From patchwork Tue Jul 31 08:42:03 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Vivier X-Patchwork-Id: 951477 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=vivier.eu Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 41fqlB3mFKz9rxx for ; Tue, 31 Jul 2018 18:45:26 +1000 (AEST) Received: from localhost ([::1]:57632 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fkQHU-00051K-4Y for incoming@patchwork.ozlabs.org; Tue, 31 Jul 2018 04:45:24 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37610) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fkQFD-0003QY-Ev for qemu-devel@nongnu.org; Tue, 31 Jul 2018 04:43:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fkQFA-0006fS-KM for qemu-devel@nongnu.org; Tue, 31 Jul 2018 04:43:03 -0400 Received: from mout.kundenserver.de ([212.227.126.187]:50368) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fkQFA-0006eC-7Z for qemu-devel@nongnu.org; Tue, 31 Jul 2018 04:43:00 -0400 Received: from localhost.localdomain ([78.238.229.36]) by mrelayeu.kundenserver.de (mreue007 [212.227.15.167]) with ESMTPSA (Nemesis) id 0MZ6Kl-1fPIqN3Z47-00VjuN; Tue, 31 Jul 2018 10:42:21 +0200 From: Laurent Vivier To: qemu-devel@nongnu.org Date: Tue, 31 Jul 2018 10:42:03 +0200 Message-Id: <20180731084203.29959-4-laurent@vivier.eu> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180731084203.29959-1-laurent@vivier.eu> References: <20180731084203.29959-1-laurent@vivier.eu> X-Provags-ID: V03:K1:SXeW0ln5CqWhvWDC6pq6qKBzrbATvlJ94XxR+30m3BhO9IF1/ZY ew4F0K/I0pflaff6bQW587GCD7w7W8HKpOEdPAPiqYdwK3QDtRdbfhvL+1VlyJhn9Um+jSi WGvqrpplvnsgWIIvGzKwJWVBuYt3s+aQKPLFzHSE+kgriR5urPxHzOybqLH8lTK+oqcfqE6 WWRsWHcnOB88m5V5EWEeg== X-UI-Out-Filterresults: notjunk:1; V01:K0:hyVXeOejetE=:kqOBbFdt4o2qBpXuwi+J7p PW8PMdhVAqr61B8vkQtB2Nl3EiYX3orKY6LKtildBzcN4HowTYBy3UJYb+QxoFd3I2cBK7yGg IKWHrvUM96G42y+uFgYBkzvVrNe4Ldk5/mfNCYD3mmYFA9z0zftyaXlmRNpxdX69WwwncMf/Q r1aj2uqAxVCDOLoO5NgMIa0388+tWidygu5fs83SV4OL3QbM3+QoN0U1XmNkoe6+lxPpdINR9 4Iqr7DSc6TNMKNYsB8gSw/JLmubdGbkIaKombOfJY2O+3kYyT+aeD7lxyY0d5Qj9C3Ask4n8a DqezAgX/jPeyA0VwVZ3Pt3ep7rP3f7HCXIy8VG6DDW6mk7+x8UAUxzJy6t/zhlErZx6NSDA8B LrAPi+AOupbTQZpclJADSUWkGqw9Yf9PrJKJUlW2hDrf+FTmRliVehRYwlsnBhlu3m3QmNLRi QlgyRLSJRI7QdOxcm6vcqiYA8q4/U0xGpldH7t7MfcR319cNlNONzUkN8qH5yHvSpC2lGgXDm r08mb0v1fykMJ5NAX4JgBJCgvGsOie4jI0X2cS3kHxvD/CnAX4Cyh0+EInGD6fueBJoc0IXuQ K7/Er1z2I11temv7oHtrduPe1EFn8V/+1+UhsjVzydhdvm/s8vTGB8ofr4VWI6vOkcs0AQ7ha VqpZJYb3FV1Bh9jvl91G70A/6H25TOaLGJS8VVyfLmdXY5IykmYe1RdFZW1JdNKQ64pc= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 212.227.126.187 Subject: [Qemu-devel] [PULL 3/3] linux-user: ppc64: don't use volatile register during safe_syscall X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Shivaprasad G Bhat , Riku Voipio , =?utf-8?q?Alex_Benn=C3=A9e?= , Laurent Vivier Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Shivaprasad G Bhat r11 is a volatile register on PPC as per calling conventions. The safe_syscall code uses it to check if the signal_pending is set during the safe_syscall. When a syscall is interrupted on return from signal handling, the r11 might be corrupted before we retry the syscall leading to a crash. The registers r0-r13 are not to be used here as they have volatile/designated/reserved usages. Change the code to use r14 which is non-volatile. Use SP+16 which is a slot for LR, for save/restore of previous value of r14. SP+16 can be used, as LR is preserved across the syscall. Steps to reproduce: On PPC host, issue `qemu-x86_64 /usr/bin/cc -E -` Attempt Ctrl-C, the issue is reproduced. Reference: https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html#REG https://openpowerfoundation.org/wp-content/uploads/2016/03/ABI64BitOpenPOWERv1.1_16July2015_pub4.pdf Signed-off-by: Shivaprasad G Bhat Tested-by: Richard Henderson Tested-by: Laurent Vivier Reviewed-by: Richard Henderson Reviewed-by: Laurent Vivier Message-Id: <153301568965.30312.10498134581068746871.stgit@dhcp-9-109-246-16> Signed-off-by: Laurent Vivier --- linux-user/host/ppc64/safe-syscall.inc.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/linux-user/host/ppc64/safe-syscall.inc.S b/linux-user/host/ppc64/safe-syscall.inc.S index d30050a67c..8ed73a5b86 100644 --- a/linux-user/host/ppc64/safe-syscall.inc.S +++ b/linux-user/host/ppc64/safe-syscall.inc.S @@ -49,7 +49,9 @@ safe_syscall_base: * and returns the result in r3 * Shuffle everything around appropriately. */ - mr 11, 3 /* signal_pending */ + std 14, 16(1) /* Preserve r14 in SP+16 */ + .cfi_offset 14, 16 + mr 14, 3 /* signal_pending */ mr 0, 4 /* syscall number */ mr 3, 5 /* syscall arguments */ mr 4, 6 @@ -67,12 +69,13 @@ safe_syscall_base: */ safe_syscall_start: /* if signal_pending is non-zero, don't do the call */ - lwz 12, 0(11) + lwz 12, 0(14) cmpwi 0, 12, 0 bne- 0f sc safe_syscall_end: /* code path when we did execute the syscall */ + ld 14, 16(1) /* restore r14 to its original value */ bnslr+ /* syscall failed; return negative errno */ @@ -81,6 +84,7 @@ safe_syscall_end: /* code path when we didn't execute the syscall */ 0: addi 3, 0, -TARGET_ERESTARTSYS + ld 14, 16(1) /* restore r14 to its orginal value */ blr .cfi_endproc