diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2020-08-18 16:57:47 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-09-01 10:58:05 +0300 |
| commit | c43a43e439e00ad2a4d98716895d961ade6bbbfc (patch) | |
| tree | f0432ac71a822b7167a53d524b1a8f09e754f60d | |
| parent | f03c412915f5f69f2d17bcd20ecdd69320bcbf7b (diff) | |
| download | linux-c43a43e439e00ad2a4d98716895d961ade6bbbfc.tar.xz | |
x86/alternatives: Teach text_poke_bp() to emulate RET
Future patches will need to poke a RET instruction, provide the
infrastructure required for this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20200818135804.982214828@infradead.org
| -rw-r--r-- | arch/x86/include/asm/text-patching.h | 19 | ||||
| -rw-r--r-- | arch/x86/kernel/alternative.c | 5 |
2 files changed, 24 insertions, 0 deletions
diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h index 6593b42cb379..b7421780e4e9 100644 --- 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 __always_inline int text_opcode_size(u8 opcode) switch(opcode) { __CASE(INT3); + __CASE(RET); __CASE(CALL); __CASE(JMP32); __CASE(JMP8); @@ -141,11 +145,26 @@ void int3_emulate_push(struct pt_regs *regs, unsigned long val) } static __always_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 __always_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 __always_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 */ diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index cdaab30880b9..4adbe65afe23 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -1103,6 +1103,10 @@ noinstr int poke_int3_handler(struct pt_regs *regs) */ 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; @@ -1277,6 +1281,7 @@ static void text_poke_loc_init(struct text_poke_loc *tp, void *addr, switch (tp->opcode) { case INT3_INSN_OPCODE: + case RET_INSN_OPCODE: break; case CALL_INSN_OPCODE: |