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SubjectRe: [PATCH 3/3] kprobes/x86: Simplify indirect-jump check in retpoline
On Mon, Oct 29, 2018 at 11:55:06PM -0700, Zhenzhong Duan wrote:
> Since CONFIG_RETPOLINE hard depends on compiler support now, so
> replacing indirect-jump check with the range check is safe in that case.

Can we put kprobes on module init text before we run alternatives on it?

> @@ -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;
> }

The resulting code is indented wrong.

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