_TEXT_PATCHING_H |
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#define _ASM_X86_TEXT_PATCHING_H |
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#include <linux/types.h> |
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#include <linux/stddef.h> |
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#include <asm/ptrace.h> |
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struct paravirt_patch_site; |
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#ifdef CONFIG_PARAVIRT |
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void apply_paravirt(struct paravirt_patch_site *start, |
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struct paravirt_patch_site *end); |
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#else |
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static inline void apply_paravirt(struct paravirt_patch_site *start, |
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struct paravirt_patch_site *end) |
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{} |
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#define __parainstructions NULL |
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#define __parainstructions_end NULL |
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#endif |
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/* |
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* Currently, the max observed size in the kernel code is |
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* JUMP_LABEL_NOP_SIZE/RELATIVEJUMP_SIZE, which are 5. |
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* Raise it if needed. |
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*/ |
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#define POKE_MAX_OPCODE_SIZE 5 |
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extern void text_poke_early(void *addr, const void *opcode, size_t len); |
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/* |
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* Clear and restore the kernel write-protection flag on the local CPU. |
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* Allows the kernel to edit read-only pages. |
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* Side-effect: any interrupt handler running between save and restore will have |
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* the ability to write to read-only pages. |
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* |
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* Warning: |
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* Code patching in the UP case is safe if NMIs and MCE handlers are stopped and |
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* no thread can be preempted in the instructions being modified (no iret to an |
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* invalid instruction possible) or if the instructions are changed from a |
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* consistent state to another consistent state atomically. |
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* On the local CPU you need to be protected against NMI or MCE handlers seeing |
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* an inconsistent instruction while you patch. |
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*/ |
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extern void *text_poke(void *addr, const void *opcode, size_t len); |
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extern void text_poke_sync(void); |
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extern void *text_poke_kgdb(void *addr, const void *opcode, size_t len); |
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extern int poke_int3_handler(struct pt_regs *regs); |
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extern void text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate); |
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extern void text_poke_queue(void *addr, const void *opcode, size_t len, const void *emulate); |
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extern void text_poke_finish(void); |
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#define INT3_INSN_SIZE 1 |
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#define INT3_INSN_OPCODE 0xCC |
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#define RET_INSN_SIZE 1 |
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#define RET_INSN_OPCODE 0xC3 |
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#define CALL_INSN_SIZE 5 |
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#define CALL_INSN_OPCODE 0xE8 |
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#define JMP32_INSN_SIZE 5 |
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#define JMP32_INSN_OPCODE 0xE9 |
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#define JMP8_INSN_SIZE 2 |
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#define JMP8_INSN_OPCODE 0xEB |
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#define DISP32_SIZE 4 |
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static __always_inline int text_opcode_size(u8 opcode) |
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{ |
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int size = 0; |
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#define __CASE(insn) \ |
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case insn##_INSN_OPCODE: size = insn##_INSN_SIZE; break |
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switch(opcode) { |
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__CASE(INT3); |
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__CASE(RET); |
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__CASE(CALL); |
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__CASE(JMP32); |
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__CASE(JMP8); |
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} |
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#undef __CASE |
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return size; |
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} |
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union text_poke_insn { |
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u8 text[POKE_MAX_OPCODE_SIZE]; |
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struct { |
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u8 opcode; |
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s32 disp; |
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} __attribute__((packed)); |
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}; |
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static __always_inline |
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void *text_gen_insn(u8 opcode, const void *addr, const void *dest) |
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{ |
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static union text_poke_insn insn; /* per instance */ |
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int size = text_opcode_size(opcode); |
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insn.opcode = opcode; |
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if (size > 1) { |
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insn.disp = (long)dest - (long)(addr + size); |
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if (size == 2) { |
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/* |
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* Ensure that for JMP9 the displacement |
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* actually fits the signed byte. |
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*/ |
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BUG_ON((insn.disp >> 31) != (insn.disp >> 7)); |
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} |
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} |
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return &insn.text; |
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} |
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extern int after_bootmem; |
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extern __ro_after_init struct mm_struct *poking_mm; |
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extern __ro_after_init unsigned long poking_addr; |
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#ifndef CONFIG_UML_X86 |
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static __always_inline |
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void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip) |
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{ |
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regs->ip = ip; |
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} |
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static __always_inline |
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void int3_emulate_push(struct pt_regs *regs, unsigned long val) |
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{ |
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/* |
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* The int3 handler in entry_64.S adds a gap between the |
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* stack where the break point happened, and the saving of |
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* pt_regs. We can extend the original stack because of |
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* this gap. See the idtentry macro's create_gap option. |
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* |
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* Similarly entry_32.S will have a gap on the stack for (any) hardware |
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* exception and pt_regs; see FIXUP_FRAME. |
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*/ |
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regs->sp -= sizeof(unsigned long); |
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*(unsigned long *)regs->sp = val; |
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} |
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static __always_inline |
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unsigned long int3_emulate_pop(struct pt_regs *regs) |
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{ |
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unsigned long val = *(unsigned long *)regs->sp; |
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regs->sp += sizeof(unsigned long); |
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return val; |
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} |
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static __always_inline |
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void int3_emulate_call(struct pt_regs *regs, unsigned long func) |
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{ |
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int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE); |
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int3_emulate_jmp(regs, func); |
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} |
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static __always_inline |
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void int3_emulate_ret(struct pt_regs *regs) |
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{ |
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unsigned long ip = int3_emulate_pop(regs); |
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int3_emulate_jmp(regs, ip); |
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} |
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#endif /* !CONFIG_UML_X86 */ |
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#endif /* _ASM_X86_TEXT_PATCHING_H */
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