Auto merge of #95548 - rcvalle:rust-cfi-2, r=nagisa

Add fine-grained LLVM CFI support to the Rust compiler

This PR improves the LLVM Control Flow Integrity (CFI) support in the Rust compiler by providing forward-edge control flow protection for Rust-compiled code only by aggregating function pointers in groups identified by their return and parameter types.

Forward-edge control flow protection for C or C++ and Rust -compiled code "mixed binaries" (i.e., for when C or C++ and Rust -compiled code share the same virtual address space) will be provided in later work as part of this project by identifying C char and integer type uses at the time types are encoded (see Type metadata in the design document in the tracking issue https://github.com/rust-lang/rust/issues/89653).

LLVM CFI can be enabled with -Zsanitizer=cfi and requires LTO (i.e., -Clto).

Thank you again, `@eddyb,` `@nagisa,` `@pcc,` and `@tmiasko` for all the help!

2 files changed, 2 insertions, 10 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index 773c55cf551..3eee58d9d1c 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -20,7 +20,7 @@ use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
 use rustc_middle::ty::{self, Instance, Ty, TypeVisitable};
 use rustc_span::source_map::Span;
 use rustc_span::{sym, Symbol};
-use rustc_symbol_mangling::typeid_for_fnabi;
+use rustc_symbol_mangling::typeid::typeid_for_fnabi;
 use rustc_target::abi::call::{ArgAbi, FnAbi, PassMode};
 use rustc_target::abi::{self, HasDataLayout, WrappingRange};
 use rustc_target::spec::abi::Abi;
@@ -918,7 +918,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             // FIXME(rcvalle): Add support for generalized identifiers.
             // FIXME(rcvalle): Create distinct unnamed MDNodes for internal identifiers.
             let typeid = typeid_for_fnabi(bx.tcx(), fn_abi);
-            let typeid_metadata = bx.typeid_metadata(typeid);
+            let typeid_metadata = self.cx.typeid_metadata(typeid);
 
             // Test whether the function pointer is associated with the type identifier.
             let cond = bx.type_test(fn_ptr, typeid_metadata);
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index ec3f7a2156a..8ee375fa9e3 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -3,7 +3,6 @@ use rustc_middle::mir;
 use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, TyAndLayout};
 use rustc_middle::ty::{self, Instance, Ty, TypeFoldable, TypeVisitable};
-use rustc_symbol_mangling::typeid_for_fnabi;
 use rustc_target::abi::call::{FnAbi, PassMode};
 
 use std::iter;
@@ -247,13 +246,6 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     for (bb, _) in traversal::reverse_postorder(&mir) {
         fx.codegen_block(bb);
     }
-
-    // For backends that support CFI using type membership (i.e., testing whether a given  pointer
-    // is associated with a type identifier).
-    if cx.tcx().sess.is_sanitizer_cfi_enabled() {
-        let typeid = typeid_for_fnabi(cx.tcx(), fn_abi);
-        bx.type_metadata(llfn, typeid);
-    }
 }
 
 /// Produces, for each argument, a `Value` pointing at the