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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4614AC43603 for ; Tue, 10 Dec 2019 13:30:54 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B5B382073B for ; Tue, 10 Dec 2019 13:30:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B5B382073B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bugzilla.kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 47XLY66ySkzDqWh for ; Wed, 11 Dec 2019 00:30:50 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=srs0=cxmp=2a=bugzilla.kernel.org=bugzilla-daemon@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=bugzilla.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 47XLQX5sSBzDqWh for ; Wed, 11 Dec 2019 00:25:08 +1100 (AEDT) From: bugzilla-daemon@bugzilla.kernel.org To: linuxppc-dev@lists.ozlabs.org Subject: [Bug 205183] PPC64: Signal delivery fails with SIGSEGV if between about 1KB and 4KB bytes of stack remain Date: Tue, 10 Dec 2019 13:25:05 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: AssignedTo platform_ppc-64@kernel-bugs.osdl.org X-Bugzilla-Product: Platform Specific/Hardware X-Bugzilla-Component: PPC-64 X-Bugzilla-Version: 2.5 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: dja@axtens.net X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P1 X-Bugzilla-Assigned-To: platform_ppc-64@kernel-bugs.osdl.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: cc Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" https://bugzilla.kernel.org/show_bug.cgi?id=3D205183 Daniel Axtens (dja@axtens.net) changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |dja@axtens.net --- Comment #2 from Daniel Axtens (dja@axtens.net) --- Hi, I'm starting to have a look at this for Daniel B. So looking at the fault that fails, I see that it's a fault with the NIP in= the _kernel_ that fails, rather than in userspace. Dumping stack we see: [ 118.917679] Call Trace: [ 118.917715] [c00000007b457820] [c000000000b71538] dump_stack+0xbc/0x104 (unreliable) [ 118.917719] [c00000007b457860] [c00000000006e8f0] __do_page_fault+0x860/0xf90 [ 118.917721] [c00000007b457940] [c00000000000af68] handle_page_fault+0x10/0x30 [ 118.917725] --- interrupt: 301 at handle_rt_signal64+0x180/0x13a0 LR =3D handle_rt_signal64+0x148/0x13a0 [ 118.917726] [c00000007b457d30] [c000000000023d30] do_notify_resume+0x2e0/0x410 [ 118.917728] [c00000007b457e20] [c00000000000e4c4] ret_from_except_lite+0x70/0x74 I'm still debugging, but it looks like handle_rt_signal64 attempts to reser= ve a stack frame for the signal, but computes a stack address that sits outside valid stack space. Then when writing to it, it pagefaults, and because it's= not a userland NIP, it refuses to expand the stack. I'll keep you up to date. Regards, Daniel A --=20 You are receiving this mail because: You are watching the assignee of the bug.=