Future patches will need to poke a RET instruction, provide the infrastructure required for this.
Signed-off-by: Peter Zijlstra (Intel) <[email protected]> --- arch/x86/include/asm/text-patching.h | 17 +++++++++++++++++ arch/x86/kernel/alternative.c | 5 +++++ 2 files changed, 22 insertions(+) --- a/arch/x86/include/asm/text-patching.h +++ b/arch/x86/include/asm/text-patching.h @@ -53,6 +53,9 @@ extern void text_poke_finish(void); #define INT3_INSN_SIZE 1 #define INT3_INSN_OPCODE 0xCC +#define RET_INSN_SIZE 1 +#define RET_INSN_OPCODE 0xC3 + #define CALL_INSN_SIZE 5 #define CALL_INSN_OPCODE 0xE8 @@ -73,6 +76,7 @@ static inline int text_opcode_size(u8 op switch(opcode) { __CASE(INT3); + __CASE(RET); __CASE(CALL); __CASE(JMP32); __CASE(JMP8); @@ -138,11 +142,24 @@ static inline void int3_emulate_push(str *(unsigned long *)regs->sp = val; } +static inline unsigned long int3_emulate_pop(struct pt_regs *regs) +{ + unsigned long val = *(unsigned long *)regs->sp; + regs->sp += sizeof(unsigned long); + return val; +} + static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func) { int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE); int3_emulate_jmp(regs, func); } + +static inline void int3_emulate_ret(struct pt_regs *regs) +{ + unsigned long ip = int3_emulate_pop(regs); + int3_emulate_jmp(regs, ip); +} #endif /* !CONFIG_UML_X86 */ #endif /* _ASM_X86_TEXT_PATCHING_H */ --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -1045,6 +1045,10 @@ int notrace poke_int3_handler(struct pt_ */ goto out_put; + case RET_INSN_OPCODE: + int3_emulate_ret(regs); + break; + case CALL_INSN_OPCODE: int3_emulate_call(regs, (long)ip + tp->rel32); break; @@ -1187,6 +1191,7 @@ void text_poke_loc_init(struct text_poke switch (tp->opcode) { case INT3_INSN_OPCODE: + case RET_INSN_OPCODE: break; case CALL_INSN_OPCODE:
