From 92174f988b0cde631ffac0dbcc9f8fca413d566e Mon Sep 17 00:00:00 2001
From: Jubilee Young <workingjubilee@gmail.com>
Date: Wed, 6 Jul 2022 19:07:52 -0700
Subject: Stop emitting CET prologues for naked functions

We can apply nocf_check as a hack for now.
---
 compiler/rustc_codegen_llvm/src/attributes.rs | 4 ++++
 compiler/rustc_codegen_llvm/src/llvm/ffi.rs   | 1 +
 2 files changed, 5 insertions(+)

(limited to 'compiler/rustc_codegen_llvm/src')

diff --git a/compiler/rustc_codegen_llvm/src/attributes.rs b/compiler/rustc_codegen_llvm/src/attributes.rs
index 9394d60134f..8c72f7dc06f 100644
--- a/compiler/rustc_codegen_llvm/src/attributes.rs
+++ b/compiler/rustc_codegen_llvm/src/attributes.rs
@@ -299,6 +299,10 @@ pub fn from_fn_attrs<'ll, 'tcx>(
     }
     if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NAKED) {
         to_add.push(AttributeKind::Naked.create_attr(cx.llcx));
+        // HACK(jubilee): "indirect branch tracking" works by attaching prologues to functions.
+        // And it is a module-level attribute, so the alternative is pulling naked functions into new LLVM modules.
+        // Otherwise LLVM's "naked" functions come with endbr prefixes per https://github.com/rust-lang/rust/issues/98768
+        to_add.push(AttributeKind::NoCfCheck.create_attr(cx.llcx));
     }
     if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::ALLOCATOR) {
         // apply to return place instead of function (unlike all other attributes applied in this function)
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 5ebc2d6139f..2c8e804fff5 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -191,6 +191,7 @@ pub enum AttributeKind {
     StackProtect = 32,
     NoUndef = 33,
     SanitizeMemTag = 34,
+    NoCfCheck = 35,
 }
 
 /// LLVMIntPredicate
-- 
cgit 1.4.1-3-g733a5