linux-kernel - Re: [PATCH -v2] x86/retpoline: Ensure default return thunk isn't used at runtime

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Date: Wed, 3 Apr 2024 22:26:19 +0200
From: Klara Modin <klarasmodin@...il.com>
To: Borislav Petkov <bp@...en8.de>
Cc: Josh Poimboeuf <jpoimboe@...nel.org>, "Kaplan, David"
 <David.Kaplan@....com>, Ingo Molnar <mingo@...nel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "linux-tip-commits@...r.kernel.org" <linux-tip-commits@...r.kernel.org>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 "x86@...nel.org" <x86@...nel.org>, David Howells <dhowells@...hat.com>
Subject: Re: [PATCH -v2] x86/retpoline: Ensure default return thunk isn't used
 at runtime

On 2024-04-03 19:30, Borislav Petkov wrote:
> On Wed, Apr 03, 2024 at 07:10:17PM +0200, Klara Modin wrote:
>> With this patch/commit, one of my machines (older P4 Xeon, 32-bit only)
>> hangs on boot with CONFIG_RETHUNK=y / CONFIG_MITIGATION_RETHUNK=y.
> 
> I wanna say your old P4 heater :) is not even affected by the crap the
> return thunks are trying to address so perhaps we should make
> CONFIG_MITIGATION_RETHUNK depend on !X86_32...
> 

Probably, I don't have much knowledge about this stuff. The machine can 
at least be useful for testing still :)