[lldb] Set static Module's load addresses via ObjectFile (#87439) #8540
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This is a followup to llvm#86359 "[lldb] [ObjectFileMachO] LLVM_COV is not mapped into firmware memory (llvm#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 (cherry picked from commit 622851a)
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JDevlieghere
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Apr 8, 2024
jasonmolenda
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This is a followup to
llvm#86359
"[lldb] [ObjectFileMachO] LLVM_COV is not mapped into firmware memory (llvm#86359)"
where I treat LLVM_COV segments in a Mach-O binary as non-loadable. There is another codepath in
DynamicLoaderStatic::LoadAllImagesAtFileAddresseswhich 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
(cherry picked from commit 622851a)