linux-kernel - Re: "stack state/frame" and "jump dest instruction" errors (was Re: Linux 6.16)

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Message-Id: <20250729224000.2f23f59acc79a78f47c1624f@kernel.org>
Date: Tue, 29 Jul 2025 22:40:00 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: "Alan J. Wylie" <alan@...ie.me.uk>, linux-kernel@...r.kernel.org,
 regressions@...ts.linux.dev, stable@...r.kernel.org, Linus Torvalds
 <torvalds@...ux-foundation.org>, Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: "stack state/frame" and "jump dest instruction" errors (was Re:
 Linux 6.16)

On Mon, 28 Jul 2025 08:42:44 -0700
Josh Poimboeuf <jpoimboe@...nel.org> wrote:

> On Mon, Jul 28, 2025 at 09:41:35AM +0100, Alan J. Wylie wrote:
> > #regzbot introduced: 6.15.8..6.16

> I don't have time to look at this for at least the next few days, but I
> suspect this one:
> 
>      1a3:	8f ea 78 10 c3 0a 06 00 00 	bextr  $0x60a,%ebx,%eax

Thanks for finding!
Indeed, this is encoded by XOP which is not currently supported
by x86 decodeer. 

> 
> in which case the kernel's x86 decoder (which objtool also uses) needs
> to be updated.

OK, let me see how XOP works.

Thank you,

-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>