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

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

fixes https://github.com/rust-lang/rust/issues/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````
This commit is contained in:
Matthias Krüger
2025-07-18 04:27:51 +02:00
committed by GitHub
parent b252014673 9c8ab89187
commit accf61dd42
22 changed files with 147 additions and 36 deletions
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2
compiler/rustc_codegen_llvm/src/attributes.rs
View File

@@ -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();

2
compiler/rustc_codegen_llvm/src/callee.rs
View File

@@ -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

4
compiler/rustc_codegen_llvm/src/mono_item.rs
View File

@@ -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()
{