tree 1f56177ca84debc27f942db38821d7eae10a4985
parent c94b44cee8376b86da85c2452e74edfe5ad4b2cf
author Peter Collingbourne <pcc@google.com> 1565223324 -0700
committer Treehugger Robot <treehugger-gerrit@google.com> 1565317529 +0000

Add assembly support for -fsanitize=hwaddress tagged globals.

As of LLVM r368102, Clang will set a pointer tag in bits 56-63 of the
address of a global when compiling with -fsanitize=hwaddress. This requires
an adjustment to assembly code that takes the address of such globals: the
code cannot use the regular R_AARCH64_ADR_PREL_PG_HI21 relocation to refer
to the global, since the tag would take the address out of range. Instead,
the code must use the non-checking (_NC) variant of the relocation (the
link-time check is substituted by a runtime check).

This change makes the necessary adjustment in all of the places where it is
needed when compiling with -fsanitize=hwaddress. The __clang_major__ >= 10
is temporary (required because prebuilt Clang doesn't support :pg_hi21_nc:)
and we should be able to remove it once we update Clang past r368102.

Test: walleye_hwasan-userdebug boots
Change-Id: Ide7f513baac42fdeb637e95a7f7c1c083441884d