Currently when processing a DWARF function, we check its entrypoint
against ftrace addresses, assuming that the ftrace address matches with
the function's entrypoint.
This is not the case on some architectures as reported by Nathan
when building kernel on arm [1].
Fix the check to take into account the whole function, not just the
entrypoint.
Most of the is_ftrace_func code was contributed by Andrii.
[1] https://lore.kernel.org/bpf/20210209034416.GA1669105@ubuntu-m3-large-x86/
Committer notes:
Test comments by Nathan:
"I did several builds with CONFIG_DEBUG_INFO_BTF enabled (arm64, ppc64le,
and x86_64) and saw no build errors. I did not do any runtime testing."
Test comments by Sedat:
Linux v5.11-rc7+ and LLVM/Clang v12.0.0-rc1 on x86 (64bit)
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Hao Luo <haoluo@google.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@chromium.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Build instructions:
1. install cmake
2. mkdir build
3. cd build
4. cmake -D__LIB=lib ..
5. make install
Default is to be installed on /usr/local, see rpm spec file for
installing on other places.
Known to work scenarios:
Mandriva Cooker:
cmake 2.4.5-1mdv2007.1
libelfutils1-devel 0.123-1mdv2007.1
Debian Unstable:
cmake 2.4.5-1
libdw-dev 0.123-2
Fedora Core 6:
cmake 2.4.5-2.fc6
elfutils-devel 0.126-1.fc6
8e1f8c904e