Re: [PATCH] x86/alternatives: gracefully skip unrecognized indirect call instructions

[Peter Zijlstra]

On Wed, Aug 12, 2026 at 05:22:14PM +0800, 李则良 wrote:
> From cd58bd112a6178593c6bc9c0f9b307d6897ae3d0 Mon Sep 17 00:00:00 2001
> From: Zeliang Li <lizeliang.linux@xxxxxxxxx>
> Date: Tue, 11 Aug 2026 19:09:09 +0800
> Subject: [PATCH v2] x86/alternative: WARN and skip unrecognized indirect call
>  only for non-O2 builds
> 
> When the kernel is compiled at a non-default optimization level
> (e.g., KCFLAGS=-O1 or -O0), the compiler may emit call instruction
> patterns that differ from the expected 6-byte sequence
> (opcodes 0xff 0x15 followed by a 32-bit displacement) checked
> by alt_replace_call().

I don't think we want to cater for this. But what actual instruction
sequences is it emitting?