[PATCH] D100568: BPF: generate BTF info for LD_imm64 loaded function pointer

[Yonghong Song via Phabricator via llvm-commits]

yonghong-song created this revision.
yonghong-song added reviewers: ast, anakryiko.
Herald added a subscriber: hiraditya.
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Herald added a subscriber: llvm-commits.

For an example like below,

  extern int do_work(int);
  long bpf_helper(void *callback_fn);
  long prog() {
      return bpf_helper(&do_work);
  }   

The final generated codes look like:

  r1 = do_work ll
  call bpf_helper
  exit

where we have debuginfo for do_work() extern function:

  !17 = !DISubprogram(name: "do_work", ...)

This patch implemented to add additional checking
in processing LD_imm64 operands for possible function pointers
so BTF for bpf function do_work() can be properly generated.
The original llvm function name processReloc() is renamed to
processGlobalValue() to better reflect what the function is doing.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D100568

Files:
  llvm/lib/Target/BPF/BTFDebug.cpp
  llvm/lib/Target/BPF/BTFDebug.h
  llvm/test/CodeGen/BPF/BTF/extern-func-ptr.ll

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