| Message ID | 20221025150329.97371-1-quentin@isovalent.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | bpftool: Add LLVM as default library for disassembling JIT-ed programs | expand |
Hello: This series was applied to bpf/bpf-next.git (master) by Alexei Starovoitov <ast@kernel.org>: On Tue, 25 Oct 2022 16:03:21 +0100 you wrote: > To disassemble instructions for JIT-ed programs, bpftool has relied on the > libbfd library. This has been problematic in the past: libbfd's interface > is not meant to be stable and has changed several times, hence the > detection of the two related features from the Makefile > (disassembler-four-args and disassembler-init-styled). When it comes to > shipping bpftool, this has also caused issues with several distribution > maintainers unwilling to support the feature (for example, Debian's page > for binutils-dev, libbfd's package, says: "Note that building Debian > packages which depend on the shared libbfd is Not Allowed."). > > [...] Here is the summary with links: - [bpf-next,v4,1/8] bpftool: Define _GNU_SOURCE only once https://git.kernel.org/bpf/bpf-next/c/b3d84af7cdfc - [bpf-next,v4,2/8] bpftool: Remove asserts from JIT disassembler https://git.kernel.org/bpf/bpf-next/c/55b4de58d0e2 - [bpf-next,v4,3/8] bpftool: Split FEATURE_TESTS/FEATURE_DISPLAY definitions in Makefile https://git.kernel.org/bpf/bpf-next/c/108326d6fa6c - [bpf-next,v4,4/8] bpftool: Group libbfd defs in Makefile, only pass them if we use libbfd https://git.kernel.org/bpf/bpf-next/c/2ea4d86a5093 - [bpf-next,v4,5/8] bpftool: Refactor disassembler for JIT-ed programs https://git.kernel.org/bpf/bpf-next/c/e1947c750ffe - [bpf-next,v4,6/8] bpftool: Add LLVM as default library for disassembling JIT-ed programs https://git.kernel.org/bpf/bpf-next/c/eb9d1acf634b - [bpf-next,v4,7/8] bpftool: Support setting alternative arch for JIT disasm with LLVM https://git.kernel.org/bpf/bpf-next/c/ce4f66086235 - [bpf-next,v4,8/8] bpftool: Add llvm feature to "bpftool version" https://git.kernel.org/bpf/bpf-next/c/08b8191ba7f9 You are awesome, thank you!
To disassemble instructions for JIT-ed programs, bpftool has relied on the libbfd library. This has been problematic in the past: libbfd's interface is not meant to be stable and has changed several times, hence the detection of the two related features from the Makefile (disassembler-four-args and disassembler-init-styled). When it comes to shipping bpftool, this has also caused issues with several distribution maintainers unwilling to support the feature (for example, Debian's page for binutils-dev, libbfd's package, says: "Note that building Debian packages which depend on the shared libbfd is Not Allowed."). This patchset adds support for LLVM as the primary library for disassembling instructions for JIT-ed programs. We keep libbfd as a fallback. One reason for this is that currently it works well, we have all we need in terms of features detection in the Makefile, so it provides a fallback for disassembling JIT-ed programs if libbfd is installed but LLVM is not. The other reason is that libbfd supports nfp instruction for Netronome's SmartNICs and can be used to disassemble offloaded programs, something that LLVM cannot do (Niklas confirmed that the feature is still in use). However, if libbfd's interface breaks again in the future, we might reconsider keeping support for it. v4: - Rebase to address a conflict with commit 2c76238eaddd ("bpftool: Add "bootstrap" feature to version output"). v3: - Extend commit description (patch 6) with notes on llvm-dev and LLVM's disassembler stability. v2: - Pass callback when creating the LLVM disassembler, so that the branch targets are printed as addresses (instead of byte offsets). - Add last commit to "support" other arch with LLVM, although we don't know any supported triple yet. - Use $(LLVM_CONFIG) instead of llvm-config in Makefile. - Pass components to llvm-config --libs to limit the number of libraries to pass on the command line, in Makefile. - Rebase split of FEATURE_TESTS and FEATURE_DISPLAY in Makefile. Quentin Monnet (8): bpftool: Define _GNU_SOURCE only once bpftool: Remove asserts from JIT disassembler bpftool: Split FEATURE_TESTS/FEATURE_DISPLAY definitions in Makefile bpftool: Group libbfd defs in Makefile, only pass them if we use libbfd bpftool: Refactor disassembler for JIT-ed programs bpftool: Add LLVM as default library for disassembling JIT-ed programs bpftool: Support setting alternative arch for JIT disasm with LLVM bpftool: Add llvm feature to "bpftool version" .../bpftool/Documentation/common_options.rst | 8 +- tools/bpf/bpftool/Makefile | 72 +++-- tools/bpf/bpftool/common.c | 12 +- tools/bpf/bpftool/iter.c | 2 + tools/bpf/bpftool/jit_disasm.c | 261 +++++++++++++++--- tools/bpf/bpftool/main.c | 7 + tools/bpf/bpftool/main.h | 32 +-- tools/bpf/bpftool/map.c | 1 - tools/bpf/bpftool/net.c | 2 + tools/bpf/bpftool/perf.c | 2 + tools/bpf/bpftool/prog.c | 23 +- tools/bpf/bpftool/xlated_dumper.c | 2 + 12 files changed, 319 insertions(+), 105 deletions(-)