Rollup merge of rust-lang#143293 - folkertdev:naked-function-kcfi, r=compiler-errors

fix `-Zsanitizer=kcfi` on `#[naked]` functions

fixes rust-lang#143266

With `-Zsanitizer=kcfi`, indirect calls happen via generated intermediate shim that forwards the call. The generated shim preserves the attributes of the original, including `#[unsafe(naked)]`. The shim is not a naked function though, and violates its invariants (like having a body that consists of a single `naked_asm!` call).

My fix here is to match on the `InstanceKind`, and only use `codegen_naked_asm` when the instance is not a `ReifyShim`. That does beg the question whether there are other `InstanceKind`s that could come up. As far as I can tell the answer is no: calling via `dyn` seems to work find, and `#[track_caller]` is disallowed in combination with `#[naked]`.

r? codegen
``@rustbot`` label +A-naked
cc ``@maurer`` ``@rcvalle``

Author: fmease

compiler/rustc_codegen_cranelift/src/driver/aot.rs

@@ -530,8 +530,8 @@ fn codegen_cgu_content(
     for (mono_item, item_data) in mono_items {
         match mono_item {
             MonoItem::Fn(instance) => {
-                if tcx.codegen_fn_attrs(instance.def_id()).flags.contains(CodegenFnAttrFlags::NAKED)
-                {
+                let flags = tcx.codegen_instance_attrs(instance.def).flags;
+                if flags.contains(CodegenFnAttrFlags::NAKED) {
                     rustc_codegen_ssa::mir::naked_asm::codegen_naked_asm(
                         &mut GlobalAsmContext { tcx, global_asm: &mut cx.global_asm },
                         instance,

compiler/rustc_codegen_cranelift/src/driver/jit.rs

@@ -127,7 +127,7 @@ fn codegen_and_compile_fn<'tcx>(
     module: &mut dyn Module,
     instance: Instance<'tcx>,
 ) {
-    if tcx.codegen_fn_attrs(instance.def_id()).flags.contains(CodegenFnAttrFlags::NAKED) {
+    if tcx.codegen_instance_attrs(instance.def).flags.contains(CodegenFnAttrFlags::NAKED) {
         tcx.dcx()
             .span_fatal(tcx.def_span(instance.def_id()), "Naked asm is not supported in JIT mode");
     }

compiler/rustc_codegen_cranelift/src/driver/mod.rs

@@ -35,7 +35,7 @@ fn predefine_mono_items<'tcx>(
                         is_compiler_builtins,
                     );
                     let is_naked = tcx
-                        .codegen_fn_attrs(instance.def_id())
+                        .codegen_instance_attrs(instance.def)
                         .flags
                         .contains(CodegenFnAttrFlags::NAKED);
                     module

compiler/rustc_codegen_gcc/src/attributes.rs

@@ -87,7 +87,7 @@ pub fn from_fn_attrs<'gcc, 'tcx>(
     #[cfg_attr(not(feature = "master"), allow(unused_variables))] func: Function<'gcc>,
     instance: ty::Instance<'tcx>,
 ) {
-    let codegen_fn_attrs = cx.tcx.codegen_fn_attrs(instance.def_id());
+    let codegen_fn_attrs = cx.tcx.codegen_instance_attrs(instance.def);
 
     #[cfg(feature = "master")]
     {

compiler/rustc_codegen_gcc/src/callee.rs

@@ -105,7 +105,7 @@ pub fn get_fn<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, instance: Instance<'tcx>)
             let is_hidden = if is_generic {
                 // This is a monomorphization of a generic function.
                 if !(cx.tcx.sess.opts.share_generics()
-                    || tcx.codegen_fn_attrs(instance_def_id).inline
+                    || tcx.codegen_instance_attrs(instance.def).inline
                         == rustc_attr_data_structures::InlineAttr::Never)
                 {
                     // When not sharing generics, all instances are in the same

compiler/rustc_codegen_gcc/src/mono_item.rs

@@ -53,7 +53,7 @@ impl<'gcc, 'tcx> PreDefineCodegenMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
         let fn_abi = self.fn_abi_of_instance(instance, ty::List::empty());
         self.linkage.set(base::linkage_to_gcc(linkage));
         let decl = self.declare_fn(symbol_name, fn_abi);
-        //let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
+        //let attrs = self.tcx.codegen_instance_attrs(instance.def);
 
         attributes::from_fn_attrs(self, decl, instance);
 

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -344,7 +344,7 @@ pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
     llfn: &'ll Value,
     instance: ty::Instance<'tcx>,
 ) {
-    let codegen_fn_attrs = cx.tcx.codegen_fn_attrs(instance.def_id());
+    let codegen_fn_attrs = cx.tcx.codegen_instance_attrs(instance.def);
 
     let mut to_add = SmallVec::<[_; 16]>::new();
 

compiler/rustc_codegen_llvm/src/callee.rs

@@ -102,7 +102,7 @@ pub(crate) fn get_fn<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, instance: Instance<'t
         let is_hidden = if is_generic {
             // This is a monomorphization of a generic function.
             if !(cx.tcx.sess.opts.share_generics()
-                || tcx.codegen_fn_attrs(instance_def_id).inline
+                || tcx.codegen_instance_attrs(instance.def).inline
                     == rustc_attr_data_structures::InlineAttr::Never)
             {
                 // When not sharing generics, all instances are in the same

compiler/rustc_codegen_llvm/src/mono_item.rs

@@ -55,8 +55,8 @@ impl<'tcx> PreDefineCodegenMethods<'tcx> for CodegenCx<'_, 'tcx> {
         let fn_abi = self.fn_abi_of_instance(instance, ty::List::empty());
         let lldecl = self.declare_fn(symbol_name, fn_abi, Some(instance));
         llvm::set_linkage(lldecl, base::linkage_to_llvm(linkage));
-        let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
-        base::set_link_section(lldecl, attrs);
+        let attrs = self.tcx.codegen_instance_attrs(instance.def);
+        base::set_link_section(lldecl, &attrs);
         if (linkage == Linkage::LinkOnceODR || linkage == Linkage::WeakODR)
             && self.tcx.sess.target.supports_comdat()
         {

compiler/rustc_codegen_ssa/src/mir/debuginfo.rs

@@ -356,7 +356,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             LocalRef::Operand(operand) => {
                 // Don't spill operands onto the stack in naked functions.
                 // See: https://github.com/rust-lang/rust/issues/42779
-                let attrs = bx.tcx().codegen_fn_attrs(self.instance.def_id());
+                let attrs = bx.tcx().codegen_instance_attrs(self.instance.def);
                 if attrs.flags.contains(CodegenFnAttrFlags::NAKED) {
                     return;
                 }