From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755431AbbLDMLY (ORCPT ); Fri, 4 Dec 2015 07:11:24 -0500 Received: from mail.skyhub.de ([78.46.96.112]:57172 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752745AbbLDMLX (ORCPT ); Fri, 4 Dec 2015 07:11:23 -0500 Date: Fri, 4 Dec 2015 13:11:15 +0100 From: Borislav Petkov To: Ingo Molnar Cc: linux-tip-commits@vger.kernel.org, vincent.weaver@maine.edu, eranian@google.com, hpa@zytor.com, efault@gmx.de, peterz@infradead.org, jolsa@redhat.com, torvalds@linux-foundation.org, tglx@linutronix.de, ak@linux.intel.com, rostedt@goodmis.org, acme@redhat.com, mingo@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [tip:perf/core] x86, tracing, perf: Add trace point for MSR accesses Message-ID: <20151204121115.GA21524@pd.tnic> References: <1449018060-1742-3-git-send-email-andi@firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: 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 On Fri, Dec 04, 2015 at 03:59:42AM -0800, tip-bot for Andi Kleen wrote: > Commit-ID: 07b41f5cf37b34ef3de4f40fbaf8547abe690abb > Gitweb: http://git.kernel.org/tip/07b41f5cf37b34ef3de4f40fbaf8547abe690abb > Author: Andi Kleen > AuthorDate: Tue, 1 Dec 2015 17:00:59 -0800 > Committer: Ingo Molnar > CommitDate: Fri, 4 Dec 2015 10:58:34 +0100 > > x86, tracing, perf: Add trace point for MSR accesses > > For debugging low level code interacting with the CPU it is often > useful to trace the MSR read/writes. This gives a concise summary of > PMU and other operations. > > perf has an ad-hoc way to do this using trace_printk, but it's > somewhat limited (and also now spews ugly boot messages when enabled) > > Instead define real trace points for all MSR accesses. > > This adds three new trace points: read_msr and write_msr and rdpmc. > > They also report if the access faulted (if *_safe is used) > > This allows filtering and triggering on specific MSR values, which > allows various more advanced debugging techniques. > > All the values are well defined in the CPU documentation. > > The trace can be post processed with > Documentation/trace/postprocess/decode_msr.py to add symbolic MSR > names to the trace. > > I only added it to native MSR accesses in C, not paravirtualized or in > entry*.S (which is not too interesting) > > Originally the patch kit moved the MSRs out of line. This uses an > alternative approach recommended by Steven Rostedt of only moving the > trace calls out of line, but open coding the access to the jump label. > > Signed-off-by: Andi Kleen > Signed-off-by: Peter Zijlstra (Intel) > Acked-by: Steven Rostedt > Cc: Arnaldo Carvalho de Melo > Cc: Jiri Olsa > Cc: Linus Torvalds > Cc: Mike Galbraith > Cc: Peter Zijlstra > Cc: Stephane Eranian > Cc: Thomas Gleixner > Cc: Vince Weaver > Link: http://lkml.kernel.org/r/1449018060-1742-3-git-send-email-andi@firstfloor.org > Signed-off-by: Ingo Molnar > --- ... > diff --git a/arch/x86/lib/msr.c b/arch/x86/lib/msr.c > index 4362373..004c861 100644 > --- a/arch/x86/lib/msr.c > +++ b/arch/x86/lib/msr.c > @@ -1,6 +1,8 @@ > #include > #include > #include > +#define CREATE_TRACE_POINTS > +#include > > struct msr *msrs_alloc(void) > { > @@ -108,3 +110,27 @@ int msr_clear_bit(u32 msr, u8 bit) > { > return __flip_bit(msr, bit, false); > } > + > +#ifdef CONFIG_TRACEPOINTS > +void do_trace_write_msr(unsigned msr, u64 val, int failed) > +{ > + trace_write_msr(msr, val, failed); > +} > +EXPORT_SYMBOL(do_trace_write_msr); > +EXPORT_TRACEPOINT_SYMBOL(write_msr); > + > +void do_trace_read_msr(unsigned msr, u64 val, int failed) > +{ > + trace_read_msr(msr, val, failed); > +} > +EXPORT_SYMBOL(do_trace_read_msr); > +EXPORT_TRACEPOINT_SYMBOL(read_msr); > + > +void do_trace_rdpmc(unsigned counter, u64 val, int failed) > +{ > + trace_rdpmc(counter, val, failed); > +} > +EXPORT_SYMBOL(do_trace_rdpmc); > +EXPORT_TRACEPOINT_SYMBOL(rdpmc); Any particular reason why those are EXPORT_SYMBOL and not EXPORT_SYMBOL_GPL? -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply.