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Message-Id: <20250510-vmlinux-mmap-v4-0-69e424b2a672@isovalent.com>
Date: Sat, 10 May 2025 08:34:53 -0400
From: Lorenz Bauer <lmb@...valent.com>
To: Arnd Bergmann <arnd@...db.de>, Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <martin.lau@...ux.dev>,
Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>,
Yonghong Song <yonghong.song@...ux.dev>,
John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>,
Jiri Olsa <jolsa@...nel.org>, Mykola Lysenko <mykolal@...com>,
Shuah Khan <shuah@...nel.org>
Cc: linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
Lorenz Bauer <lmb@...valent.com>
Subject: [PATCH bpf-next v4 0/3] Allow mmap of /sys/kernel/btf/vmlinux
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@...valent.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
---
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 | 85 ++++++++++++++++++----
tools/testing/selftests/bpf/prog_tests/btf_sysfs.c | 81 +++++++++++++++++++++
4 files changed, 184 insertions(+), 17 deletions(-)
---
base-commit: 7220eabff8cb4af3b93cd021aa853b9f5df2923f
change-id: 20250501-vmlinux-mmap-2ec5563c3ef1
Best regards,
--
Lorenz Bauer <lmb@...valent.com>
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