From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELu+ycR5bafWTG3Gkrtgr7KOOrHyKa4WMkrK3/8FNcL/RAzRgJ3YSedZAH6RZVMXFHwsQKMH ARC-Seal: i=1; a=rsa-sha256; t=1521238230; cv=none; d=google.com; s=arc-20160816; b=YPMvGSU97odh4SxA9Kmo2tX6HjGqDZ9G/UQ5FegbxqruIIZzpxW21Swiq0umHkPS8a 58I4vLPl5vR2STH/u07rq/uUYVLS6Goi0Xt1etlljAMB6Q3J/4YSPS0E06rpFRhatRA9 lOU7ewxB6BlRYPPdtvAA6x1p77N6rqARQZJvtmUrAdzf3vOSw+uahHl5f7mhUR8XoQV0 wreycv7N+7S0E5bchjwXCzrcPmidTy0qs7aMe3JgQWAhdDRaZAILf0sLHn5hZ9KzXB2R x+7yWWCwBKXdEUpNFowdDorwt1RoqJA4yW3gtsYyAjq+Ea9szq6sKK/LmBFZ5pzbTIA0 05CQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding :content-language:in-reply-to:mime-version:user-agent:date :message-id:from:cc:references:to:subject:arc-authentication-results; bh=t2Gl5WIon2O9Tgne6fbFKJhpzTHhnfSFs6j6kUnnIIQ=; b=TzQZfMNXVP3qnS7i5v8QkNqs/qAatbTT/hkxxlzexOpC5LysOJE9r4Apy/RwUT9SEj I0u/OQiK0L/KMBkSvHPKHVHN63W6NnDF5woy3hQLeXczpFWWZ7VEipIAg7RvuKgKPiLC Iw2/JT6i40AncoYQOQghdVIng4Z5UblVtWCqSw/UpifmNIwGsMuFow67i26CQRpG/Lfy ww3egjjtEbdkS7Yw7I3BnTjZ3Git9Ye6N4UtzdUuWl5k9rFPysSXmzXYcC06eymfTREh cgUeiOG6Xs3fJk3BglmpGDUs0hZ5USlO4+l9hGQ/l1M+D15TYVbKe3gB7K4i/tsWcMmN XDzg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kselftest-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kselftest-owner@vger.kernel.org Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kselftest-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kselftest-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751468AbeCPWKR (ORCPT ); Fri, 16 Mar 2018 18:10:17 -0400 Received: from mga14.intel.com ([192.55.52.115]:50519 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751245AbeCPWKQ (ORCPT ); Fri, 16 Mar 2018 18:10:16 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,317,1517904000"; d="scan'208";a="25369736" Subject: Re: [PATCH v12 08/22] selftests/vm: clear the bits in shadow reg when a pkey is freed. To: Ram Pai , shuahkh@osg.samsung.com, linux-kselftest@vger.kernel.org References: <1519264541-7621-1-git-send-email-linuxram@us.ibm.com> <1519264541-7621-9-git-send-email-linuxram@us.ibm.com> Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, akpm@linux-foundation.org, benh@kernel.crashing.org, paulus@samba.org, khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, hbabu@us.ibm.com, mhocko@kernel.org, bauerman@linux.vnet.ibm.com, ebiederm@xmission.com, arnd@arndb.de From: Dave Hansen Message-ID: Date: Fri, 16 Mar 2018 15:10:07 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <1519264541-7621-9-git-send-email-linuxram@us.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kselftest-owner@vger.kernel.org X-Mailing-List: linux-kselftest@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1593064595048468921?= X-GMAIL-MSGID: =?utf-8?q?1595133899000849241?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 02/21/2018 05:55 PM, Ram Pai wrote: > When a key is freed, the key is no more effective. > Clear the bits corresponding to the pkey in the shadow > register. Otherwise it will carry some spurious bits > which can trigger false-positive asserts. ... > diff --git a/tools/testing/selftests/vm/protection_keys.c b/tools/testing/selftests/vm/protection_keys.c > index ca54a95..aaf9f09 100644 > --- a/tools/testing/selftests/vm/protection_keys.c > +++ b/tools/testing/selftests/vm/protection_keys.c > @@ -582,6 +582,9 @@ int alloc_pkey(void) > int sys_pkey_free(unsigned long pkey) > { > int ret = syscall(SYS_pkey_free, pkey); > + > + if (!ret) > + shadow_pkey_reg &= reset_bits(pkey, PKEY_DISABLE_ACCESS); > dprintf1("%s(pkey=%ld) syscall ret: %d\n", __func__, pkey, ret); > return ret; > } Did this cause problems for you in practice? On x86, sys_pkey_free() does not affect PKRU, so this isn't quite right. I'd much rather have the actual tests explicitly clear the PKRU bits and also in the process clear the shadow bits.