From patchwork Fri Apr 27 09:00:07 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vaibhav Jain X-Patchwork-Id: 905537 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 40XSZc01vVz9s0v for ; Fri, 27 Apr 2018 19:00:40 +1000 (AEST) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.vnet.ibm.com Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 40XSZb56trzF24s for ; Fri, 27 Apr 2018 19:00:39 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.vnet.ibm.com X-Original-To: skiboot@lists.ozlabs.org Delivered-To: skiboot@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=linux.vnet.ibm.com (client-ip=148.163.158.5; helo=mx0a-001b2d01.pphosted.com; envelope-from=vaibhav@linux.vnet.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.vnet.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 40XSZP0s8KzF24K for ; Fri, 27 Apr 2018 19:00:27 +1000 (AEST) Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w3R8wvnC037324 for ; Fri, 27 Apr 2018 05:00:24 -0400 Received: from e06smtp12.uk.ibm.com (e06smtp12.uk.ibm.com [195.75.94.108]) by mx0a-001b2d01.pphosted.com with ESMTP id 2hkwdnrh6e-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 27 Apr 2018 05:00:23 -0400 Received: from localhost by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Fri, 27 Apr 2018 10:00:18 +0100 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w3R90Irm8061316; Fri, 27 Apr 2018 09:00:18 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6E1B852059; Fri, 27 Apr 2018 08:50:53 +0100 (BST) Received: from vajain21.in.ibm.com (unknown [9.109.222.180]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTP id 0889B52049; Fri, 27 Apr 2018 08:50:51 +0100 (BST) From: Vaibhav Jain To: Nicholas Piggin , Stewart Smith Date: Fri, 27 Apr 2018 14:30:07 +0530 X-Mailer: git-send-email 2.14.3 X-TM-AS-GCONF: 00 x-cbid: 18042709-0008-0000-0000-000004F0A1E0 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18042709-0009-0000-0000-00001E84AD34 Message-Id: <20180427090007.19780-1-vaibhav@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2018-04-27_02:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1804270091 Subject: [Skiboot] [PATCH] asm/head: Fix comparison in opal_entry for switching to emergency X-BeenThere: skiboot@lists.ozlabs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: Mailing list for skiboot development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: skiboot@lists.ozlabs.org, Frederic Barrat MIME-Version: 1.0 Errors-To: skiboot-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Skiboot" Commit 3fdd2629516d ("core/opal: Emergency stack for re-entry") introduced an emergency stack for re-entrant OPAL calls. A branch was added in opal_entry() that switches to emergency stack checks if current thread is already in an active opal call. However the conditional branch that checks the value cpu_thread->in_opal_call is reverse forcing the use of emergency stack in even in non re-entrant cases. This causes a opal stack guard routine __mcount_stack_check() to falsely assume that stack is overflown as stack pointer of EMERGENCY_STACK is compared against the bounds of NORMAL_STACK, forcing the function to call abort() with an error message of this form: INIT: Starting kernel at 0x20010000, fdt at 0x3073f708 53664 bytes) CPU 0004 Stack overflow detected ! pc=3001d8ec sp=31c27c90 (gap=30488) token=70 Aborting! CPU 0004 Backtrace: S: 0000000031c27b20 R: 000000003001ca2c E ._abort+0x60 S: 0000000031c27bb0 R: 0000000030013e10 E .__mcount_stack_check+0x168 S: 0000000031c27c90 R: 000000003001d8ec E .opal_entry_check+0x1c S: 0000000031c27d20 R: 00000000300051a4 E opal_entry+0xf4 --- OPAL call token: 0x46 caller R1: 0xc0000000011e3e50 --- So this patch update the 'bne' branch in opal_entry() to 'bgt' branch so that switch to emergency stack only happens when current cpu_thread->is_opal_call is greater than 1 indicating an re-entrant opal call. Fixes: 3fdd2629516d ("core/opal: Emergency stack for re-entry") Signed-off-by: Vaibhav Jain Signed-off-by: Mahesh J Salgaonkar Reviewed-by: Nicholas Piggin --- asm/head.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/asm/head.S b/asm/head.S index 48d3acb0..2cf4a6b2 100644 --- a/asm/head.S +++ b/asm/head.S @@ -1023,7 +1023,7 @@ opal_entry: cmpwi %r11,1 mfspr %r12,SPR_PIR - beq 5f + bgt 5f GET_STACK(%r12,%r12) b 6f 5: