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| author | Mark Brown <broonie@kernel.org> | 2026-05-29 22:22:27 +0100 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2026-05-29 22:22:29 +0100 |
| commit | b3d57e9a70525347708e83b5c72915746deb3955 (patch) | |
| tree | 4d53da795aacd5868666691cb735b471555af8a6 /Documentation | |
| parent | 091bddd6f3606ee19980772e41e0d5c8cb34dce7 (diff) | |
| parent | 9a720e090eb5155fbd584a3f7eca18f82610a2b3 (diff) | |
| download | linux-next-history-b3d57e9a70525347708e83b5c72915746deb3955.tar.gz | |
Merge branch 'for-next' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/bpf/btf.rst | 6 | ||||
| -rw-r--r-- | Documentation/bpf/kfuncs.rst | 36 |
2 files changed, 36 insertions, 6 deletions
diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst index 3b60583f5db23..3f05f17990ade 100644 --- a/Documentation/bpf/btf.rst +++ b/Documentation/bpf/btf.rst @@ -97,10 +97,8 @@ Each type contains the following common data:: struct btf_type { __u32 name_off; /* "info" bits arrangement - * bits 0-15: vlen (e.g. # of struct's members) - * bits 16-23: unused - * bits 24-28: kind (e.g. int, ptr, array...etc) - * bits 29-30: unused + * bits 0-23: vlen (e.g. # of struct's members) + * bits 24-30: kind (e.g. int, ptr, array...etc) * bit 31: kind_flag, currently used by * struct, union, enum, fwd, enum64, * decl_tag and type_tag diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst index 75e6c078e0e72..4c814ff6061e0 100644 --- a/Documentation/bpf/kfuncs.rst +++ b/Documentation/bpf/kfuncs.rst @@ -207,8 +207,26 @@ Here, the buffer may be NULL. If the buffer is not NULL, it must be at least buffer__szk bytes in size. The kfunc is responsible for checking if the buffer is NULL before using it. -2.3.5 __str Annotation ----------------------------- +2.3.5 __nonown_allowed Annotation +--------------------------------- + +This annotation is used to indicate that the parameter may be a non-owning reference. + +An example is given below:: + + __bpf_kfunc int bpf_list_add(..., struct bpf_list_node + *prev__nonown_allowed, ...) + { + ... + } + +For the ``prev__nonown_allowed`` parameter (resolved as ``KF_ARG_PTR_TO_LIST_NODE``), +suffix ``__nonown_allowed`` retains the usual owning-pointer rules and also +permits a non-owning reference with no ref_obj_id (e.g. the return value of +bpf_list_front() / bpf_list_back()). + +2.3.6 __str Annotation +---------------------- This annotation is used to indicate that the argument is a constant string. An example is given below:: @@ -462,6 +480,20 @@ In order to accommodate such requirements, the verifier will enforce strict PTR_TO_BTF_ID type matching if two types have the exact same name, with one being suffixed with ``___init``. +2.8 Accessing arena memory through kfunc arguments +-------------------------------------------------- + +A read or write at any address inside an arena does not oops the kernel. +Unallocated arena pages are lazily backed by a scratch page and the +access is reported through the program's BPF stream as an error. Only +the BPF program's correctness is affected; the kernel itself remains +intact. + +The arena is followed by a ``GUARD_SZ / 2`` (32 KiB) guard region that +is also covered by this recovery. A kfunc handed an arena pointer may +therefore access up to ``GUARD_SZ / 2`` past it without bounds-checking +against the arena. Larger accesses must verify the range explicitly. + .. _BPF_kfunc_lifecycle_expectations: 3. kfunc lifecycle expectations |