From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.alien8.de (mail.alien8.de [65.109.113.108]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0901D46F4AD for ; Wed, 12 Aug 2026 15:31:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=65.109.113.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786548695; cv=none; b=C7ASKEPZdAlMKggj444ahxKglA3xBG5EkYoTGMAFswoCyhzR7qKWKxwFYz3LyBfDEwI5FImfmNyrMyomQApcJvGNGqcaXDQWkEyf9U27CvcaDKEGbjK8BRqB1W1z08iomt4riTdBR+hpCQrVJyJ26JxKtxbmh8QggdTIBmv2e8c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786548695; c=relaxed/simple; bh=NwKdtaaeIH7kwN99cZyDu0zSqLCivRFnSVWpkKzoZVA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NTJxFVRi05MgwYF7LfWG08I9SQzliNVY/46fUhBWWcT8u756Dh2QSwYWDdm8R+cEVrdjyKkOZUTQgJL3zLi+gVnZ+87E8pTmx/z4+y0KDxGvY6DJTfnBIpnLulpHVX6djMzkABLcC1YBL2do1eu2TtQQMmCZcdOUK6GV2wz4LHk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de; spf=pass smtp.mailfrom=alien8.de; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b=eG8yZEvW; arc=none smtp.client-ip=65.109.113.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=alien8.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b="eG8yZEvW" Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTP id 2386A40E019C; Wed, 12 Aug 2026 15:31:23 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at mail.alien8.de Authentication-Results: mail.alien8.de (amavisd-new); dkim=pass (4096-bit key) header.d=alien8.de Received: from mail.alien8.de ([127.0.0.1]) by localhost (mail.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id iyw6-b3x8sZZ; Wed, 12 Aug 2026 15:31:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=alien8; t=1786548673; bh=f1UG+hWKidCd/dbM3M50lrKVIbrlIa/B3E78WIemYbs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eG8yZEvWL8bGwkUqyzp6Ov8iLxbgjG6BGN/5/H/jS+ldD0PP85Afr2F20i54FtocL 6+fLjePgcdfvi+krALllXLKmjMOT4KOEfcM+cfKjeRNNsmOATlCNB+JxupVJr+NGzT ni2/5nq5Yy65dVGXJs5E2sGznAqqmJxOJloCuBgh7/IOYChLuFXJ62zMmxDIGMfk9z Z1ICygz6IYRC+8h9+col6hagHmzqBc2Yn5hhp7DEXyzV4rl1hNZV6SzbUgjd2VatWV kwTk9vWxLKSGlgnYHNkP0Ns3G1NYzaFBvC3+qvB2N4+t9jFx1oO52RtjCCJW3dK90W sjDxbZdTya5fmCVpImyDw8oh9iGh5JHau/7MzGDoqmzzHRW5ELQRX+9Oo4nVPFrlHZ VGcjGKF9dRbNYITL5r+LaSUQfgomDoqYUEElWrTCk2ClXrZSNWUmNVHI69WIxRrV8D FB6BooUzSXXfrjrgl6SkaqOfsk+7VCFxColnHJl9xV1hhWPMn+TLaQ9+gszvDdPyH+ TDoz3FMiQYULLczOEQI/JvDSFKuJec8uXhfhpSuAdel0VrU0nDUakS7DSt6H1EDwQe WqucVJFfTU3bK3oySmOPcnesuGQlmJt0bsk6wHqGKsgwPI43x6LZKcaJFQHzSXOLG2 +DrDU/c2QMXJmnUazYggElco= Received: from stx.tnic (unknown [IPv6:2600:1700:38ca:c00::1b]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 9A98440E0198; Wed, 12 Aug 2026 15:31:00 +0000 (UTC) Date: Wed, 12 Aug 2026 08:30:56 -0700 From: Borislav Petkov To: "H. Peter Anvin" Cc: Peter Zijlstra , =?utf-8?B?5p2O5YiZ6Imv?= , =?utf-8?B?SsO8cmdlbiBHcm/Dnw==?= , Thomas Gleixner , Ingo Molnar , Dave Hansen , x86@kernel.org, Kees Cook , Nathan Chancellor , Josh Poimboeuf , linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/alternatives: gracefully skip unrecognized indirect call instructions Message-ID: <20260812153056.GAanyRsELYJPNAwluf@fat_crate.local> References: <191300ae-0f0d-430e-955f-bdd2aea4997e@suse.com> <20260812110023.GL776954@noisy.programming.kicks-ass.net> <0232397A-11D1-409E-8C85-E1E63EB4D181@zytor.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <0232397A-11D1-409E-8C85-E1E63EB4D181@zytor.com> On Wed, Aug 12, 2026 at 04:24:37AM -0700, H. Peter Anvin wrote: > >I don't think we want to cater for this. But what actual instruction > >sequences is it emitting? > > I'm kind of surprised the kernel compiles with -O0 at all; it certainly didn't used to. -Og was created for a reason. I'm with PeterZ on this. If you hack the tree to modify KCFLAGS, then you get to keep the pieces too. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette