| Message ID | 20230918024813.237475-1-hengqi.chen@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | libbpf: Support symbol versioning for uprobe | expand |
Hello: This series was applied to bpf/bpf-next.git (master) by Andrii Nakryiko <andrii@kernel.org>: On Mon, 18 Sep 2023 02:48:10 +0000 you wrote: > Dynamic symbols in shared library may have the same name, for example: > > $ nm -D /lib/x86_64-linux-gnu/libc.so.6 | grep rwlock_wrlock > 000000000009b1a0 T __pthread_rwlock_wrlock@GLIBC_2.2.5 > 000000000009b1a0 T pthread_rwlock_wrlock@@GLIBC_2.34 > 000000000009b1a0 T pthread_rwlock_wrlock@GLIBC_2.2.5 > > [...] Here is the summary with links: - [bpf-next,v4,1/3] libbpf: Resolve symbol conflicts at the same offset for uprobe https://git.kernel.org/bpf/bpf-next/c/7257cee65269 - [bpf-next,v4,2/3] libbpf: Support symbol versioning for uprobe https://git.kernel.org/bpf/bpf-next/c/bb7fa09399b9 - [bpf-next,v4,3/3] selftests/bpf: Add tests for symbol versioning for uprobe https://git.kernel.org/bpf/bpf-next/c/7089f85a9eb9 You are awesome, thank you!
Dynamic symbols in shared library may have the same name, for example: $ nm -D /lib/x86_64-linux-gnu/libc.so.6 | grep rwlock_wrlock 000000000009b1a0 T __pthread_rwlock_wrlock@GLIBC_2.2.5 000000000009b1a0 T pthread_rwlock_wrlock@@GLIBC_2.34 000000000009b1a0 T pthread_rwlock_wrlock@GLIBC_2.2.5 $ readelf -W --dyn-syms /lib/x86_64-linux-gnu/libc.so.6 | grep rwlock_wrlock 706: 000000000009b1a0 878 FUNC GLOBAL DEFAULT 15 __pthread_rwlock_wrlock@GLIBC_2.2.5 2568: 000000000009b1a0 878 FUNC GLOBAL DEFAULT 15 pthread_rwlock_wrlock@@GLIBC_2.34 2571: 000000000009b1a0 878 FUNC GLOBAL DEFAULT 15 pthread_rwlock_wrlock@GLIBC_2.2.5 There are two pthread_rwlock_wrlock symbols in libc.so .dynsym section. The one with @@ is the default version, the other is hidden. Note that the version info is stored in .gnu.version and .gnu.version_d sections of libc and the two symbols are at the _same_ offset. Currently, specify `pthread_rwlock_wrlock`, `pthread_rwlock_wrlock@@GLIBC_2.34` or `pthread_rwlock_wrlock@GLIBC_2.2.5` in bpf_uprobe_opts::func_name won't work. Because there are two `pthread_rwlock_wrlock` in .dynsym sections without the version suffix and both are global bind. We could solve this by introducing symbol versioning ([0]). So that users can specify func, func@LIB_VERSION or func@@LIB_VERSION to attach a uprobe. This patchset resolves symbol conflicts and add symbol versioning for uprobe. - Patch 1 resolves symbol conflicts at the same offset - Patch 2 adds symbol versioning for dynsym - Patch 3 adds selftests for the above changes Changes from v3: - Address comments from Andrii Changes from v2: - Add uretprobe selfttest (Alan) - Check symbol exact match (Alan) - Fix typo (Jiri) Changes from v1: - Address comments from Alan and Jiri - Add selftests (Someone reminds me that there is an attempt at [1] and part of the selftest code from Andrii is taken from there) [0]: https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/symversion.html [1]: https://lore.kernel.org/lkml/CAEf4BzZTrjjyyOm3ak9JsssPSh6T_ZmGd677a2rt5e5rBLUrpQ@mail.gmail.com/ Hengqi Chen (3): libbpf: Resolve symbol conflicts at the same offset for uprobe libbpf: Support symbol versioning for uprobe selftests/bpf: Add tests for symbol versioning for uprobe tools/lib/bpf/elf.c | 139 ++++++++++++++++-- tools/lib/bpf/libbpf.c | 2 +- tools/testing/selftests/bpf/Makefile | 5 +- .../testing/selftests/bpf/liburandom_read.map | 15 ++ .../testing/selftests/bpf/prog_tests/uprobe.c | 95 ++++++++++++ .../testing/selftests/bpf/progs/test_uprobe.c | 61 ++++++++ tools/testing/selftests/bpf/urandom_read.c | 15 +- .../testing/selftests/bpf/urandom_read_lib1.c | 22 +++ 8 files changed, 337 insertions(+), 17 deletions(-) create mode 100644 tools/testing/selftests/bpf/liburandom_read.map create mode 100644 tools/testing/selftests/bpf/prog_tests/uprobe.c create mode 100644 tools/testing/selftests/bpf/progs/test_uprobe.c