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Hardware-assisted AddressSanitizer (llvm part).
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Authored by eugenis on Dec 6 2017, 4:57 PM.

Details

Summary

This is LLVM instrumentation for the new HWASan tool. It is basically
a stripped down copy of ASan at this point, w/o stack or global
support. Instrumenation adds a global constructor + runtime callbacks
for every load and store.

HWASan comes with its own IR attribute.

A brief design document can be found in
clang/docs/HardwareAssistedAddressSanitizerDesign.rst (submitted earlier).

Event Timeline

eugenis created this revision.Dec 6 2017, 4:57 PM
kcc edited edge metadata.Dec 6 2017, 5:06 PM

Please document the new attribute and explain why the old attribute doesn't work for us (there are cases when we need one, but not the other, in both directions)

llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
16

Do you really need all these includes?

103

update comment

eugenis updated this revision to Diff 125866.Dec 6 2017, 5:54 PM
eugenis marked an inline comment as done.

Documented the new attribute.

eugenis added inline comments.Dec 6 2017, 5:54 PM
llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
16

I'm not sure how to find the ones that are unused.

kcc added inline comments.Dec 6 2017, 6:11 PM
llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
16

I don't think we have a tool for that.
I've done it like this:

given e.g. #include "llvm/IR/MDBuilder.h" search for MDBuilder in the code. 
If none found, remove the include and rebuild. If build passes, you don't need the header.

There is clearly a risk that some other file actually includes MDBuilder and this code will break
with further refactoring of header files. But that's tolerable IMHO.

227

do you need this section of code at all?
If not, I'd suggest to remove it and reinstate if needed, with a test.

257

Do you need this? Do you have a test?
I'd prefer if we don't add code from asan/msan that we might not need in hwasan

337

no {}

eugenis updated this revision to Diff 125867.Dec 6 2017, 6:27 PM
eugenis marked 2 inline comments as done.

removed some extra code and includes

eugenis marked an inline comment as done.Dec 6 2017, 6:27 PM
eugenis added inline comments.
llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
257

added a test

kcc added a comment.Dec 7 2017, 11:21 AM

LGTM, please wait for (at least) Aleksey's review.

alekseyshl accepted this revision.Dec 7 2017, 4:22 PM
This revision is now accepted and ready to land.Dec 7 2017, 4:22 PM
This revision was automatically updated to reflect the committed changes.