[PATCH] D35422: Add MemoryMappedSection struct for two-level memory map iteration

[Francis Ricci via Phabricator via llvm-commits]

fjricci added inline comments.


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Comment at: lib/sanitizer_common/sanitizer_procmaps.h:67
   u8 uuid[kModuleUUIDSize];
+  bool has_sections;
 };
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fjricci wrote:
> alekseyshl wrote:
> > Is it possible to drop has_sections and MemoryMappedSection, and add the current section info right here, under #if MAC? No other but Mac specific code will need to be changed.
> > 
> > If it turns out to be beneficial to have MemoryMappedSection defined, well, maybe define it inside the MemoryMappedSegment, under the same #if and call it just Segment?
> > 
> > That would lead to a platform specific function AddSegmentAddressRange(MemoryMappedSegment *segment, LoadedModule *module); and all the Mac specific stuff will be contained in _mac files.
> > 
> > What do you think? It's totally possible I miss some details precluding us from doing so.
> Hmm, I'm not sure I completely understand what you mean. The reason why the MemoryMappedSection is a separate struct is because each MemoryMappedSegment will have multiple MemoryMappedSection's (at least on Darwin), so there isn't a 1:1 correspondence. The MemoryMappedSection is also quite a bit lighter-weight/smaller than using a full MemoryMappedSegment struct for each section.
> 
> I'm alright with moving Section inside of MemoryMappedSegment.
> 
> I thought about making the MemoryMappedSection Darwin-specific (and I'm still open to it), but that will cause issues if we ever end up with non-platform specific code that needs to iterate at the level of a section (something like tsan etc). I *think* that this shouldn't ever happen, because any code that can tell the difference between a section and a segment will probably be mac-specific code by definition.
Ahh, there's another piece I forgot about in terms of has_section. The original reason why I added it is that not all Darwin segments contain sections, and in the case where there are no sections, you need to use the address range for the segment itself. So even if we move things into darwin-specific ifdefs, we'll still need has_section.


https://reviews.llvm.org/D35422