Since CONFIG_RETPOLINE hard depends on compiler support now, so replacing indirect-jump check with the range check is safe in that case.
Signed-off-by: Zhenzhong Duan <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: David Woodhouse <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Konrad Rzeszutek Wilk <[email protected]> --- arch/x86/kernel/kprobes/opt.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index 40b16b2..1136b29 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -203,6 +203,7 @@ static int copy_optimized_instructions(u8 *dest, u8 *src, u8 *real) return len; } +#ifndef CONFIG_RETPOLINE /* Check whether insn is indirect jump */ static int __insn_is_indirect_jump(struct insn *insn) { @@ -210,6 +211,7 @@ static int __insn_is_indirect_jump(struct insn *insn) (X86_MODRM_REG(insn->modrm.value) & 6) == 4) || /* Jump */ insn->opcode.bytes[0] == 0xea); /* Segment based jump */ } +#endif /* Check whether insn jumps into specified address range */ static int insn_jump_into_range(struct insn *insn, unsigned long start, int len) @@ -240,20 +242,16 @@ static int insn_jump_into_range(struct insn *insn, unsigned long start, int len) static int insn_is_indirect_jump(struct insn *insn) { - int ret = __insn_is_indirect_jump(insn); + int ret; #ifdef CONFIG_RETPOLINE - /* - * Jump to x86_indirect_thunk_* is treated as an indirect jump. - * Note that even with CONFIG_RETPOLINE=y, the kernel compiled with - * older gcc may use indirect jump. So we add this check instead of - * replace indirect-jump check. - */ - if (!ret) + /* Jump to x86_indirect_thunk_* is treated as an indirect jump. */ ret = insn_jump_into_range(insn, (unsigned long)__indirect_thunk_start, (unsigned long)__indirect_thunk_end - (unsigned long)__indirect_thunk_start); +#else + ret = __insn_is_indirect_jump(insn); #endif return ret; } -- 1.8.3.1
