Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757612AbcDGU7j (ORCPT ); Thu, 7 Apr 2016 16:59:39 -0400 Received: from casper.infradead.org ([85.118.1.10]:49171 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932540AbcDGU7E (ORCPT ); Thu, 7 Apr 2016 16:59:04 -0400 From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Wang Nan , Adrian Hunter , Cody P Schafer , He Kuang , Jiri Olsa , Kirill Smelkov , Li Zefan , Masami Hiramatsu , pi3orama@163.com, Arnaldo Carvalho de Melo Subject: [PATCH 19/19] perf symbols: Adjust symbol for shared objects Date: Thu, 7 Apr 2016 17:58:40 -0300 Message-Id: <1460062720-21736-20-git-send-email-acme@kernel.org> X-Mailer: git-send-email 2.5.5 In-Reply-To: <1460062720-21736-1-git-send-email-acme@kernel.org> References: <1460062720-21736-1-git-send-email-acme@kernel.org> 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: 4101 Lines: 125 From: Wang Nan 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 Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Cody P Schafer Cc: He Kuang Cc: Jiri Olsa Cc: Kirill Smelkov Cc: Li Zefan Cc: Masami Hiramatsu Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1460024671-64774-3-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo --- 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 bc229a74c6a9..3f9d6798bd18 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) { -- 2.5.5