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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY, 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 A218BC10F13 for ; Thu, 11 Apr 2019 08:01:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 78C4B21905 for ; Thu, 11 Apr 2019 08:01:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726957AbfDKIBa (ORCPT ); Thu, 11 Apr 2019 04:01:30 -0400 Received: from smtp2200-217.mail.aliyun.com ([121.197.200.217]:35340 "EHLO smtp2200-217.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726230AbfDKIB1 (ORCPT ); Thu, 11 Apr 2019 04:01:27 -0400 X-Alimail-AntiSpam: AC=CONTINUE;BC=0.07436284|-1;CH=green;DM=CONTINUE|CONTINUE|true|0.647045-0.0311521-0.321803;FP=0|0|0|0|0|-1|-1|-1;HT=e02c03291;MF=han_mao@c-sky.com;NM=1;PH=DS;RN=3;RT=3;SR=0;TI=SMTPD_---.EJof5z._1554969684; Received: from localhost(mailfrom:han_mao@c-sky.com fp:SMTPD_---.EJof5z._1554969684) by smtp.aliyun-inc.com(10.147.42.241); Thu, 11 Apr 2019 16:01:24 +0800 From: Mao Han To: linux-kernel@vger.kernel.org Cc: Mao Han , Palmer Dabbelt Subject: [PATCH 1/3] riscv: Add perf callchain support Date: Thu, 11 Apr 2019 15:53:48 +0800 Message-Id: <195185ea63240ed396026505d96d1f6449963482.1554961908.git.han_mao@c-sky.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch add support for perf callchain sampling on riscv platform. The return address of leaf function is retrieved from pt_regs as it is not saved in the outmost frame. Signed-off-by: Mao Han CC: Palmer Dabbelt --- arch/riscv/kernel/Makefile | 3 +- arch/riscv/kernel/perf_callchain.c | 122 +++++++++++++++++++++++++++++++++++++ 2 files changed, 124 insertions(+), 1 deletion(-) create mode 100644 arch/riscv/kernel/perf_callchain.c diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 5985681..dd2ba44 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -37,6 +37,7 @@ obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o -obj-$(CONFIG_PERF_EVENTS) += perf_event.o +obj-$(CONFIG_PERF_EVENTS) += perf_event.o +obj-$(CONFIG_PERF_EVENTS) += perf_callchain.o clean: diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c new file mode 100644 index 0000000..eb3ddbb --- /dev/null +++ b/arch/riscv/kernel/perf_callchain.c @@ -0,0 +1,122 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. + +#include +#include + +/* Kernel callchain */ +struct stackframe { + unsigned long fp; + unsigned long ra; +}; + +static int unwind_frame_kernel(struct stackframe *frame) +{ + int graph = 0; + + /* 0x3 means misalignment */ + if (!kstack_end((void *)frame->fp) && + !((unsigned long)frame->fp & 0x3) && + ((unsigned long)frame->fp >= TASK_SIZE)) { + frame->ra = ((struct stackframe *)frame->fp - 1)->ra; + frame->fp = ((struct stackframe *)frame->fp - 1)->fp; + /* make sure CONFIG_FUNCTION_GRAPH_TRACER is turned on */ + if (__kernel_text_address(frame->ra)) + frame->ra = ftrace_graph_ret_addr(NULL, &graph, + frame->ra, NULL); + return 0; + } else { + return -EPERM; + } +} + +static void notrace walk_stackframe(struct stackframe *fr, + struct perf_callchain_entry_ctx *entry) +{ + while (1) { + int ret; + + perf_callchain_store(entry, fr->ra); + + ret = unwind_frame_kernel(fr); + if (ret < 0) + break; + } +} + +/* + * Get the return address for a single stackframe and return a pointer to the + * next frame tail. + */ +static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry, + unsigned long fp, unsigned long reg_ra) +{ + struct stackframe buftail; + unsigned long ra = 0; + unsigned long *user_frame_tail = (unsigned long *)(fp - sizeof(struct stackframe)); + + /* Check accessibility of one struct frame_tail beyond */ + if (!access_ok(user_frame_tail, sizeof(buftail))) + return 0; + if (__copy_from_user_inatomic(&buftail, user_frame_tail, + sizeof(buftail))) + return 0; + + if (reg_ra != 0) + ra = reg_ra; + else + ra = buftail.ra; + + fp = buftail.fp; + perf_callchain_store(entry, ra); + + return fp; +} + +/* + * This will be called when the target is in user mode + * This function will only be called when we use + * "PERF_SAMPLE_CALLCHAIN" in + * kernel/events/core.c:perf_prepare_sample() + * + * How to trigger perf_callchain_[user/kernel] : + * $ perf record -e cpu-clock --call-graph fp ./program + * $ perf report --call-graph + * + * On RISC-V platform, the program being sampled and the C library + * need to be compiled with * -mbacktrace, otherwise the user + * stack will not contain function frame. + */ +void perf_callchain_user(struct perf_callchain_entry_ctx *entry, + struct pt_regs *regs) +{ + unsigned long fp = 0; + + /* RISC-V does not support virtualization. */ + if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) + return; + + fp = regs->s0; + perf_callchain_store(entry, regs->sepc); + + fp = user_backtrace(entry, fp, regs->ra); + while ((entry->nr < entry->max_stack) && + fp && !((unsigned long)fp & 0x3)) + fp = user_backtrace(entry, fp, 0); +} + +void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, + struct pt_regs *regs) +{ + struct stackframe fr; + + /* RISC-V does not support virtualization. */ + if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) { + pr_warn("RISC-V does not support perf in guest mode!"); + return; + } + + fr.fp = regs->s0; + fr.ra = regs->ra; + walk_stackframe(&fr, entry); +} -- 2.7.4