Auto merge of #99679 - repnop:kernel-address-sanitizer, r=cuviper

Add `kernel-address` sanitizer support for freestanding targets

This PR adds support for KASan (kernel address sanitizer) instrumentation in freestanding targets. I included the minimal set of `x86_64-unknown-none`, `riscv64{imac, gc}-unknown-none-elf`, and `aarch64-unknown-none` but there's likely other targets it can be added to. (`linux_kernel_base.rs`?) KASan uses the address sanitizer attributes but has the `CompileKernel` parameter set to `true` in the pass creation.

compiler/rustc_codegen_llvm/src/attributes.rs

@@ -62,7 +62,7 @@ pub fn sanitize_attrs<'ll>(
 ) -> SmallVec<[&'ll Attribute; 4]> {
     let mut attrs = SmallVec::new();
     let enabled = cx.tcx.sess.opts.unstable_opts.sanitizer - no_sanitize;
-    if enabled.contains(SanitizerSet::ADDRESS) {
+    if enabled.contains(SanitizerSet::ADDRESS) || enabled.contains(SanitizerSet::KERNELADDRESS) {
         attrs.push(llvm::AttributeKind::SanitizeAddress.create_attr(cx.llcx));
     }
     if enabled.contains(SanitizerSet::MEMORY) {

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -442,6 +442,10 @@ pub(crate) unsafe fn llvm_optimize(
             sanitize_thread: config.sanitizer.contains(SanitizerSet::THREAD),
             sanitize_hwaddress: config.sanitizer.contains(SanitizerSet::HWADDRESS),
             sanitize_hwaddress_recover: config.sanitizer_recover.contains(SanitizerSet::HWADDRESS),
+            sanitize_kernel_address: config.sanitizer.contains(SanitizerSet::KERNELADDRESS),
+            sanitize_kernel_address_recover: config
+                .sanitizer_recover
+                .contains(SanitizerSet::KERNELADDRESS),
         })
     } else {
         None

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -482,6 +482,8 @@ pub struct SanitizerOptions {
     pub sanitize_thread: bool,
     pub sanitize_hwaddress: bool,
     pub sanitize_hwaddress_recover: bool,
+    pub sanitize_kernel_address: bool,
+    pub sanitize_kernel_address_recover: bool,
 }
 
 /// LLVMRelocMode