Support BTF_KIND_TYPE_TAG for btf_type_tag attributes #2100
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=577773 expired. Closing PR. |
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Master branch: 3a75111 Pull request is NOT updated. Failed to apply https://patchwork.kernel.org/project/netdevbpf/list/?series=578993 conflict: |
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=578993 expired. Closing PR. |
LLVM patches ([1] for clang, [2] and [3] for BPF backend) added support for btf_type_tag attributes. This patch added support for the kernel. The main motivation for btf_type_tag is to bring kernel annotations __user, __rcu etc. to btf. With such information available in btf, bpf verifier can detect mis-usages and reject the program. For example, for __user tagged pointer, developers can then use proper helper like bpf_probe_read_user() etc. to read the data. BTF_KIND_TYPE_TAG may also useful for other tracing facility where instead of to require user to specify kernel/user address type, the kernel can detect it by itself with btf. [1] https://reviews.llvm.org/D111199 [2] https://reviews.llvm.org/D113222 [3] https://reviews.llvm.org/D113496 Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Yonghong Song <yhs@fb.com>
Add libbpf support for BTF_KIND_TYPE_TAG. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Yonghong Song <yhs@fb.com>
Add bpftool support for BTF_KIND_TYPE_TAG. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Yonghong Song <yhs@fb.com>
Add unit tests for btf__add_type_tag(). Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Yonghong Song <yhs@fb.com>
Add BTF_KIND_TYPE_TAG unit tests. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Yonghong Song <yhs@fb.com>
Add BTF_KIND_TYPE_TAG duplication unit tests. Signed-off-by: Yonghong Song <yhs@fb.com>
Rename progs/tag.c to progs/btf_decl_tag.c so we can introduce progs/btf_type_tag.c in the next patch. Also create a subtest for btf_decl_tag in prog_tests/btf_tag.c so we can introduce btf_type_tag subtest in the next patch. I also took opportunity to remove the check whether __has_attribute is defined or not in progs/btf_decl_tag.c since all recent clangs should already support this macro. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Yonghong Song <yhs@fb.com>
The following is the main btf_type_tag usage in the
C test:
#define __tag1 __attribute__((btf_type_tag("tag1")))
#define __tag2 __attribute__((btf_type_tag("tag2")))
struct btf_type_tag_test {
int __tag1 * __tag1 __tag2 *p;
} g;
The bpftool raw dump with related types:
[4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
[11] STRUCT 'btf_type_tag_test' size=8 vlen=1
'p' type_id=14 bits_offset=0
[12] TYPE_TAG 'tag1' type_id=16
[13] TYPE_TAG 'tag2' type_id=12
[14] PTR '(anon)' type_id=13
[15] TYPE_TAG 'tag1' type_id=4
[16] PTR '(anon)' type_id=15
[17] VAR 'g' type_id=11, linkage=global
With format C dump, we have
struct btf_type_tag_test {
int __attribute__((btf_type_tag("tag1"))) * __attribute__((btf_type_tag("tag1"))) __attribute__((btf_type_tag("tag2"))) *p;
};
The result C code is identical to the original definition except macro's are gone.
Signed-off-by: Yonghong Song <yhs@fb.com>
btf_tag selftest needs certain llvm versions (>= llvm14). Make it clear in the selftests README.rst file. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Yonghong Song <yhs@fb.com>
Add BTF_KIND_TYPE_TAG documentation in btf.rst. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Yonghong Song <yhs@fb.com>
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=579013 irrelevant now. Closing PR. |
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Pull request for series with
subject: Support BTF_KIND_TYPE_TAG for btf_type_tag attributes
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=577773