Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755754AbcDGKZ2 (ORCPT ); Thu, 7 Apr 2016 06:25:28 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:26901 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755663AbcDGKZ1 (ORCPT ); Thu, 7 Apr 2016 06:25:27 -0400 From: Wang Nan To: CC: , , , , Adrian Hunter , Cody P Schafer , He Kuang , Jiri Olsa , Kirill Smelkov , Masami Hiramatsu Subject: [RESEND PATCH 2/2] perf tools: Adjust symbol for shared objects Date: Thu, 7 Apr 2016 10:24:31 +0000 Message-ID: <1460024671-64774-3-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1460024671-64774-1-git-send-email-wangnan0@huawei.com> References: <1460024671-64774-1-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.193.248] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020205.57063573.007C,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: f502ff3d3522a849bd80cc5a7f05f25b Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3842 Lines: 120 He Kuang reported a problem that perf fails to get correct symbol on Android platform in [1]. The problem can be reproduced on normal x86_64 platform. I will describe the reproducing steps in detail at the end of commit message. The reason of this problem is the missing of symbol adjustment for normal shared objects. In most of the cases skipping adjustment is okay. However, when '.text' section have different 'address' and 'offset' the result is wrong. I checked all shared objects in my working platform, only wine dll objects and debug objects (in .debug) have this problem. However, it is common on Android. For example: $ readelf -S ./libsurfaceflinger.so | grep \.text [10] .text PROGBITS 0000000000029030 00012030 This patch enables symbol adjustment for dynamic objects so the symbol address got from elfutils would be adjusted correctly. Now nearly all types of ELF files should adjust symbols. Makes ss->adjust_symbols default to true. Steps to reproduce the problem: $ cat ./Makefile PWD := $(shell pwd) LDFLAGS += "-Wl,-rpath=$(PWD)" CFLAGS += -g main: main.c libbuggy.so libbuggy.so: buggy.c gcc -g -shared -fPIC -Wl,-Ttext-segment=0x200000 $< -o $@ clean: rm -rf main libbuggy.so *.o $ cat ./buggy.c int fib(int x) { return (x == 0) ? 1 : (x == 1) ? 1 : fib(x - 1) + fib(x - 2); } $ cat ./main.c #include extern int fib(int x); int main() { int i; for (i = 0; i < 40; i++) printf("%d\n", fib(i)); return 0; } $ make $ perf record ./main ... $ perf report --stdio # Overhead Command Shared Object Symbol # ........ ....... ................. ............................... # 14.97% main libbuggy.so [.] 0x000000000000066c 8.68% main libbuggy.so [.] 0x00000000000006aa 8.52% main libbuggy.so [.] fib@plt 7.95% main libbuggy.so [.] 0x0000000000000664 5.94% main libbuggy.so [.] 0x00000000000006a9 5.35% main libbuggy.so [.] 0x0000000000000678 ... The correct result should be (after this patch): # Overhead Command Shared Object Symbol # ........ ....... ................. ............................... # 91.47% main libbuggy.so [.] fib 8.52% main libbuggy.so [.] fib@plt 0.00% main [kernel.kallsyms] [k] kmem_cache_free [1] http://lkml.kernel.org/g/1452567507-54013-1-git-send-email-hekuang@huawei.com Signed-off-by: Wang Nan Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Arnaldo Carvalho de Melo Cc: Cody P Schafer Cc: He Kuang Cc: Jiri Olsa Cc: Kirill Smelkov Cc: Masami Hiramatsu Cc: Li Zefan Cc: pi3orama@163.com --- tools/perf/util/symbol-elf.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index bc229a7..3f9d679 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -709,17 +709,10 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, if (ss->opdshdr.sh_type != SHT_PROGBITS) ss->opdsec = NULL; - if (dso->kernel == DSO_TYPE_USER) { - GElf_Shdr shdr; - ss->adjust_symbols = (ehdr.e_type == ET_EXEC || - ehdr.e_type == ET_REL || - dso__is_vdso(dso) || - elf_section_by_name(elf, &ehdr, &shdr, - ".gnu.prelink_undo", - NULL) != NULL); - } else { + if (dso->kernel == DSO_TYPE_USER) + ss->adjust_symbols = true; + else ss->adjust_symbols = elf__needs_adjust_symbols(ehdr); - } ss->name = strdup(name); if (!ss->name) { -- 1.8.3.4