Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755172AbaF3Iva (ORCPT ); Mon, 30 Jun 2014 04:51:30 -0400 Received: from mga09.intel.com ([134.134.136.24]:43142 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755122AbaF3Iv1 (ORCPT ); Mon, 30 Jun 2014 04:51:27 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,573,1400050800"; d="scan'208";a="536451121" From: "Yan, Zheng" To: linux-kernel@vger.kernel.org Cc: a.p.zijlstra@chello.nl, mingo@kernel.org, acme@infradead.org, eranian@google.com, andi@firstfloor.org, "Yan, Zheng" Subject: [PATCH V4 12/16] perf, x86: use LBR call stack to get user callchain Date: Mon, 30 Jun 2014 16:50:49 +0800 Message-Id: <1404118253-19532-13-git-send-email-zheng.z.yan@intel.com> X-Mailer: git-send-email 1.9.0 In-Reply-To: <1404118253-19532-1-git-send-email-zheng.z.yan@intel.com> References: <1404118253-19532-1-git-send-email-zheng.z.yan@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Haswell has a new feature that utilizes the existing Last Branch Record facility to record call chains. When the feature is enabled, function call will be collected as normal, but as return instructions are executed the last captured branch record is popped from the on-chip LBR registers. The LBR call stack facility can help perf to get call chains of progam without frame pointer. This patch makes x86's perf_callchain_user() failback to use LBR call stack data when there is no frame pointer in the user program. The 'from' address of branch entry is used as 'return' address of function call. Signed-off-by: Yan, Zheng --- arch/x86/kernel/cpu/perf_event.c | 33 ++++++++++++++++++++++++++---- arch/x86/kernel/cpu/perf_event_intel.c | 2 +- arch/x86/kernel/cpu/perf_event_intel_lbr.c | 2 ++ include/linux/perf_event.h | 1 + 4 files changed, 33 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 3ed9c6a..41daa7b 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -1999,12 +1999,28 @@ static unsigned long get_segment_base(unsigned int segment) return get_desc_base(desc + idx); } +static inline void +perf_callchain_lbr_callstack(struct perf_callchain_entry *entry, + struct perf_sample_data *data) +{ + struct perf_branch_stack *br_stack = data->br_stack; + + if (br_stack && br_stack->user_callstack) { + int i = 0; + while (i < br_stack->nr && entry->nr < PERF_MAX_STACK_DEPTH) { + perf_callchain_store(entry, br_stack->entries[i].from); + i++; + } + } +} + #ifdef CONFIG_COMPAT #include static inline int -perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry) +perf_callchain_user32(struct perf_callchain_entry *entry, + struct pt_regs *regs, struct perf_sample_data *data) { /* 32-bit process in 64-bit kernel. */ unsigned long ss_base, cs_base; @@ -2033,11 +2049,16 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry) perf_callchain_store(entry, cs_base + frame.return_address); fp = compat_ptr(ss_base + frame.next_frame); } + + if (fp == compat_ptr(regs->bp)) + perf_callchain_lbr_callstack(entry, data); + return 1; } #else static inline int -perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry) +perf_callchain_user32(struct perf_callchain_entry *entry, + struct pt_regs *regs, struct perf_sample_data *data) { return 0; } @@ -2067,12 +2088,12 @@ void perf_callchain_user(struct perf_callchain_entry *entry, if (!current->mm) return; - if (perf_callchain_user32(regs, entry)) + if (perf_callchain_user32(entry, regs, data)) return; while (entry->nr < PERF_MAX_STACK_DEPTH) { unsigned long bytes; - frame.next_frame = NULL; + frame.next_frame = NULL; frame.return_address = 0; bytes = copy_from_user_nmi(&frame, fp, sizeof(frame)); @@ -2085,6 +2106,10 @@ void perf_callchain_user(struct perf_callchain_entry *entry, perf_callchain_store(entry, frame.return_address); fp = frame.next_frame; } + + /* try LBR callstack if there is no frame pointer */ + if (fp == (void __user *)regs->bp) + perf_callchain_lbr_callstack(entry, data); } /* diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c index a14489b..1082609 100644 --- a/arch/x86/kernel/cpu/perf_event_intel.c +++ b/arch/x86/kernel/cpu/perf_event_intel.c @@ -1395,7 +1395,7 @@ again: perf_sample_data_init(&data, 0, event->hw.last_period); - if (has_branch_stack(event)) + if (needs_branch_stack(event)) data.br_stack = &cpuc->lbr_stack; if (perf_event_overflow(event, &data, regs)) diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index 639ab1d..f059b98 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -721,6 +721,8 @@ intel_pmu_lbr_filter(struct cpu_hw_events *cpuc) int i, j, type; bool compress = false; + cpuc->lbr_stack.user_callstack = branch_user_callstack(br_sel); + /* if sampling all branches, then nothing to filter */ if ((br_sel & X86_BR_ALL) == X86_BR_ALL) return; diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index cc0b86e..b5515dc 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -74,6 +74,7 @@ struct perf_raw_record { * recent branch. */ struct perf_branch_stack { + bool user_callstack; __u64 nr; struct perf_branch_entry entries[0]; }; -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/