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[bpf-next,v5,0/3] Allow mmap of /sys/kernel/btf/vmlinux

Message ID 20250520-vmlinux-mmap-v5-0-e8c941acc414@isovalent.com
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Series Allow mmap of /sys/kernel/btf/vmlinux | expand

Message

Lorenz Bauer May 20, 2025, 1:01 p.m. UTC 
I'd like to cut down the memory usage of parsing vmlinux BTF in ebpf-go.
With some upcoming changes the library is sitting at 5MiB for a parse.
Most of that memory is simply copying the BTF blob into user space.
By allowing vmlinux BTF to be mmapped read-only into user space I can
cut memory usage by about 75%.

Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
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Changes in v5:
- Fix error return of btf_parse_raw_mmap (Andrii)
- Link to v4: https://lore.kernel.org/r/20250510-vmlinux-mmap-v4-0-69e424b2a672@isovalent.com

Changes in v4:
- Go back to remap_pfn_range for aarch64 compat
- Dropped btf_new_no_copy (Andrii)
- Fixed nits in selftests (Andrii)
- Clearer error handling in the mmap handler (Andrii)
- Fixed build on s390
- Link to v3: https://lore.kernel.org/r/20250505-vmlinux-mmap-v3-0-5d53afa060e8@isovalent.com

Changes in v3:
- Remove slightly confusing calculation of trailing (Alexei)
- Use vm_insert_page (Alexei)
- Simplified libbpf code
- Link to v2: https://lore.kernel.org/r/20250502-vmlinux-mmap-v2-0-95c271434519@isovalent.com

Changes in v2:
- Use btf__new in selftest
- Avoid vm_iomap_memory in btf_vmlinux_mmap
- Add VM_DONTDUMP
- Add support to libbpf
- Link to v1: https://lore.kernel.org/r/20250501-vmlinux-mmap-v1-0-aa2724572598@isovalent.com

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Lorenz Bauer (3):
      btf: allow mmap of vmlinux btf
      selftests: bpf: add a test for mmapable vmlinux BTF
      libbpf: Use mmap to parse vmlinux BTF from sysfs

 include/asm-generic/vmlinux.lds.h                  |  3 +-
 kernel/bpf/sysfs_btf.c                             | 32 ++++++++
 tools/lib/bpf/btf.c                                | 89 +++++++++++++++++-----
 tools/testing/selftests/bpf/prog_tests/btf_sysfs.c | 81 ++++++++++++++++++++
 4 files changed, 186 insertions(+), 19 deletions(-)
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base-commit: 7220eabff8cb4af3b93cd021aa853b9f5df2923f
change-id: 20250501-vmlinux-mmap-2ec5563c3ef1

Best regards,