[PATCH] D98875: [HWASan] Use page aliasing on x86_64.

[Xiang Zhang via Phabricator via llvm-commits]

xiangzhangllvm added inline comments.


================
Comment at: compiler-rt/lib/hwasan/hwasan.h:41
+// Tags are done in middle bits using userspace aliasing.
+constexpr unsigned kAddressTagShift = 39;
+constexpr unsigned kTagBits = 3;
----------------
Hello @morehouse, I have some questions here:
1) Does the "page alias" in your patch mean "tagged address and untagged address map to same place" ?
2) "The alias region is placed **next **to the shadow", what does the "alias region" here mean?
3) Why kAddressTagShift = 39 , kTagBits = 3 ? Does it mean the "alias region" size is 2^39Bytes ?  It seems to me that the ""alias region is placed **inside** the shadow? 

Thank you !


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D98875/new/

https://reviews.llvm.org/D98875