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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 52849C48BDE for ; Sun, 7 Jul 2019 19:43:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3406A20663 for ; Sun, 7 Jul 2019 19:43:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728278AbfGGTnG (ORCPT ); Sun, 7 Jul 2019 15:43:06 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:57554 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727602AbfGGTiL (ORCPT ); Sun, 7 Jul 2019 15:38:11 -0400 Received: from 94.197.121.43.threembb.co.uk ([94.197.121.43] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hkCz9-0006kJ-2y; Sun, 07 Jul 2019 20:38:07 +0100 Received: from ben by deadeye with local (Exim 4.92) (envelope-from ) id 1hkCz7-0005dw-5r; Sun, 07 Jul 2019 20:38:05 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Michael Ellerman" , "Christophe Leroy" Date: Sun, 07 Jul 2019 17:54:17 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 095/129] powerpc/32: Clear on-stack exception marker upon exception return In-Reply-To: X-SA-Exim-Connect-IP: 94.197.121.43 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.70-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Christophe Leroy commit 9580b71b5a7863c24a9bd18bcd2ad759b86b1eff upstream. Clear the on-stack STACK_FRAME_REGS_MARKER on exception exit in order to avoid confusing stacktrace like the one below. Call Trace: [c0e9dca0] [c01c42a0] print_address_description+0x64/0x2bc (unreliable) [c0e9dcd0] [c01c4684] kasan_report+0xfc/0x180 [c0e9dd10] [c0895130] memchr+0x24/0x74 [c0e9dd30] [c00a9e38] msg_print_text+0x124/0x574 [c0e9dde0] [c00ab710] console_unlock+0x114/0x4f8 [c0e9de40] [c00adc60] vprintk_emit+0x188/0x1c4 --- interrupt: c0e9df00 at 0x400f330 LR = init_stack+0x1f00/0x2000 [c0e9de80] [c00ae3c4] printk+0xa8/0xcc (unreliable) [c0e9df20] [c0c27e44] early_irq_init+0x38/0x108 [c0e9df50] [c0c15434] start_kernel+0x310/0x488 [c0e9dff0] [00003484] 0x3484 With this patch the trace becomes: Call Trace: [c0e9dca0] [c01c42c0] print_address_description+0x64/0x2bc (unreliable) [c0e9dcd0] [c01c46a4] kasan_report+0xfc/0x180 [c0e9dd10] [c0895150] memchr+0x24/0x74 [c0e9dd30] [c00a9e58] msg_print_text+0x124/0x574 [c0e9dde0] [c00ab730] console_unlock+0x114/0x4f8 [c0e9de40] [c00adc80] vprintk_emit+0x188/0x1c4 [c0e9de80] [c00ae3e4] printk+0xa8/0xcc [c0e9df20] [c0c27e44] early_irq_init+0x38/0x108 [c0e9df50] [c0c15434] start_kernel+0x310/0x488 [c0e9dff0] [00003484] 0x3484 Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Signed-off-by: Ben Hutchings --- arch/powerpc/kernel/entry_32.S | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -757,6 +757,9 @@ fast_exception_return: mtcr r10 lwz r10,_LINK(r11) mtlr r10 + /* Clear the exception_marker on the stack to avoid confusing stacktrace */ + li r10, 0 + stw r10, 8(r11) REST_GPR(10, r11) mtspr SPRN_SRR1,r9 mtspr SPRN_SRR0,r12 @@ -987,6 +990,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRE mtcrf 0xFF,r10 mtlr r11 + /* Clear the exception_marker on the stack to avoid confusing stacktrace */ + li r10, 0 + stw r10, 8(r1) /* * Once we put values in SRR0 and SRR1, we are in a state * where exceptions are not recoverable, since taking an @@ -1024,6 +1030,9 @@ exc_exit_restart_end: mtlr r11 lwz r10,_CCR(r1) mtcrf 0xff,r10 + /* Clear the exception_marker on the stack to avoid confusing stacktrace */ + li r10, 0 + stw r10, 8(r1) REST_2GPRS(9, r1) .globl exc_exit_restart exc_exit_restart: