linux-kernel - Re: [PATCH v7 0/8] x86/kexec: Add exception handling for relocate

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Message-ID: <f14d092ac976b0f7fc60a45553ee6a4a36195ad9.camel@infradead.org>
Date: Fri, 14 Mar 2025 10:37:45 +0000
From: David Woodhouse <dwmw2@...radead.org>
To: Ingo Molnar <mingo@...nel.org>
Cc: kexec@...ts.infradead.org, Thomas Gleixner <tglx@...utronix.de>, Ingo
 Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
 <dave.hansen@...ux.intel.com>, x86@...nel.org, "H . Peter Anvin"
 <hpa@...or.com>,  "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
 Kai Huang <kai.huang@...el.com>, Nikolay Borisov <nik.borisov@...e.com>, 
 linux-kernel@...r.kernel.org, Simon Horman <horms@...nel.org>, Dave Young
 <dyoung@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
 jpoimboe@...nel.org,  bsz@...zon.de
Subject: Re: [PATCH v7 0/8] x86/kexec: Add exception handling for
 relocate_kernel

On Fri, 2025-03-14 at 11:21 +0100, Ingo Molnar wrote:
> 
> I've applied patch #1 back to tip:x86/boot.
> 
> I've skipped the -v7 versions of patch #2 and #3 because AFAICS you've 
> changed exc_handler already, so a backmerge of this annotation fix 
> wouldn't be enough.

I haven't (yet) changed exc_handler, but I did post that annotation fix
as a patch against patch 3 in the series, when actually it should be
applied as as fixup to patch 2.

I *am* cleaning up exc_handler in patch 3 though, for a more 'warm and
fuzzy' experience on int3 rather than dumping the full register set. So
I'll repost it from patch 2 against the new tip/x86/boot, including the
annotation fix in the right place.

Thanks.

I haven't yet decided what to do about the unconditional int3. Slightly
tempted to suggest we put it in #ifdef CONFIG_DEBUG_ENTRY now I've been
reminded that option exists? But we should *also* be doing better
testing of kexec-jump, with something like that test case I posted, and
adding an int3 into that would be trivial too.

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