linux-toradex.git/Documentation/bpf, branch v6.12

docs/bpf: Add missing BPF program types to docs

2024-09-12T17:56:41+00:00

Update the table of program types in the libbpf documentation with the
recently added program types.

Signed-off-by: Donald Hunter 
Signed-off-by: Andrii Nakryiko 
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

Make the values of the symbolic constants that define the valid linkages
for functions and variables explicit.

Signed-off-by: Will Hawkins 
Signed-off-by: Andrii Nakryiko 
Acked-by: Yonghong Song 
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

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 
Link: https://lore.kernel.org/r/20240829031712.198489-1-kxiang@umich.edu
Signed-off-by: Alexei Starovoitov

bpf, docs: Address comments from IETF Area Directors

2024-06-23T16:10:26+00:00

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 
Signed-off-by: Dave Thaler 
Link: https://lore.kernel.org/r/20240623150453.10613-1-dthaler1968@gmail.com
Signed-off-by: Alexei Starovoitov

libbpf: Configure log verbosity with env variable

2024-05-28T23:25:06+00:00

Configure logging verbosity by setting LIBBPF_LOG_LEVEL environment
variable, which is applied only to default logger. Once user set their
custom logging callback, it is up to them to handle filtering.

Signed-off-by: Mykyta Yatsenko 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240524131840.114289-1-yatsenko@meta.com

bpf, docs: Fix instruction.rst indentation

2024-05-26T16:58:42+00:00

The table captions patch corrected indented most tables to work with
the table directive for adding a caption but missed two of them.

Signed-off-by: Dave Thaler 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20240526061815.22497-1-dthaler1968@gmail.com
Signed-off-by: Alexei Starovoitov

bpf, docs: Clarify call local offset

2024-05-25T17:41:57+00:00

In the Jump instructions section it explains that the offset is
"relative to the instruction following the jump instruction".
But the program-local section confusingly said "referenced by
offset from the call instruction, similar to JA".

This patch updates that sentence with consistent wording, saying
it's relative to the instruction following the call instruction.

Signed-off-by: Dave Thaler 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/r/20240525153332.21355-1-dthaler1968@gmail.com
Signed-off-by: Alexei Starovoitov

bpf, docs: Add table captions

2024-05-25T17:39:31+00:00

As suggested by Ines Robles in his IETF GENART review at
https://datatracker.ietf.org/doc/review-ietf-bpf-isa-02-genart-lc-robles-2024-05-16/

Signed-off-by: Dave Thaler 
Link: https://lore.kernel.org/r/20240524164618.18894-1-dthaler1968@gmail.com
Signed-off-by: Alexei Starovoitov

bpf, docs: clarify sign extension of 64-bit use of 32-bit imm

2024-05-25T17:39:03+00:00

imm is defined as a 32-bit signed integer.

{MOV, K, ALU64} says it does "dst = src" (where src is 'imm') and it
does do dst = (s64)imm, which in that sense does sign extend imm. The MOVSX
instruction is explained as sign extending, so added the example of
{MOV, K, ALU64} to make this more clear.

{JLE, K, JMP} says it does "PC += offset if dst <= src" (where src is 'imm',
and the comparison is unsigned). This was apparently ambiguous to some
readers as to whether the comparison was "dst <= (u64)(u32)imm" or
"dst <= (u64)(s64)imm" so added an example to make this more clear.

v1 -> v2: Address comments from Yonghong

Signed-off-by: Dave Thaler 
Acked-by: Yonghong Song 
Acked-by: David Vernet 
Link: https://lore.kernel.org/r/20240520215255.10595-1-dthaler1968@gmail.com
Signed-off-by: Alexei Starovoitov

bpf, docs: Use RFC 2119 language for ISA requirements

2024-05-25T17:38:35+00:00

Per IETF convention and discussion at LSF/MM/BPF, use MUST etc.
keywords as requested by IETF Area Director review.  Also as
requested, indicate that documenting BTF is out of scope of this
document and will be covered by a separate IETF specification.

Added paragraph about the terminology that is required IETF boilerplate
and must be worded exactly as such.

Signed-off-by: Dave Thaler 
Acked-by: David Vernet 
Link: https://lore.kernel.org/r/20240517165855.4688-1-dthaler1968@gmail.com
Signed-off-by: Alexei Starovoitov