ardb created this revision.
ardb added reviewers: nickdesaulniers, peter.smith, nathanchance, kees.
Herald added subscribers: hiraditya, kristof.beyls.
ardb requested review of this revision.
Herald added projects: clang, LLVM.
Herald added subscribers: llvm-commits, cfe-commits.
Implement support for loading the stack canary from a memory location held in
the TLS register, with an optional offset applied. This is used by the Linux
kernel to implement per-task stack canaries, which is impossible on SMP systems
when using a global variable for the stack canary.
This also involves implementing LOAD_STACK_GUARD for other ARM targets than
Mach-O.
Suggestions for how to test this and where to insert the test code into the
tree are kindly welcomed.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D112768
Files:
clang/lib/Driver/ToolChains/Clang.cpp
clang/test/Driver/stack-protector-guard.c
llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
llvm/lib/Target/ARM/ARMISelLowering.cpp
llvm/lib/Target/ARM/ARMInstrInfo.cpp
llvm/lib/Target/ARM/Thumb2InstrInfo.cpp
Index: llvm/lib/Target/ARM/Thumb2InstrInfo.cpp
===================================================================
--- llvm/lib/Target/ARM/Thumb2InstrInfo.cpp
+++ llvm/lib/Target/ARM/Thumb2InstrInfo.cpp
@@ -250,7 +250,20 @@
void Thumb2InstrInfo::expandLoadStackGuard(
MachineBasicBlock::iterator MI) const {
MachineFunction &MF = *MI->getParent()->getParent();
- if (MF.getTarget().isPositionIndependent())
+ MachineBasicBlock &MBB = *MI->getParent();
+ Module &M = *MBB.getParent()->getFunction().getParent();
+
+ if (M.getStackProtectorGuard() == "tls") {
+ expandLoadStackGuardBase(MI, ARM::t2MRC, ARM::t2LDRi12);
+ return;
+ }
+
+ const GlobalValue *GV =
+ cast<GlobalValue>((*MI->memoperands_begin())->getValue());
+
+ if (MF.getSubtarget<ARMSubtarget>().isGVInGOT(GV))
+ expandLoadStackGuardBase(MI, ARM::tLDRLIT_ga_pcrel, ARM::t2LDRi12);
+ else if (MF.getTarget().isPositionIndependent())
expandLoadStackGuardBase(MI, ARM::t2MOV_ga_pcrel, ARM::t2LDRi12);
else
expandLoadStackGuardBase(MI, ARM::t2MOVi32imm, ARM::t2LDRi12);
Index: llvm/lib/Target/ARM/ARMInstrInfo.cpp
===================================================================
--- llvm/lib/Target/ARM/ARMInstrInfo.cpp
+++ llvm/lib/Target/ARM/ARMInstrInfo.cpp
@@ -95,8 +95,18 @@
MachineFunction &MF = *MI->getParent()->getParent();
const ARMSubtarget &Subtarget = MF.getSubtarget<ARMSubtarget>();
const TargetMachine &TM = MF.getTarget();
+ MachineBasicBlock &MBB = *MI->getParent();
+ Module &M = *MBB.getParent()->getFunction().getParent();
+
+ if (M.getStackProtectorGuard() == "tls") {
+ expandLoadStackGuardBase(MI, ARM::MRC, ARM::LDRi12);
+ return;
+ }
- if (!Subtarget.useMovt()) {
+ const GlobalValue *GV =
+ cast<GlobalValue>((*MI->memoperands_begin())->getValue());
+
+ if (!Subtarget.useMovt() || Subtarget.isGVInGOT(GV)) {
if (TM.isPositionIndependent())
expandLoadStackGuardBase(MI, ARM::LDRLIT_ga_pcrel, ARM::LDRi12);
else
@@ -109,15 +119,11 @@
return;
}
- const GlobalValue *GV =
- cast<GlobalValue>((*MI->memoperands_begin())->getValue());
-
if (!Subtarget.isGVIndirectSymbol(GV)) {
expandLoadStackGuardBase(MI, ARM::MOV_ga_pcrel, ARM::LDRi12);
return;
}
- MachineBasicBlock &MBB = *MI->getParent();
DebugLoc DL = MI->getDebugLoc();
Register Reg = MI->getOperand(0).getReg();
MachineInstrBuilder MIB;
Index: llvm/lib/Target/ARM/ARMISelLowering.cpp
===================================================================
--- llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -20687,9 +20687,8 @@
return InsertFencesForAtomic;
}
-// This has so far only been implemented for MachO.
bool ARMTargetLowering::useLoadStackGuardNode() const {
- return Subtarget->isTargetMachO();
+ return true;
}
void ARMTargetLowering::insertSSPDeclarations(Module &M) const {
Index: llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
===================================================================
--- llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -1682,8 +1682,6 @@
bool ARMBaseInstrInfo::expandPostRAPseudo(MachineInstr &MI) const {
if (MI.getOpcode() == TargetOpcode::LOAD_STACK_GUARD) {
- assert(getSubtarget().getTargetTriple().isOSBinFormatMachO() &&
- "LOAD_STACK_GUARD currently supported only for MachO.");
expandLoadStackGuard(MI);
MI.getParent()->erase(MI);
return true;
@@ -4884,8 +4882,6 @@
return true;
}
-// LoadStackGuard has so far only been implemented for MachO. Different code
-// sequence is needed for other targets.
void ARMBaseInstrInfo::expandLoadStackGuardBase(MachineBasicBlock::iterator MI,
unsigned LoadImmOpc,
unsigned LoadOpc) const {
@@ -4895,27 +4891,48 @@
MachineBasicBlock &MBB = *MI->getParent();
DebugLoc DL = MI->getDebugLoc();
Register Reg = MI->getOperand(0).getReg();
- const GlobalValue *GV =
- cast<GlobalValue>((*MI->memoperands_begin())->getValue());
MachineInstrBuilder MIB;
+ int Offset = 0;
- BuildMI(MBB, MI, DL, get(LoadImmOpc), Reg)
- .addGlobalAddress(GV, 0, ARMII::MO_NONLAZY);
+ if (LoadImmOpc == ARM::MRC || LoadImmOpc == ARM::t2MRC) {
+ BuildMI(MBB, MI, DL, get(LoadImmOpc), Reg)
+ .addImm(15)
+ .addImm(0)
+ .addImm(13)
+ .addImm(0)
+ .addImm(3)
+ .add(predOps(ARMCC::AL));
- if (Subtarget.isGVIndirectSymbol(GV)) {
- MIB = BuildMI(MBB, MI, DL, get(LoadOpc), Reg);
- MIB.addReg(Reg, RegState::Kill).addImm(0);
- auto Flags = MachineMemOperand::MOLoad |
- MachineMemOperand::MODereferenceable |
- MachineMemOperand::MOInvariant;
- MachineMemOperand *MMO = MBB.getParent()->getMachineMemOperand(
- MachinePointerInfo::getGOT(*MBB.getParent()), Flags, 4, Align(4));
- MIB.addMemOperand(MMO).add(predOps(ARMCC::AL));
+ Module &M = *MBB.getParent()->getFunction().getParent();
+ Offset = M.getStackProtectorGuardOffset();
+ } else {
+ const GlobalValue *GV =
+ cast<GlobalValue>((*MI->memoperands_begin())->getValue());
+
+ unsigned TargetFlags = ARMII::MO_NO_FLAG;
+ if (Subtarget.isTargetMachO())
+ TargetFlags |= ARMII::MO_NONLAZY;
+ else if (Subtarget.isGVInGOT(GV))
+ TargetFlags |= ARMII::MO_GOT;
+
+ BuildMI(MBB, MI, DL, get(LoadImmOpc), Reg)
+ .addGlobalAddress(GV, 0, TargetFlags);
+
+ if (Subtarget.isGVIndirectSymbol(GV)) {
+ MIB = BuildMI(MBB, MI, DL, get(LoadOpc), Reg);
+ MIB.addReg(Reg, RegState::Kill).addImm(0);
+ auto Flags = MachineMemOperand::MOLoad |
+ MachineMemOperand::MODereferenceable |
+ MachineMemOperand::MOInvariant;
+ MachineMemOperand *MMO = MBB.getParent()->getMachineMemOperand(
+ MachinePointerInfo::getGOT(*MBB.getParent()), Flags, 4, Align(4));
+ MIB.addMemOperand(MMO).add(predOps(ARMCC::AL));
+ }
}
MIB = BuildMI(MBB, MI, DL, get(LoadOpc), Reg);
MIB.addReg(Reg, RegState::Kill)
- .addImm(0)
+ .addImm(Offset)
.cloneMemRefs(*MI)
.add(predOps(ARMCC::AL));
}
Index: clang/test/Driver/stack-protector-guard.c
===================================================================
--- clang/test/Driver/stack-protector-guard.c
+++ clang/test/Driver/stack-protector-guard.c
@@ -15,7 +15,7 @@
// RUN: FileCheck -check-prefix=CHECK-GS %s
// Invalid arch
-// RUN: not %clang -target arm-eabi-c -mstack-protector-guard=tls %s 2>&1 | \
+// RUN: not %clang -target powerpc64le-linux-gnu -mstack-protector-guard=tls %s 2>&1 | \
// RUN: FileCheck -check-prefix=INVALID-ARCH %s
// INVALID-ARCH: unsupported option '-mstack-protector-guard=tls' for target
@@ -23,7 +23,7 @@
// RUN: FileCheck -check-prefix=INVALID-ARCH2 %s
// INVALID-ARCH2: unsupported option '-mstack-protector-guard-reg=fs' for target
-// RUN: not %clang -target arm-linux-gnueabi -mstack-protector-guard-offset=10 %s 2>&1 | \
+// RUN: not %clang -target powerpc64le-linux-gnu -mstack-protector-guard-offset=10 %s 2>&1 | \
// RUN: FileCheck -check-prefix=INVALID-ARCH3 %s
// INVALID-ARCH3: unsupported option '-mstack-protector-guard-offset=10' for target
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -3161,10 +3161,14 @@
const std::string &TripleStr = EffectiveTriple.getTriple();
if (Arg *A = Args.getLastArg(options::OPT_mstack_protector_guard_EQ)) {
StringRef Value = A->getValue();
- if (!EffectiveTriple.isX86() && !EffectiveTriple.isAArch64())
+ if (!EffectiveTriple.isX86() && !EffectiveTriple.isAArch64() &&
+ !EffectiveTriple.isARM() && !EffectiveTriple.isThumb())
D.Diag(diag::err_drv_unsupported_opt_for_target)
<< A->getAsString(Args) << TripleStr;
- if (EffectiveTriple.isX86() && Value != "tls" && Value != "global") {
+ if ((EffectiveTriple.isX86() ||
+ EffectiveTriple.isARM() ||
+ EffectiveTriple.isThumb()) &&
+ Value != "tls" && Value != "global") {
D.Diag(diag::err_drv_invalid_value_with_suggestion)
<< A->getOption().getName() << Value << "tls global";
return;
@@ -3179,7 +3183,8 @@
if (Arg *A = Args.getLastArg(options::OPT_mstack_protector_guard_offset_EQ)) {
StringRef Value = A->getValue();
- if (!EffectiveTriple.isX86() && !EffectiveTriple.isAArch64())
+ if (!EffectiveTriple.isX86() && !EffectiveTriple.isAArch64() &&
+ !EffectiveTriple.isARM() && !EffectiveTriple.isThumb())
D.Diag(diag::err_drv_unsupported_opt_for_target)
<< A->getAsString(Args) << TripleStr;
int Offset;
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