Some BPF programs compiled on s390 fail to load, because s390
arch-specific linux headers contain float and double types.
Introduce support for such types by representing them using the new
BTF_KIND_FLOAT. This series deals with libbpf, bpftool, in-kernel BTF
parser as well as selftests and documentation.
There are also pahole and LLVM parts:
* https://github.com/iii-i/dwarves/commit/btf-kind-float-v2
* https://reviews.llvm.org/D83289
but they should go in after the libbpf part is integrated.
---
v0: https://lore.kernel.org/bpf/20210210030317.78820-1-iii@xxxxxxxxxxxxx/
v0 -> v1: Per Andrii's suggestion, remove the unnecessary trailing u32.
v1: https://lore.kernel.org/bpf/20210216011216.3168-1-iii@xxxxxxxxxxxxx/
v1 -> v2: John noticed that sanitization corrupts BTF, because new and
old sizes don't match. Per Yonghong's suggestion, use a
modifier type (which has the same size as the float type) as
a replacement.
Per Yonghong's suggestion, add size and alignment checks to
the kernel BTF parser.
v2: https://lore.kernel.org/bpf/20210219022543.20893-1-iii@xxxxxxxxxxxxx/
v2 -> v3: Based on Yonghong's suggestions: Use BTF_KIND_CONST instead of
BTF_KIND_TYPEDEF and make sure that the C code generated from
the sanitized BTF is well-formed; fix size calculation in
tests and use NAME_TBD everywhere; limit allowed sizes to 2,
4, 8, 12 and 16 (this should also fix m68k and nds32le
builds).
Based on Alexei's feedback [1] I'm proceeding with the BTF_KIND_FLOAT
approach.
[1] https://lore.kernel.org/bpf/CAADnVQKWPODWZ2RSJ5FJhfYpxkuV0cvSAL1O+FSr9oP1ercoBg@xxxxxxxxxxxxxx/
Ilya Leoshkevich (6):
bpf: Add BTF_KIND_FLOAT to uapi
libbpf: Add BTF_KIND_FLOAT support
tools/bpftool: Add BTF_KIND_FLOAT support
bpf: Add BTF_KIND_FLOAT support
selftest/bpf: Add BTF_KIND_FLOAT tests
bpf: Document BTF_KIND_FLOAT in btf.rst
Documentation/bpf/btf.rst | 17 ++-
include/uapi/linux/btf.h | 5 +-
kernel/bpf/btf.c | 77 ++++++++++-
tools/bpf/bpftool/btf.c | 8 ++
tools/bpf/bpftool/btf_dumper.c | 1 +
tools/include/uapi/linux/btf.h | 5 +-
tools/lib/bpf/btf.c | 44 +++++++
tools/lib/bpf/btf.h | 8 ++
tools/lib/bpf/btf_dump.c | 4 +
tools/lib/bpf/libbpf.c | 48 ++++++-
tools/lib/bpf/libbpf.map | 5 +
tools/lib/bpf/libbpf_internal.h | 2 +
tools/testing/selftests/bpf/btf_helpers.c | 4 +
tools/testing/selftests/bpf/prog_tests/btf.c | 129 +++++++++++++++++++
tools/testing/selftests/bpf/test_btf.h | 3 +
15 files changed, 351 insertions(+), 9 deletions(-)
--
2.29.2
