From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 963BDC433FF for ; Wed, 7 Aug 2019 16:35:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 73EA92231F for ; Wed, 7 Aug 2019 16:35:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730196AbfHGQe4 (ORCPT ); Wed, 7 Aug 2019 12:34:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:33024 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729278AbfHGQe4 (ORCPT ); Wed, 7 Aug 2019 12:34:56 -0400 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 5B0EB22297; Wed, 7 Aug 2019 16:34:55 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.92) (envelope-from ) id 1hvOtq-0007n7-BD; Wed, 07 Aug 2019 12:34:54 -0400 Message-Id: <20190807163454.230809268@goodmis.org> User-Agent: quilt/0.65 Date: Wed, 07 Aug 2019 12:34:02 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Joel Fernandes , Jiping Ma , mingo@redhat.com, catalin.marinas@arm.com, will.deacon@arm.com, linux-arm-kernel@lists.infradead.org Subject: [PATCH 1/2] tracing/arm64: Have max stack tracer handle the case of return address after data References: <20190807163401.570339297@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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) --- arch/arm64/include/asm/ftrace.h | 1 + kernel/trace/trace_stack.c | 14 ++++++++++++++ 2 files changed, 15 insertions(+) diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index 5ab5200b2bdc..13a4832cfb00 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -13,6 +13,7 @@ #define HAVE_FUNCTION_GRAPH_FP_TEST #define MCOUNT_ADDR ((unsigned long)_mcount) #define MCOUNT_INSN_SIZE AARCH64_INSN_SIZE +#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)) { -- 2.20.1