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[PAC][ELF][AArch64] Support signed personality function pointer (#113148)
If function pointer signing is enabled, sign personality function pointer stored in `.DW.ref.__gxx_personality_v0` section with IA key, 0x7EAD = `ptrauth_string_discriminator("personality")` constant discriminator and address diversity enabled.
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16 files changed

+176
-8
lines changed

16 files changed

+176
-8
lines changed

‎clang/lib/CodeGen/CodeGenModule.cpp‎

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@@ -1218,6 +1218,9 @@ void CodeGenModule::Release() {
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getModule().addModuleFlag(llvm::Module::Min, "ptrauth-elf-got", 1);
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if (getTriple().isOSLinux()) {
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if (LangOpts.PointerAuthCalls)
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getModule().addModuleFlag(llvm::Module::Min, "ptrauth-sign-personality",
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1);
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assert(getTriple().isOSBinFormatELF());
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using namespace llvm::ELF;
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uint64_t PAuthABIVersion =

‎clang/test/CodeGen/ptrauth-module-flags.c‎

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@@ -1,8 +1,13 @@
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// RUN: %clang_cc1 -triple aarch64-linux-gnu -emit-llvm %s -o - | FileCheck %s --check-prefix=OFF
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// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-elf-got -emit-llvm %s -o - | FileCheck %s --check-prefix=ELFGOT
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// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-calls -emit-llvm %s -o - | FileCheck %s --check-prefix=PERSONALITY
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// ELFGOT: !llvm.module.flags = !{
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// ELFGOT-SAME: !1
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// ELFGOT: !1 = !{i32 8, !"ptrauth-elf-got", i32 1}
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// PERSONALITY: !llvm.module.flags = !{
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// PERSONALITY-SAME: !1
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// PERSONALITY: !1 = !{i32 8, !"ptrauth-sign-personality", i32 1}
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// OFF-NOT: "ptrauth-

‎llvm/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h‎

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@@ -52,7 +52,13 @@ class TargetLoweringObjectFileELF : public TargetLoweringObjectFile {
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void emitModuleMetadata(MCStreamer &Streamer, Module &M) const override;
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void emitPersonalityValue(MCStreamer &Streamer, const DataLayout &DL,
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const MCSymbol *Sym) const override;
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const MCSymbol *Sym,
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const MachineModuleInfo *MMI) const override;
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virtual void emitPersonalityValueImpl(MCStreamer &Streamer,
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const DataLayout &DL,
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const MCSymbol *Sym,
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const MachineModuleInfo *MMI) const;
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/// Given a constant with the SectionKind, return a section that it should be
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/// placed in.

‎llvm/include/llvm/Target/TargetLoweringObjectFile.h‎

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@@ -82,7 +82,8 @@ class TargetLoweringObjectFile : public MCObjectFileInfo {
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virtual void Initialize(MCContext &ctx, const TargetMachine &TM);
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virtual void emitPersonalityValue(MCStreamer &Streamer, const DataLayout &TM,
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const MCSymbol *Sym) const;
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const MCSymbol *Sym,
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const MachineModuleInfo *MMI) const;
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/// Emit the module-level metadata that the platform cares about.
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virtual void emitModuleMetadata(MCStreamer &Streamer, Module &M) const {}

‎llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp‎

Lines changed: 2 additions & 1 deletion
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@@ -50,7 +50,8 @@ void DwarfCFIException::endModule() {
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// Emit indirect reference table for all used personality functions
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for (const GlobalValue *Personality : Personalities) {
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MCSymbol *Sym = Asm->getSymbol(Personality);
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TLOF.emitPersonalityValue(*Asm->OutStreamer, Asm->getDataLayout(), Sym);
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TLOF.emitPersonalityValue(*Asm->OutStreamer, Asm->getDataLayout(), Sym,
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Asm->MMI);
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}
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Personalities.clear();
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}

‎llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp‎

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Original file line numberDiff line numberDiff line change
@@ -413,7 +413,8 @@ MCSymbol *TargetLoweringObjectFileELF::getCFIPersonalitySymbol(
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}
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void TargetLoweringObjectFileELF::emitPersonalityValue(
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MCStreamer &Streamer, const DataLayout &DL, const MCSymbol *Sym) const {
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MCStreamer &Streamer, const DataLayout &DL, const MCSymbol *Sym,
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const MachineModuleInfo *MMI) const {
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SmallString<64> NameData("DW.ref.");
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NameData += Sym->getName();
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MCSymbolELF *Label =
@@ -431,6 +432,13 @@ void TargetLoweringObjectFileELF::emitPersonalityValue(
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Streamer.emitELFSize(Label, E);
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Streamer.emitLabel(Label);
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435+
emitPersonalityValueImpl(Streamer, DL, Sym, MMI);
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}
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void TargetLoweringObjectFileELF::emitPersonalityValueImpl(
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MCStreamer &Streamer, const DataLayout &DL, const MCSymbol *Sym,
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const MachineModuleInfo *MMI) const {
441+
unsigned Size = DL.getPointerSize();
434442
Streamer.emitSymbolValue(Sym, Size);
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}
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‎llvm/lib/Target/AArch64/AArch64MachineModuleInfo.cpp‎

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@@ -0,0 +1,32 @@
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//===--- AArch64MachineModuleInfo.cpp ---------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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/// \file
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/// AArch64 Machine Module Info.
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///
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//
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//===----------------------------------------------------------------------===//
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#include "AArch64MachineModuleInfo.h"
16+
#include "llvm/IR/Constants.h"
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#include "llvm/IR/Module.h"
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namespace llvm {
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AArch64MachineModuleInfo::AArch64MachineModuleInfo(const MachineModuleInfo &MMI)
22+
: MachineModuleInfoELF(MMI) {
23+
const Module *M = MMI.getModule();
24+
const auto *Flag = mdconst::extract_or_null<ConstantInt>(
25+
M->getModuleFlag("ptrauth-sign-personality"));
26+
if (Flag && Flag->getZExtValue() == 1)
27+
HasSignedPersonality = true;
28+
else
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HasSignedPersonality = false;
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}
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} // end namespace llvm

‎llvm/lib/Target/AArch64/AArch64MachineModuleInfo.h‎

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@@ -0,0 +1,35 @@
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//===--- AArch64MachineModuleInfo.h -----------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6+
//
7+
//===----------------------------------------------------------------------===//
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//
9+
/// \file
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/// AArch64 Machine Module Info.
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///
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_AARCH64_AARCH64MACHINEMODULEINFO_H
16+
#define LLVM_LIB_TARGET_AARCH64_AARCH64MACHINEMODULEINFO_H
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#include "llvm/CodeGen/MachineModuleInfoImpls.h"
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20+
namespace llvm {
21+
22+
class AArch64MachineModuleInfo final : public MachineModuleInfoELF {
23+
/// HasSignedPersonality is true if the corresponding IR module has the
24+
/// "ptrauth-sign-personality" flag set to 1.
25+
bool HasSignedPersonality = false;
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27+
public:
28+
AArch64MachineModuleInfo(const MachineModuleInfo &);
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30+
bool hasSignedPersonality() const { return HasSignedPersonality; }
31+
};
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} // end namespace llvm
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#endif // LLVM_LIB_TARGET_AARCH64_AARCH64MACHINEMODULEINFO_H

‎llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp‎

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@@ -7,8 +7,10 @@
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//===----------------------------------------------------------------------===//
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#include "AArch64TargetObjectFile.h"
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#include "AArch64MachineModuleInfo.h"
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#include "AArch64TargetMachine.h"
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#include "MCTargetDesc/AArch64MCExpr.h"
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#include "MCTargetDesc/AArch64TargetStreamer.h"
1214
#include "llvm/BinaryFormat/Dwarf.h"
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#include "llvm/CodeGen/MachineModuleInfoImpls.h"
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#include "llvm/IR/Mangler.h"
@@ -28,6 +30,21 @@ void AArch64_ELFTargetObjectFile::Initialize(MCContext &Ctx,
2830
SupportDebugThreadLocalLocation = false;
2931
}
3032

33+
void AArch64_ELFTargetObjectFile::emitPersonalityValueImpl(
34+
MCStreamer &Streamer, const DataLayout &DL, const MCSymbol *Sym,
35+
const MachineModuleInfo *MMI) const {
36+
if (!MMI->getObjFileInfo<AArch64MachineModuleInfo>().hasSignedPersonality()) {
37+
TargetLoweringObjectFileELF::emitPersonalityValueImpl(Streamer, DL, Sym,
38+
MMI);
39+
return;
40+
}
41+
auto *TS = static_cast<AArch64TargetStreamer *>(Streamer.getTargetStreamer());
42+
// The value is ptrauth_string_discriminator("personality")
43+
constexpr uint16_t Discriminator = 0x7EAD;
44+
TS->emitAuthValue(MCSymbolRefExpr::create(Sym, getContext()), Discriminator,
45+
AArch64PACKey::IA, /*HasAddressDiversity=*/true);
46+
}
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3148
const MCExpr *AArch64_ELFTargetObjectFile::getIndirectSymViaGOTPCRel(
3249
const GlobalValue *GV, const MCSymbol *Sym, const MCValue &MV,
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int64_t Offset, MachineModuleInfo *MMI, MCStreamer &Streamer) const {

‎llvm/lib/Target/AArch64/AArch64TargetObjectFile.h‎

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@@ -35,6 +35,10 @@ class AArch64_ELFTargetObjectFile : public TargetLoweringObjectFileELF {
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MachineModuleInfo *MMI, const MCSymbol *RawSym,
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AArch64PACKey::ID Key,
3737
uint16_t Discriminator) const;
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39+
void emitPersonalityValueImpl(MCStreamer &Streamer, const DataLayout &DL,
40+
const MCSymbol *Sym,
41+
const MachineModuleInfo *MMI) const override;
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};
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/// AArch64_MachoTargetObjectFile - This TLOF implementation is used for Darwin.

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