[PATCH v5 0/5] Add support for remote unwind

From: He Kuang
Date: Tue May 24 2016 - 05:21:54 EST

v4 url:

Currently, perf script uses host unwind methods(local unwind) to parse
perf.data callchain info regardless of the target architecture. So we
get wrong result and no promotion when do remote unwind on other

This patchset checks whether a dso is 32-bit or 64-bit according to
elf class info for each thread to let perf use the correct remote
unwind methods instead.

Only x86 and aarch64 is added in this patchset to show the work flow,
other platforms can be added easily.

We can see the right result for unwind info on different machines, for
example: perf.data recorded on i686 qemu with '-g' option and parsed
on x86_64 machine.

before this patchset:

hello 1219 [001] 72190.667975: probe:sys_close: (c1169d60)
c1169d61 sys_close ([kernel.kallsyms])
c189c0d7 sysenter_past_esp ([kernel.kallsyms])
b777aba9 [unknown] ([vdso32])

(Add vdso into buildid-cache first by 'perf buildid-cache -a' and
libraries are provided in symfs dir)

hello 1219 [001] 72190.667975: probe:sys_close: (c1169d60)
c1169d61 sys_close ([kernel.kallsyms])
c189c0d7 sysenter_past_esp ([kernel.kallsyms])
b777aba9 __kernel_vsyscall ([vdso32])
b76971cc close (/lib/libc-2.22.so)
804842e fib (/tmp/hello)
804849d main (/tmp/hello)
b75d746e __libc_start_main (/lib/libc-2.22.so)
8048341 _start (/tmp/hello)

For using remote libunwind libraries, reference this:

and now we can use LIBUNWIND_DIR to specific custom dirctories
containing libunwind libs.


- Support LIBUNWIND_DIR args for detect remote libunwind libraries.
- Change patch 2/5 commit messages for better understanding.
- Self test for local (un)supported, remote un(supported) cases and
fix some bugs in v4.


- Move reference of buildid dir to 'symfs/.debug' if --symfs is
- Split makefile changes out from patch 'Add support for
cross-platform unwind'.
- Use existing code normalize_arch() for testing the arch of


- Remove --vdso option, store vdso buildid in perf.data and let perf
fetch it automatically.
- Use existing dso__type() function to test if dso is 32-bit or


- Explain the reason why we can omit dwarf judgement when recording
in commit message.
- Elaborate on why we need to add a custom vdso path option, and
change the type name to DSO_BINARY_TYPE__VDSO.
- Hide the build tests status for cross platform unwind.
- Keep generic version of libunwind-debug-frame test.
- Put 32/64-bit test functions into separate patch.
- Extract unwind related functions to unwind-libunwind.c and add new
file for common parts used by both local and remote unwind.
- Eliminate most of the ifdefs in .c file.


He Kuang (5):
perf tools: Use LIBUNWIND_DIR for remote libunwind feature check
perf tools: Show warnings for unsupported cross-platform unwind
perf callchain: Add support for cross-platform unwind
perf callchain: Support x86 target platform
perf callchain: Support aarch64 cross-platform

.../arch/arm64/include/libunwind/libunwind-arch.h | 18 ++++
tools/perf/arch/arm64/util/unwind-libunwind.c | 5 +-
tools/perf/arch/common.c | 2 +-
tools/perf/arch/common.h | 1 +
.../arch/x86/include/libunwind/libunwind-arch.h | 18 ++++
tools/perf/arch/x86/util/Build | 2 +-
tools/perf/arch/x86/util/unwind-libunwind.c | 19 +++-
tools/perf/config/Makefile | 49 ++++++++-
tools/perf/util/Build | 13 ++-
tools/perf/util/thread.c | 7 +-
tools/perf/util/thread.h | 17 +++-
tools/perf/util/unwind-libunwind.c | 49 +++++++--
tools/perf/util/unwind-libunwind_common.c | 109 +++++++++++++++++++++
tools/perf/util/unwind.h | 50 ++++++++--
14 files changed, 323 insertions(+), 36 deletions(-)
create mode 100644 tools/perf/arch/arm64/include/libunwind/libunwind-arch.h
create mode 100644 tools/perf/arch/x86/include/libunwind/libunwind-arch.h
create mode 100644 tools/perf/util/unwind-libunwind_common.c