[clang] d179acd - [clang] Implement -fptrauth-auth-traps. (#102417)

[via cfe-commits]

Author: Ahmed Bougacha
Date: 2024-08-09T12:32:01-07:00
New Revision: d179acd0484bac30c5ebbbed4d29a4734d92ac93

URL: https://github.com/llvm/llvm-project/commit/d179acd0484bac30c5ebbbed4d29a4734d92ac93
DIFF: https://github.com/llvm/llvm-project/commit/d179acd0484bac30c5ebbbed4d29a4734d92ac93.diff

LOG: [clang] Implement -fptrauth-auth-traps. (#102417)

This provides -fptrauth-auth-traps, which at the frontend level only
controls the addition of the "ptrauth-auth-traps" function attribute.

The attribute in turn controls various aspects of backend codegen, by
providing the guarantee that every "auth" operation generated will trap
on failure.

This can either be delegated to the hardware (if AArch64 FPAC is known
to be available), in which case this attribute doesn't change codegen.
Otherwise, if FPAC isn't available, this asks the backend to emit
additional instructions to check and trap on auth failure.

Added: 
    

Modified: 
    clang/include/clang/Basic/PointerAuthOptions.h
    clang/lib/CodeGen/CodeGenFunction.cpp
    clang/lib/Frontend/CompilerInvocation.cpp
    clang/test/CodeGen/ptrauth-function-attributes.c

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Basic/PointerAuthOptions.h b/clang/include/clang/Basic/PointerAuthOptions.h
index a847bf4a4b4f6d..3deb666b375136 100644
--- a/clang/include/clang/Basic/PointerAuthOptions.h
+++ b/clang/include/clang/Basic/PointerAuthOptions.h
@@ -166,6 +166,9 @@ struct PointerAuthOptions {
   /// Should return addresses be authenticated?
   bool ReturnAddresses = false;
 
+  /// Do authentication failures cause a trap?
+  bool AuthTraps = 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
index 4dc57d0ff5b269..2b2e23f1e5d7fb 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -884,6 +884,8 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
     Fn->addFnAttr("ptrauth-returns");
   if (CodeGenOpts.PointerAuth.FunctionPointers)
     Fn->addFnAttr("ptrauth-calls");
+  if (CodeGenOpts.PointerAuth.AuthTraps)
+    Fn->addFnAttr("ptrauth-auth-traps");
   if (CodeGenOpts.PointerAuth.IndirectGotos)
     Fn->addFnAttr("ptrauth-indirect-gotos");
 

diff  --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 4370342ab22f31..e3911c281985b7 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1510,16 +1510,17 @@ void CompilerInvocation::setDefaultPointerAuthOptions(
           Discrimination::Constant, InitFiniPointerConstantDiscriminator);
     }
   }
-  Opts.IndirectGotos = LangOpts.PointerAuthIndirectGotos;
   Opts.ReturnAddresses = LangOpts.PointerAuthReturns;
+  Opts.AuthTraps = LangOpts.PointerAuthAuthTraps;
+  Opts.IndirectGotos = LangOpts.PointerAuthIndirectGotos;
 }
 
 static void parsePointerAuthOptions(PointerAuthOptions &Opts,
                                     const LangOptions &LangOpts,
                                     const llvm::Triple &Triple,
                                     DiagnosticsEngine &Diags) {
-  if (!LangOpts.PointerAuthCalls && !LangOpts.PointerAuthIndirectGotos &&
-      !LangOpts.PointerAuthReturns)
+  if (!LangOpts.PointerAuthCalls && !LangOpts.PointerAuthReturns &&
+      !LangOpts.PointerAuthAuthTraps && !LangOpts.PointerAuthIndirectGotos)
     return;
 
   CompilerInvocation::setDefaultPointerAuthOptions(Opts, LangOpts, Triple);

diff  --git a/clang/test/CodeGen/ptrauth-function-attributes.c b/clang/test/CodeGen/ptrauth-function-attributes.c
index 17ebf9d6e2e01c..e7081f00b4f686 100644
--- a/clang/test/CodeGen/ptrauth-function-attributes.c
+++ b/clang/test/CodeGen/ptrauth-function-attributes.c
@@ -8,6 +8,9 @@
 // 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-auth-traps -emit-llvm %s -o - | FileCheck %s --check-prefixes=ALL,TRAPS
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-auth-traps -emit-llvm %s -o - | FileCheck %s --check-prefixes=ALL,TRAPS
+
 // RUN: %clang_cc1 -triple arm64-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
 
@@ -19,6 +22,8 @@ void test() {
 
 // RETS: attributes #0 = {{{.*}} "ptrauth-returns" {{.*}}}
 
+// TRAPS: attributes #0 = {{{.*}} "ptrauth-auth-traps" {{.*}}}
+
 // GOTOS: attributes #0 = {{{.*}} "ptrauth-indirect-gotos" {{.*}}}
 
 // OFF-NOT: attributes {{.*}} "ptrauth-