Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753252AbdF0NB7 (ORCPT ); Tue, 27 Jun 2017 09:01:59 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:44242 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753179AbdF0Mub (ORCPT ); Tue, 27 Jun 2017 08:50:31 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Naveen N. Rao" , Masami Hiramatsu , "Steven Rostedt (VMware)" , Michael Ellerman Subject: [PATCH 3.18 07/16] powerpc/kprobes: Pause function_graph tracing during jprobes handling Date: Tue, 27 Jun 2017 14:49:44 +0200 Message-Id: <20170627124437.717989859@linuxfoundation.org> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170627124436.634493038@linuxfoundation.org> References: <20170627124436.634493038@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1925 Lines: 57 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Naveen N. Rao commit a9f8553e935f26cb5447f67e280946b0923cd2dc upstream. This fixes a crash when function_graph and jprobes are used together. This is essentially commit 237d28db036e ("ftrace/jprobes/x86: Fix conflict between jprobes and function graph tracing"), but for powerpc. Jprobes breaks function_graph tracing since the jprobe hook needs to use jprobe_return(), which never returns back to the hook, but instead to the original jprobe'd function. The solution is to momentarily pause function_graph tracing before invoking the jprobe hook and re-enable it when returning back to the original jprobe'd function. Fixes: 6794c78243bf ("powerpc64: port of the function graph tracer") Signed-off-by: Naveen N. Rao Acked-by: Masami Hiramatsu Acked-by: Steven Rostedt (VMware) Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/kprobes.c | 11 +++++++++++ 1 file changed, 11 insertions(+) --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -514,6 +514,15 @@ int __kprobes setjmp_pre_handler(struct #endif #endif + /* + * jprobes use jprobe_return() which skips the normal return + * path of the function, and this messes up the accounting of the + * function graph tracer. + * + * Pause function graph tracing while performing the jprobe function. + */ + pause_graph_tracing(); + return 1; } @@ -536,6 +545,8 @@ int __kprobes longjmp_break_handler(stru * saved regs... */ memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); + /* It's OK to start function graph tracing again */ + unpause_graph_tracing(); preempt_enable_no_resched(); return 1; }