Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751250AbbEBF6t (ORCPT ); Sat, 2 May 2015 01:58:49 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:15797 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750778AbbEBF6s (ORCPT ); Sat, 2 May 2015 01:58:48 -0400 From: Hou Pengyang To: , , , , CC: , , , Subject: [PATCH v3 1/2] arm: perf: Fix callchain parse error with kernel tracepoint events Date: Sat, 2 May 2015 05:58:16 +0000 Message-ID: <1430546297-80481-2-git-send-email-houpengyang@huawei.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1430546297-80481-1-git-send-email-houpengyang@huawei.com> References: <1430546297-80481-1-git-send-email-houpengyang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.197.210] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2122 Lines: 58 For ARM, when tracing with tracepoint events, the IP and cpsr are set to 0, preventing the perf code parsing the callchain and resolving the symbols correctly. ./perf record -e sched:sched_switch -g --call-graph dwarf ls [ perf record: Captured and wrote 0.006 MB perf.data ] ./perf report -f Samples: 5 of event 'sched:sched_switch', Event count (approx.): 5 Children Self Command Shared Object Symbol 100.00% 100.00% ls [unknown] [.] 00000000 The fix is to implement perf_arch_fetch_caller_regs for ARM, which fills several necessary registers used for callchain unwinding, including pc,sp, fp and cpsr. With this patch, callchain can be parsed correctly as : ..... - 100.00% 100.00% ls [kernel.kallsyms] [k] __sched_text_start + __sched_text_start + 20.00% 0.00% ls libc-2.18.so [.] _dl_addr + 20.00% 0.00% ls libc-2.18.so [.] write ..... Jean Pihet found this in ARM and come up with a patch: http://thread.gmane.org/gmane.linux.kernel/1734283/focus=1734280 This patch rewrite Jean's patch in C. Signed-off-by: Hou Pengyang --- arch/arm/include/asm/perf_event.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/arm/include/asm/perf_event.h b/arch/arm/include/asm/perf_event.h index d9cf138..4f9dec4 100644 --- a/arch/arm/include/asm/perf_event.h +++ b/arch/arm/include/asm/perf_event.h @@ -19,4 +19,11 @@ extern unsigned long perf_misc_flags(struct pt_regs *regs); #define perf_misc_flags(regs) perf_misc_flags(regs) #endif +#define perf_arch_fetch_caller_regs(regs, __ip) { \ + (regs)->ARM_pc = (__ip); \ + (regs)->ARM_fp = (unsigned long) __builtin_frame_address(0); \ + (regs)->ARM_sp = current_stack_pointer; \ + (regs)->ARM_cpsr = SVC_MODE; \ +} + #endif /* __ARM_PERF_EVENT_H__ */ -- 1.8.3.4 -- 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/