tree 46f4c746af6508b7a89391bcb3f6a5a103fe43db
parent 0a3845b70f4fc36b4656aba9a568a00fdaf5bab4
author Scott Constable <scott.d.constable@intel.com> 1585889987 -0700
committer Craig Topper <craig.topper@gmail.com> 1585899279 -0700

[X86] Add Indirect Thunk Support to X86 to mitigate Load Value Injection (LVI)

This pass replaces each indirect call/jump with a direct call to a thunk that looks like:

lfence
jmpq *%r11

This ensures that if the value in register %r11 was loaded from memory, then
the value in %r11 is (architecturally) correct prior to the jump.
Also adds a new target feature to X86: +lvi-cfi
("cfi" meaning control-flow integrity)
The feature can be added via clang CLI using -mlvi-cfi.

This is an alternate implementation to https://reviews.llvm.org/D75934 That merges the thunk insertion functionality with the existing X86 retpoline code.

Differential Revision: https://reviews.llvm.org/D76812