Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751778AbbEAQno (ORCPT ); Fri, 1 May 2015 12:43:44 -0400 Received: from foss.arm.com ([217.140.101.70]:38954 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750920AbbEAQnn (ORCPT ); Fri, 1 May 2015 12:43:43 -0400 Date: Fri, 1 May 2015 17:43:38 +0100 From: Will Deacon To: Hou Pengyang Cc: "a.p.zijlstra@chello.nl" , "paulus@samba.org" , "acme@kernel.org" , "mingo@redhat.com" , "wannan0@huawei.com" , Catalin Marinas , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH v2] arm & arm64: perf: Fix callchain parse error with kernel tracepoint events Message-ID: <20150501164338.GE25524@arm.com> References: <1430402332-52750-1-git-send-email-houpengyang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1430402332-52750-1-git-send-email-houpengyang@huawei.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3458 Lines: 87 On Thu, Apr 30, 2015 at 02:58:52PM +0100, Hou Pengyang wrote: > For ARM & ARM64, 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 0.146 MB perf.data ] > ./perf report -f > Samples: 194 of event 'sched:sched_switch', Event count (approx.): 194 > Children Self Command Shared Object Symbol > 100.00% 100.00% ls [unknown] [.] 0000000000000000 > > The fix is to implement perf_arch_fetch_caller_regs for ARM64, which fills > several necessary registers used for callchain unwinding, including pc,sp, > fp and psr . Thanks for the v2. > With this patch, callchain can be parsed correctly as follows: > > ...... > + 2.63% 0.00% ls [kernel.kallsyms] [k] vfs_symlink > + 2.63% 0.00% ls [kernel.kallsyms] [k] follow_down > + 2.63% 0.00% ls [kernel.kallsyms] [k] pfkey_get > + 2.63% 0.00% ls [kernel.kallsyms] [k] do_execveat_common.isra.33 > - 2.63% 0.00% ls [kernel.kallsyms] [k] pfkey_send_policy_notify > pfkey_send_policy_notify > pfkey_get > v9fs_vfs_rename > page_follow_link_light > link_path_walk > el0_svc_naked > ....... > > Jean Pihet found this in ARM and come up with a patch: > http://thread.gmane.org/gmane.linux.kernel/1734283/focus=1734280 > > Signed-off-by: Hou Pengyang > --- > arch/arm/include/asm/perf_event.h | 7 +++++++ > arch/arm64/include/asm/perf_event.h | 7 +++++++ > 2 files changed, 14 insertions(+) Can you split this into two patches, please? > diff --git a/arch/arm/include/asm/perf_event.h b/arch/arm/include/asm/perf_event.h > index d9cf138..17705e2b 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 |= SYSTEM_MODE; \ You don't need to |= (just = is fine, perf memset's the thing to 0 anyway) and this should be SVC_MODE not SYSTEM_MODE. > +} > + > #endif /* __ARM_PERF_EVENT_H__ */ > diff --git a/arch/arm64/include/asm/perf_event.h b/arch/arm64/include/asm/perf_event.h > index d26d1d5..e6911a4 100644 > --- a/arch/arm64/include/asm/perf_event.h > +++ b/arch/arm64/include/asm/perf_event.h > @@ -24,4 +24,11 @@ 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 |= PSR_MODE_EL1h; \ Similarly here, just use an assignment. Will -- 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/