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| author | Yonghong Song <yhs@fb.com> | 2021-09-15 01:30:15 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-09-15 04:45:52 +0300 |
| commit | b5ea834dde6b6e7f75e51d5f66dac8cd7c97b5ef (patch) | |
| tree | b82684f92084ac8a9c1f81e860e478db4f558283 /tools/include | |
| parent | 41ced4cd88020c9d4b71ff7c50d020f081efa4a0 (diff) | |
| download | linux-b5ea834dde6b6e7f75e51d5f66dac8cd7c97b5ef.tar.xz | |
bpf: Support for new btf kind BTF_KIND_TAG
LLVM14 added support for a new C attribute ([1])
__attribute__((btf_tag("arbitrary_str")))
This attribute will be emitted to dwarf ([2]) and pahole
will convert it to BTF. Or for bpf target, this
attribute will be emitted to BTF directly ([3], [4]).
The attribute is intended to provide additional
information for
- struct/union type or struct/union member
- static/global variables
- static/global function or function parameter.
For linux kernel, the btf_tag can be applied
in various places to specify user pointer,
function pre- or post- condition, function
allow/deny in certain context, etc. Such information
will be encoded in vmlinux BTF and can be used
by verifier.
The btf_tag can also be applied to bpf programs
to help global verifiable functions, e.g.,
specifying preconditions, etc.
This patch added basic parsing and checking support
in kernel for new BTF_KIND_TAG kind.
[1] https://reviews.llvm.org/D106614
[2] https://reviews.llvm.org/D106621
[3] https://reviews.llvm.org/D106622
[4] https://reviews.llvm.org/D109560
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210914223015.245546-1-yhs@fb.com
Diffstat (limited to 'tools/include')
| -rw-r--r-- | tools/include/uapi/linux/btf.h | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/tools/include/uapi/linux/btf.h b/tools/include/uapi/linux/btf.h index 10e401073dd1..642b6ecb37d7 100644 --- a/tools/include/uapi/linux/btf.h +++ b/tools/include/uapi/linux/btf.h @@ -43,7 +43,7 @@ struct btf_type { * "size" tells the size of the type it is describing. * * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT, - * FUNC, FUNC_PROTO and VAR. + * FUNC, FUNC_PROTO, VAR and TAG. * "type" is a type_id referring to another type. */ union { @@ -74,6 +74,7 @@ enum { BTF_KIND_VAR = 14, /* Variable */ BTF_KIND_DATASEC = 15, /* Section */ BTF_KIND_FLOAT = 16, /* Floating point */ + BTF_KIND_TAG = 17, /* Tag */ NR_BTF_KINDS, BTF_KIND_MAX = NR_BTF_KINDS - 1, @@ -173,4 +174,15 @@ struct btf_var_secinfo { __u32 size; }; +/* BTF_KIND_TAG is followed by a single "struct btf_tag" to describe + * additional information related to the tag applied location. + * If component_idx == -1, the tag is applied to a struct, union, + * variable or function. Otherwise, it is applied to a struct/union + * member or a func argument, and component_idx indicates which member + * or argument (0 ... vlen-1). + */ +struct btf_tag { + __s32 component_idx; +}; + #endif /* _UAPI__LINUX_BTF_H__ */ |