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[mips] Implement NaCl sandboxing of indirect jumps:

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* Align targets of indirect jumps to instruction bundle boundaries (in MI layer).
  * Add masking instructions before indirect jumps (in MC layer).

Differential Revision: http://llvm-reviews.chandlerc.com/D2847


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202479 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sasa Stankovic
2014-02-28 10:00:38 +00:00
parent 72c42d9341
commit 068a8c145a
8 changed files with 298 additions and 7 deletions
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35
lib/Target/Mips/MipsAsmPrinter.cpp
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@@ -15,6 +15,7 @@
#define DEBUG_TYPE "mips-asm-printer"
#include "InstPrinter/MipsInstPrinter.h"
#include "MCTargetDesc/MipsBaseInfo.h"
#include "MCTargetDesc/MipsMCNaCl.h"
#include "Mips.h"
#include "MipsAsmPrinter.h"
#include "MipsInstrInfo.h"
@@ -27,6 +28,7 @@
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/DataLayout.h"
@@ -72,6 +74,11 @@ bool MipsAsmPrinter::runOnMachineFunction(MachineFunction &MF) {
StubsNeeded[Symbol] = Signature;
}
MCP = MF.getConstantPool();
// In NaCl, all indirect jump targets must be aligned to bundle size.
if (Subtarget->isTargetNaCl())
NaClAlignIndirectJumpTargets(MF);
AsmPrinter::runOnMachineFunction(MF);
return true;
}
@@ -270,6 +277,12 @@ const char *MipsAsmPrinter::getCurrentABIString() const {
void MipsAsmPrinter::EmitFunctionEntryLabel() {
MipsTargetStreamer &TS = getTargetStreamer();
// NaCl sandboxing requires that indirect call instructions are masked.
// This means that function entry points should be bundle-aligned.
if (Subtarget->isTargetNaCl())
EmitAlignment(std::max(MF->getAlignment(), MIPS_NACL_BUNDLE_ALIGN));
if (Subtarget->inMicroMipsMode())
TS.emitDirectiveSetMicroMips();
// leave out until FSF available gas has micromips changes
@@ -906,6 +919,28 @@ void MipsAsmPrinter::PrintDebugValueComment(const MachineInstr *MI,
// TODO: implement
}
// Align all targets of indirect branches on bundle size. Used only if target
// is NaCl.
void MipsAsmPrinter::NaClAlignIndirectJumpTargets(MachineFunction &MF) {
// Align all blocks that are jumped to through jump table.
if (MachineJumpTableInfo *JtInfo = MF.getJumpTableInfo()) {
const std::vector<MachineJumpTableEntry> &JT = JtInfo->getJumpTables();
for (unsigned I = 0; I < JT.size(); ++I) {
const std::vector<MachineBasicBlock*> &MBBs = JT[I].MBBs;
for (unsigned J = 0; J < MBBs.size(); ++J)
MBBs[J]->setAlignment(MIPS_NACL_BUNDLE_ALIGN);
}
}
// If basic block address is taken, block can be target of indirect branch.
for (MachineFunction::iterator MBB = MF.begin(), E = MF.end();
MBB != E; ++MBB) {
if (MBB->hasAddressTaken())
MBB->setAlignment(MIPS_NACL_BUNDLE_ALIGN);
}
}
// Force static initialization.
extern "C" void LLVMInitializeMipsAsmPrinter() {
RegisterAsmPrinter<MipsAsmPrinter> X(TheMipsTarget);