[BOLT] Add reading support for Linux kernel exception table #83100
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Read Linux exception table and ignore functions with exceptions for now. Proper support requires an introduction of new control flow since some instructions with memory access can cause a control flow change. Hence looking at disassembly or CFG with exceptions annotations is valuable for code analysis, delay marking functions with exceptions as non-simple until immediately before emitting the code.
maksfb
requested review from
aaupov,
rafaelauler,
ayermolo and
dcci
as code owners
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LGTM. I'd appreciate another pair of eyes in case I'm missing something @rafaelauler / @aaupov @ayermolo
| uint32_t EntryID = 0; | ||
| while (Cursor && Cursor.tell() < ExceptionsSection->getSize()) { | ||
| const uint64_t InstAddress = | ||
| SectionAddress + Cursor.tell() + (int32_t)DE.getU32(Cursor); |
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is int in the structure mapping to int32_t everywhere? I assume this is true for every architecture in the world we support but I don't know if this is a general assumption. Nothing needs to change because I assume BOLT has this assumption baked in many other places, but I was curious anyway and wanted to point out.
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I assume you are talking about the int in the Linux kernel structure. We support x86 kernels only (at least at this moment) and the data structure itself is architecture-specific. So it's not just the type of the field that can vary. Some architectures don't have exception table at all, others have different fields in the structure.
Read Linux exception table and ignore functions with exceptions for now. Proper support requires an introduction of new control flow since some instructions with memory access can cause a control flow change.
Hence looking at disassembly or CFG with exceptions annotations is valuable for code analysis, delay marking functions with exceptions as non-simple until immediately before emitting the code.