From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=82.195.75.108 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793629704; b=HBXBtH5qQ9Kwh04K46kJw6ZBV6lH5fJ/+KtGvW+DnBnlZ9IIsf2hSAUJ8JfStWCKSFDM yU3q/J6KrkqYL4jaYAWhw/PiFAkAu1DNBWnAjQl0XpUciYJ98aVPaKma+VGI9tcYZsLX8 sATOdiisFX6KyHYRVO4j8Ktbc9ixkw9BwmpjR/V0GeE+cJ5xXY3cq/IAG6Q1wNZqljw0a k6vVw6XRPUbSPM84qx1qDhJW0Ia1qPmE89M3nUd0/DnSg57IQA+TcWUeq5BmUXh8BxwWk DgNpuHlTz5qDaW3M3QJtwYuwNmnB04LRPEno1DTdCjaDUFeJp/XXe30iC/jHhgn2vdA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793629704; h=DMARC-Filter:DKIM-Signature:Received:Date:From:To:Cc:Subject: Message-ID:References:MIME-Version:Content-Type:Content-Disposition: In-Reply-To:X-Debian-User; bh=0pK5ommQQILhJiDusmehxqIo5bMBDGkmBkDJ10oCG08=; b=jNg5Piw+t566sirLvTXuphbg1dElGzQFA931xSrTHJajlpdHBPur4Bqn58GxmOx/K9L/ t10S/oRaaCV0WTBSuuY2Pl5hQqA03aC34W/JS80r9VoN7+3mVHXQs2uKlVBQelFiehWXa /d5+jTme+VqB+uBxWgXZn9GdIsROVnfQUIPNUHmEHvJ4sP9jgiuy0ixnU+kzplmNec4Tj Hxy9aXEwchtmK73zuBaCeoj5t0jBeRHX7KsiwLMW8tEC3Q/CH5IdiCjZcGiFvjywqBeST ufaZxUMfoU4Pwng4o0O7M7fTMYEjqe2hSZvMtcGbfxsdJpr6alLndW36nNVsEu0RMlg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass header.d=debian.org header.i=@debian.org header.a=rsa-sha256 header.s=smtpauto.stravinsky header.b=UWtE8HH7; arc=none smtp.remote-ip=82.195.75.108 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 306566080A7B for ; Mon, 2 Nov 2026 14:28:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 306566080A7B Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=debian.org header.i=@debian.org header.a=rsa-sha256 header.s=smtpauto.stravinsky header.b=UWtE8HH7 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=0pK5ommQQILhJiDusmehxqIo5bMBDGkmBkDJ10oCG08=; b=UWtE8HH7eZ6iSZazPdkqJkDkIg cB50hz3vyI6tD7uicnv3+ep19TXlarSmv78cMQyCUgeL36Ii1DMKTXs4nngvBjtiVM6BvR8sZLCtQ uAH4PQs52SdmZD2okGbWOfIL/e8M6j5VhquxwLPJfA+XhZYfbp6UEqO04ViMp0aMXk+AQpjaWmCPS Up7Q+mHgFS0wH7IPIA80hewpdf/1jTUi9P/Yrrwj9IBWVo7Paq0T/8FIrWZv0FB4aEZ6GL7c9Y9lQ lgFpQL/NzFBoVg3hcRsiVb9WbK9rFiUidm9S2C0CWDnaBDpgE0vl9Vq5NOni509ue6gqDNZ5N0sTq APIDUVOA==; Received: from authenticated-user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1xNt1H-006DcX-1R; Mon, 02 Nov 2026 14:28:19 +0000 Date: Mon, 2 Nov 2026 06:28:14 -0800 From: Breno Leitao To: Peter Zijlstra 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 Message-ID: References: <20261102112549.714541309@infradead.org> <20261102114000.436794287@infradead.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261102114000.436794287@infradead.org> X-Debian-User: leitao 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) Thanks for the patchset. Tested-by: Breno Leitao