[clang] Wire -fptrauth-returns to "ptrauth-returns" fn attribute. (ll…

…vm#102416) We already ended up with -fptrauth-returns, the feature macro, the lang opt, and the actual backend lowering. The only part left is threading it all through PointerAuthOptions, to drive the addition of the "ptrauth-returns" attribute to generated functions. While there, do minor cleanup on ptrauth-function-attributes.c. This also adds ptrauth_key_return_address to ptrauth.h.
bwendling · Aug 15, 2024 · d974968 · d974968
1 parent fbdc96f
commit d974968
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Showing 5 changed files with 21 additions and 3 deletions.
diff --git a/clang/include/clang/Basic/PointerAuthOptions.h b/clang/include/clang/Basic/PointerAuthOptions.h
@@ -163,6 +163,9 @@ class PointerAuthSchema {
 };
 
 struct PointerAuthOptions {
+  /// Should return addresses be authenticated?
+  bool ReturnAddresses = false;
+
   /// Do indirect goto label addresses need to be authenticated?
   bool IndirectGotos = false;
 

diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -880,6 +880,8 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
 
   // Add pointer authentication attributes.
   const CodeGenOptions &CodeGenOpts = CGM.getCodeGenOpts();
+  if (CodeGenOpts.PointerAuth.ReturnAddresses)
+    Fn->addFnAttr("ptrauth-returns");
   if (CodeGenOpts.PointerAuth.FunctionPointers)
     Fn->addFnAttr("ptrauth-calls");
   if (CodeGenOpts.PointerAuth.IndirectGotos)

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1511,13 +1511,15 @@ void CompilerInvocation::setDefaultPointerAuthOptions(
     }
   }
   Opts.IndirectGotos = LangOpts.PointerAuthIndirectGotos;
+  Opts.ReturnAddresses = LangOpts.PointerAuthReturns;
 }
 
 static void parsePointerAuthOptions(PointerAuthOptions &Opts,
                                     const LangOptions &LangOpts,
                                     const llvm::Triple &Triple,
                                     DiagnosticsEngine &Diags) {
-  if (!LangOpts.PointerAuthCalls && !LangOpts.PointerAuthIndirectGotos)
+  if (!LangOpts.PointerAuthCalls && !LangOpts.PointerAuthIndirectGotos &&
+      !LangOpts.PointerAuthReturns)
     return;
 
   CompilerInvocation::setDefaultPointerAuthOptions(Opts, LangOpts, Triple);

diff --git a/clang/lib/Headers/ptrauth.h b/clang/lib/Headers/ptrauth.h
@@ -28,6 +28,12 @@ typedef enum {
   /* A process-specific key which can be used to sign data pointers. */
   ptrauth_key_process_dependent_data = ptrauth_key_asdb,
 
+  /* The key used to sign return addresses on the stack.
+     The extra data is based on the storage address of the return address.
+     On AArch64, that is always the storage address of the return address + 8
+     (or, in other words, the value of the stack pointer on function entry) */
+  ptrauth_key_return_address = ptrauth_key_process_dependent_code,
+
   /* The key used to sign C function pointers.
      The extra data is always 0. */
   ptrauth_key_function_pointer = ptrauth_key_process_independent_code,

diff --git a/clang/test/CodeGen/ptrauth-function-attributes.c b/clang/test/CodeGen/ptrauth-function-attributes.c
@@ -1,11 +1,14 @@
+// RUN: %clang_cc1 -triple arm64-apple-ios                    -emit-llvm %s  -o - | FileCheck %s --check-prefixes=ALL,OFF
 // RUN: %clang_cc1 -triple arm64e-apple-ios                   -emit-llvm %s  -o - | FileCheck %s --check-prefixes=ALL,OFF
 // RUN: %clang_cc1 -triple aarch64-linux-gnu                  -emit-llvm %s  -o - | FileCheck %s --check-prefixes=ALL,OFF
 
-// RUN: %clang_cc1 -triple arm64-apple-ios  -fptrauth-calls   -emit-llvm %s  -o - | FileCheck %s --check-prefixes=ALL,CALLS
+// RUN: %clang_cc1 -triple arm64-apple-ios   -fptrauth-calls  -emit-llvm %s  -o - | FileCheck %s --check-prefixes=ALL,CALLS
 // RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-calls  -emit-llvm %s  -o - | FileCheck %s --check-prefixes=ALL,CALLS
 
+// RUN: %clang_cc1 -triple arm64-apple-ios   -fptrauth-returns -emit-llvm %s -o - | FileCheck %s --check-prefixes=ALL,RETS
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-returns -emit-llvm %s -o - | FileCheck %s --check-prefixes=ALL,RETS
+
 // RUN: %clang_cc1 -triple arm64-apple-ios   -fptrauth-indirect-gotos -emit-llvm %s -o - | FileCheck %s --check-prefixes=ALL,GOTOS
-// RUN: %clang_cc1 -triple arm64e-apple-ios  -fptrauth-indirect-gotos -emit-llvm %s -o - | FileCheck %s --check-prefixes=ALL,GOTOS
 // RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-indirect-gotos -emit-llvm %s -o - | FileCheck %s --check-prefixes=ALL,GOTOS
 
 // ALL: define {{(dso_local )?}}void @test() #0
@@ -14,6 +17,8 @@ void test() {
 
 // CALLS: attributes #0 = {{{.*}} "ptrauth-calls" {{.*}}}
 
+// RETS: attributes #0 = {{{.*}} "ptrauth-returns" {{.*}}}
+
 // GOTOS: attributes #0 = {{{.*}} "ptrauth-indirect-gotos" {{.*}}}
 
 // OFF-NOT: attributes {{.*}} "ptrauth-