linux.git/Documentation/bpf, branch v6.15 Linux kernel source tree bpf: Add namespace to BPF internal symbols 2025-04-25T16:21:23+00:00 Alexei Starovoitov ast@kernel.org 2025-04-25T01:45:42+00:00 f88886de0927a2adf4c1b4c5c1f1d31d2023ef74 Add namespace to BPF internal symbols used by light skeleton to prevent abuse and document with the code their allowed usage. Fixes: b1d18a7574d0 ("bpf: Extend sys_bpf commands for bpf_syscall programs.") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/bpf/20250425014542.62385-1-alexei.starovoitov@gmail.com 
Add namespace to BPF internal symbols used by light skeleton
to prevent abuse and document with the code their allowed usage.

Fixes: b1d18a7574d0 ("bpf: Extend sys_bpf commands for bpf_syscall programs.")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20250425014542.62385-1-alexei.starovoitov@gmail.com
bpf, docs: Fix broken link to renamed bpf_iter_task_vmas.c 2025-03-15T18:48:56+00:00 T.J. Mercier tjmercier@google.com 2025-03-04T20:45:19+00:00 dc438a9bc7610f23cca29a21bb5588b3c09d37f0 This file was renamed from bpf_iter_task_vma.c. Fixes: 45b38941c81f ("selftests/bpf: Rename bpf_iter_task_vma.c to bpf_iter_task_vmas.c") Signed-off-by: T.J. Mercier <tjmercier@google.com> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20250304204520.201115-1-tjmercier@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
This file was renamed from bpf_iter_task_vma.c.

Fixes: 45b38941c81f ("selftests/bpf: Rename bpf_iter_task_vma.c to bpf_iter_task_vmas.c")
Signed-off-by: T.J. Mercier <tjmercier@google.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20250304204520.201115-1-tjmercier@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
docs/bpf: Document some special sdiv/smod operations 2025-02-26T15:54:49+00:00 Yonghong Song yonghong.song@linux.dev 2024-11-07T17:09:24+00:00 b123480eec64dd879785c28f2a2d582d111cfb59 Patch [1] fixed possible kernel crash due to specific sdiv/smod operations in bpf program. The following are related operations and the expected results of those operations: - LLONG_MIN/-1 = LLONG_MIN - INT_MIN/-1 = INT_MIN - LLONG_MIN%-1 = 0 - INT_MIN%-1 = 0 Those operations are replaced with codes which won't cause kernel crash. This patch documents what operations may cause exception and what replacement operations are. [1] https://lore.kernel.org/all/20240913150326.1187788-1-yonghong.song@linux.dev/ Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20241107170924.2944681-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
Patch [1] fixed possible kernel crash due to specific sdiv/smod operations
in bpf program. The following are related operations and the expected results
of those operations:
  - LLONG_MIN/-1 = LLONG_MIN
  - INT_MIN/-1 = INT_MIN
  - LLONG_MIN%-1 = 0
  - INT_MIN%-1 = 0

Those operations are replaced with codes which won't cause
kernel crash. This patch documents what operations may cause exception and
what replacement operations are.

  [1] https://lore.kernel.org/all/20240913150326.1187788-1-yonghong.song@linux.dev/

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20241107170924.2944681-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
docs/bpf: Document the semantics of BTF tags with kind_flag 2025-02-06T00:17:59+00:00 Ihor Solodrai ihor.solodrai@linux.dev 2025-01-30T20:12:35+00:00 ea70faa1f244ea0bd30f413e4ec7c79a3b5b96f1 Explain the meaning of kind_flag in BTF type_tags and decl_tags. Update uapi btf.h kind_flag comment to reflect the changes. Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20250130201239.1429648-3-ihor.solodrai@linux.dev 
Explain the meaning of kind_flag in BTF type_tags and decl_tags.
Update uapi btf.h kind_flag comment to reflect the changes.

Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250130201239.1429648-3-ihor.solodrai@linux.dev
bpf: Remove trailing whitespace in verifier.rst 2024-11-11T16:17:48+00:00 Abhinav Saxena xandfury@gmail.com 2024-11-07T06:37:08+00:00 5249b164e666cbdea970c88f2f0e5b06577f9e7b Remove trailing whitespace in Documentation/bpf/verifier.rst. Signed-off-by: Abhinav Saxena <xandfury@gmail.com> Link: https://lore.kernel.org/r/20241107063708.106340-2-xandfury@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> 
Remove trailing whitespace in Documentation/bpf/verifier.rst.

Signed-off-by: Abhinav Saxena <xandfury@gmail.com>
Link: https://lore.kernel.org/r/20241107063708.106340-2-xandfury@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
docs/bpf: Add description of .BTF.base section 2024-10-29T20:15:36+00:00 Alan Maguire alan.maguire@oracle.com 2024-10-28T09:15:43+00:00 8a0cfd8adf81c438b9a0f527fcc3537498441785 Now that .BTF.base sections are generated for out-of-tree kernel modules (provided pahole supports the "distilled_base" BTF feature), document .BTF.base and its role in supporting resilient split BTF and BTF relocation. Changes since v1: - updated formatting, corrected typo, used BTF ID[s] consistently (Andrii) Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20241028091543.2175967-1-alan.maguire@oracle.com 
Now that .BTF.base sections are generated for out-of-tree kernel
modules (provided pahole supports the "distilled_base" BTF feature),
document .BTF.base and its role in supporting resilient split BTF
and BTF relocation.

Changes since v1:

- updated formatting, corrected typo, used BTF ID[s] consistently
  (Andrii)

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241028091543.2175967-1-alan.maguire@oracle.com
docs/bpf: Add missing BPF program types to docs 2024-09-12T17:56:41+00:00 Donald Hunter donald.hunter@gmail.com 2024-09-12T09:59:44+00:00 6182e0b80f9b5c8da19ab3a60db2e4cc10b259e8 Update the table of program types in the libbpf documentation with the recently added program types. Signed-off-by: Donald Hunter <donald.hunter@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240912095944.6386-1-donald.hunter@gmail.com 
Update the table of program types in the libbpf documentation with the
recently added program types.

Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240912095944.6386-1-donald.hunter@gmail.com
docs/bpf: Add constant values for linkages 2024-09-11T20:47:04+00:00 Will Hawkins hawkinsw@obs.cr 2024-09-11T05:50:32+00:00 c229c17a76e9c52950ea345323d5a19993610f57 Make the values of the symbolic constants that define the valid linkages for functions and variables explicit. Signed-off-by: Will Hawkins <hawkinsw@obs.cr> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/bpf/20240911055033.2084881-1-hawkinsw@obs.cr 
Make the values of the symbolic constants that define the valid linkages
for functions and variables explicit.

Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20240911055033.2084881-1-hawkinsw@obs.cr
docs/bpf: Fix a typo in verifier.rst 2024-08-29T19:19:30+00:00 Yiming Xiang kxiang@umich.edu 2024-08-29T03:17:12+00:00 89dd9bb25597621ca0500aa598140ff0858091e2 In verifier.rst, there is a typo in section 'Register parentage chains'. Caller saved registers are r0-r5, callee saved registers are r6-r9. Here by context it means callee saved registers rather than caller saved registers. This may confuse users. Signed-off-by: Yiming Xiang <kxiang@umich.edu> Link: https://lore.kernel.org/r/20240829031712.198489-1-kxiang@umich.edu Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
In verifier.rst, there is a typo in section 'Register parentage chains'.
Caller saved registers are r0-r5, callee saved registers are r6-r9.

Here by context it means callee saved registers rather than caller saved
registers. This may confuse users.

Signed-off-by: Yiming Xiang <kxiang@umich.edu>
Link: https://lore.kernel.org/r/20240829031712.198489-1-kxiang@umich.edu
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
bpf, docs: Address comments from IETF Area Directors 2024-06-23T16:10:26+00:00 Dave Thaler dthaler1968@googlemail.com 2024-06-23T15:04:53+00:00 04efaebd72d1d3d9991841051fafc6b195f3676d This patch does the following to address IETF feedback: * Remove mention of "program type" and reference future docs (and mention platform-specific docs exist) for helper functions and BTF. Addresses Roman Danyliw's comments based on GENART review from Ines Robles [0]. * Add reference for endianness as requested by John Scudder [1]. * Added bit numbers to top of 32-bit wide format diagrams as requested by Paul Wouters [2]. * Added more text about why BPF doesn't stand for anything, based on text from ebpf.io [3], as requested by Eric Vyncke and Gunter Van de Velde [4]. * Replaced "htobe16" (and similar) and the direction-specific description with just "be16" (and similar) and a direction-agnostic description, to match the direction-agnostic description in the Byteswap Instructions section. Based on feedback from Eric Vyncke [5]. [0] https://mailarchive.ietf.org/arch/msg/bpf/DvDgDWOiwk05OyNlWlAmELZFPlM/ [1] https://mailarchive.ietf.org/arch/msg/bpf/eKNXpU4jCLjsbZDSw8LjI29M3tM/ [2] https://mailarchive.ietf.org/arch/msg/bpf/hGk8HkYxeZTpdu9qW_MvbGKj7WU/ [3] https://ebpf.io/what-is-ebpf/#what-do-ebpf-and-bpf-stand-for [4] https://mailarchive.ietf.org/arch/msg/bpf/i93lzdN3ewnzzS_JMbinCIYxAIU/ [5] https://mailarchive.ietf.org/arch/msg/bpf/KBWXbMeDcSrq4vsKR_KkBbV6hI4/ Acked-by: David Vernet <void@manifault.com> Signed-off-by: Dave Thaler <dthaler1968@googlemail.com> Link: https://lore.kernel.org/r/20240623150453.10613-1-dthaler1968@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> 
This patch does the following to address IETF feedback:

* Remove mention of "program type" and reference future
  docs (and mention platform-specific docs exist) for
  helper functions and BTF. Addresses Roman Danyliw's
  comments based on GENART review from Ines Robles [0].

* Add reference for endianness as requested by John
  Scudder [1].

* Added bit numbers to top of 32-bit wide format diagrams
  as requested by Paul Wouters [2].

* Added more text about why BPF doesn't stand for anything, based
  on text from ebpf.io [3], as requested by Eric Vyncke and
  Gunter Van de Velde [4].

* Replaced "htobe16" (and similar) and the direction-specific
  description with just "be16" (and similar) and a direction-agnostic
  description, to match the direction-agnostic description in
  the Byteswap Instructions section. Based on feedback from Eric
  Vyncke [5].

[0] https://mailarchive.ietf.org/arch/msg/bpf/DvDgDWOiwk05OyNlWlAmELZFPlM/

[1] https://mailarchive.ietf.org/arch/msg/bpf/eKNXpU4jCLjsbZDSw8LjI29M3tM/

[2] https://mailarchive.ietf.org/arch/msg/bpf/hGk8HkYxeZTpdu9qW_MvbGKj7WU/

[3] https://ebpf.io/what-is-ebpf/#what-do-ebpf-and-bpf-stand-for

[4] https://mailarchive.ietf.org/arch/msg/bpf/i93lzdN3ewnzzS_JMbinCIYxAIU/

[5] https://mailarchive.ietf.org/arch/msg/bpf/KBWXbMeDcSrq4vsKR_KkBbV6hI4/

Acked-by: David Vernet <void@manifault.com>
Signed-off-by: Dave Thaler <dthaler1968@googlemail.com>
Link: https://lore.kernel.org/r/20240623150453.10613-1-dthaler1968@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>