diff options
| author | Peter Zijlstra <[email protected]> | 2022-06-14 23:15:40 +0200 |
|---|---|---|
| committer | Borislav Petkov <[email protected]> | 2022-06-27 10:33:58 +0200 |
| commit | 1f001e9da6bbf482311e45e48f53c2bd2179e59c (patch) | |
| tree | 13fca8c49b5b1f687e8e14cc1f87206186119412 | |
| parent | ee88d363d15617ff50ac24fab0ffec11113b2aeb (diff) | |
x86/ftrace: Use alternative RET encoding
Use the return thunk in ftrace trampolines, if needed.
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Josh Poimboeuf <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
| -rw-r--r-- | arch/x86/kernel/ftrace.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 5b4efc927d80..24b9fa89aa27 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -301,7 +301,7 @@ union ftrace_op_code_union { } __attribute__((packed)); }; -#define RET_SIZE 1 + IS_ENABLED(CONFIG_SLS) +#define RET_SIZE (IS_ENABLED(CONFIG_RETPOLINE) ? 5 : 1 + IS_ENABLED(CONFIG_SLS)) static unsigned long create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size) @@ -357,7 +357,10 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size) goto fail; ip = trampoline + size; - memcpy(ip, retq, RET_SIZE); + if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) + __text_gen_insn(ip, JMP32_INSN_OPCODE, ip, &__x86_return_thunk, JMP32_INSN_SIZE); + else + memcpy(ip, retq, sizeof(retq)); /* No need to test direct calls on created trampolines */ if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) { |