https://github.com/kovdan01 updated
https://github.com/llvm/llvm-project/pull/102199
>From 0c20bcdf35f3c15024986da50cafb2a8c155e3cf Mon Sep 17 00:00:00 2001
From: Daniil Kovalev <dkova...@accesssoftek.com>
Date: Tue, 6 Aug 2024 20:48:02 +0300
Subject: [PATCH 1/3] [PAC] Fix address discrimination for type info vtable
pointers
In #99726, `-fptrauth-type-info-vtable-pointer-discrimination` was introduced,
which is intended to enable type and address discrimination for type_info
vtable pointers. However, some codegen logic for actually enabling address
discrimination was missing. This patch addresses the issue.
Fixes #101716
---
clang/lib/CodeGen/ItaniumCXXABI.cpp | 20 ++++++++++++++++---
.../CodeGenCXX/ptrauth-type-info-vtable.cpp | 2 +-
llvm/include/llvm/IR/Constants.h | 18 +++++++++++------
.../AArch64/ptrauth-type-info-vptr-discr.ll | 20 +++++++++++++++++++
4 files changed, 50 insertions(+), 10 deletions(-)
create mode 100644 llvm/test/CodeGen/AArch64/ptrauth-type-info-vptr-discr.ll
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp
b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 9b5227772125b2..13aeb3e75d6843 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -3955,9 +3955,23 @@ void ItaniumRTTIBuilder::BuildVTablePointer(const Type
*Ty) {
VTable, Two);
}
- if (auto &Schema = CGM.getCodeGenOpts().PointerAuth.CXXTypeInfoVTablePointer)
- VTable = CGM.getConstantSignedPointer(VTable, Schema, nullptr,
GlobalDecl(),
- QualType(Ty, 0));
+ if (const auto &Schema =
+ CGM.getCodeGenOpts().PointerAuth.CXXTypeInfoVTablePointer) {
+ llvm::PointerType *PtrTy = llvm::PointerType::get(
+ CGM.getLLVMContext(),
+ CGM.getModule().getDataLayout().getProgramAddressSpace());
+ llvm::Constant *StorageAddress =
+ (Schema.isAddressDiscriminated()
+ ? llvm::ConstantExpr::getIntToPtr(
+ llvm::ConstantInt::get(
+ CGM.IntPtrTy,
+ llvm::ConstantPtrAuth::
+ AddrDiscriminator_CXXTypeInfoVTablePointer),
+ PtrTy)
+ : nullptr);
+ VTable = CGM.getConstantSignedPointer(VTable, Schema, StorageAddress,
+ GlobalDecl(), QualType(Ty, 0));
+ }
Fields.push_back(VTable);
}
diff --git a/clang/test/CodeGenCXX/ptrauth-type-info-vtable.cpp
b/clang/test/CodeGenCXX/ptrauth-type-info-vtable.cpp
index 174aeda89d1755..61eef73b5be2a4 100644
--- a/clang/test/CodeGenCXX/ptrauth-type-info-vtable.cpp
+++ b/clang/test/CodeGenCXX/ptrauth-type-info-vtable.cpp
@@ -65,7 +65,7 @@ extern "C" int disc_std_type_info =
__builtin_ptrauth_string_discriminator("_ZTV
// NODISC: @_ZTI10TestStruct = constant { ptr, ptr } { ptr ptrauth (ptr
getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64
2), i32 2), ptr @_ZTS10TestStruct }, align 8
-// DISC: @_ZTI10TestStruct = constant { ptr, ptr } { ptr ptrauth (ptr
getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64
2), i32 2, i64 [[STDTYPEINFO_DISC]]), ptr @_ZTS10TestStruct }, align 8
+// DISC: @_ZTI10TestStruct = constant { ptr, ptr } { ptr ptrauth (ptr
getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64
2), i32 2, i64 [[STDTYPEINFO_DISC]], ptr inttoptr (i64 1 to ptr)), ptr
@_ZTS10TestStruct }, align 8
struct TestStruct {
virtual ~TestStruct();
diff --git a/llvm/include/llvm/IR/Constants.h b/llvm/include/llvm/IR/Constants.h
index 2788751e8b62a1..aaa1c197651a66 100644
--- a/llvm/include/llvm/IR/Constants.h
+++ b/llvm/include/llvm/IR/Constants.h
@@ -1056,12 +1056,18 @@ class ConstantPtrAuth final : public Constant {
return !getAddrDiscriminator()->isNullValue();
}
- /// A constant value for the address discriminator which has special
- /// significance to ctors/dtors lowering. Regular address discrimination
can't
- /// be applied for them since uses of llvm.global_{c|d}tors are disallowed
- /// (see Verifier::visitGlobalVariable) and we can't emit getelementptr
- /// expressions referencing these special arrays.
- enum { AddrDiscriminator_CtorsDtors = 1 };
+ /// Constant values for the address discriminator which have special
+ /// significance to lowering in some contexts.
+ /// - For ctors/dtors, regular address discrimination can't
+ /// be applied for them since uses of llvm.global_{c|d}tors are disallowed
+ /// (see Verifier::visitGlobalVariable) and we can't emit getelementptr
+ /// expressions referencing these special arrays.
+ /// - For vtable pointers of std::type_info and classes derived from it,
+ /// we do not know the storage address when emitting ptrauth constant.
+ enum {
+ AddrDiscriminator_CtorsDtors = 1,
+ AddrDiscriminator_CXXTypeInfoVTablePointer = 1
+ };
/// Whether the address uses a special address discriminator.
/// These discriminators can't be used in real pointer-auth values; they
diff --git a/llvm/test/CodeGen/AArch64/ptrauth-type-info-vptr-discr.ll
b/llvm/test/CodeGen/AArch64/ptrauth-type-info-vptr-discr.ll
new file mode 100644
index 00000000000000..b25a32f856b7ab
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/ptrauth-type-info-vptr-discr.ll
@@ -0,0 +1,20 @@
+; RUN: llc -mtriple aarch64-linux-gnu -mattr=+pauth -filetype=asm -o - %s |
FileCheck --check-prefix=ELF %s
+; RUN: llc -mtriple aarch64-apple-darwin -mattr=+pauth -filetype=asm -o - %s |
FileCheck --check-prefix=MACHO %s
+
+; ELF-LABEL: _ZTI10Disc:
+; ELF-NEXT: .xword
(_ZTVN10__cxxabiv117__class_type_infoE+16)@AUTH(da,45546,addr)
+; ELF-LABEL: _ZTI10NoDisc:
+; ELF-NEXT: .xword
(_ZTVN10__cxxabiv117__class_type_infoE+16)@AUTH(da,45546)
+
+; MACHO-LABEL: __ZTI10Disc:
+; MACHO-NEXT: .quad
(__ZTVN10__cxxabiv117__class_type_infoE+16)@AUTH(da,45546,addr)
+; MACHO-LABEL: __ZTI10NoDisc:
+; MACHO-NEXT: .quad
(__ZTVN10__cxxabiv117__class_type_infoE+16)@AUTH(da,45546)
+
+@_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
+
+@_ZTS10Disc = constant [4 x i8] c"Disc", align 1
+@_ZTI10Disc = constant { ptr, ptr } { ptr ptrauth (ptr getelementptr
inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64 2), i32 2, i64
45546, ptr inttoptr (i64 1 to ptr)), ptr @_ZTS10Disc }, align 8
+
+@_ZTS10NoDisc = constant [6 x i8] c"NoDisc", align 1
+@_ZTI10NoDisc = constant { ptr, ptr } { ptr ptrauth (ptr getelementptr
inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64 2), i32 2, i64
45546), ptr @_ZTS10NoDisc }, align 8
>From 130ff558e146a0da1ed542b62b9cb46b4d102327 Mon Sep 17 00:00:00 2001
From: Daniil Kovalev <dkova...@accesssoftek.com>
Date: Mon, 16 Sep 2024 18:19:25 +0300
Subject: [PATCH 2/3] Use real addr instead of placeholder for signed type info
vt ptrs
---
clang/lib/CodeGen/ItaniumCXXABI.cpp | 43 +++++++++++++------
.../CodeGenCXX/ptrauth-type-info-vtable.cpp | 2 +-
llvm/include/llvm/IR/Constants.h | 18 +++-----
.../AArch64/ptrauth-type-info-vptr-discr.ll | 2 +-
4 files changed, 38 insertions(+), 27 deletions(-)
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp
b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 21168cd485ef12..ed253be1ad257a 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -3975,18 +3975,9 @@ void ItaniumRTTIBuilder::BuildVTablePointer(const Type
*Ty) {
if (const auto &Schema =
CGM.getCodeGenOpts().PointerAuth.CXXTypeInfoVTablePointer) {
- llvm::PointerType *PtrTy = llvm::PointerType::get(
- CGM.getLLVMContext(),
- CGM.getModule().getDataLayout().getProgramAddressSpace());
- llvm::Constant *StorageAddress =
- (Schema.isAddressDiscriminated()
- ? llvm::ConstantExpr::getIntToPtr(
- llvm::ConstantInt::get(
- CGM.IntPtrTy,
- llvm::ConstantPtrAuth::
- AddrDiscriminator_CXXTypeInfoVTablePointer),
- PtrTy)
- : nullptr);
+ // If address discrimination is enabled, we'll re-write that to actual
+ // storage address later in ItaniumRTTIBuilder::BuildTypeInfo.
+ llvm::Constant *StorageAddress = nullptr;
VTable = CGM.getConstantSignedPointer(VTable, Schema, StorageAddress,
GlobalDecl(), QualType(Ty, 0));
}
@@ -4107,6 +4098,7 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(
llvm::GlobalValue::DLLStorageClassTypes DLLStorageClass) {
// Add the vtable pointer.
BuildVTablePointer(cast<Type>(Ty));
+ size_t VTablePointerIdx = Fields.size() - 1;
// And the name.
llvm::GlobalVariable *TypeName = GetAddrOfTypeName(Ty, Linkage);
@@ -4222,7 +4214,6 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(
}
llvm::Constant *Init = llvm::ConstantStruct::getAnon(Fields);
-
SmallString<256> Name;
llvm::raw_svector_ostream Out(Name);
CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty, Out);
@@ -4231,6 +4222,32 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(M, Init->getType(),
/*isConstant=*/true, Linkage, Init, Name);
+ if (const auto &Schema =
+ CGM.getCodeGenOpts().PointerAuth.CXXTypeInfoVTablePointer) {
+ if (Schema.isAddressDiscriminated()) {
+ // If type info vtable pointer is signed with address discrimination
+ // enabled, we need to place actual storage address (which was unknown
+ // during construction in ItaniumRTTIBuilder::BuildVTablePointer) in the
+ // corresponding field.
+ ConstantInitBuilder Builder(CGM);
+ auto InitBuilder = Builder.beginStruct();
+ for (size_t I = 0; I < Fields.size(); ++I) {
+ if (I != VTablePointerIdx) {
+ InitBuilder.add(Fields[I]);
+ continue;
+ }
+ auto *SignedVTablePointer = cast<llvm::ConstantPtrAuth>(Fields[I]);
+ llvm::Constant *UnsignedVtablePointer =
+ SignedVTablePointer->getPointer();
+ llvm::Constant *StorageAddress =
+ InitBuilder.getAddrOfCurrentPosition(CGM.UnqualPtrTy);
+ InitBuilder.add(CGM.getConstantSignedPointer(
+ UnsignedVtablePointer, Schema, StorageAddress, GlobalDecl(),
+ QualType(cast<Type>(Ty), 0)));
+ }
+ InitBuilder.finishAndSetAsInitializer(GV);
+ }
+ }
// Export the typeinfo in the same circumstances as the vtable is exported.
auto GVDLLStorageClass = DLLStorageClass;
diff --git a/clang/test/CodeGenCXX/ptrauth-type-info-vtable.cpp
b/clang/test/CodeGenCXX/ptrauth-type-info-vtable.cpp
index 61eef73b5be2a4..bb692484c94ece 100644
--- a/clang/test/CodeGenCXX/ptrauth-type-info-vtable.cpp
+++ b/clang/test/CodeGenCXX/ptrauth-type-info-vtable.cpp
@@ -65,7 +65,7 @@ extern "C" int disc_std_type_info =
__builtin_ptrauth_string_discriminator("_ZTV
// NODISC: @_ZTI10TestStruct = constant { ptr, ptr } { ptr ptrauth (ptr
getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64
2), i32 2), ptr @_ZTS10TestStruct }, align 8
-// DISC: @_ZTI10TestStruct = constant { ptr, ptr } { ptr ptrauth (ptr
getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64
2), i32 2, i64 [[STDTYPEINFO_DISC]], ptr inttoptr (i64 1 to ptr)), ptr
@_ZTS10TestStruct }, align 8
+// DISC: @_ZTI10TestStruct = constant { ptr, ptr } { ptr ptrauth (ptr
getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64
2), i32 2, i64 [[STDTYPEINFO_DISC]], ptr @_ZTI10TestStruct), ptr
@_ZTS10TestStruct }, align 8
struct TestStruct {
virtual ~TestStruct();
diff --git a/llvm/include/llvm/IR/Constants.h b/llvm/include/llvm/IR/Constants.h
index a49d13b6568696..3b16aa039a5087 100644
--- a/llvm/include/llvm/IR/Constants.h
+++ b/llvm/include/llvm/IR/Constants.h
@@ -1067,18 +1067,12 @@ class ConstantPtrAuth final : public Constant {
return !getAddrDiscriminator()->isNullValue();
}
- /// Constant values for the address discriminator which have special
- /// significance to lowering in some contexts.
- /// - For ctors/dtors, regular address discrimination can't
- /// be applied for them since uses of llvm.global_{c|d}tors are disallowed
- /// (see Verifier::visitGlobalVariable) and we can't emit getelementptr
- /// expressions referencing these special arrays.
- /// - For vtable pointers of std::type_info and classes derived from it,
- /// we do not know the storage address when emitting ptrauth constant.
- enum {
- AddrDiscriminator_CtorsDtors = 1,
- AddrDiscriminator_CXXTypeInfoVTablePointer = 1
- };
+ /// A constant value for the address discriminator which has special
+ /// significance to ctors/dtors lowering. Regular address discrimination
can't
+ /// be applied for them since uses of llvm.global_{c|d}tors are disallowed
+ /// (see Verifier::visitGlobalVariable) and we can't emit getelementptr
+ /// expressions referencing these special arrays.
+ enum { AddrDiscriminator_CtorsDtors = 1 };
/// Whether the address uses a special address discriminator.
/// These discriminators can't be used in real pointer-auth values; they
diff --git a/llvm/test/CodeGen/AArch64/ptrauth-type-info-vptr-discr.ll
b/llvm/test/CodeGen/AArch64/ptrauth-type-info-vptr-discr.ll
index b25a32f856b7ab..704cccdc1107a1 100644
--- a/llvm/test/CodeGen/AArch64/ptrauth-type-info-vptr-discr.ll
+++ b/llvm/test/CodeGen/AArch64/ptrauth-type-info-vptr-discr.ll
@@ -14,7 +14,7 @@
@_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
@_ZTS10Disc = constant [4 x i8] c"Disc", align 1
-@_ZTI10Disc = constant { ptr, ptr } { ptr ptrauth (ptr getelementptr
inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64 2), i32 2, i64
45546, ptr inttoptr (i64 1 to ptr)), ptr @_ZTS10Disc }, align 8
+@_ZTI10Disc = constant { ptr, ptr } { ptr ptrauth (ptr getelementptr
inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64 2), i32 2, i64
45546, ptr @_ZTI10Disc), ptr @_ZTS10Disc }, align 8
@_ZTS10NoDisc = constant [6 x i8] c"NoDisc", align 1
@_ZTI10NoDisc = constant { ptr, ptr } { ptr ptrauth (ptr getelementptr
inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64 2), i32 2, i64
45546), ptr @_ZTS10NoDisc }, align 8
>From 55fc2c822f8f543d335e443a13860ae72fb5ce6d Mon Sep 17 00:00:00 2001
From: Daniil Kovalev <dkova...@accesssoftek.com>
Date: Mon, 30 Sep 2024 07:51:09 +0300
Subject: [PATCH 3/3] Address review comments
---
clang/lib/CodeGen/ItaniumCXXABI.cpp | 35 +++++++++++------------------
1 file changed, 13 insertions(+), 22 deletions(-)
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp
b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index ed253be1ad257a..43a4a22abc7b2f 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -4098,7 +4098,8 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(
llvm::GlobalValue::DLLStorageClassTypes DLLStorageClass) {
// Add the vtable pointer.
BuildVTablePointer(cast<Type>(Ty));
- size_t VTablePointerIdx = Fields.size() - 1;
+ assert(Fields.size() == 1);
+ size_t VTablePointerIdx = 0;
// And the name.
llvm::GlobalVariable *TypeName = GetAddrOfTypeName(Ty, Linkage);
@@ -4213,15 +4214,14 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(
break;
}
- llvm::Constant *Init = llvm::ConstantStruct::getAnon(Fields);
SmallString<256> Name;
llvm::raw_svector_ostream Out(Name);
CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty, Out);
llvm::Module &M = CGM.getModule();
llvm::GlobalVariable *OldGV = M.getNamedGlobal(Name);
- llvm::GlobalVariable *GV =
- new llvm::GlobalVariable(M, Init->getType(),
- /*isConstant=*/true, Linkage, Init, Name);
+ llvm::GlobalVariable *GV = new llvm::GlobalVariable(
+ M, llvm::ConstantStruct::getTypeForElements(Fields),
+ /*isConstant=*/true, Linkage, /*Initializer=*/nullptr, Name);
if (const auto &Schema =
CGM.getCodeGenOpts().PointerAuth.CXXTypeInfoVTablePointer) {
if (Schema.isAddressDiscriminated()) {
@@ -4229,25 +4229,16 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(
// enabled, we need to place actual storage address (which was unknown
// during construction in ItaniumRTTIBuilder::BuildVTablePointer) in the
// corresponding field.
- ConstantInitBuilder Builder(CGM);
- auto InitBuilder = Builder.beginStruct();
- for (size_t I = 0; I < Fields.size(); ++I) {
- if (I != VTablePointerIdx) {
- InitBuilder.add(Fields[I]);
- continue;
- }
- auto *SignedVTablePointer = cast<llvm::ConstantPtrAuth>(Fields[I]);
- llvm::Constant *UnsignedVtablePointer =
- SignedVTablePointer->getPointer();
- llvm::Constant *StorageAddress =
- InitBuilder.getAddrOfCurrentPosition(CGM.UnqualPtrTy);
- InitBuilder.add(CGM.getConstantSignedPointer(
- UnsignedVtablePointer, Schema, StorageAddress, GlobalDecl(),
- QualType(cast<Type>(Ty), 0)));
- }
- InitBuilder.finishAndSetAsInitializer(GV);
+ llvm::Constant *UnsignedVtablePointer =
+ cast<llvm::ConstantPtrAuth>(Fields[VTablePointerIdx])->getPointer();
+ assert(VTablePointerIdx == 0 && "Expected 0 offset for StorageAddress");
+ llvm::Constant *StorageAddress = GV;
+ Fields[VTablePointerIdx] = CGM.getConstantSignedPointer(
+ UnsignedVtablePointer, Schema, StorageAddress, GlobalDecl(),
+ QualType(cast<Type>(Ty), 0));
}
}
+ GV->replaceInitializer(llvm::ConstantStruct::getAnon(Fields));
// Export the typeinfo in the same circumstances as the vtable is exported.
auto GVDLLStorageClass = DLLStorageClass;
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