[all-commits] [llvm/llvm-project] 622851: [lldb] Set static Module's load addresses via Obje...

[Jason Molenda via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 622851a9059694487811a7f6078312fc2cce5486
      https://github.com/llvm/llvm-project/commit/622851a9059694487811a7f6078312fc2cce5486
  Author: Jason Molenda <jmolenda at apple.com>
  Date:   2024-04-03 (Wed, 03 Apr 2024)

  Changed paths:
    M lldb/source/Plugins/DynamicLoader/Static/DynamicLoaderStatic.cpp

  Log Message:
  -----------
  [lldb] Set static Module's load addresses via ObjectFile (#87439)

This is a followup to
https://github.com/llvm/llvm-project/pull/86359
"[lldb] [ObjectFileMachO] LLVM_COV is not mapped into firmware memory
(#86359)"

where I treat LLVM_COV segments in a Mach-O binary as non-loadable.
There is another codepath in
`DynamicLoaderStatic::LoadAllImagesAtFileAddresses` which is called to
set the load addresses for a Module to the file addresses. It has no
logic to detect a segment that is not loaded in virtual memory
(ObjectFileMachO::SectionIsLoadable), so it would set the load address
for this LLVM_COV segment to the file address and shadow actual code,
breaking lldb behavior.

This method currently sets the load address for any section that doesn't
have a load address set already. This presumes that a Module was added
to the Target, some mechanism set the correct load address for SOME
segments, and then this method is going to set the other segments to a
no-slide value, assuming they were forgotten.

ObjectFile base class doesn't, today, vend a SectionIsLoadable method,
but we do have ObjectFile::SetLoadAddress and at a higher level,
Module::SetLoadAddress, when we're setting the same slide to all
segments.

That's the behavior we want in this method. If any section has a load
address, we don't touch this Module. Otherwise we set all sections to
have a load address that is the same as the file address.

I also audited the other parts of lldb that are calling
SectionList::SectionLoadAddress and looked if they should be more
correctly using Module::SetLoadAddress for the entire binary. But in
most cases, we have the potential for different slides for different
sections so this section-by-section approach must be taken.

rdar://125800290



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