From: Breno Leitao <leitao@debian.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
jpoimboe@kernel.org, keescook@chromium.org, hpa@zytor.com
Subject: Re: [PATCH 1/6] x86_64/entry: Unconditionally use -fno-jump-table
Date: Mon, 2 Nov 2026 06:28:14 -0800 [thread overview]
Message-ID: <auid5MjnGmbN4Iif@gmail.com> (raw)
In-Reply-To: <20261102114000.436794287@infradead.org>
On Mon, Nov 02, 2026 at 12:25:50PM +0100, Peter Zijlstra wrote:
> Currently we force -fno-jump-table for RETPOLINE=y || X86_KERNEL_IBT=y, which
> means that it is effectively disabled for most everyone these days.
>
> Simply unconditionally disable jump tables for x86_64 to take away the edge
> case.
>
> Doing so, allows removing the array_index_nospec() barrier in the syscall
> dispatch since it cannot be an array index anymore.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Thanks for the patchset.
Tested-by: Breno Leitao <leitao@debian.org>
next prev parent reply other threads:[~2026-11-02 14:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-02 11:25 [PATCH 0/6] x86: Harden syscall dispatch Peter Zijlstra
2026-11-02 11:25 ` [PATCH 1/6] x86_64/entry: Unconditionally use -fno-jump-table Peter Zijlstra
2026-11-02 14:28 ` Breno Leitao [this message]
2026-11-02 11:25 ` [PATCH 2/6] objtool: Add instrumentation_weak() Peter Zijlstra
2026-11-02 11:25 ` [PATCH 3/6] x86_64/entry: Make syscall dispatch noinstr Peter Zijlstra
2026-11-02 11:25 ` [PATCH 4/6] x86_64/entry: Mark all syscalls __noendbr Peter Zijlstra
2026-11-02 17:06 ` David Laight
2026-11-02 11:25 ` [PATCH 5/6] objtool: Allow EXPORT_SYMBOL() of __noendbr functions Peter Zijlstra
2026-11-02 11:25 ` [PATCH 6/6] x86_64/entry: Mark C noinstr __noendbr Peter Zijlstra
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