selftests/bpf: Add a test with a bpf program with btf_tag attributes

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Add a bpf program with btf_tag attributes. The program is
loaded successfully with the kernel. With the command
  bpftool btf dump file ./tag.o
the following dump shows that tags are properly encoded:
  [8] STRUCT 'key_t' size=12 vlen=3
          'a' type_id=2 bits_offset=0
          'b' type_id=2 bits_offset=32
          'c' type_id=2 bits_offset=64
  [9] TAG 'tag1' type_id=8 component_id=-1
  [10] TAG 'tag2' type_id=8 component_id=-1
  [11] TAG 'tag1' type_id=8 component_id=1
  [12] TAG 'tag2' type_id=8 component_id=1
  ...
  [21] FUNC_PROTO '(anon)' ret_type_id=2 vlen=1
          'x' type_id=2
  [22] FUNC 'foo' type_id=21 linkage=static
  [23] TAG 'tag1' type_id=22 component_id=0
  [24] TAG 'tag2' type_id=22 component_id=0
  [25] TAG 'tag1' type_id=22 component_id=-1
  [26] TAG 'tag2' type_id=22 component_id=-1
  ...
  [29] VAR 'total' type_id=27, linkage=global
  [30] TAG 'tag1' type_id=29 component_id=-1
  [31] TAG 'tag2' type_id=29 component_id=-1

If an old clang compiler, which does not support btf_tag attribute,
is used, these btf_tag attributes will be silently ignored.

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/20210914223058.248949-1-yhs@fb.com

...

This commit is contained in:

Yonghong Song 2021-09-14 15:30:58 -07:00 • committed by Alexei Starovoitov

parent ad526474ae

commit c240ba2878

2 changed files with 53 additions and 0 deletions

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14

tools/testing/selftests/bpf/prog_tests/btf_tag.c

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39

tools/testing/selftests/bpf/progs/tag.c

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