From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Bill Wendling" <morbo@google.com>,
"Nathan Chancellor" <nathan@kernel.org>,
"Josh Poimboeuf" <jpoimboe@kernel.org>,
"Harry Wentland" <harry.wentland@amd.com>,
"Leo Li" <sunpeng.li@amd.com>,
"Alex Deucher" <alexander.deucher@amd.com>,
"Christian König" <christian.koenig@amd.com>,
"David Airlie" <airlied@gmail.com>,
"Simona Vetter" <simona@ffwll.ch>,
"Nick Desaulniers" <nick.desaulniers+lkml@gmail.com>,
"Justin Stitt" <justinstitt@google.com>,
"the arch/x86 maintainers" <x86@kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
llvm@lists.linux.dev
Subject: Re: clang and drm issue: objtool warnings from clang build
Date: Tue, 29 Apr 2025 11:17:42 +0200 [thread overview]
Message-ID: <20250429091742.GF4198@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <CAHk-=wgrT9++rFTnM1vh3bwx2Pcc18anDGQCwEL+0d2nDm3p+A@mail.gmail.com>
On Mon, Apr 28, 2025 at 12:34:27PM -0700, Linus Torvalds wrote:
> And yes, this really is a very potential and real security issue. In
> the kernel I don't think we have this ever happening, partly because a
> lot of configurations use gcc which afaik doesn't have this particular
> horrendous model of UD.
I see more and more people use clang, in a large part because of Rust.
Anyway, I've seen clang pull this stop-codegen-on-UB trick before (link
was upstream in the thread) and yes, it is horrific crap. At the time I
proposed emitting at the very least a UD2 instruction rather than just
straight up stopping code gen, but I think your proposal for a code-gen
knob to just not do this 'optimisation' at all is much better.
next prev parent reply other threads:[~2025-04-29 9:17 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-26 17:42 clang and drm issue: objtool warnings from clang build Linus Torvalds
2025-04-26 17:52 ` Linus Torvalds
2025-04-26 20:05 ` Nathan Chancellor
2025-04-26 20:56 ` Linus Torvalds
2025-04-26 23:23 ` Nathan Chancellor
2025-04-27 0:31 ` Linus Torvalds
2025-04-28 18:08 ` Bill Wendling
2025-04-28 19:34 ` Linus Torvalds
2025-04-28 19:54 ` Josh Poimboeuf
2025-04-28 20:57 ` Linus Torvalds
2025-04-28 20:58 ` Bill Wendling
2025-04-29 9:17 ` Peter Zijlstra [this message]
2025-04-28 17:53 ` Bill Wendling
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