{"id":817407,"url":"http://patchwork.ozlabs.org/api/patches/817407/?format=json","web_url":"http://patchwork.ozlabs.org/project/linuxppc-dev/patch/94a52b3862789611138480bdc879334caa535066.1505934128.git.naveen.n.rao@linux.vnet.ibm.com/","project":{"id":2,"url":"http://patchwork.ozlabs.org/api/projects/2/?format=json","name":"Linux PPC development","link_name":"linuxppc-dev","list_id":"linuxppc-dev.lists.ozlabs.org","list_email":"linuxppc-dev@lists.ozlabs.org","web_url":"https://github.com/linuxppc/wiki/wiki","scm_url":"https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git","webscm_url":"https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/","list_archive_url":"https://lore.kernel.org/linuxppc-dev/","list_archive_url_format":"https://lore.kernel.org/linuxppc-dev/{}/","commit_url_format":"https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id={}"},"msgid":"<94a52b3862789611138480bdc879334caa535066.1505934128.git.naveen.n.rao@linux.vnet.ibm.com>","list_archive_url":"https://lore.kernel.org/linuxppc-dev/94a52b3862789611138480bdc879334caa535066.1505934128.git.naveen.n.rao@linux.vnet.ibm.com/","date":"2017-09-22T09:10:46","name":"[v2,4/6] powerpc/kprobes: Fix warnings from __this_cpu_read() on preempt kernels","commit_ref":"c179ea270100488c416890beef6424ce390ceb38","pull_url":null,"state":"accepted","archived":false,"hash":"189dbda0f80466da019e18b28e8ff2d3c760187c","submitter":{"id":15185,"url":"http://patchwork.ozlabs.org/api/people/15185/?format=json","name":"Naveen N. Rao","email":"naveen.n.rao@linux.vnet.ibm.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linuxppc-dev/patch/94a52b3862789611138480bdc879334caa535066.1505934128.git.naveen.n.rao@linux.vnet.ibm.com/mbox/","series":[{"id":4580,"url":"http://patchwork.ozlabs.org/api/series/4580/?format=json","web_url":"http://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=4580","date":"2017-09-22T09:10:23","name":"powerpc/kprobes: More fixes","version":2,"mbox":"http://patchwork.ozlabs.org/series/4580/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/817407/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/817407/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":["patchwork-incoming@ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Delivered-To":["patchwork-incoming@ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Received":["from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3])\n\t(using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3xz7D83VJYz9sNc\n\tfor ;\n\tFri, 22 Sep 2017 19:17:28 +1000 (AEST)","from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3])\n\tby lists.ozlabs.org (Postfix) with ESMTP id 3xz7D82F7czDsNg\n\tfor ;\n\tFri, 22 Sep 2017 19:17:28 +1000 (AEST)","from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com\n\t[148.163.156.1])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256\n\tbits)) (No client certificate requested)\n\tby lists.ozlabs.org (Postfix) with ESMTPS id 3xz75143thzDsM7\n\tfor ;\n\tFri, 22 Sep 2017 19:11:17 +1000 (AEST)","from pps.filterd (m0098409.ppops.net [127.0.0.1])\n\tby mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id\n\tv8M9AQl3022458\n\tfor ; Fri, 22 Sep 2017 05:11:15 -0400","from e23smtp07.au.ibm.com (e23smtp07.au.ibm.com [202.81.31.140])\n\tby mx0a-001b2d01.pphosted.com with ESMTP id 2d4pnhjxtm-1\n\t(version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT)\n\tfor ; Fri, 22 Sep 2017 05:11:15 -0400","from localhost\n\tby e23smtp07.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use\n\tOnly! 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Violators will be prosecuted; \n\tFri, 22 Sep 2017 19:11:11 +1000","from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138])\n\tby d23relay09.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id\n\tv8M9BBKr41746528\n\tfor ; Fri, 22 Sep 2017 19:11:11 +1000","from d23av02.au.ibm.com (localhost [127.0.0.1])\n\tby d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id\n\tv8M9B2Np020647\n\tfor ; Fri, 22 Sep 2017 19:11:02 +1000","from naverao1-tp.ibm.com ([9.77.124.51])\n\tby d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id\n\tv8M9AoTY020313; Fri, 22 Sep 2017 19:10:59 +1000"],"Authentication-Results":"ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=linux.vnet.ibm.com\n\t(client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com;\n\tenvelope-from=naveen.n.rao@linux.vnet.ibm.com; receiver=)","From":"\"Naveen N. Rao\" ","To":"Michael Ellerman ","Subject":"[PATCH v2 4/6] powerpc/kprobes: Fix warnings from __this_cpu_read()\n\ton preempt kernels","Date":"Fri, 22 Sep 2017 14:40:46 +0530","X-Mailer":"git-send-email 2.14.1","In-Reply-To":["<9e98f74834af349564b71bc8443bdad55d6e37c6.1505934128.git.naveen.n.rao@linux.vnet.ibm.com>",""],"References":["<9e98f74834af349564b71bc8443bdad55d6e37c6.1505934128.git.naveen.n.rao@linux.vnet.ibm.com>",""],"X-TM-AS-MML":"disable","x-cbid":"17092209-0044-0000-0000-00000287A088","X-IBM-AV-DETECTION":"SAVI=unused REMOTE=unused XFE=unused","x-cbparentid":"17092209-0045-0000-0000-0000071D8E34","Message-Id":"<94a52b3862789611138480bdc879334caa535066.1505934128.git.naveen.n.rao@linux.vnet.ibm.com>","X-Proofpoint-Virus-Version":"vendor=fsecure engine=2.50.10432:, ,\n\tdefinitions=2017-09-22_02:, , signatures=0","X-Proofpoint-Spam-Details":"rule=outbound_notspam policy=outbound score=0\n\tspamscore=0 suspectscore=0\n\tmalwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam\n\tadjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000\n\tdefinitions=main-1709220128","X-BeenThere":"linuxppc-dev@lists.ozlabs.org","X-Mailman-Version":"2.1.24","Precedence":"list","List-Id":"Linux on PowerPC Developers Mail List\n\t","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"linuxppc-dev@lists.ozlabs.org, Masami Hiramatsu ,\n\tKamalesh Babulal ","Errors-To":"linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org","Sender":"\"Linuxppc-dev\"\n\t"},"content":"Kamalesh pointed out that we are getting the below call traces with\nlivepatched functions when we enable CONFIG_PREEMPT:\n\n[ 495.470721] BUG: using __this_cpu_read() in preemptible [00000000] code: cat/8394\n[ 495.471167] caller is is_current_kprobe_addr+0x30/0x90\n[ 495.471171] CPU: 4 PID: 8394 Comm: cat Tainted: G K 4.13.0-rc7-nnr+ #95\n[ 495.471173] Call Trace:\n[ 495.471178] [c00000008fd9b960] [c0000000009f039c] dump_stack+0xec/0x160 (unreliable)\n[ 495.471184] [c00000008fd9b9a0] [c00000000059169c] check_preemption_disabled+0x15c/0x170\n[ 495.471187] [c00000008fd9ba30] [c000000000046460] is_current_kprobe_addr+0x30/0x90\n[ 495.471191] [c00000008fd9ba60] [c00000000004e9a0] ftrace_call+0x1c/0xb8\n[ 495.471195] [c00000008fd9bc30] [c000000000376fd8] seq_read+0x238/0x5c0\n[ 495.471199] [c00000008fd9bcd0] [c0000000003cfd78] proc_reg_read+0x88/0xd0\n[ 495.471203] [c00000008fd9bd00] [c00000000033e5d4] __vfs_read+0x44/0x1b0\n[ 495.471206] [c00000008fd9bd90] [c0000000003402ec] vfs_read+0xbc/0x1b0\n[ 495.471210] [c00000008fd9bde0] [c000000000342138] SyS_read+0x68/0x110\n[ 495.471214] [c00000008fd9be30] [c00000000000bc6c] system_call+0x58/0x6c\n\nCommit c05b8c4474c030 (\"powerpc/kprobes: Skip livepatch_handler() for\njprobes\") introduced a helper is_current_kprobe_addr() to help determine\nif the current function has been livepatched or if it has a jprobe\ninstalled, both of which modify the NIP. This was subsequently renamed\nto __is_active_jprobe().\n\nIn the case of a jprobe, kprobe_ftrace_handler() disables pre-emption\nbefore calling into setjmp_pre_handler() which returns without disabling\npre-emption. This is done to ensure that the jprobe handler won't\ndisappear beneath us if the jprobe is unregistered between the\nsetjmp_pre_handler() and the subsequent longjmp_break_handler() called\nfrom the jprobe handler. Due to this, we can use __this_cpu_read() in\n__is_active_jprobe() with the pre-emption check as we know that\npre-emption will be disabled.\n\nHowever, if this function has been livepatched, we are still doing this\ncheck and when we do so, pre-emption won't necessarily be disabled. This\nresults in the call trace shown above.\n\nFix this by only invoking __is_active_jprobe() when pre-emption is\ndisabled. And since we now guard this within a pre-emption check, we can\ninstead use raw_cpu_read() to get the current_kprobe value skipping the\ncheck done by __this_cpu_read().\n\nFixes: c05b8c4474c030 (\"powerpc/kprobes: Skip livepatch_handler() for jprobes\")\nReported-by: Kamalesh Babulal \nTested-by: Kamalesh Babulal \nSigned-off-by: Naveen N. Rao \n---\n arch/powerpc/kernel/kprobes-ftrace.c | 8 ++++++--\n 1 file changed, 6 insertions(+), 2 deletions(-)","diff":"diff --git a/arch/powerpc/kernel/kprobes-ftrace.c b/arch/powerpc/kernel/kprobes-ftrace.c\nindex 48f675a73cff..1e54ec8ad85f 100644\n--- a/arch/powerpc/kernel/kprobes-ftrace.c\n+++ b/arch/powerpc/kernel/kprobes-ftrace.c\n@@ -32,8 +32,12 @@\n */\n int __is_active_jprobe(unsigned long addr)\n {\n-\tstruct kprobe *p = kprobe_running();\n-\treturn (p && (unsigned long)p->addr == addr) ? 1 : 0;\n+\tif (!preemptible()) {\n+\t\tstruct kprobe *p = raw_cpu_read(current_kprobe);\n+\t\treturn (p && (unsigned long)p->addr == addr) ? 1 : 0;\n+\t}\n+\n+\treturn 0;\n }\n \n static nokprobe_inline\n","prefixes":["v2","4/6"]}