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| author | Will Hawkins <hawkinsw@obs.cr> | 2024-09-11 07:50:32 +0200 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2024-09-11 22:47:04 +0200 |
| commit | c229c17a76e9c52950ea345323d5a19993610f57 (patch) | |
| tree | a9e6684f06cd800df92e78943004f3e432dd2053 /Documentation/bpf | |
| parent | bpf: Use fake pt_regs when doing bpf syscall tracepoint tracing (diff) | |
| download | linux-c229c17a76e9c52950ea345323d5a19993610f57.tar.xz linux-c229c17a76e9c52950ea345323d5a19993610f57.zip | |
docs/bpf: Add constant values for linkages
Make the values of the symbolic constants that define the valid linkages
for functions and variables explicit.
Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20240911055033.2084881-1-hawkinsw@obs.cr
Diffstat (limited to 'Documentation/bpf')
| -rw-r--r-- | Documentation/bpf/btf.rst | 39 |
1 files changed, 35 insertions, 4 deletions
diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst index 257a7e1cdf5d..93060283b6fd 100644 --- a/Documentation/bpf/btf.rst +++ b/Documentation/bpf/btf.rst @@ -368,7 +368,7 @@ No additional type data follow ``btf_type``. * ``info.kind_flag``: 0 * ``info.kind``: BTF_KIND_FUNC * ``info.vlen``: linkage information (BTF_FUNC_STATIC, BTF_FUNC_GLOBAL - or BTF_FUNC_EXTERN) + or BTF_FUNC_EXTERN - see :ref:`BTF_Function_Linkage_Constants`) * ``type``: a BTF_KIND_FUNC_PROTO type No additional type data follow ``btf_type``. @@ -424,9 +424,8 @@ following data:: __u32 linkage; }; -``struct btf_var`` encoding: - * ``linkage``: currently only static variable 0, or globally allocated - variable in ELF sections 1 +``btf_var.linkage`` may take the values: BTF_VAR_STATIC, BTF_VAR_GLOBAL_ALLOCATED or BTF_VAR_GLOBAL_EXTERN - +see :ref:`BTF_Var_Linkage_Constants`. Not all type of global variables are supported by LLVM at this point. The following is currently available: @@ -549,6 +548,38 @@ The ``btf_enum64`` encoding: If the original enum value is signed and the size is less than 8, that value will be sign extended into 8 bytes. +2.3 Constant Values +------------------- + +.. _BTF_Function_Linkage_Constants: + +2.3.1 Function Linkage Constant Values +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.. table:: Function Linkage Values and Meanings + + =================== ===== =========== + kind value description + =================== ===== =========== + ``BTF_FUNC_STATIC`` 0x0 definition of subprogram not visible outside containing compilation unit + ``BTF_FUNC_GLOBAL`` 0x1 definition of subprogram visible outside containing compilation unit + ``BTF_FUNC_EXTERN`` 0x2 declaration of a subprogram whose definition is outside the containing compilation unit + =================== ===== =========== + + +.. _BTF_Var_Linkage_Constants: + +2.3.2 Variable Linkage Constant Values +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.. table:: Variable Linkage Values and Meanings + + ============================ ===== =========== + kind value description + ============================ ===== =========== + ``BTF_VAR_STATIC`` 0x0 definition of global variable not visible outside containing compilation unit + ``BTF_VAR_GLOBAL_ALLOCATED`` 0x1 definition of global variable visible outside containing compilation unit + ``BTF_VAR_GLOBAL_EXTERN`` 0x2 declaration of global variable whose definition is outside the containing compilation unit + ============================ ===== =========== + 3. BTF Kernel API ================= |