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[IRGen] Upstream pointer auth for value witness tables #74625

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Jul 1, 2024
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[IRGen] Upstream pointer auth for value witness tables #74625

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3 changes: 3 additions & 0 deletions include/swift/AST/IRGenOptions.h
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Original file line number Diff line number Diff line change
Expand Up @@ -109,6 +109,9 @@ struct PointerAuthOptions : clang::PointerAuthOptions {
/// Swift value witness functions.
PointerAuthSchema ValueWitnesses;

/// Pointers to Swift value witness tables stored in type metadata.
PointerAuthSchema ValueWitnessTable;

/// Swift protocol witness functions.
PointerAuthSchema ProtocolWitnesses;

Expand Down
5 changes: 3 additions & 2 deletions include/swift/Remote/MetadataReader.h
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Expand Up @@ -699,10 +699,11 @@ class MetadataReader {
// pointer's referenced address.
TargetValueWitnessTable<Runtime> VWT;
auto ValueWitnessTableAddrAddr = MetadataAddress - sizeof(StoredPointer);
StoredPointer ValueWitnessTableAddr;
StoredSignedPointer SignedValueWitnessTableAddr;
if (!Reader->readInteger(RemoteAddress(ValueWitnessTableAddrAddr),
&ValueWitnessTableAddr))
&SignedValueWitnessTableAddr))
return std::nullopt;
auto ValueWitnessTableAddr = stripSignedPointer(SignedValueWitnessTableAddr);
if (!Reader->readBytes(RemoteAddress(ValueWitnessTableAddr),
(uint8_t *)&VWT, sizeof(VWT)))
return std::nullopt;
Expand Down
68 changes: 56 additions & 12 deletions lib/IRGen/GenMeta.cpp
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Expand Up @@ -37,6 +37,7 @@
#include "swift/Strings.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclObjC.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
Expand Down Expand Up @@ -4036,7 +4037,14 @@ namespace {

void addValueWitnessTable() {
assert(!isPureObjC());
B.add(asImpl().getValueWitnessTable(false).getValue());

auto wtable = asImpl().getValueWitnessTable(false).getValue();
if (!isa<llvm::ConstantPointerNull>(wtable)) {
auto schema = IGM.getOptions().PointerAuth.ValueWitnessTable;
B.addSignedPointer(wtable, schema, PointerAuthEntity());
} else {
B.add(wtable);
}
}

llvm::Constant *getAddrOfMetaclassObject(ForDefinition_t forDefinition) {
Expand Down Expand Up @@ -5411,19 +5419,36 @@ emitInvariantLoadFromMetadataAtIndex(IRGenFunction &IGF,
/// Given a type metadata pointer, load its value witness table.
llvm::Value *
IRGenFunction::emitValueWitnessTableRefForMetadata(llvm::Value *metadata) {
auto witness = emitInvariantLoadFromMetadataAtIndex(*this, metadata, nullptr,
-1, IGM.WitnessTablePtrTy,
".valueWitnesses");
llvm::Value *addrOfWitnessTablePtr = nullptr;
llvm::LoadInst *loadOfWitnessTablePtr = emitInvariantLoadFromMetadataAtIndex(
*this, metadata, &addrOfWitnessTablePtr, -1, IGM.WitnessTablePtrTy,
".valueWitnesses");

const auto &ptrAuthOpts = IGM.getOptions().PointerAuth;
if (auto schema = IGM.getOptions().PointerAuth.ValueWitnessTable) {
llvm::Value *signedWitnessTablePtr = loadOfWitnessTablePtr;
llvm::Value *witnessTablePtr = emitPointerAuthAuth(
*this, signedWitnessTablePtr,
PointerAuthInfo::emit(*this, schema, addrOfWitnessTablePtr,
PointerAuthEntity()));

// TODO: We might be able to flag witnessTablePtr as dereferencable (see
// below) by adding an attribute (not setting the metadata). However, it
// is unclear if there are any benefits to be had at the cost of
// changing the APIs in multiple places.
return witnessTablePtr;
}

// A value witness table is dereferenceable to the number of value witness
// pointers.

// TODO: If we know the type statically has extra inhabitants, we know
// there are more witnesses.
auto numValueWitnesses
= unsigned(ValueWitness::Last_RequiredValueWitness) + 1;
setDereferenceableLoad(witness,
setDereferenceableLoad(loadOfWitnessTablePtr,
IGM.getPointerSize().getValue() * numValueWitnesses);
return witness;
return loadOfWitnessTablePtr;
}

/// Given a lowered SIL type, load a value witness table that represents its
Expand Down Expand Up @@ -5570,7 +5595,10 @@ namespace {
}

void addValueWitnessTable() {
B.add(asImpl().getValueWitnessTable(false).getValue());
auto vwtPointer = asImpl().getValueWitnessTable(false).getValue();
B.addSignedPointer(vwtPointer,
IGM.getOptions().PointerAuth.ValueWitnessTable,
PointerAuthEntity());
}

llvm::Constant *emitLayoutString() {
Expand Down Expand Up @@ -6051,7 +6079,11 @@ namespace {
}

void addValueWitnessTable() {
B.add(asImpl().getValueWitnessTable(false).getValue());
auto vwtPointer =
asImpl().getValueWitnessTable(/*relative*/ false).getValue();
B.addSignedPointer(vwtPointer,
IGM.getOptions().PointerAuth.ValueWitnessTable,
PointerAuthEntity());
}

llvm::Constant *emitNominalTypeDescriptor() {
Expand Down Expand Up @@ -6533,7 +6565,9 @@ namespace {
? IGM.Context.getAnyObjectType()
: IGM.Context.TheNativeObjectType);
auto wtable = IGM.getAddrOfValueWitnessTable(type);
B.add(wtable);
B.addSignedPointer(wtable,
IGM.getOptions().PointerAuth.ValueWitnessTable,
PointerAuthEntity());
}

void addMetadataFlags() {
Expand Down Expand Up @@ -6604,7 +6638,11 @@ namespace {

void addValueWitnessTable() {
auto type = getTargetType()->getCanonicalType();
B.add(irgen::emitValueWitnessTable(IGM, type, false, false).getValue());
auto vwtPointer =
irgen::emitValueWitnessTable(IGM, type, false, false).getValue();
B.addSignedPointer(vwtPointer,
IGM.getOptions().PointerAuth.ValueWitnessTable,
PointerAuthEntity());
}

void addMetadataFlags() {
Expand Down Expand Up @@ -6643,7 +6681,10 @@ namespace {
}

void addValueWitnessTable() {
B.add(emitValueWitnessTable(/*relative*/ false).getValue());
auto vwtPointer = emitValueWitnessTable(/*relative*/ false).getValue();
B.addSignedPointer(vwtPointer,
IGM.getOptions().PointerAuth.ValueWitnessTable,
PointerAuthEntity());
}

void flagUnfilledFieldOffset() {
Expand All @@ -6670,7 +6711,10 @@ namespace {
}

void addValueWitnessTable() {
B.add(emitValueWitnessTable(/*relative*/ false).getValue());
auto vwtPointer = emitValueWitnessTable(/*relative*/ false).getValue();
B.addSignedPointer(vwtPointer,
IGM.getOptions().PointerAuth.ValueWitnessTable,
PointerAuthEntity());
}

void addPayloadSize() const {
Expand Down
3 changes: 3 additions & 0 deletions lib/IRGen/IRGen.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -727,6 +727,9 @@ static void setPointerAuthOptions(PointerAuthOptions &opts,
PointerAuthSchema(codeKey, /*address*/ true, Discrimination::Decl);
opts.ValueWitnesses =
PointerAuthSchema(codeKey, /*address*/ true, Discrimination::Decl);
opts.ValueWitnessTable =
PointerAuthSchema(dataKey, /*address*/ true, Discrimination::Constant,
SpecialPointerAuthDiscriminators::ValueWitnessTable);
opts.ProtocolWitnesses =
PointerAuthSchema(codeKey, /*address*/ true, Discrimination::Decl);
opts.ProtocolAssociatedTypeAccessFunctions =
Expand Down
68 changes: 56 additions & 12 deletions test/IRGen/ptrauth-value-witnesses.sil
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Expand Up @@ -7,6 +7,9 @@
import Builtin

struct S { var a, b, c: Builtin.NativeObject }

// Check the constant discriminators for all value witnesses.

// CHECK: @"$s4test1SVwCP.ptrauth" = private constant {{.*}} i64 55882
// CHECK: @"$s4test1SVwxx.ptrauth" = private constant {{.*}} i64 1272
// CHECK: @"$s4test1SVwcp.ptrauth" = private constant {{.*}} i64 58298
Expand All @@ -16,15 +19,26 @@ struct S { var a, b, c: Builtin.NativeObject }
// CHECK: @"$s4test1SVwet.ptrauth" = private constant {{.*}} i64 24816
// CHECK: @"$s4test1SVwst.ptrauth" = private constant {{.*}} i64 41169

// The pointer to the value witness table is signed too.

// 0x2e3f == 11839 is the constant discriminator for value witness tables.
// CHECK: @"$s4test1SVWV.ptrauth" = private constant {{.*}} i64 11839

sil @test_destroy : $@convention(thin) <T> (@in T) -> () {
bb0(%0 : $*T):
destroy_addr %0 : $*T
%result = tuple ()
return %result : $()
}
// CHECK-LABEL: define swiftcc void @test_destroy(
// CHECK: [[VWT:%.*]] = load ptr,
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[VWT]], i32
// CHECK: [[SIGNED_VWT_ADDR:%.*]] = getelementptr inbounds ptr, ptr {{%.*}}, i64 -1
// CHECK: [[SIGNED_VWT:%.*]] = load ptr, ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[SIGNED_VWT_ADDR_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[BLENDED_ADDR:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[SIGNED_VWT_ADDR_INT]], i64 11839)
// CHECK: [[SIGNED_VWT_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT]]
// CHECK: [[AUTHENTICATED_VWT_INT:%.*]] = call i64 @llvm.ptrauth.auth(i64 [[SIGNED_VWT_INT]], i32 2, i64 [[BLENDED_ADDR]])
// CHECK: [[AUTHENTICATED_VWT:%.*]] = inttoptr i64 [[AUTHENTICATED_VWT_INT]]
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[AUTHENTICATED_VWT]], i32
// CHECK-NEXT: [[T0:%.*]] = load ptr, ptr [[SLOT]], align
// CHECK-NEXT: [[T1:%.*]] = ptrtoint ptr [[SLOT]] to i64
// CHECK-NEXT: [[DISC:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[T1]], i64 1272)
Expand All @@ -38,8 +52,14 @@ bb0(%0 : $*T, %1 : $*T):
return %result : $()
}
// CHECK-LABEL: define swiftcc void @test_copy_init(
// CHECK: [[VWT:%.*]] = load ptr,
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[VWT]], i32
// CHECK: [[SIGNED_VWT_ADDR:%.*]] = getelementptr inbounds ptr, ptr {{%.*}}, i64 -1
// CHECK: [[SIGNED_VWT:%.*]] = load ptr, ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[SIGNED_VWT_ADDR_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[BLENDED_ADDR:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[SIGNED_VWT_ADDR_INT]], i64 11839)
// CHECK: [[SIGNED_VWT_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT]]
// CHECK: [[AUTHENTICATED_VWT_INT:%.*]] = call i64 @llvm.ptrauth.auth(i64 [[SIGNED_VWT_INT]], i32 2, i64 [[BLENDED_ADDR]])
// CHECK: [[AUTHENTICATED_VWT:%.*]] = inttoptr i64 [[AUTHENTICATED_VWT_INT]]
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[AUTHENTICATED_VWT]], i32
// CHECK-NEXT: [[T0:%.*]] = load ptr, ptr [[SLOT]], align
// CHECK-NEXT: [[T1:%.*]] = ptrtoint ptr [[SLOT]] to i64
// CHECK-NEXT: [[DISC:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[T1]], i64 58298)
Expand All @@ -53,8 +73,14 @@ bb0(%0 : $*T, %1 : $*T):
return %result : $()
}
// CHECK-LABEL: define swiftcc void @test_take_init(
// CHECK: [[VWT:%.*]] = load ptr,
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[VWT]], i32
// CHECK: [[SIGNED_VWT_ADDR:%.*]] = getelementptr inbounds ptr, ptr {{%.*}}, i64 -1
// CHECK: [[SIGNED_VWT:%.*]] = load ptr, ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[SIGNED_VWT_ADDR_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[BLENDED_ADDR:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[SIGNED_VWT_ADDR_INT]], i64 11839)
// CHECK: [[SIGNED_VWT_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT]]
// CHECK: [[AUTHENTICATED_VWT_INT:%.*]] = call i64 @llvm.ptrauth.auth(i64 [[SIGNED_VWT_INT]], i32 2, i64 [[BLENDED_ADDR]])
// CHECK: [[AUTHENTICATED_VWT:%.*]] = inttoptr i64 [[AUTHENTICATED_VWT_INT]]
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[AUTHENTICATED_VWT]], i32
// CHECK-NEXT: [[T0:%.*]] = load ptr, ptr [[SLOT]], align
// CHECK-NEXT: [[T1:%.*]] = ptrtoint ptr [[SLOT]] to i64
// CHECK-NEXT: [[DISC:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[T1]], i64 18648)
Expand All @@ -68,8 +94,14 @@ bb0(%0 : $*T, %1 : $*T):
return %result : $()
}
// CHECK-LABEL: define swiftcc void @test_copy_assign(
// CHECK: [[VWT:%.*]] = load ptr,
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[VWT]], i32
// CHECK: [[SIGNED_VWT_ADDR:%.*]] = getelementptr inbounds ptr, ptr {{%.*}}, i64 -1
// CHECK: [[SIGNED_VWT:%.*]] = load ptr, ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[SIGNED_VWT_ADDR_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[BLENDED_ADDR:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[SIGNED_VWT_ADDR_INT]], i64 11839)
// CHECK: [[SIGNED_VWT_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT]]
// CHECK: [[AUTHENTICATED_VWT_INT:%.*]] = call i64 @llvm.ptrauth.auth(i64 [[SIGNED_VWT_INT]], i32 2, i64 [[BLENDED_ADDR]])
// CHECK: [[AUTHENTICATED_VWT:%.*]] = inttoptr i64 [[AUTHENTICATED_VWT_INT]]
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[AUTHENTICATED_VWT]], i32
// CHECK-NEXT: [[T0:%.*]] = load ptr, ptr [[SLOT]], align
// CHECK-NEXT: [[T1:%.*]] = ptrtoint ptr [[SLOT]] to i64
// CHECK-NEXT: [[DISC:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[T1]], i64 34641)
Expand All @@ -83,8 +115,14 @@ bb0(%0 : $*T, %1 : $*T):
return %result : $()
}
// CHECK-LABEL: define swiftcc void @test_take_assign(
// CHECK: [[VWT:%.*]] = load ptr,
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[VWT]], i32
// CHECK: [[SIGNED_VWT_ADDR:%.*]] = getelementptr inbounds ptr, ptr {{%.*}}, i64 -1
// CHECK: [[SIGNED_VWT:%.*]] = load ptr, ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[SIGNED_VWT_ADDR_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[BLENDED_ADDR:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[SIGNED_VWT_ADDR_INT]], i64 11839)
// CHECK: [[SIGNED_VWT_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT]]
// CHECK: [[AUTHENTICATED_VWT_INT:%.*]] = call i64 @llvm.ptrauth.auth(i64 [[SIGNED_VWT_INT]], i32 2, i64 [[BLENDED_ADDR]])
// CHECK: [[AUTHENTICATED_VWT:%.*]] = inttoptr i64 [[AUTHENTICATED_VWT_INT]]
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[AUTHENTICATED_VWT]], i32
// CHECK-NEXT: [[T0:%.*]] = load ptr, ptr [[SLOT]], align
// CHECK-NEXT: [[T1:%.*]] = ptrtoint ptr [[SLOT]] to i64
// CHECK-NEXT: [[DISC:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[T1]], i64 61402)
Expand All @@ -100,8 +138,14 @@ bb0(%0 : $*T, %1 : $*T):
return %result : $()
}
// CHECK-LABEL: define swiftcc void @test_destroy_twice(
// CHECK: [[VWT:%.*]] = load ptr,
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[VWT]], i32
// CHECK: [[SIGNED_VWT_ADDR:%.*]] = getelementptr inbounds ptr, ptr {{%.*}}, i64 -1
// CHECK: [[SIGNED_VWT:%.*]] = load ptr, ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[SIGNED_VWT_ADDR_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT_ADDR]]
// CHECK: [[BLENDED_ADDR:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[SIGNED_VWT_ADDR_INT]], i64 11839)
// CHECK: [[SIGNED_VWT_INT:%.*]] = ptrtoint ptr [[SIGNED_VWT]]
// CHECK: [[AUTHENTICATED_VWT_INT:%.*]] = call i64 @llvm.ptrauth.auth(i64 [[SIGNED_VWT_INT]], i32 2, i64 [[BLENDED_ADDR]])
// CHECK: [[AUTHENTICATED_VWT:%.*]] = inttoptr i64 [[AUTHENTICATED_VWT_INT]]
// CHECK-NEXT: [[SLOT:%.*]] = getelementptr inbounds ptr, ptr [[AUTHENTICATED_VWT]], i32
// CHECK-NEXT: [[T0:%.*]] = load ptr, ptr [[SLOT]], align
// CHECK-NEXT: [[T1:%.*]] = ptrtoint ptr [[SLOT]] to i64
// CHECK-NEXT: [[DISC:%.*]] = call i64 @llvm.ptrauth.blend(i64 [[T1]], i64 1272)
Expand Down