From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 AC5E63C5845 for ; Fri, 10 Jul 2026 11:41:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783683692; cv=none; b=epKIqNCAoGSOQ9/SWRMTAo7UDbSY2Al6BINv9bwUYgSoS74YjGVy7bEx7l3MYbRaSJkfrUfUUcqrJtA4icg3sPTjaetYL6YokbhvPP+bM+rUzSh+gXaa8LiX1UIU3dl8AX8z+DC2vBtmMyMct6yZmTbZDWG6MZtyUTmbtWEZl94= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783683692; c=relaxed/simple; bh=yn22xVYmK++EhinRZRQNCMhLcj+IBqHTKVWiPIkBZ3c=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=W+BPbsUcrzQs16rtVbIKBqJNykkVJSMMTC21WsEPR3E1bmetoNKORo/LoSpimhXVQk3BFuSlNNVCanhVTKm65dRlhPcHsBpF8eh6TcKR3+hPqn8pRe8pU2IkEu2um4W5Fl9jnKi3fdWCGyqmM2IZxn5flLV9clkka3/l71H0S08= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=gB8KvqQt; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="gB8KvqQt" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1783683674; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=okIzKFIsL/4R4vmkR+TFByt5pFrNsTBzPM+Bl8mNt+c=; b=gB8KvqQtkCwjUId5ixbI+j0gBNQLfB/YYdBim+MLenqQwWryn3W4fE7R4mvC9HIzp9XHRw Ay1n9xtiM9r6yJComGfZWZc6Jvdj5P5I5n4BUUHDB2UFQ1AY0+Gr6TGs9As25TE2aKuemF Pud98YTepTVyLOAsA8jYu+EyBdwJHdg= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-21-qfsr_rx-O6mPQrP7hF_qjQ-1; Fri, 10 Jul 2026 07:41:12 -0400 X-MC-Unique: qfsr_rx-O6mPQrP7hF_qjQ-1 X-Mimecast-MFC-AGG-ID: qfsr_rx-O6mPQrP7hF_qjQ_1783683667 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B188F1800844; Fri, 10 Jul 2026 11:41:03 +0000 (UTC) Received: from fedora (unknown [10.44.49.164]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 8F127195419F; Fri, 10 Jul 2026 11:40:45 +0000 (UTC) Received: by fedora (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 10 Jul 2026 13:41:03 +0200 (CEST) Date: Fri, 10 Jul 2026 13:40:43 +0200 From: Oleg Nesterov To: Michal =?iso-8859-1?Q?Such=E1nek?= Cc: Thomas Gleixner , LKML , Peter Zijlstra , Michael Ellerman , Shrikanth Hegde , linuxppc-dev@lists.ozlabs.org, Kees Cook , Huacai Chen , loongarch@lists.linux.dev, Paul Walmsley , Palmer Dabbelt , linux-riscv@lists.infradead.org, Sven Schnelle , linux-s390@vger.kernel.org, x86@kernel.org, Mark Rutland , Jinjie Ruan , Andy Lutomirski , Richard Henderson , Russell King , Catalin Marinas , Guo Ren , Geert Uytterhoeven , Thomas Bogendoerfer , Helge Deller , Yoshinori Sato , Richard Weinberger , Chris Zankel , linux-arm-kernel@lists.infradead.org, linux-alpha@vger.kernel.org, linux-csky@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-sh@vger.kernel.org, linux-um@lists.infradead.org, Arnd Bergmann , Vineet Gupta , Will Deacon , Brian Cain , Michal Simek , Dinh Nguyen , "David S. Miller" , Andreas Larsson , linux-snps-arc@lists.infradead.org, linux-hexagon@vger.kernel.org, linux-openrisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, Jonathan Corbet , linux-doc@vger.kernel.org Subject: Re: [patch 13/18] entry: Make trace_syscall_enter() return type bool Message-ID: References: <20260707181957.433213175@kernel.org> <20260707190254.338083894@kernel.org> <87se5tqkyp.ffs@fw13> Precedence: bulk X-Mailing-List: linux-hexagon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 On 07/10, Michal Suchánek wrote: > > On Wed, Jul 08, 2026 at 10:34:38PM +0200, Thomas Gleixner wrote: > > > > 1) The set in stone rule is that if the entry code returns -1L as the > > syscall number then the architecture code has to skip the syscall > > invocation _and_ is not supposed to change the return value. > > Which stone? > > Pics or it did not happen. > > > > > 2) There is no guarantee and never has been that any of the involved > > mechanisms (ptrace, seccomp, tracing) will change the return value > > when it sets the syscall number to -1L. > > For ptrace to correctly emulate a syscall it needs to set the syscall nr > to an invalid value on entry, and the desired result if the syscall on > exit AFAICT. I can only say that ptrace users do want to skip the syscall and set the return value on entry. See [PATCH v5 1/2] ptrace: add PTRACE_SET_SYSCALL_INFO syscall skipping support https://lore.kernel.org/all/20260709100949.94345-2-renzo@cs.unibo.it/ The changelog explains that currently this doesn't work because among the arches which define HAVE_ARCH_TRACEHOOK (at least) arch/mips is broken in this regard. Oleg.