Re: [PATCH] uprobes/x86: allow to probe a "nop" insn with 0x66 prefix

From: Thomas Gleixner
Date: Fri Dec 02 2022 - 06:52:25 EST


On Thu, Dec 01 2022 at 15:26, Oleg Nesterov wrote:

> From: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
>
> Intel icc -hotpatch inserts 2-byte "0x66 0x90" NOP at the start of each
> function to reserve extra space for hot-patching, and currently it is not
> possible to probe these functions because branch_setup_xol_ops() wrongly
> nacks NOP with REP prefix.
>
> Fixes: 250bbd12c2fe ("uprobes/x86: Refuse to attach uprobe to "word-sized" branch insns")
> Reported-by: Seiji Nishikawa <snishika@xxxxxxxxxx>
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>

The SOB chain is invalid as it lacks the author's signoff.