[X86] Add a Pass that builds a Condensed CFG for Load Value Injection (LVI) Gadgets

Adds a new data structure, ImmutableGraph, and uses RDF to find LVI gadgets and add them to a MachineGadgetGraph.

More specifically, a new X86 machine pass finds Load Value Injection (LVI) gadgets consisting of a load from memory (i.e., SOURCE), and any operation that may transmit the value loaded from memory over a covert channel, or use the value loaded from memory to determine a branch/call target (i.e., SINK).

Also adds a new target feature to X86: +lvi-load-hardening

The feature can be added via the clang CLI using -mlvi-hardening.

Differential Revision: https://reviews.llvm.org/D75936

1 files changed, 7 insertions, 1 deletions

diff --git a/clang/lib/Driver/ToolChains/Arch/X86.cpp b/clang/lib/Driver/ToolChains/Arch/X86.cpp
index 477e04485bf..d170b7ac3a7 100644
--- a/clang/lib/Driver/ToolChains/Arch/X86.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/X86.cpp
@@ -173,7 +173,13 @@ void x86::getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
   }
 
   auto LVIOpt = clang::driver::options::ID::OPT_INVALID;
-  if (Args.hasFlag(options::OPT_mlvi_cfi, options::OPT_mno_lvi_cfi, false)) {
+  if (Args.hasFlag(options::OPT_mlvi_hardening, options::OPT_mno_lvi_hardening,
+                   false)) {
+    Features.push_back("+lvi-load-hardening");
+    Features.push_back("+lvi-cfi"); // load hardening implies CFI protection
+    LVIOpt = options::OPT_mlvi_hardening;
+  } else if (Args.hasFlag(options::OPT_mlvi_cfi, options::OPT_mno_lvi_cfi,
+                          false)) {
     Features.push_back("+lvi-cfi");
     LVIOpt = options::OPT_mlvi_cfi;
   }