blob: 3411e8a6f4858f4832c69ae3aaefcdfc6ba3712f [file] [log] [blame]
Name: libunwindstack
Revision: 235e2604e2fa3c1f8f7a68c5e285f9622e741e64
Date: Sep 20, 2022
License: Apache 2.0 and BSD
License File: LICENSE
Security Critical: yes
Canonical library to unwind Android call stacks.
libunwindstack (and its relevant dependencies) are copied from Android's
system/unwinding. libunwindstack handles many of the details of unwinding on Android,
which is inherently more difficult than on other platforms due to the wider
variety of frame types that occur on Android. These include Java frames, JITted
Java frames, Chrome C++ frames, and system library C++ frames. Different frame
types can have different call frame information (CFI) formats that the unwinder
must parse to know how to move up the stack. These formats include DWARF,
MiniDebugInfo, and EHABI. libunwindstack handles much of this complexity.
libunwindstack is copied from the Android tree and utilizes common Android
libraries from that tree. This is analagous to how a static library that is
built within the Chromium tree might utilize //base and //threading. For
libunwindstack, we copy its Android tree dependencies into this directory.
libunwindstack uses libdexfile for symbolizing interpreted java frames on client side,
doing the same on server side is not trivial at the moment. libdexfile is backwards
compatible and could parse the dex files for chrome apk built with min-sdk version 23
and dex version 35. And should be able to handle future min-sdk version bumps, given
it can currently parse version from 35-40. libdexfile and its dependency libartbase
comes from platform/art/ repo in AOSP.
Dependent Android libraries pulled in partially:
| name | path in Android source code | License | revisions |
| ----------- | ----------------------------------------------------------- | ------- | ---------------------------------------- |
| libprocinfo | system/libprocinfo/ | Apache | ad9e6cd57e0135be0e76b7d0570141fb4aaf87a3 |
| libbase | system/libbase/ | Apache | 55f3f005930249a1031e6aa5ccb84e47f5a84c8b |
| libdexfile | art/libdexfile/ | Apache | 754936451408e6dfe23a301f6b638d658cbc5d59 |
| libartbase | art/libartbase/ | Apache | 754936451408e6dfe23a301f6b638d658cbc5d59 |
Steps to update libunwindstack:
1. Update the contents to the upstream revision.
rm -rf src
mkdir temp src
git clone -b master src/libprocinfo
git clone -b master src/android-base
git clone -b master temp/unwinding
git clone -b master temp/art
cp -pr temp/unwinding/libunwindstack src/libunwindstack
cp -pr temp/art/libdexfile src/libartbase
cp -pr temp/art/libartbase src/libunwindstack
# ... get revisions of repositories
head {src,temp}/*/.git/refs/heads/master
rm -rf src/*/.git temp
find src/* -name .clang-format -exec rm \{\} \;
# ... manually update the revision info in README.chromium ...
git add --all
git commit -m 'step 1'
2. Build and apply/update/add patches until the code compiles with component
debug builds. Some linker errors will not be surfaced on release builds
as it does aggresive code elimination. Update existing patches so that they
apply cleanly. Remove any patches that are no longer required.
# Apply patches
patch -p1 < patches/... # etc.
# Build `stack_unwinder` module in component debug build
gn gen ../../out/libunwindstack_test_build --args=" \
target_os=\"android\" \
use_goma=true \
is_component_build=true \
is_debug=true" && \
autoninja -C ../../out/libunwindstack_test_build stack_unwinder
# Remove remnants of failed patch attempts.
find src -name \*.orig -o -name \*.rej | xargs rm
git add --all
git commit -m 'step 2'
3. Prune to the subset of libunwindstack sources that should be compiled and
checked in.
tools/ out/libunwindstack_test_build > required_sources
# Replace 'public' files with these:
grep src/libunwindstack/include required_sources | sed 's/.*/ "&",/'
# Replace 'sources' files with these:
grep -v 'src/libunwindstack/include\|\.S$' required_sources | \
sed 's/.*/ "&",/'
# Remove unused files.
find src -type f | sort | comm -2 -3 - required_sources | xargs rm
find src -depth -type d -empty -exec rmdir \{\} \;
rm required_sources
git add -u src
git commit -m 'step 3'
4. Prepare CLs to land the changes. Using `git rebase -i master` reorder the
commits as
step 1
step 3
step 2
and squash the step 3 commit into step 1.
Land a CL with step1, which contains the upstream libunwindstack changes to
the files we need. After landing `master` will be in a noncompiling state.
Land a CL with step2, which contains the Chrome-specific changes required to
build libunwindstack.
Local modifications:
- Android's base/ directory is renamed android-base/.
- 0001-disable-fdsan.patch:
Disables fdsan on unique_fd.h. fdsan isn't available in Android NDK version 16
(it was first made available in 29, as per
- 0002-create-local-process-memory.patch:
Exposes an interface to create and return a Memory subclass for reading local
process memory, as a unique_ptr.
- 0003-remove-file-logging.patch:
Stubs out PLOG() in android-base/file.cpp, which allows us to remove the
dependency on android-base/logging.cpp. logging.cpp is problematic because it
attempts to use BSD's getprogname(), which isn't available in Android NDK
version 16 (it was first made available in 21, as per
- 0004-remove-std-iterator.patch
Removes all usages of std::iterator, which is deprecated in C++17.
- 0005-dont-include-bionic-headers.patch
Some bionic headers are not part of NDK even though build flag __BIONIC__ is
defined when buliding with NDK. Adds extra check of !defined(__ANDROID_NDK__)
to not include those headers.
- 0006-include-algorithm-header.patch
libunwindstack/DwarfSection.cpp uses std::upper_bound which is declared in
<algorithm> header, include header to compile it.
- 0007-stub-out-logging-libunwindstack.patch
Stub out libunwindstack log methods. It helps to suppress log statements and
avoid liblog dependency which the upstream libunwindstack depends on.
- 0008-remove-extra-semicolon.patch
Chrome builds with `-Wextra-semi`, redundant semicolons need to be removed to
build successfully.
- 0009-disable-thread-annotations.patch
flag defined. Chromium's libdexfile and libunwindstack builds as part of
a single source_set, defining the flag would turn on safety checks for
both libunwindstack and libdexfile, libunwindstack upstream doesn't
annotate it's code for thread safety so the build errors out when built
with the flag.
- 0010-replace-allocator-destroy-construct-calls.patch
Replace calls to destroy, construct members of allocator, with call to
destroy, construct defined in std::allocator_traits<T>
- 0011-dont-compile-unused-functions.patch
Some unused symbols don't get eliminated for debug builds, explicitly
don't compile the unused sections. Required to make component debug builds