rust: Proper bindgen sources for BTF debug builds #835
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What about calling it |
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Yeah, I can reproduce the bindgen issue, opening an issue... |
As Clang 14 supports the btf_type_tag attribute and building with PAHOLE_HAS_BTF_TAG defines BTF_TYPE_TAG(value) to be __attribute__((btf_type_tag(#value))). Because of this bindgen might get confused and discards constness of attributed function parameters that are indeed const pointers (like const char __user * -> char *). This patch fixes that by passing a BINDGEN_RUN definition to bindgen that causes BTF_TYPE_TAG(value) to be defined as nothing, thus generating proper definitions for functions like write in the file_operations struct. Signed-off-by: Martin Rodriguez Reboredo <[email protected]>
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That was an habit from working with Shiboken, but yeah, |
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Cc @yonghong-song who introduced it |
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Thanks @YakoYakoYokuYoku! |
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You are welcome and thanks for merging too. |
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I was testing a BTF debug info build while using a patched pahole that supports excluding Rust. I've noticed that Clang 14 introduced support for the
btf_type_tagattribute, resultingBTF_TYPE_TAG(value)to be expanded as so.This is all cool and dandy, but watch what happens when bindgen is fed with functions that contains attributed const pointers (like
const char __user *), bindgen discards its constness, causing that some sources that expect the param to be const failing in their compilation.For example the
writefield infile_operationshas a const pointer, a vtable inrust/kernel/file.rsbased on said struct also uses a const pointer, but if bindgen fails to generate a proper binding it results in the failure of the compilation of thekernelcrate.See this Zulip thread for context.