From patchwork Wed Aug 7 17:28:27 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 11082529 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EE5AA13B1 for ; Wed, 7 Aug 2019 17:29:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DD6A528A60 for ; Wed, 7 Aug 2019 17:29:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D0CB128A62; Wed, 7 Aug 2019 17:29:22 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5E27A28A61 for ; Wed, 7 Aug 2019 17:29:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:Subject:To:From :Date:Message-Id:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: List-Owner; bh=6nGwHu+Y5mQCupLc1w2bDmjctZQXdf9/9Ai8TsRTGbg=; b=WlL/LLax7AnkRB RLbNz5OBfskZ23io6CTTHDs55uJ6SgsMlwWHPrsWUlrW3kb/dWxEs6wZela5vS+kEfTFBeWFch7kR EL5TyWbQ53NBWRCzJm2+DfCqhnsNELrPyc9+NC/ZmQXOgaXKEBiYRh6RNi485xZmCcKUztDxOBeJx ru4WxPtdZPKr1Snb1tPLZ0wOji9N8wC3gYvUnwwNx5kvt5+uXJo3IghCVq+bX8+sNRQMeL6N8T2IY kYcCB+Uq9rjtRX73XwL7LYmi0bRNJYTABo5HcTSmn0CjgBehq16Z6XJTde8kyQkJRrttiVbPGDONT MThRiKdPfdgOqO4bdnUg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hvPkY-00071T-0L; Wed, 07 Aug 2019 17:29:22 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hvPkK-0006qL-Dm for linux-arm-kernel@lists.infradead.org; Wed, 07 Aug 2019 17:29:09 +0000 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 20D90222FC; Wed, 7 Aug 2019 17:29:08 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.92) (envelope-from ) id 1hvPkJ-0007zT-8a; Wed, 07 Aug 2019 13:29:07 -0400 Message-Id: <20190807172907.155165959@goodmis.org> User-Agent: quilt/0.65 Date: Wed, 07 Aug 2019 13:28:27 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Subject: [PATCH 1/2 v2] tracing/arm64: Have max stack tracer handle the case of return address after data References: <20190807172826.352574408@goodmis.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190807_102908_482343_C821CE58 X-CRM114-Status: GOOD ( 15.15 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jiping Ma , catalin.marinas@arm.com, will.deacon@arm.com, mingo@redhat.com, Joel Fernandes , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: "Steven Rostedt (VMware)" Most archs (well at least x86) store the function call return address on the stack before storing the local variables for the function. The max stack tracer depends on this in its algorithm to display the stack size of each function it finds in the back trace. Some archs (arm64), may store the return address (from its link register) just before calling a nested function. There's no reason to save the link register on leaf functions, as it wont be updated. This breaks the algorithm of the max stack tracer. Add a new define ARCH_RET_ADDR_AFTER_LOCAL_VARS that an architecture may set if it stores the return address (link register) after it stores the function's local variables, and have the stack trace shift the values of the mapped stack size to the appropriate functions. Link: 20190802094103.163576-1-jiping.ma2@windriver.com Reported-by: Jiping Ma Signed-off-by: Steven Rostedt (VMware) Acked-by: Will Deacon Reported-by: Jiping Ma Acked-by: Will Deacon Signed-off-by: Steven Rostedt (VMware) Acked-by: Mark Rutland --- arch/arm64/include/asm/ftrace.h | 13 +++++++++++++ kernel/trace/trace_stack.c | 14 ++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index 5ab5200b2bdc..961e98618db4 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -14,6 +14,19 @@ #define MCOUNT_ADDR ((unsigned long)_mcount) #define MCOUNT_INSN_SIZE AARCH64_INSN_SIZE +/* + * Currently, gcc tends to save the link register after the local variables + * on the stack. This causes the max stack tracer to report the function + * frame sizes for the wrong functions. By defining + * ARCH_RET_ADDR_AFTER_LOCAL_VARS, it will tell the stack tracer to expect + * to find the return address on the stack after the local variables have + * been set up. + * + * Note, this may change in the future, and we will need to deal with that + * if it were to happen. + */ +#define ARCH_RET_ADDR_AFTER_LOCAL_VARS 1 + #ifndef __ASSEMBLY__ #include diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c index 5d16f73898db..40e4a88eea8f 100644 --- a/kernel/trace/trace_stack.c +++ b/kernel/trace/trace_stack.c @@ -158,6 +158,20 @@ static void check_stack(unsigned long ip, unsigned long *stack) i++; } +#ifdef ARCH_RET_ADDR_AFTER_LOCAL_VARS + /* + * Some archs will store the link register before calling + * nested functions. This means the saved return address + * comes after the local storage, and we need to shift + * for that. + */ + if (x > 1) { + memmove(&stack_trace_index[0], &stack_trace_index[1], + sizeof(stack_trace_index[0]) * (x - 1)); + x--; + } +#endif + stack_trace_nr_entries = x; if (task_stack_end_corrupted(current)) {