Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757854Ab1CaNz7 (ORCPT ); Thu, 31 Mar 2011 09:55:59 -0400 Received: from casper.infradead.org ([85.118.1.10]:50086 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757737Ab1CaNz5 (ORCPT ); Thu, 31 Mar 2011 09:55:57 -0400 Date: Thu, 31 Mar 2011 10:46:38 -0300 From: Arnaldo Carvalho de Melo To: Lin Ming Cc: Masami Hiramatsu , Peter Zijlstra , Frederic Weisbecker , LKML , "2nddept-manager@sdl.hitachi.co.jp" <2nddept-manager@sdl.hitachi.co.jp> Subject: Re: [RFC PATCH] perf report: add sort by file lines Message-ID: <20110331134638.GA25095@ghostprotocols.net> References: <1301391136.14111.98.camel@minggr.sh.intel.com> <1301392457.4859.74.camel@twins> <1301417155.3620.8.camel@localhost> <1301418183.2250.416.camel@laptop> <1301418404.2250.417.camel@laptop> <1301418533.2250.419.camel@laptop> <20110329174556.GC24129@ghostprotocols.net> <4D92818A.8020405@hitachi.com> <1301561155.14111.288.camel@minggr.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1301561155.14111.288.camel@minggr.sh.intel.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.21 (2010-09-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2524 Lines: 71 Em Thu, Mar 31, 2011 at 04:45:55PM +0800, Lin Ming escreveu: > On Wed, 2011-03-30 at 09:04 +0800, Masami Hiramatsu wrote: > > > foo: > > > .cfi_startproc > > > pushq %rbp > > > .cfi_def_cfa_offset 16 > > > movq %rsp, %rbp > > > .cfi_offset 6, -16 > > > .cfi_def_cfa_register 6 > > > movq %rdi, -8(%rbp) > > > movq %rsi, -16(%rbp) > > > movq -8(%rbp), %rax /* load foo arg from stack */ > > > movq 24(%rax), %rax /* load foo->bar */ > > > movq -16(%rbp), %rdx /* load tmp arg from stack */ > > > movl 32(%rdx), %edx /* load tmp->blah */ > > > movl %edx, 20(%rax) /* store bar->fubar */ <<==(1) > > > leave > > > ret > > > .cfi_endproc > > > > At (1), dwarf tells us the location of 'foo' is -8(%rbp) and 'tmp' is > > -16(%rbp), but doesn't know to what 20(%rax) is mapped, because > > foo->bar->fubar is not a real variable. > > I am considering if it is possible to do "instruction unwind" to get a > map from (temporarily used) register to a specific member of a data > structure pointed by a pointer. > > 4004a0: movq -8(%rbp), %rax /* load foo arg from stack */ > 4004a4: movq 24(%rax), %rax /* load foo->bar */ > 4004a8: movq -16(%rbp), %rdx /* load tmp arg from stack */ > 4004ac: movl 32(%rdx), %edx /* load tmp->blah */ > 4004af: movl %edx, 20(%rax) /* store bar->fubar */ > > foo: -8(%rbp) > tmp: -16(%rbp) > > Assume we are now at ip 4004af, from the instruction decoder, we know > it's a store operation, and we want to find out what %rax is. > > 1. unwind to 4004ac > Ignore this, because it does not touch %rax > > 2. unwind to 4004a8 > Ignore this, because it does not touch %rax > > 3. unwind to 4004a4 > 20(%rax) => 20(24(%rax)), continue to unwind because we still > have no idea what %rax is > > 4. unwind to 4004a0 > 20(24(%rax)) => 20(24(-8(%rbp))), stop unwind, because we now know > -8(%rbp) is foo. > > So the original 20(%rax) is replace as 20(24(-8(%rbp))), and it means > foo->bar->fubar > > Does this make sense? I think it does, so we do just like with annotation, but parsing objdump -S output, is that what you're planning? After we have the members we can do data annotation, in much the same way we do with code annotation, i.e. augmenting pahole output. - Arnaldo -- 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/