linux/tools/perf/util/unwind-libdw.c

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 14:07:57 +00:00
// SPDX-License-Identifier: GPL-2.0
#include <linux/compiler.h>
#include <elfutils/libdw.h>
#include <elfutils/libdwfl.h>
#include <inttypes.h>
#include <errno.h>
#include "debug.h"
#include "unwind.h"
#include "unwind-libdw.h"
#include "machine.h"
#include "map.h"
#include "thread.h"
#include <linux/types.h>
#include "event.h"
#include "perf_regs.h"
#include "callchain.h"
#include "util.h"
static char *debuginfo_path;
static const Dwfl_Callbacks offline_callbacks = {
.find_debuginfo = dwfl_standard_find_debuginfo,
.debuginfo_path = &debuginfo_path,
.section_address = dwfl_offline_section_address,
};
static int __report_module(struct addr_location *al, u64 ip,
struct unwind_info *ui)
{
Dwfl_Module *mod;
struct dso *dso = NULL;
/*
* Some callers will use al->sym, so we can't just use the
* cheaper thread__find_map() here.
*/
thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);
if (al->map)
dso = al->map->dso;
if (!dso)
return 0;
mod = dwfl_addrmodule(ui->dwfl, ip);
perf report: Ensure the perf DSO mapping matches what libdw sees In some situations the libdw unwinder stopped working properly. I.e. with libunwind we see: ~~~~~ heaptrack_gui 2228 135073.400112: 641314 cycles: e8ed _dl_fixup (/usr/lib/ld-2.25.so) 15f06 _dl_runtime_resolve_sse_vex (/usr/lib/ld-2.25.so) ed94c KDynamicJobTracker::KDynamicJobTracker (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0) 608f3 _GLOBAL__sub_I_kdynamicjobtracker.cpp (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0) f199 call_init.part.0 (/usr/lib/ld-2.25.so) f2a5 _dl_init (/usr/lib/ld-2.25.so) db9 _dl_start_user (/usr/lib/ld-2.25.so) ~~~~~ But with libdw and without this patch this sample is not properly unwound: ~~~~~ heaptrack_gui 2228 135073.400112: 641314 cycles: e8ed _dl_fixup (/usr/lib/ld-2.25.so) 15f06 _dl_runtime_resolve_sse_vex (/usr/lib/ld-2.25.so) ed94c KDynamicJobTracker::KDynamicJobTracker (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0) ~~~~~ Debug output showed me that libdw found a module for the last frame address, but it thinks it belongs to /usr/lib/ld-2.25.so. This patch double-checks what libdw sees and what perf knows. If the mappings mismatch, we now report the elf known to perf. This fixes the situation above, and the libdw unwinder produces the same stack as libunwind. Signed-off-by: Milian Wolff <milian.wolff@kdab.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Link: http://lkml.kernel.org/r/20170602143753.16907-1-milian.wolff@kdab.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2017-06-02 14:37:52 +00:00
if (mod) {
Dwarf_Addr s;
dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
perf unwind: Take pgoff into account when reporting elf to libdwfl libdwfl parses an ELF file itself and creates mappings for the individual sections. perf on the other hand sees raw mmap events which represent individual sections. When we encounter an address pointing into a mapping with pgoff != 0, we must take that into account and report the file at the non-offset base address. This fixes unwinding with libdwfl in some cases. E.g. for a file like: ``` using namespace std; mutex g_mutex; double worker() { lock_guard<mutex> guard(g_mutex); uniform_real_distribution<double> uniform(-1E5, 1E5); default_random_engine engine; double s = 0; for (int i = 0; i < 1000; ++i) { s += norm(complex<double>(uniform(engine), uniform(engine))); } cout << s << endl; return s; } int main() { vector<std::future<double>> results; for (int i = 0; i < 10000; ++i) { results.push_back(async(launch::async, worker)); } return 0; } ``` Compile it with `g++ -g -O2 -lpthread cpp-locking.cpp -o cpp-locking`, then record it with `perf record --call-graph dwarf -e sched:sched_switch`. When you analyze it with `perf script` and libunwind, you should see: ``` cpp-locking 20038 [005] 54830.236589: sched:sched_switch: prev_comm=cpp-locking prev_pid=20038 prev_prio=120 prev_state=T ==> next_comm=swapper/5 next_pid=0 next_prio=120 ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1670208 schedule+0x28 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb16737cc rwsem_down_read_failed+0xec (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1665e04 call_rwsem_down_read_failed+0x14 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1672a03 down_read+0x13 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb106bd85 __do_page_fault+0x445 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb18015f5 page_fault+0x45 (/lib/modules/4.14.78-1-lts/build/vmlinux) 7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so) 7f38e4252d0b arena_get2.part.4+0x2fb (/usr/lib/libc-2.28.so) 7f38e4255b1c tcache_init.part.6+0xec (/usr/lib/libc-2.28.so) 7f38e42569e5 __GI___libc_malloc+0x115 (inlined) 7f38e4241790 __GI__IO_file_doallocate+0x90 (inlined) 7f38e424fbbf __GI__IO_doallocbuf+0x4f (inlined) 7f38e424ee47 __GI__IO_file_overflow+0x197 (inlined) 7f38e424df36 _IO_new_file_xsputn+0x116 (inlined) 7f38e4242bfb __GI__IO_fwrite+0xdb (inlined) 7f38e463fa6d std::basic_streambuf<char, std::char_traits<char> >::sputn(char const*, long)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> >::_M_put(char const*, long)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::__write<char>(std::ostreambuf_iterator<char, std::char_traits<char> >, char const*, int)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::_M_insert_float<double>(std::ostreambuf_iterator<c> 7f38e464bd70 std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, double) const+0x90 (inl> 7f38e464bd70 std::ostream& std::ostream::_M_insert<double>(double)+0x90 (/usr/lib/libstdc++.so.6.0.25) 563b9cb502f7 std::ostream::operator<<(double)+0xb7 (inlined) 563b9cb502f7 worker()+0xb7 (/ssd/milian/projects/kdab/rnd/hotspot/build/tests/test-clients/cpp-locking/cpp-locking) 563b9cb506fb double std::__invoke_impl<double, double (*)()>(std::__invoke_other, double (*&&)())+0x2b (inlined) 563b9cb506fb std::__invoke_result<double (*)()>::type std::__invoke<double (*)()>(double (*&&)())+0x2b (inlined) 563b9cb506fb decltype (__invoke((_S_declval<0ul>)())) std::thread::_Invoker<std::tuple<double (*)()> >::_M_invoke<0ul>(std::_Index_tuple<0ul>)+0x2b (inlined) 563b9cb506fb std::thread::_Invoker<std::tuple<double (*)()> >::operator()()+0x2b (inlined) 563b9cb506fb std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<double>, std::__future_base::_Result_base::_Deleter>, std::thread::_Invoker<std::tuple<double (*)()> >, dou> 563b9cb506fb std::_Function_handler<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> (), std::__future_base::_Task_setter<std::unique_ptr<std::__future_> 563b9cb507e8 std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>::operator()() const+0x28 (inlined) 563b9cb507e8 std::__future_base::_State_baseV2::_M_do_set(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*)+0x28 (/ssd/milian/> 7f38e46d24fe __pthread_once_slow+0xbe (/usr/lib/libpthread-2.28.so) 563b9cb51149 __gthread_once+0xe9 (inlined) 563b9cb51149 void std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*)> 563b9cb51149 std::__future_base::_State_baseV2::_M_set_result(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>, bool)+0xe9 (inlined) 563b9cb51149 std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<double (*)()> >&&)::{lambda()#1}::op> 563b9cb51149 void std::__invoke_impl<void, std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<double> 563b9cb51149 std::__invoke_result<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<double (*)()> >> 563b9cb51149 decltype (__invoke((_S_declval<0ul>)())) std::thread::_Invoker<std::tuple<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_> 563b9cb51149 std::thread::_Invoker<std::tuple<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<dou> 563b9cb51149 std::thread::_State_impl<std::thread::_Invoker<std::tuple<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread> 7f38e45f0062 execute_native_thread_routine+0x12 (/usr/lib/libstdc++.so.6.0.25) 7f38e46caa9c start_thread+0xfc (/usr/lib/libpthread-2.28.so) 7f38e42ccb22 __GI___clone+0x42 (inlined) ``` Before this patch, using libdwfl, you would see: ``` cpp-locking 20038 [005] 54830.236589: sched:sched_switch: prev_comm=cpp-locking prev_pid=20038 prev_prio=120 prev_state=T ==> next_comm=swapper/5 next_pid=0 next_prio=120 ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1670208 schedule+0x28 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb16737cc rwsem_down_read_failed+0xec (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1665e04 call_rwsem_down_read_failed+0x14 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1672a03 down_read+0x13 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb106bd85 __do_page_fault+0x445 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb18015f5 page_fault+0x45 (/lib/modules/4.14.78-1-lts/build/vmlinux) 7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so) a041161e77950c5c [unknown] ([unknown]) ``` With this patch applied, we get a bit further in unwinding: ``` cpp-locking 20038 [005] 54830.236589: sched:sched_switch: prev_comm=cpp-locking prev_pid=20038 prev_prio=120 prev_state=T ==> next_comm=swapper/5 next_pid=0 next_prio=120 ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1670208 schedule+0x28 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb16737cc rwsem_down_read_failed+0xec (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1665e04 call_rwsem_down_read_failed+0x14 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1672a03 down_read+0x13 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb106bd85 __do_page_fault+0x445 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb18015f5 page_fault+0x45 (/lib/modules/4.14.78-1-lts/build/vmlinux) 7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so) 7f38e4252d0b arena_get2.part.4+0x2fb (/usr/lib/libc-2.28.so) 7f38e4255b1c tcache_init.part.6+0xec (/usr/lib/libc-2.28.so) 7f38e42569e5 __GI___libc_malloc+0x115 (inlined) 7f38e4241790 __GI__IO_file_doallocate+0x90 (inlined) 7f38e424fbbf __GI__IO_doallocbuf+0x4f (inlined) 7f38e424ee47 __GI__IO_file_overflow+0x197 (inlined) 7f38e424df36 _IO_new_file_xsputn+0x116 (inlined) 7f38e4242bfb __GI__IO_fwrite+0xdb (inlined) 7f38e463fa6d std::basic_streambuf<char, std::char_traits<char> >::sputn(char const*, long)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> >::_M_put(char const*, long)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::__write<char>(std::ostreambuf_iterator<char, std::char_traits<char> >, char const*, int)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::_M_insert_float<double>(std::ostreambuf_iterator<c> 7f38e464bd70 std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, double) const+0x90 (inl> 7f38e464bd70 std::ostream& std::ostream::_M_insert<double>(double)+0x90 (/usr/lib/libstdc++.so.6.0.25) 563b9cb502f7 std::ostream::operator<<(double)+0xb7 (inlined) 563b9cb502f7 worker()+0xb7 (/ssd/milian/projects/kdab/rnd/hotspot/build/tests/test-clients/cpp-locking/cpp-locking) 6eab825c1ee3e4ff [unknown] ([unknown]) ``` Note that the backtrace is still stopping too early, when compared to the nice results obtained via libunwind. It's unclear so far what the reason for that is. Committer note: Further comment by Milian on the thread started on the Link: tag below: --- The remaining issue is due to a bug in elfutils: https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html With both patches applied, libunwind and elfutils produce the same output for the above scenario. --- Signed-off-by: Milian Wolff <milian.wolff@kdab.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: http://lkml.kernel.org/r/20181029141644.3907-1-milian.wolff@kdab.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2018-10-29 14:16:44 +00:00
if (s != al->map->start - al->map->pgoff)
perf report: Ensure the perf DSO mapping matches what libdw sees In some situations the libdw unwinder stopped working properly. I.e. with libunwind we see: ~~~~~ heaptrack_gui 2228 135073.400112: 641314 cycles: e8ed _dl_fixup (/usr/lib/ld-2.25.so) 15f06 _dl_runtime_resolve_sse_vex (/usr/lib/ld-2.25.so) ed94c KDynamicJobTracker::KDynamicJobTracker (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0) 608f3 _GLOBAL__sub_I_kdynamicjobtracker.cpp (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0) f199 call_init.part.0 (/usr/lib/ld-2.25.so) f2a5 _dl_init (/usr/lib/ld-2.25.so) db9 _dl_start_user (/usr/lib/ld-2.25.so) ~~~~~ But with libdw and without this patch this sample is not properly unwound: ~~~~~ heaptrack_gui 2228 135073.400112: 641314 cycles: e8ed _dl_fixup (/usr/lib/ld-2.25.so) 15f06 _dl_runtime_resolve_sse_vex (/usr/lib/ld-2.25.so) ed94c KDynamicJobTracker::KDynamicJobTracker (/home/milian/projects/compiled/kf5/lib64/libKF5KIOWidgets.so.5.35.0) ~~~~~ Debug output showed me that libdw found a module for the last frame address, but it thinks it belongs to /usr/lib/ld-2.25.so. This patch double-checks what libdw sees and what perf knows. If the mappings mismatch, we now report the elf known to perf. This fixes the situation above, and the libdw unwinder produces the same stack as libunwind. Signed-off-by: Milian Wolff <milian.wolff@kdab.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Link: http://lkml.kernel.org/r/20170602143753.16907-1-milian.wolff@kdab.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2017-06-02 14:37:52 +00:00
mod = 0;
}
if (!mod)
mod = dwfl_report_elf(ui->dwfl, dso->short_name,
perf unwind: Take pgoff into account when reporting elf to libdwfl libdwfl parses an ELF file itself and creates mappings for the individual sections. perf on the other hand sees raw mmap events which represent individual sections. When we encounter an address pointing into a mapping with pgoff != 0, we must take that into account and report the file at the non-offset base address. This fixes unwinding with libdwfl in some cases. E.g. for a file like: ``` using namespace std; mutex g_mutex; double worker() { lock_guard<mutex> guard(g_mutex); uniform_real_distribution<double> uniform(-1E5, 1E5); default_random_engine engine; double s = 0; for (int i = 0; i < 1000; ++i) { s += norm(complex<double>(uniform(engine), uniform(engine))); } cout << s << endl; return s; } int main() { vector<std::future<double>> results; for (int i = 0; i < 10000; ++i) { results.push_back(async(launch::async, worker)); } return 0; } ``` Compile it with `g++ -g -O2 -lpthread cpp-locking.cpp -o cpp-locking`, then record it with `perf record --call-graph dwarf -e sched:sched_switch`. When you analyze it with `perf script` and libunwind, you should see: ``` cpp-locking 20038 [005] 54830.236589: sched:sched_switch: prev_comm=cpp-locking prev_pid=20038 prev_prio=120 prev_state=T ==> next_comm=swapper/5 next_pid=0 next_prio=120 ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1670208 schedule+0x28 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb16737cc rwsem_down_read_failed+0xec (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1665e04 call_rwsem_down_read_failed+0x14 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1672a03 down_read+0x13 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb106bd85 __do_page_fault+0x445 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb18015f5 page_fault+0x45 (/lib/modules/4.14.78-1-lts/build/vmlinux) 7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so) 7f38e4252d0b arena_get2.part.4+0x2fb (/usr/lib/libc-2.28.so) 7f38e4255b1c tcache_init.part.6+0xec (/usr/lib/libc-2.28.so) 7f38e42569e5 __GI___libc_malloc+0x115 (inlined) 7f38e4241790 __GI__IO_file_doallocate+0x90 (inlined) 7f38e424fbbf __GI__IO_doallocbuf+0x4f (inlined) 7f38e424ee47 __GI__IO_file_overflow+0x197 (inlined) 7f38e424df36 _IO_new_file_xsputn+0x116 (inlined) 7f38e4242bfb __GI__IO_fwrite+0xdb (inlined) 7f38e463fa6d std::basic_streambuf<char, std::char_traits<char> >::sputn(char const*, long)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> >::_M_put(char const*, long)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::__write<char>(std::ostreambuf_iterator<char, std::char_traits<char> >, char const*, int)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::_M_insert_float<double>(std::ostreambuf_iterator<c> 7f38e464bd70 std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, double) const+0x90 (inl> 7f38e464bd70 std::ostream& std::ostream::_M_insert<double>(double)+0x90 (/usr/lib/libstdc++.so.6.0.25) 563b9cb502f7 std::ostream::operator<<(double)+0xb7 (inlined) 563b9cb502f7 worker()+0xb7 (/ssd/milian/projects/kdab/rnd/hotspot/build/tests/test-clients/cpp-locking/cpp-locking) 563b9cb506fb double std::__invoke_impl<double, double (*)()>(std::__invoke_other, double (*&&)())+0x2b (inlined) 563b9cb506fb std::__invoke_result<double (*)()>::type std::__invoke<double (*)()>(double (*&&)())+0x2b (inlined) 563b9cb506fb decltype (__invoke((_S_declval<0ul>)())) std::thread::_Invoker<std::tuple<double (*)()> >::_M_invoke<0ul>(std::_Index_tuple<0ul>)+0x2b (inlined) 563b9cb506fb std::thread::_Invoker<std::tuple<double (*)()> >::operator()()+0x2b (inlined) 563b9cb506fb std::__future_base::_Task_setter<std::unique_ptr<std::__future_base::_Result<double>, std::__future_base::_Result_base::_Deleter>, std::thread::_Invoker<std::tuple<double (*)()> >, dou> 563b9cb506fb std::_Function_handler<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> (), std::__future_base::_Task_setter<std::unique_ptr<std::__future_> 563b9cb507e8 std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>::operator()() const+0x28 (inlined) 563b9cb507e8 std::__future_base::_State_baseV2::_M_do_set(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*)+0x28 (/ssd/milian/> 7f38e46d24fe __pthread_once_slow+0xbe (/usr/lib/libpthread-2.28.so) 563b9cb51149 __gthread_once+0xe9 (inlined) 563b9cb51149 void std::call_once<void (std::__future_base::_State_baseV2::*)(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>*, bool*)> 563b9cb51149 std::__future_base::_State_baseV2::_M_set_result(std::function<std::unique_ptr<std::__future_base::_Result_base, std::__future_base::_Result_base::_Deleter> ()>, bool)+0xe9 (inlined) 563b9cb51149 std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<double (*)()> >&&)::{lambda()#1}::op> 563b9cb51149 void std::__invoke_impl<void, std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<double> 563b9cb51149 std::__invoke_result<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<double (*)()> >> 563b9cb51149 decltype (__invoke((_S_declval<0ul>)())) std::thread::_Invoker<std::tuple<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_> 563b9cb51149 std::thread::_Invoker<std::tuple<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread::_Invoker<std::tuple<dou> 563b9cb51149 std::thread::_State_impl<std::thread::_Invoker<std::tuple<std::__future_base::_Async_state_impl<std::thread::_Invoker<std::tuple<double (*)()> >, double>::_Async_state_impl(std::thread> 7f38e45f0062 execute_native_thread_routine+0x12 (/usr/lib/libstdc++.so.6.0.25) 7f38e46caa9c start_thread+0xfc (/usr/lib/libpthread-2.28.so) 7f38e42ccb22 __GI___clone+0x42 (inlined) ``` Before this patch, using libdwfl, you would see: ``` cpp-locking 20038 [005] 54830.236589: sched:sched_switch: prev_comm=cpp-locking prev_pid=20038 prev_prio=120 prev_state=T ==> next_comm=swapper/5 next_pid=0 next_prio=120 ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1670208 schedule+0x28 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb16737cc rwsem_down_read_failed+0xec (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1665e04 call_rwsem_down_read_failed+0x14 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1672a03 down_read+0x13 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb106bd85 __do_page_fault+0x445 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb18015f5 page_fault+0x45 (/lib/modules/4.14.78-1-lts/build/vmlinux) 7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so) a041161e77950c5c [unknown] ([unknown]) ``` With this patch applied, we get a bit further in unwinding: ``` cpp-locking 20038 [005] 54830.236589: sched:sched_switch: prev_comm=cpp-locking prev_pid=20038 prev_prio=120 prev_state=T ==> next_comm=swapper/5 next_pid=0 next_prio=120 ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb166fec5 __sched_text_start+0x545 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1670208 schedule+0x28 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb16737cc rwsem_down_read_failed+0xec (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1665e04 call_rwsem_down_read_failed+0x14 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb1672a03 down_read+0x13 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb106bd85 __do_page_fault+0x445 (/lib/modules/4.14.78-1-lts/build/vmlinux) ffffffffb18015f5 page_fault+0x45 (/lib/modules/4.14.78-1-lts/build/vmlinux) 7f38e4252591 new_heap+0x101 (/usr/lib/libc-2.28.so) 7f38e4252d0b arena_get2.part.4+0x2fb (/usr/lib/libc-2.28.so) 7f38e4255b1c tcache_init.part.6+0xec (/usr/lib/libc-2.28.so) 7f38e42569e5 __GI___libc_malloc+0x115 (inlined) 7f38e4241790 __GI__IO_file_doallocate+0x90 (inlined) 7f38e424fbbf __GI__IO_doallocbuf+0x4f (inlined) 7f38e424ee47 __GI__IO_file_overflow+0x197 (inlined) 7f38e424df36 _IO_new_file_xsputn+0x116 (inlined) 7f38e4242bfb __GI__IO_fwrite+0xdb (inlined) 7f38e463fa6d std::basic_streambuf<char, std::char_traits<char> >::sputn(char const*, long)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> >::_M_put(char const*, long)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::__write<char>(std::ostreambuf_iterator<char, std::char_traits<char> >, char const*, int)+0x1cd (inlined) 7f38e463fa6d std::ostreambuf_iterator<char, std::char_traits<char> > std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::_M_insert_float<double>(std::ostreambuf_iterator<c> 7f38e464bd70 std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > >::put(std::ostreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, char, double) const+0x90 (inl> 7f38e464bd70 std::ostream& std::ostream::_M_insert<double>(double)+0x90 (/usr/lib/libstdc++.so.6.0.25) 563b9cb502f7 std::ostream::operator<<(double)+0xb7 (inlined) 563b9cb502f7 worker()+0xb7 (/ssd/milian/projects/kdab/rnd/hotspot/build/tests/test-clients/cpp-locking/cpp-locking) 6eab825c1ee3e4ff [unknown] ([unknown]) ``` Note that the backtrace is still stopping too early, when compared to the nice results obtained via libunwind. It's unclear so far what the reason for that is. Committer note: Further comment by Milian on the thread started on the Link: tag below: --- The remaining issue is due to a bug in elfutils: https://sourceware.org/ml/elfutils-devel/2018-q4/msg00089.html With both patches applied, libunwind and elfutils produce the same output for the above scenario. --- Signed-off-by: Milian Wolff <milian.wolff@kdab.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: http://lkml.kernel.org/r/20181029141644.3907-1-milian.wolff@kdab.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2018-10-29 14:16:44 +00:00
(dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff,
false);
return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
}
static int report_module(u64 ip, struct unwind_info *ui)
{
struct addr_location al;
return __report_module(&al, ip, ui);
}
/*
* Store all entries within entries array,
* we will process it after we finish unwind.
*/
static int entry(u64 ip, struct unwind_info *ui)
{
struct unwind_entry *e = &ui->entries[ui->idx++];
struct addr_location al;
if (__report_module(&al, ip, ui))
return -1;
perf script: Show correct offsets for DWARF-based unwinding When perf/data is recorded with the dwarf call-graph option, the callchain shown by 'perf script' still shows the binary offsets of the userspace symbols instead of their virtual addresses. Since the symbol offset calculation is based on using virtual address as the ip, we see incorrect offsets as well. The use of virtual addresses affects the ability to find out the line number in the corresponding source file to which an address maps to as described in commit 67540759151a ("perf unwind: Use addr_location::addr instead of ip for entries"). This has also been addressed by temporarily converting the virtual address to the correponding binary offset so that it can be mapped to the source line number correctly. This is a follow-up for commit 19610184693c ("perf script: Show virtual addresses instead of offsets"). This can be verified on a powerpc64le system running Fedora 27 as shown below: # perf probe -x /usr/lib64/libc-2.26.so -a inet_pton # perf record -e probe_libc:inet_pton --call-graph=dwarf ping -6 -c 1 ::1 Before: # perf report --stdio --no-children -s sym,srcline -g address # Samples: 1 of event 'probe_libc:inet_pton' # Event count (approx.): 1 # # Overhead Symbol Source:Line # ........ .................... ........... # 100.00% [.] __GI___inet_pton inet_pton.c | ---gaih_inet getaddrinfo.c:537 (inlined) __GI_getaddrinfo getaddrinfo.c:2304 (inlined) main ping.c:519 generic_start_main libc-start.c:308 (inlined) __libc_start_main libc-start.c:102 ... # perf script -F comm,ip,sym,symoff,srcline,dso ping 15af28 __GI___inet_pton+0xffff000099160008 (/usr/lib64/libc-2.26.so) libc-2.26.so[ffff80004ca0af28] 10fa53 gaih_inet+0xffff000099160f43 libc-2.26.so[ffff80004c9bfa53] (inlined) 1105b3 __GI_getaddrinfo+0xffff000099160163 libc-2.26.so[ffff80004c9c05b3] (inlined) 2d6f main+0xfffffffd9f1003df (/usr/bin/ping) ping[fffffffecf882d6f] 2369f generic_start_main+0xffff00009916013f libc-2.26.so[ffff80004c8d369f] (inlined) 23897 __libc_start_main+0xffff0000991600b7 (/usr/lib64/libc-2.26.so) libc-2.26.so[ffff80004c8d3897] After: # perf report --stdio --no-children -s sym,srcline -g address # Samples: 1 of event 'probe_libc:inet_pton' # Event count (approx.): 1 # # Overhead Symbol Source:Line # ........ .................... ........... # 100.00% [.] __GI___inet_pton inet_pton.c | ---gaih_inet.constprop.7 getaddrinfo.c:537 getaddrinfo getaddrinfo.c:2304 main ping.c:519 generic_start_main.isra.0 libc-start.c:308 __libc_start_main libc-start.c:102 ... # perf script -F comm,ip,sym,symoff,srcline,dso ping 7fffb38aaf28 __GI___inet_pton+0x8 (/usr/lib64/libc-2.26.so) inet_pton.c:68 7fffb385fa53 gaih_inet.constprop.7+0xf43 (/usr/lib64/libc-2.26.so) getaddrinfo.c:537 7fffb38605b3 getaddrinfo+0x163 (/usr/lib64/libc-2.26.so) getaddrinfo.c:2304 130782d6f main+0x3df (/usr/bin/ping) ping.c:519 7fffb377369f generic_start_main.isra.0+0x13f (/usr/lib64/libc-2.26.so) libc-start.c:308 7fffb3773897 __libc_start_main+0xb7 (/usr/lib64/libc-2.26.so) libc-start.c:102 Signed-off-by: Sandipan Das <sandipan@linux.ibm.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Cc: Milian Wolff <milian.wolff@kdab.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Fixes: 67540759151a ("perf unwind: Use addr_location::addr instead of ip for entries") Link: http://lkml.kernel.org/r/20180703120555.32971-1-sandipan@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2018-07-03 12:05:55 +00:00
e->ip = ip;
e->map = al.map;
e->sym = al.sym;
pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
al.sym ? al.sym->name : "''",
ip,
al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
return 0;
}
static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
{
/* We want only single thread to be processed. */
if (*thread_argp != NULL)
return 0;
*thread_argp = arg;
return dwfl_pid(dwfl);
}
static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
Dwarf_Word *data)
{
struct addr_location al;
ssize_t size;
if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) {
pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
return -1;
}
if (!al.map->dso)
return -1;
size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
addr, (u8 *) data, sizeof(*data));
return !(size == sizeof(*data));
}
static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
void *arg)
{
struct unwind_info *ui = arg;
struct stack_dump *stack = &ui->sample->user_stack;
u64 start, end;
int offset;
int ret;
ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
if (ret)
return false;
end = start + stack->size;
/* Check overflow. */
if (addr + sizeof(Dwarf_Word) < addr)
return false;
if (addr < start || addr + sizeof(Dwarf_Word) > end) {
ret = access_dso_mem(ui, addr, result);
if (ret) {
pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
" 0x%" PRIx64 "-0x%" PRIx64 "\n",
addr, start, end);
return false;
}
return true;
}
offset = addr - start;
*result = *(Dwarf_Word *)&stack->data[offset];
pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
addr, (unsigned long)*result, offset);
return true;
}
static const Dwfl_Thread_Callbacks callbacks = {
.next_thread = next_thread,
.memory_read = memory_read,
.set_initial_registers = libdw__arch_set_initial_registers,
};
static int
frame_callback(Dwfl_Frame *state, void *arg)
{
struct unwind_info *ui = arg;
Dwarf_Addr pc;
perf report: Fix off-by-one for non-activation frames As the documentation for dwfl_frame_pc says, frames that are no activation frames need to have their program counter decremented by one to properly find the function of the caller. This fixes many cases where perf report currently attributes the cost to the next line. I.e. I have code like this: ~~~~~~~~~~~~~~~ #include <thread> #include <chrono> using namespace std; int main() { this_thread::sleep_for(chrono::milliseconds(1000)); this_thread::sleep_for(chrono::milliseconds(100)); this_thread::sleep_for(chrono::milliseconds(10)); return 0; } ~~~~~~~~~~~~~~~ Now compile and record it: ~~~~~~~~~~~~~~~ g++ -std=c++11 -g -O2 test.cpp echo 1 | sudo tee /proc/sys/kernel/sched_schedstats perf record \ --event sched:sched_stat_sleep \ --event sched:sched_process_exit \ --event sched:sched_switch --call-graph=dwarf \ --output perf.data.raw \ ./a.out echo 0 | sudo tee /proc/sys/kernel/sched_schedstats perf inject --sched-stat --input perf.data.raw --output perf.data ~~~~~~~~~~~~~~~ Before this patch, the report clearly shows the off-by-one issue. Most notably, the last sleep invocation is incorrectly attributed to the "return 0;" line: ~~~~~~~~~~~~~~~ Overhead Source:Line ........ ........... 100.00% core.c:0 | ---__schedule core.c:0 schedule do_nanosleep hrtimer.c:0 hrtimer_nanosleep sys_nanosleep entry_SYSCALL_64_fastpath .tmp_entry_64.o:0 __nanosleep_nocancel .:0 std::this_thread::sleep_for<long, std::ratio<1l, 1000l> > thread:323 | |--90.08%--main test.cpp:9 | __libc_start_main | _start | |--9.01%--main test.cpp:10 | __libc_start_main | _start | --0.91%--main test.cpp:13 __libc_start_main _start ~~~~~~~~~~~~~~~ With this patch here applied, the issue is fixed. The report becomes much more usable: ~~~~~~~~~~~~~~~ Overhead Source:Line ........ ........... 100.00% core.c:0 | ---__schedule core.c:0 schedule do_nanosleep hrtimer.c:0 hrtimer_nanosleep sys_nanosleep entry_SYSCALL_64_fastpath .tmp_entry_64.o:0 __nanosleep_nocancel .:0 std::this_thread::sleep_for<long, std::ratio<1l, 1000l> > thread:323 | |--90.08%--main test.cpp:8 | __libc_start_main | _start | |--9.01%--main test.cpp:9 | __libc_start_main | _start | --0.91%--main test.cpp:10 __libc_start_main _start ~~~~~~~~~~~~~~~ Similarly it works for signal frames: ~~~~~~~~~~~~~~~ __noinline void bar(void) { volatile long cnt = 0; for (cnt = 0; cnt < 100000000; cnt++); } __noinline void foo(void) { bar(); } void sig_handler(int sig) { foo(); } int main(void) { signal(SIGUSR1, sig_handler); raise(SIGUSR1); foo(); return 0; } ~~~~~~~~~~~~~~~~ Before, the report wrongly points to `signal.c:29` after raise(): ~~~~~~~~~~~~~~~~ $ perf report --stdio --no-children -g srcline -s srcline ... 100.00% signal.c:11 | ---bar signal.c:11 | |--50.49%--main signal.c:29 | __libc_start_main | _start | --49.51%--0x33a8f raise .:0 main signal.c:29 __libc_start_main _start ~~~~~~~~~~~~~~~~ With this patch in, the issue is fixed and we instead get: ~~~~~~~~~~~~~~~~ 100.00% signal signal [.] bar | ---bar signal.c:11 | |--50.49%--main signal.c:29 | __libc_start_main | _start | --49.51%--0x33a8f raise .:0 main signal.c:27 __libc_start_main _start ~~~~~~~~~~~~~~~~ Note how this patch fixes this issue for both unwinding methods, i.e. both dwfl and libunwind. The former case is straight-forward thanks to dwfl_frame_pc(). For libunwind, we replace the functionality via unw_is_signal_frame() for any but the very first frame. Signed-off-by: Milian Wolff <milian.wolff@kdab.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yao Jin <yao.jin@linux.intel.com> Cc: kernel-team@lge.com Link: http://lkml.kernel.org/r/20170524062129.32529-4-namhyung@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-24 06:21:25 +00:00
bool isactivation;
perf unwind: Report module before querying isactivation in dwfl unwind The PC returned by dwfl_frame_pc() may map into a not-yet-reported module. We have to report it before we continue unwinding. But when we query for the isactivation flag in dwfl_frame_pc, libdw will actually do one more unwinding step internally which can then break and lead to missed frames or broken stacks. With libunwind we get e.g.: ~~~~~ heaptrack_gui 2228 135073.400474: 613969 cycles: 108c8e [unknown] (/usr/lib/libQt5Core.so.5.8.0) 1093bc [unknown] (/usr/lib/libQt5Core.so.5.8.0) 109e7b QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0) 1470ff [unknown] (/usr/lib/libQt5Core.so.5.8.0) 147f67 QSystemLocale::query (/usr/lib/libQt5Core.so.5.8.0) 109fbf QLocalePrivate::updateSystemPrivate (/usr/lib/libQt5Core.so.5.8.0) 10aa27 QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0) 1e02c3 [unknown] (/usr/lib/libQt5Core.so.5.8.0) 2113bb [unknown] (/usr/lib/libQt5Core.so.5.8.0) 211505 [unknown] (/usr/lib/libQt5Core.so.5.8.0) 1b5df0 QFileInfo::exists (/usr/lib/libQt5Core.so.5.8.0) 92eb2 [unknown] (/usr/lib/libQt5Core.so.5.8.0) 93423 [unknown] (/usr/lib/libQt5Core.so.5.8.0) 93d2a QLibraryInfo::location (/usr/lib/libQt5Core.so.5.8.0) 2170af [unknown] (/usr/lib/libQt5Core.so.5.8.0) 297c53 QCoreApplicationPrivate::init (/usr/lib/libQt5Core.so.5.8.0) f7cde QGuiApplicationPrivate::init (/usr/lib/libQt5Gui.so.5.8.0) 1589e8 QApplicationPrivate::init (/usr/lib/libQt5Widgets.so.5.8.0) 78622 main (/home/milian/projects/compiled/other/bin/heaptrack_gui) 20439 __libc_start_main (/usr/lib/libc-2.25.so) 78299 _start (/home/milian/projects/compiled/other/bin/heaptrack_gui) heaptrack_gui 2228 135073.401156: 569521 cycles: 131633 QString::endsWith (/usr/lib/libQt5Core.so.5.8.0) 1a0701 QDir::cleanPath (/usr/lib/libQt5Core.so.5.8.0) 21b82d [unknown] (/usr/lib/libQt5Core.so.5.8.0) 1b3727 QFileInfo::canonicalFilePath (/usr/lib/libQt5Core.so.5.8.0) 2780c7 QFactoryLoader::update (/usr/lib/libQt5Core.so.5.8.0) 279525 QFactoryLoader::QFactoryLoader (/usr/lib/libQt5Core.so.5.8.0) e5bd0 QPlatformIntegrationFactory::create (/usr/lib/libQt5Gui.so.5.8.0) f5a1c QGuiApplicationPrivate::createPlatformIntegration (/usr/lib/libQt5Gui.so.5.8.0) f650c QGuiApplicationPrivate::createEventDispatcher (/usr/lib/libQt5Gui.so.5.8.0) 298524 QCoreApplicationPrivate::init (/usr/lib/libQt5Core.so.5.8.0) f7cde QGuiApplicationPrivate::init (/usr/lib/libQt5Gui.so.5.8.0) 1589e8 QApplicationPrivate::init (/usr/lib/libQt5Widgets.so.5.8.0) 78622 main (/home/milian/projects/compiled/other/bin/heaptrack_gui) 20439 __libc_start_main (/usr/lib/libc-2.25.so) 78299 _start (/home/milian/projects/compiled/other/bin/heaptrack_gui) ~~~~~ Note the two frames 1589e8 and 78622 in the first sample. These are missing when unwinding with libdw. The second sample's breakage is more obvious: ~~~~~ heaptrack_gui 2228 135073.400474: 613969 cycles: 108c8e [unknown] (/usr/lib/libQt5Core.so.5.8.0) 1093bc [unknown] (/usr/lib/libQt5Core.so.5.8.0) 109e7b QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0) 1470ff [unknown] (/usr/lib/libQt5Core.so.5.8.0) 147f67 QSystemLocale::query (/usr/lib/libQt5Core.so.5.8.0) 109fbf QLocalePrivate::updateSystemPrivate (/usr/lib/libQt5Core.so.5.8.0) 10aa27 QLocale::QLocale (/usr/lib/libQt5Core.so.5.8.0) 1e02c3 [unknown] (/usr/lib/libQt5Core.so.5.8.0) 2113bb [unknown] (/usr/lib/libQt5Core.so.5.8.0) 211505 [unknown] (/usr/lib/libQt5Core.so.5.8.0) 1b5df0 QFileInfo::exists (/usr/lib/libQt5Core.so.5.8.0) 92eb2 [unknown] (/usr/lib/libQt5Core.so.5.8.0) 93423 [unknown] (/usr/lib/libQt5Core.so.5.8.0) 93d2a QLibraryInfo::location (/usr/lib/libQt5Core.so.5.8.0) 2170af [unknown] (/usr/lib/libQt5Core.so.5.8.0) 297c53 QCoreApplicationPrivate::init (/usr/lib/libQt5Core.so.5.8.0) f7cde QGuiApplicationPrivate::init (/usr/lib/libQt5Gui.so.5.8.0) 20439 __libc_start_main (/usr/lib/libc-2.25.so) 78299 _start (/home/milian/projects/compiled/other/bin/heaptrack_gui) heaptrack_gui 2228 135073.401156: 569521 cycles: 131633 QString::endsWith (/usr/lib/libQt5Core.so.5.8.0) 1a0701 QDir::cleanPath (/usr/lib/libQt5Core.so.5.8.0) 21b82d [unknown] (/usr/lib/libQt5Core.so.5.8.0) 1b3727 QFileInfo::canonicalFilePath (/usr/lib/libQt5Core.so.5.8.0) 2780c7 QFactoryLoader::update (/usr/lib/libQt5Core.so.5.8.0) 279525 QFactoryLoader::QFactoryLoader (/usr/lib/libQt5Core.so.5.8.0) e5bd0 QPlatformIntegrationFactory::create (/usr/lib/libQt5Gui.so.5.8.0) 723dbf [unknown] ([unknown]) ~~~~~ This patch fixes this issue and the libdw unwinder mimicks the libunwind behavior more closely. Signed-off-by: Milian Wolff <milian.wolff@kdab.com> Acked-by: Jan Kratochvil <jan.kratochvil@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Link: http://lkml.kernel.org/r/20170602143753.16907-2-milian.wolff@kdab.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2017-06-02 14:37:53 +00:00
if (!dwfl_frame_pc(state, &pc, NULL)) {
pr_err("%s", dwfl_errmsg(-1));
return DWARF_CB_ABORT;
}
// report the module before we query for isactivation
report_module(pc, ui);
perf report: Fix off-by-one for non-activation frames As the documentation for dwfl_frame_pc says, frames that are no activation frames need to have their program counter decremented by one to properly find the function of the caller. This fixes many cases where perf report currently attributes the cost to the next line. I.e. I have code like this: ~~~~~~~~~~~~~~~ #include <thread> #include <chrono> using namespace std; int main() { this_thread::sleep_for(chrono::milliseconds(1000)); this_thread::sleep_for(chrono::milliseconds(100)); this_thread::sleep_for(chrono::milliseconds(10)); return 0; } ~~~~~~~~~~~~~~~ Now compile and record it: ~~~~~~~~~~~~~~~ g++ -std=c++11 -g -O2 test.cpp echo 1 | sudo tee /proc/sys/kernel/sched_schedstats perf record \ --event sched:sched_stat_sleep \ --event sched:sched_process_exit \ --event sched:sched_switch --call-graph=dwarf \ --output perf.data.raw \ ./a.out echo 0 | sudo tee /proc/sys/kernel/sched_schedstats perf inject --sched-stat --input perf.data.raw --output perf.data ~~~~~~~~~~~~~~~ Before this patch, the report clearly shows the off-by-one issue. Most notably, the last sleep invocation is incorrectly attributed to the "return 0;" line: ~~~~~~~~~~~~~~~ Overhead Source:Line ........ ........... 100.00% core.c:0 | ---__schedule core.c:0 schedule do_nanosleep hrtimer.c:0 hrtimer_nanosleep sys_nanosleep entry_SYSCALL_64_fastpath .tmp_entry_64.o:0 __nanosleep_nocancel .:0 std::this_thread::sleep_for<long, std::ratio<1l, 1000l> > thread:323 | |--90.08%--main test.cpp:9 | __libc_start_main | _start | |--9.01%--main test.cpp:10 | __libc_start_main | _start | --0.91%--main test.cpp:13 __libc_start_main _start ~~~~~~~~~~~~~~~ With this patch here applied, the issue is fixed. The report becomes much more usable: ~~~~~~~~~~~~~~~ Overhead Source:Line ........ ........... 100.00% core.c:0 | ---__schedule core.c:0 schedule do_nanosleep hrtimer.c:0 hrtimer_nanosleep sys_nanosleep entry_SYSCALL_64_fastpath .tmp_entry_64.o:0 __nanosleep_nocancel .:0 std::this_thread::sleep_for<long, std::ratio<1l, 1000l> > thread:323 | |--90.08%--main test.cpp:8 | __libc_start_main | _start | |--9.01%--main test.cpp:9 | __libc_start_main | _start | --0.91%--main test.cpp:10 __libc_start_main _start ~~~~~~~~~~~~~~~ Similarly it works for signal frames: ~~~~~~~~~~~~~~~ __noinline void bar(void) { volatile long cnt = 0; for (cnt = 0; cnt < 100000000; cnt++); } __noinline void foo(void) { bar(); } void sig_handler(int sig) { foo(); } int main(void) { signal(SIGUSR1, sig_handler); raise(SIGUSR1); foo(); return 0; } ~~~~~~~~~~~~~~~~ Before, the report wrongly points to `signal.c:29` after raise(): ~~~~~~~~~~~~~~~~ $ perf report --stdio --no-children -g srcline -s srcline ... 100.00% signal.c:11 | ---bar signal.c:11 | |--50.49%--main signal.c:29 | __libc_start_main | _start | --49.51%--0x33a8f raise .:0 main signal.c:29 __libc_start_main _start ~~~~~~~~~~~~~~~~ With this patch in, the issue is fixed and we instead get: ~~~~~~~~~~~~~~~~ 100.00% signal signal [.] bar | ---bar signal.c:11 | |--50.49%--main signal.c:29 | __libc_start_main | _start | --49.51%--0x33a8f raise .:0 main signal.c:27 __libc_start_main _start ~~~~~~~~~~~~~~~~ Note how this patch fixes this issue for both unwinding methods, i.e. both dwfl and libunwind. The former case is straight-forward thanks to dwfl_frame_pc(). For libunwind, we replace the functionality via unw_is_signal_frame() for any but the very first frame. Signed-off-by: Milian Wolff <milian.wolff@kdab.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yao Jin <yao.jin@linux.intel.com> Cc: kernel-team@lge.com Link: http://lkml.kernel.org/r/20170524062129.32529-4-namhyung@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-24 06:21:25 +00:00
if (!dwfl_frame_pc(state, &pc, &isactivation)) {
pr_err("%s", dwfl_errmsg(-1));
return DWARF_CB_ABORT;
}
perf report: Fix off-by-one for non-activation frames As the documentation for dwfl_frame_pc says, frames that are no activation frames need to have their program counter decremented by one to properly find the function of the caller. This fixes many cases where perf report currently attributes the cost to the next line. I.e. I have code like this: ~~~~~~~~~~~~~~~ #include <thread> #include <chrono> using namespace std; int main() { this_thread::sleep_for(chrono::milliseconds(1000)); this_thread::sleep_for(chrono::milliseconds(100)); this_thread::sleep_for(chrono::milliseconds(10)); return 0; } ~~~~~~~~~~~~~~~ Now compile and record it: ~~~~~~~~~~~~~~~ g++ -std=c++11 -g -O2 test.cpp echo 1 | sudo tee /proc/sys/kernel/sched_schedstats perf record \ --event sched:sched_stat_sleep \ --event sched:sched_process_exit \ --event sched:sched_switch --call-graph=dwarf \ --output perf.data.raw \ ./a.out echo 0 | sudo tee /proc/sys/kernel/sched_schedstats perf inject --sched-stat --input perf.data.raw --output perf.data ~~~~~~~~~~~~~~~ Before this patch, the report clearly shows the off-by-one issue. Most notably, the last sleep invocation is incorrectly attributed to the "return 0;" line: ~~~~~~~~~~~~~~~ Overhead Source:Line ........ ........... 100.00% core.c:0 | ---__schedule core.c:0 schedule do_nanosleep hrtimer.c:0 hrtimer_nanosleep sys_nanosleep entry_SYSCALL_64_fastpath .tmp_entry_64.o:0 __nanosleep_nocancel .:0 std::this_thread::sleep_for<long, std::ratio<1l, 1000l> > thread:323 | |--90.08%--main test.cpp:9 | __libc_start_main | _start | |--9.01%--main test.cpp:10 | __libc_start_main | _start | --0.91%--main test.cpp:13 __libc_start_main _start ~~~~~~~~~~~~~~~ With this patch here applied, the issue is fixed. The report becomes much more usable: ~~~~~~~~~~~~~~~ Overhead Source:Line ........ ........... 100.00% core.c:0 | ---__schedule core.c:0 schedule do_nanosleep hrtimer.c:0 hrtimer_nanosleep sys_nanosleep entry_SYSCALL_64_fastpath .tmp_entry_64.o:0 __nanosleep_nocancel .:0 std::this_thread::sleep_for<long, std::ratio<1l, 1000l> > thread:323 | |--90.08%--main test.cpp:8 | __libc_start_main | _start | |--9.01%--main test.cpp:9 | __libc_start_main | _start | --0.91%--main test.cpp:10 __libc_start_main _start ~~~~~~~~~~~~~~~ Similarly it works for signal frames: ~~~~~~~~~~~~~~~ __noinline void bar(void) { volatile long cnt = 0; for (cnt = 0; cnt < 100000000; cnt++); } __noinline void foo(void) { bar(); } void sig_handler(int sig) { foo(); } int main(void) { signal(SIGUSR1, sig_handler); raise(SIGUSR1); foo(); return 0; } ~~~~~~~~~~~~~~~~ Before, the report wrongly points to `signal.c:29` after raise(): ~~~~~~~~~~~~~~~~ $ perf report --stdio --no-children -g srcline -s srcline ... 100.00% signal.c:11 | ---bar signal.c:11 | |--50.49%--main signal.c:29 | __libc_start_main | _start | --49.51%--0x33a8f raise .:0 main signal.c:29 __libc_start_main _start ~~~~~~~~~~~~~~~~ With this patch in, the issue is fixed and we instead get: ~~~~~~~~~~~~~~~~ 100.00% signal signal [.] bar | ---bar signal.c:11 | |--50.49%--main signal.c:29 | __libc_start_main | _start | --49.51%--0x33a8f raise .:0 main signal.c:27 __libc_start_main _start ~~~~~~~~~~~~~~~~ Note how this patch fixes this issue for both unwinding methods, i.e. both dwfl and libunwind. The former case is straight-forward thanks to dwfl_frame_pc(). For libunwind, we replace the functionality via unw_is_signal_frame() for any but the very first frame. Signed-off-by: Milian Wolff <milian.wolff@kdab.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yao Jin <yao.jin@linux.intel.com> Cc: kernel-team@lge.com Link: http://lkml.kernel.org/r/20170524062129.32529-4-namhyung@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-24 06:21:25 +00:00
if (!isactivation)
--pc;
return entry(pc, ui) || !(--ui->max_stack) ?
DWARF_CB_ABORT : DWARF_CB_OK;
}
int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
struct thread *thread,
struct perf_sample *data,
int max_stack)
{
struct unwind_info *ui, ui_buf = {
.sample = data,
.thread = thread,
.machine = thread->mg->machine,
.cb = cb,
.arg = arg,
.max_stack = max_stack,
};
Dwarf_Word ip;
int err = -EINVAL, i;
if (!data->user_regs.regs)
return -EINVAL;
ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
if (!ui)
return -ENOMEM;
*ui = ui_buf;
ui->dwfl = dwfl_begin(&offline_callbacks);
if (!ui->dwfl)
goto out;
err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
if (err)
goto out;
err = report_module(ip, ui);
if (err)
goto out;
err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui);
if (err)
goto out;
err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui);
perf report: Include partial stacks unwound with libdw So far the whole stack was thrown away when any error occurred before the maximum stack depth was unwound. This is actually a very common scenario though. The stacks that got unwound so far are still interesting. This removes a large chunk of differences when comparing perf script output for libunwind and libdw perf unwinding. E.g. with libunwind: ~~~~~ heaptrack_gui 2228 135073.388524: 479408 cycles: ffffffff811749ed perf_iterate_ctx ([kernel.kallsyms]) ffffffff81181662 perf_event_mmap ([kernel.kallsyms]) ffffffff811cf5ed mmap_region ([kernel.kallsyms]) ffffffff811cfe6b do_mmap ([kernel.kallsyms]) ffffffff811b0dca vm_mmap_pgoff ([kernel.kallsyms]) ffffffff811cdb0c sys_mmap_pgoff ([kernel.kallsyms]) ffffffff81033acb sys_mmap ([kernel.kallsyms]) ffffffff81631d37 entry_SYSCALL_64_fastpath ([kernel.kallsyms]) 192ca mmap64 (/usr/lib/ld-2.25.so) 59a9 _dl_map_object_from_fd (/usr/lib/ld-2.25.so) 83d0 _dl_map_object (/usr/lib/ld-2.25.so) cda1 openaux (/usr/lib/ld-2.25.so) 1834f _dl_catch_error (/usr/lib/ld-2.25.so) cfe2 _dl_map_object_deps (/usr/lib/ld-2.25.so) 3481 dl_main (/usr/lib/ld-2.25.so) 17387 _dl_sysdep_start (/usr/lib/ld-2.25.so) 4d37 _dl_start (/usr/lib/ld-2.25.so) d87 _start (/usr/lib/ld-2.25.so) heaptrack_gui 2228 135073.388677: 611329 cycles: 1a3e0 strcmp (/usr/lib/ld-2.25.so) 82b2 _dl_map_object (/usr/lib/ld-2.25.so) cda1 openaux (/usr/lib/ld-2.25.so) 1834f _dl_catch_error (/usr/lib/ld-2.25.so) cfe2 _dl_map_object_deps (/usr/lib/ld-2.25.so) 3481 dl_main (/usr/lib/ld-2.25.so) 17387 _dl_sysdep_start (/usr/lib/ld-2.25.so) 4d37 _dl_start (/usr/lib/ld-2.25.so) d87 _start (/usr/lib/ld-2.25.so) ~~~~~ With libdw without this patch: ~~~~~ heaptrack_gui 2228 135073.388524: 479408 cycles: ffffffff811749ed perf_iterate_ctx ([kernel.kallsyms]) ffffffff81181662 perf_event_mmap ([kernel.kallsyms]) ffffffff811cf5ed mmap_region ([kernel.kallsyms]) ffffffff811cfe6b do_mmap ([kernel.kallsyms]) ffffffff811b0dca vm_mmap_pgoff ([kernel.kallsyms]) ffffffff811cdb0c sys_mmap_pgoff ([kernel.kallsyms]) ffffffff81033acb sys_mmap ([kernel.kallsyms]) ffffffff81631d37 entry_SYSCALL_64_fastpath ([kernel.kallsyms]) heaptrack_gui 2228 135073.388677: 611329 cycles: ~~~~~ With this patch applied, the libdw unwinder will produce the same output as the libunwind unwinder. Signed-off-by: Milian Wolff <milian.wolff@kdab.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Link: http://lkml.kernel.org/r/20170601210021.20046-1-milian.wolff@kdab.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2017-06-01 21:00:21 +00:00
if (err && ui->max_stack != max_stack)
err = 0;
/*
* Display what we got based on the order setup.
*/
for (i = 0; i < ui->idx && !err; i++) {
int j = i;
if (callchain_param.order == ORDER_CALLER)
j = ui->idx - i - 1;
err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
}
out:
if (err)
pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));
dwfl_end(ui->dwfl);
free(ui);
return 0;
}