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

On Tue, 29 Jul 2025 22:40:00 +0900 Masami Hiramatsu (Google) mhiramat@kernel.org wrote:

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

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On Mon, Jul 28, 2025 at 09:41:35AM +0100, Alan J. Wylie wrote:

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#regzbot introduced: 6.15.8..6.16

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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.

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

OK, let me see how XOP works.

I've sent it to;

https://lore.kernel.org/all/175386161199.564247.597496379413236944.stgit@dev...

I confirmed it worked with the XOP encoded "bextr".

Thank you,