[all-commits] [llvm/llvm-project] 667e1f: [profile] Use base+vaddr for `__llvm_write_binary_...

[Josh Stone via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 667e1fadcf4376ce41f5cae7cabab9f5ccc77b15
      https://github.com/llvm/llvm-project/commit/667e1fadcf4376ce41f5cae7cabab9f5ccc77b15
  Author: Josh Stone <jistone at redhat.com>
  Date:   2024-11-21 (Thu, 21 Nov 2024)

  Changed paths:
    M compiler-rt/lib/profile/InstrProfilingPlatformLinux.c
    A compiler-rt/test/profile/Linux/binary-id-offset.c

  Log Message:
  -----------
  [profile] Use base+vaddr for `__llvm_write_binary_ids` note pointers (#114907)

This function is always examining its own ELF headers in memory, but it
was trying to use conditions between examining files or memory, and it
wasn't accounting for LOAD offsets at runtime. This is especially bad if
a loaded segment has additional padding that's not in the file offsets.

Now we do a first scan of the program headers to figure out the runtime
base address based on `PT_PHDR` and/or `PT_DYNAMIC` (else assume zero),
similar to libc's `do_start`. Then each `PT_NOTE` pointer is simply the
base plus the segments's `pt_vaddr`, which includes LOAD offsets.

Fixes #114605



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