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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 BE529C433E6 for ; Fri, 22 Jan 2021 17:10:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 73C21233FA for ; Fri, 22 Jan 2021 17:10:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729716AbhAVRKK (ORCPT ); Fri, 22 Jan 2021 12:10:10 -0500 Received: from foss.arm.com ([217.140.110.172]:55698 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729570AbhAVQUq (ORCPT ); Fri, 22 Jan 2021 11:20:46 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 94AFB1595; Fri, 22 Jan 2021 08:20:00 -0800 (PST) Received: from e125528.arm.com (unknown [10.57.9.161]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 282773F719; Fri, 22 Jan 2021 08:19:54 -0800 (PST) From: Alexandre Truong To: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Cc: Alexandre Truong , John Garry , Will Deacon , Mathieu Poirier , Leo Yan , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Kemeng Shi , Ian Rogers , Andi Kleen , Kan Liang , Jin Yao , Adrian Hunter , Suzuki K Poulose , Al Grant , James Clark , Wilco Dijkstra Subject: [PATCH 4/4] perf tools: determine if LR is the return address Date: Fri, 22 Jan 2021 16:18:54 +0000 Message-Id: <20210122161854.5289-4-alexandre.truong@arm.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20210122161854.5289-1-alexandre.truong@arm.com> References: <20210122161854.5289-1-alexandre.truong@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On arm64 and frame pointer mode (e.g: perf record --callgraph fp), use dwarf unwind info to check if the link register is the return address in order to inject it to the frame pointer stack. Write the following application: int a = 10; void f2(void) { for (int i = 0; i < 1000000; i++) a *= a; } void f1() { f2(); } int main (void) { f1(); return 0; } with the following compilation flags: gcc -g -fno-omit-frame-pointer -fno-inline -O1 The compiler omits the frame pointer for f2 on arm. This is a problem with any leaf call, for example an application with many different calls to malloc() would always omit the calling frame, even if it can be determined. ./perf record --call-graph fp ./a.out ./perf report currently gives the following stack: 0xffffea52f361 _start __libc_start_main main f2 After this change, perf report correctly shows f1() calling f2(), even though it was missing from the frame pointer unwind: ./perf report 0xffffea52f361 _start __libc_start_main main f1 f2 Signed-off-by: Alexandre Truong Cc: John Garry Cc: Will Deacon Cc: Mathieu Poirier Cc: Leo Yan Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Mark Rutland Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Namhyung Kim Cc: Kemeng Shi Cc: Ian Rogers Cc: Andi Kleen Cc: Kan Liang Cc: Jin Yao Cc: Adrian Hunter Cc: Suzuki K Poulose Cc: Al Grant Cc: James Clark Cc: Wilco Dijkstra --- tools/perf/util/Build | 1 + .../util/arm-frame-pointer-unwind-support.c | 43 +++++++++++++++++++ .../util/arm-frame-pointer-unwind-support.h | 7 +++ tools/perf/util/machine.c | 9 ++-- 4 files changed, 57 insertions(+), 3 deletions(-) create mode 100644 tools/perf/util/arm-frame-pointer-unwind-support.c create mode 100644 tools/perf/util/arm-frame-pointer-unwind-support.h diff --git a/tools/perf/util/Build b/tools/perf/util/Build index e2563d0154eb..2009d5f02972 100644 --- a/tools/perf/util/Build +++ b/tools/perf/util/Build @@ -1,3 +1,4 @@ +perf-y += arm-frame-pointer-unwind-support.o perf-y += annotate.o perf-y += block-info.o perf-y += block-range.o diff --git a/tools/perf/util/arm-frame-pointer-unwind-support.c b/tools/perf/util/arm-frame-pointer-unwind-support.c new file mode 100644 index 000000000000..2901ae2917e9 --- /dev/null +++ b/tools/perf/util/arm-frame-pointer-unwind-support.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "../arch/arm64/include/uapi/asm/perf_regs.h" +#include "arch/arm64/include/perf_regs.h" +#include "event.h" +#include "arm-frame-pointer-unwind-support.h" +#include "callchain.h" +#include "unwind.h" + +struct entries { + u64 stack[2]; + int i; +}; + +static bool get_leaf_frame_caller_enabled(struct perf_sample *sample) +{ + return callchain_param.record_mode != CALLCHAIN_FP || !sample->user_regs.regs + || sample->user_regs.mask != PERF_REGS_MASK; +} + +static int add_entry(struct unwind_entry *entry, void *arg) +{ + struct entries *entries = arg; + + entries->stack[entries->i++] = entry->ip; + return 0; +} + +u64 get_leaf_frame_caller_aarch64(struct perf_sample *sample, struct thread *thread) +{ + u64 leaf_frame; + struct entries entries = {{0, 0}, 0}; + + if (get_leaf_frame_caller_enabled(sample)) + return 0; + + unwind__get_entries(add_entry, &entries, thread, sample, 2); + leaf_frame = callchain_param.order == ORDER_CALLER ? + entries.stack[0] : entries.stack[1]; + + if (leaf_frame + 1 == sample->user_regs.regs[PERF_REG_ARM64_LR]) + return sample->user_regs.regs[PERF_REG_ARM64_LR]; + return 0; +} diff --git a/tools/perf/util/arm-frame-pointer-unwind-support.h b/tools/perf/util/arm-frame-pointer-unwind-support.h new file mode 100644 index 000000000000..16dc03fa9abe --- /dev/null +++ b/tools/perf/util/arm-frame-pointer-unwind-support.h @@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __PERF_ARM_FRAME_POINTER_UNWIND_SUPPORT_H +#define __PERF_ARM_FRAME_POINTER_UNWIND_SUPPORT_H + +u64 get_leaf_frame_caller_aarch64(struct perf_sample *sample, struct thread *thread); + +#endif /* __PERF_ARM_FRAME_POINTER_UNWIND_SUPPORT_H */ diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index 40082d70eec1..bc6147e46c89 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -34,6 +34,7 @@ #include "bpf-event.h" #include // page_size #include "cgroup.h" +#include "arm-frame-pointer-unwind-support.h" #include #include @@ -2671,10 +2672,12 @@ static int find_prev_cpumode(struct ip_callchain *chain, struct thread *thread, return err; } -static u64 get_leaf_frame_caller(struct perf_sample *sample __maybe_unused, - struct thread *thread __maybe_unused) +static u64 get_leaf_frame_caller(struct perf_sample *sample, struct thread *thread) { - return 0; + if (strncmp(thread->maps->machine->env->arch, "aarch64", 7) == 0) + return get_leaf_frame_caller_aarch64(sample, thread); + else + return 0; } static int thread__resolve_callchain_sample(struct thread *thread, -- 2.23.0