From: Peter Zijlstra <peterz@infradead.org>
To: Kees Cook <kees@kernel.org>
Cc: Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Sami Tolvanen <samitolvanen@google.com>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Bill Wendling <morbo@google.com>,
Justin Stitt <justinstitt@google.com>,
x86@kernel.org, llvm@lists.linux.dev,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH 2/3] x86/kcfi: Emit the FineIBT paranoid "cs" prefix as a byte
Date: Mon, 12 Oct 2026 11:16:01 +0200 [thread overview]
Message-ID: <20261012091601.GN4121339@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20261012090436.1676525-2-kees@kernel.org>
On Mon, Oct 12, 2026 at 02:04:25AM -0700, Kees Cook wrote:
> The "cs" prefix on the LEA in the FineIBT paranoid caller template is
> padding: it places the LEA's 0xf0 immediate byte where it doubles as the
> LOCK prefix that makes the failing Jcc raise #UD. GNU as warns about it
> in every CONFIG_FINEIBT=y build:
>
> Warning: segment override on `lea' is ineffectual
Shees...
next prev parent reply other threads:[~2026-10-12 9:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-12 9:04 [PATCH 0/3] x86/cfi: Fix a few kCFI issues found with GCC Kees Cook
2026-10-12 9:04 ` [PATCH 1/3] x86/kcfi: Decode the kCFI check from the trap address Kees Cook
2026-10-12 9:59 ` [tip: x86/urgent] " tip-bot2 for Kees Cook
2026-10-12 9:04 ` [PATCH 2/3] x86/kcfi: Emit the FineIBT paranoid "cs" prefix as a byte Kees Cook
2026-10-12 9:16 ` Peter Zijlstra [this message]
2026-10-12 19:05 ` Andrew Cooper
2026-10-12 9:59 ` [tip: x86/core] " tip-bot2 for Kees Cook
2026-10-12 9:04 ` [PATCH 3/3] objtool: Skip jump table jumps in the kCFI indirect call check Kees Cook
2026-10-12 9:22 ` Peter Zijlstra
2026-10-12 18:41 ` Kees Cook
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