From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 69C54496D56; Tue, 15 Sep 2026 11:59:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789473597; cv=none; b=kP6tIeRr+wKycC1UVAbF2F3RGzL+pFP/1EzpZZubv1Y1b9nxd6qfyNNumpstKkug0PuZjadzFWnOoDCPZJtYBU9c2TPDyFELPb8BsMFvXRPtRIvorsI01IiBZtoYLd+XUMOo8aPE3L6Chsck4E9Rgv75t1SaeiACX5Vk9QK7Row= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789473597; c=relaxed/simple; bh=LV6KjSBSCoMl1BpNEbGW5jNdELn3H1EoTm8/n0WGG8s=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=jPwA1RNrFhKRcDvu12rRUAT1BS1mGEHkUb6wnOGk8K239lJU5gteXgbRMClHR3Jm1pKTQz+VH3DlD9oXhllDb7jGfhdLiwANNH/G3Bgvx1Q1X7XAFZseZxZTHNlWaatubvaoEFdDAXZ+rU/+47J/YQFapITNcHrY8nhQAg+n49A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LuDfDBIp; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LuDfDBIp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B93C1F00893; Tue, 15 Sep 2026 11:59:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789473596; bh=XROzleDAWNHKip4xHBVteIb0cCuN7FAQoMQU9zewp/g=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=LuDfDBIpgc+rUudqugD7YWLMIYTyPSh1djqeFTSZvIqwl+MCFr2F9Jod5sQ3BdeBH Fs4P2kaC4Rq/e2WctPCUaANEEugIP/+ZEAefkQjg3r930Bx3+wPmgnd43osNu5U8C9 EyuNiUbu78gNfTdrTeVFFD2nhC1r5SHLm94AIfGff4/9p19OhtUCSOkAUYL8ijEd9H l9DN/Fa9wQdaggqiklG21wysLrbu7J9tNRHYcAgnuhIFYUQdGWbvPhv23a8BBnteix dj3Dz8036WkGhtwkv8ziLkCVxCa1RZBk5Y1nQhcVea1ZYeF0cF/u11/S008mj3HeiR /EId/I6+w1CIA== From: sashiko-bot@kernel.org Subject: Re: [PATCH RFC POC 05/50] ARM: commit fds on syscall exit Reply-To: sashiko-reviews@lists.linux.dev To: "Christian Brauner" , "Linus Torvalds" Cc: linux-um@lists.infradead.org, linux-openrisc@vger.kernel.org, "Michael S. Tsirkin" , "Peter Zijlstra" , bpf@vger.kernel.org, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-gpio@vger.kernel.org, "Eugenio Perez" , virtualization@lists.linux.dev, "Jan Kara" , "Oleg Nesterov" , linux-hyperv@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-alpha@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-snps-arc@lists.infradead.org, linux-parisc@vger.kernel.org, io-uring@vger.kernel.org, "Ingo Molnar" , kvm@vger.kernel.org, "Jens Axboe" , "David Airlie" , linuxppc-dev@lists.ozlabs.org, "Alexander Viro" , "Jann Horn" , linux-sh@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-arm-kernel@lists.infradead.org, sparclinux@vger.kernel.org, linux-mips@vger.kernel.org, =?utf-8?b?Q2hyaXN0aWFuIEJyYXVuZXIgKEFtdXRhYmxlKQ==?= , kexec@lists.infradead.org In-Reply-To: <20260915-work-fd-reserve-unify-folded-v1-5-4d5217d6b246@kernel.org> References: <20260915-work-fd-reserve-unify-folded-v1-0-4d5217d6b246@kernel.org> <20260915-work-fd-reserve-unify-folded-v1-5-4d5217d6b246@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 15 Sep 2026 11:59:54 +0000 Message-Id: <20260915115954.7B93C1F00893@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-hexagon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [Low] arm: redundant TIF_FD_SLOTS check due to bit-shift overlap -- commit bdf52635177f575c1b58cdb7e902386551a36647 Author: Christian Brauner ARM: commit fds on syscall exit Add TIF_FD_SLOTS and test it where the syscall return path decides between the syscall work and the plain work pending slow path. A task that reserved descriptors goes through __sys_trace_return_nosave where syscall_trace_exit() commits them before audit and the ptrace exit stop. > diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-commo= n.S > index 88336a1292bb7..59a70d90b0b61 100644 > --- a/arch/arm/kernel/entry-common.S > +++ b/arch/arm/kernel/entry-common.S [ ... ] > @@ -83,6 +83,8 @@ ENDPROC(ret_fast_syscall) > =20 > tst r1, #_TIF_SYSCALL_WORK > bne __sys_trace_return_nosave > + tst r1, #(_TIF_FD_SLOTS << 16) @ r1 holds TI_FLAGS << 16 > + bne __sys_trace_return_nosave [Severity: Low] Is this newly added check reachable? The preceding tst r1, #_TIF_SYSCALL_WORK instruction appears to intercept the branch because it inadvertently catches this condition. In ret_fast_syscall, r1 is loaded with TI_FLAGS << 16. TIF_FD_SLOTS is bit 5, so shifting it by 16 places it at bit 21 in r1. _TIF_SYSCALL_WORK naturally includes bit 21 (_TIF_SYSCALL_AUDIT). Because of this bit-shift overlap, the first test against _TIF_SYSCALL_WORK will evaluate to non-zero whenever TIF_FD_SLOTS is set. This means the branch to __sys_trace_return_nosave is taken early, making the new tst instruction unreachable dead code. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260915-work-fd-re= serve-unify-folded-v1-0-4d5217d6b246@kernel.org?part=3D5 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2F157C982C3 for ; Tue, 15 Sep 2026 12:00:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Reply-To:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id:Date: References:In-Reply-To:Cc:To:Subject:From:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=/H0+PIMV7ykKlaBTJNx0YGDdLCNhS3Bry4ERrPRhGEo=; b=OLUAgToJsk3XYt MruyzP+GIJNVyV6I3dAM6SUfsJXpHd1qOnfqQsrn7Tczkop8oiVPBxCofnqA7cnepJ/X/wd3au9d8 /+uuD3Q+fuaqkqokrF6iyv/Ccld/k1F273QEirFL1IRHovXRcjoWf8PnP2fXwFDT8mA7bbBosXGZv w0NtFk3QLADD6hBgbJYCkBwH5J8Ipvyx4Np9r6+AHkxzPyKwY49Qrq1Ssx53PQWzya5Kprr+ft4jN NPg7VAr6zAV9U3ipJmeT+qTQWXsG/oeoyiENDUwFgDfYthksbOuRGTrz2WGbsJQFGcWlOvcldL8VU TNOHvS+64LrO8bU36zow==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x6RpR-00000006LlQ-3AVb; Tue, 15 Sep 2026 12:00:01 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x6RpN-00000006Lgs-1PMB; Tue, 15 Sep 2026 11:59:57 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 9A98B602BE; Tue, 15 Sep 2026 11:59:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B93C1F00893; Tue, 15 Sep 2026 11:59:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789473596; bh=XROzleDAWNHKip4xHBVteIb0cCuN7FAQoMQU9zewp/g=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=LuDfDBIpgc+rUudqugD7YWLMIYTyPSh1djqeFTSZvIqwl+MCFr2F9Jod5sQ3BdeBH Fs4P2kaC4Rq/e2WctPCUaANEEugIP/+ZEAefkQjg3r930Bx3+wPmgnd43osNu5U8C9 EyuNiUbu78gNfTdrTeVFFD2nhC1r5SHLm94AIfGff4/9p19OhtUCSOkAUYL8ijEd9H l9DN/Fa9wQdaggqiklG21wysLrbu7J9tNRHYcAgnuhIFYUQdGWbvPhv23a8BBnteix dj3Dz8036WkGhtwkv8ziLkCVxCa1RZBk5Y1nQhcVea1ZYeF0cF/u11/S008mj3HeiR /EId/I6+w1CIA== From: sashiko-bot@kernel.org Subject: Re: [PATCH RFC POC 05/50] ARM: commit fds on syscall exit To: "Christian Brauner" , "Linus Torvalds" Cc: linux-um@lists.infradead.org, linux-openrisc@vger.kernel.org, "Michael S. Tsirkin" , "Peter Zijlstra" , bpf@vger.kernel.org, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-gpio@vger.kernel.org, "Eugenio Perez" , virtualization@lists.linux.dev, "Jan Kara" , "Oleg Nesterov" , linux-hyperv@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-alpha@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-snps-arc@lists.infradead.org, linux-parisc@vger.kernel.org, io-uring@vger.kernel.org, "Ingo Molnar" , kvm@vger.kernel.org, "Jens Axboe" , "David Airlie" , linuxppc-dev@lists.ozlabs.org, "Alexander Viro" , "Jann Horn" , linux-sh@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-arm-kernel@lists.infradead.org, sparclinux@vger.kernel.org, linux-mips@vger.kernel.org, =?utf-8?b?Q2hyaXN0aWFuIEJyYXVuZXIgKEFtdXRhYmxlKQ==?= , kexec@lists.infradead.org In-Reply-To: <20260915-work-fd-reserve-unify-folded-v1-5-4d5217d6b246@kernel.org> References: <20260915-work-fd-reserve-unify-folded-v1-0-4d5217d6b246@kernel.org> <20260915-work-fd-reserve-unify-folded-v1-5-4d5217d6b246@kernel.org> Date: Tue, 15 Sep 2026 11:59:54 +0000 Message-Id: <20260915115954.7B93C1F00893@smtp.kernel.org> X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sashiko-reviews@lists.linux.dev MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+linux-snps-arc=archiver.kernel.org@lists.infradead.org VGhhbmsgeW91IGZvciB5b3VyIGNvbnRyaWJ1dGlvbiEgU2FzaGlrbyBBSSByZXZpZXcgZm91bmQg MSBwb3RlbnRpYWwgaXNzdWUocykgdG8gY29uc2lkZXI6Ci0gW0xvd10gYXJtOiByZWR1bmRhbnQg VElGX0ZEX1NMT1RTIGNoZWNrIGR1ZSB0byBiaXQtc2hpZnQgb3ZlcmxhcAotLQoKY29tbWl0IGJk ZjUyNjM1MTc3ZjU3NWMxYjU4Y2RiN2U5MDIzODY1NTFhMzY2NDcKQXV0aG9yOiBDaHJpc3RpYW4g QnJhdW5lciA8YnJhdW5lckBrZXJuZWwub3JnPgoKQVJNOiBjb21taXQgZmRzIG9uIHN5c2NhbGwg ZXhpdAoKQWRkIFRJRl9GRF9TTE9UUyBhbmQgdGVzdCBpdCB3aGVyZSB0aGUgc3lzY2FsbCByZXR1 cm4gcGF0aCBkZWNpZGVzCmJldHdlZW4gdGhlIHN5c2NhbGwgd29yayBhbmQgdGhlIHBsYWluIHdv cmsgcGVuZGluZyBzbG93IHBhdGguIEEgdGFzawp0aGF0IHJlc2VydmVkIGRlc2NyaXB0b3JzIGdv ZXMgdGhyb3VnaCBfX3N5c190cmFjZV9yZXR1cm5fbm9zYXZlCndoZXJlIHN5c2NhbGxfdHJhY2Vf ZXhpdCgpIGNvbW1pdHMgdGhlbSBiZWZvcmUgYXVkaXQgYW5kIHRoZSBwdHJhY2UKZXhpdCBzdG9w LgoKPiBkaWZmIC0tZ2l0IGEvYXJjaC9hcm0va2VybmVsL2VudHJ5LWNvbW1vbi5TIGIvYXJjaC9h cm0va2VybmVsL2VudHJ5LWNvbW1vbi5TCj4gaW5kZXggODgzMzZhMTI5MmJiNy4uNTlhNzBkOTBi MGI2MSAxMDA2NDQKPiAtLS0gYS9hcmNoL2FybS9rZXJuZWwvZW50cnktY29tbW9uLlMKPiArKysg Yi9hcmNoL2FybS9rZXJuZWwvZW50cnktY29tbW9uLlMKClsgLi4uIF0KCj4gQEAgLTgzLDYgKzgz LDggQEAgRU5EUFJPQyhyZXRfZmFzdF9zeXNjYWxsKQo+ICAKPiAgCXRzdAlyMSwgI19USUZfU1lT Q0FMTF9XT1JLCj4gIAlibmUJX19zeXNfdHJhY2VfcmV0dXJuX25vc2F2ZQo+ICsJdHN0CXIxLCAj KF9USUZfRkRfU0xPVFMgPDwgMTYpCUAgcjEgaG9sZHMgVElfRkxBR1MgPDwgMTYKPiArCWJuZQlf X3N5c190cmFjZV9yZXR1cm5fbm9zYXZlCgpbU2V2ZXJpdHk6IExvd10KSXMgdGhpcyBuZXdseSBh ZGRlZCBjaGVjayByZWFjaGFibGU/CgpUaGUgcHJlY2VkaW5nIHRzdCByMSwgI19USUZfU1lTQ0FM TF9XT1JLIGluc3RydWN0aW9uIGFwcGVhcnMgdG8gaW50ZXJjZXB0CnRoZSBicmFuY2ggYmVjYXVz ZSBpdCBpbmFkdmVydGVudGx5IGNhdGNoZXMgdGhpcyBjb25kaXRpb24uCgpJbiByZXRfZmFzdF9z eXNjYWxsLCByMSBpcyBsb2FkZWQgd2l0aCBUSV9GTEFHUyA8PCAxNi4gVElGX0ZEX1NMT1RTIGlz CmJpdCA1LCBzbyBzaGlmdGluZyBpdCBieSAxNiBwbGFjZXMgaXQgYXQgYml0IDIxIGluIHIxLgoK X1RJRl9TWVNDQUxMX1dPUksgbmF0dXJhbGx5IGluY2x1ZGVzIGJpdCAyMSAoX1RJRl9TWVNDQUxM X0FVRElUKS4gQmVjYXVzZSBvZgp0aGlzIGJpdC1zaGlmdCBvdmVybGFwLCB0aGUgZmlyc3QgdGVz dCBhZ2FpbnN0IF9USUZfU1lTQ0FMTF9XT1JLIHdpbGwKZXZhbHVhdGUgdG8gbm9uLXplcm8gd2hl bmV2ZXIgVElGX0ZEX1NMT1RTIGlzIHNldC4gVGhpcyBtZWFucyB0aGUgYnJhbmNoIHRvCl9fc3lz X3RyYWNlX3JldHVybl9ub3NhdmUgaXMgdGFrZW4gZWFybHksIG1ha2luZyB0aGUgbmV3IHRzdCBp bnN0cnVjdGlvbgp1bnJlYWNoYWJsZSBkZWFkIGNvZGUuCgotLSAKU2FzaGlrbyBBSSByZXZpZXcg wrcgaHR0cHM6Ly9zYXNoaWtvLmRldi8jL3BhdGNoc2V0LzIwMjYwOTE1LXdvcmstZmQtcmVzZXJ2 ZS11bmlmeS1mb2xkZWQtdjEtMC00ZDUyMTdkNmIyNDZAa2VybmVsLm9yZz9wYXJ0PTUKCl9fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmxpbnV4LXNucHMtYXJj IG1haWxpbmcgbGlzdApsaW51eC1zbnBzLWFyY0BsaXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9s aXN0cy5pbmZyYWRlYWQub3JnL21haWxtYW4vbGlzdGluZm8vbGludXgtc25wcy1hcmMK