Revert "Insert random noops to increase security against ROP attacks (llvm)"

This reverts commit:
http://reviews.llvm.org/D3392

llvm-svn: 225948

6 files changed, 0 insertions, 174 deletions

diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index 672b6ba..48bf354 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -71,7 +71,6 @@ add_llvm_library(LLVMCodeGen
   MachineSink.cpp
   MachineTraceMetrics.cpp
   MachineVerifier.cpp
-  NoopInsertion.cpp
   OcamlGC.cpp
   OptimizePHIs.cpp
   PHIElimination.cpp
diff --git a/llvm/lib/CodeGen/CodeGen.cpp b/llvm/lib/CodeGen/CodeGen.cpp
index fdb89438..307dec5 100644
--- a/llvm/lib/CodeGen/CodeGen.cpp
+++ b/llvm/lib/CodeGen/CodeGen.cpp
@@ -51,7 +51,6 @@ void llvm::initializeCodeGen(PassRegistry &Registry) {
   initializeMachineSchedulerPass(Registry);
   initializeMachineSinkingPass(Registry);
   initializeMachineVerifierPassPass(Registry);
-  initializeNoopInsertionPass(Registry);
   initializeOptimizePHIsPass(Registry);
   initializePHIEliminationPass(Registry);
   initializePeepholeOptimizerPass(Registry);
diff --git a/llvm/lib/CodeGen/NoopInsertion.cpp b/llvm/lib/CodeGen/NoopInsertion.cpp
deleted file mode 100644
index f2291b8..0000000
--- a/llvm/lib/CodeGen/NoopInsertion.cpp
+++ /dev/null
@@ -1,101 +0,0 @@
-//===- NoopInsertion.cpp - Noop Insertion ---------------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This pass adds fine-grained diversity by displacing code using randomly
-// placed (optionally target supplied) Noop instructions.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/CodeGen/NoopInsertion.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/CodeGen/MachineInstrBuilder.h"
-#include "llvm/CodeGen/MachineModuleInfo.h"
-#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/CodeGen/Passes.h"
-#include "llvm/IR/BasicBlock.h"
-#include "llvm/IR/Function.h"
-#include "llvm/IR/Module.h"
-#include "llvm/Support/Allocator.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/RandomNumberGenerator.h"
-#include "llvm/Target/TargetInstrInfo.h"
-using namespace llvm;
-
-#define DEBUG_TYPE "noop-insertion"
-
-static cl::opt<unsigned> NoopInsertionPercentage(
-    "noop-insertion-percentage",
-    cl::desc("Percentage of instructions that have Noops prepended"),
-    cl::init(25)); // Default is a good balance between entropy and
-                   // performance impact
-
-static cl::opt<unsigned> MaxNoopsPerInstruction(
-    "max-noops-per-instruction",
-    llvm::cl::desc("Maximum number of Noops per instruction"),
-    llvm::cl::init(1));
-
-STATISTIC(InsertedNoops,
-          "Total number of noop type instructions inserted for diversity");
-
-char NoopInsertion::ID = 0;
-char &llvm::NoopInsertionID = NoopInsertion::ID;
-INITIALIZE_PASS(NoopInsertion, "noop-insertion",
-                "Noop Insertion for fine-grained code randomization", false,
-                false)
-
-NoopInsertion::NoopInsertion() : MachineFunctionPass(ID) {
-  initializeNoopInsertionPass(*PassRegistry::getPassRegistry());
-
-  // clamp percentage to 100
-  if (NoopInsertionPercentage > 100)
-    NoopInsertionPercentage = 100;
-}
-
-void NoopInsertion::getAnalysisUsage(AnalysisUsage &AU) const {
-  AU.setPreservesCFG();
-  MachineFunctionPass::getAnalysisUsage(AU);
-}
-
-bool NoopInsertion::runOnMachineFunction(MachineFunction &Fn) {
-  // The RNG must be initialized on first use so we have a Module to
-  // construct it from
-  if (!RNG)
-    RNG.reset(Fn.getFunction()->getParent()->createRNG(this));
-
-  const TargetInstrInfo *TII = Fn.getSubtarget().getInstrInfo();
-
-  unsigned FnInsertedNoopCount = 0;
-
-  for (auto &BB : Fn) {
-    MachineBasicBlock::iterator FirstTerm = BB.getFirstTerminator();
-
-    for (MachineBasicBlock::iterator I = BB.begin(), E = BB.end(); I != E;
-         ++I) {
-      if (I->isPseudo())
-        continue;
-
-      // Insert random number of Noop-like instructions.
-      for (unsigned i = 0; i < MaxNoopsPerInstruction; i++) {
-        if (Distribution(*RNG) >= NoopInsertionPercentage)
-          continue;
-
-        TII->insertNoop(BB, I, *RNG);
-
-        ++FnInsertedNoopCount;
-      }
-
-      if (I == FirstTerm)
-        break;
-    }
-  }
-
-  InsertedNoops += FnInsertedNoopCount;
-
-  return FnInsertedNoopCount > 0;
-}
diff --git a/llvm/lib/CodeGen/Passes.cpp b/llvm/lib/CodeGen/Passes.cpp
index a5d3210..28e9f84 100644
--- a/llvm/lib/CodeGen/Passes.cpp
+++ b/llvm/lib/CodeGen/Passes.cpp
@@ -583,9 +583,6 @@ void TargetPassConfig::addMachinePasses() {
       addPass(createGCInfoPrinter(dbgs()), false, false);
   }
 
-  if (TM->Options.NoopInsertion)
-    addPass(&NoopInsertionID);
-
   // Basic block placement.
   if (getOptLevel() != CodeGenOpt::None)
     addBlockPlacement();
diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 92fccf3..4615693 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -34,7 +34,6 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/RandomNumberGenerator.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetOptions.h"
 #include <limits>
@@ -5621,66 +5620,6 @@ void X86InstrInfo::setExecutionDomain(MachineInstr *MI, unsigned Domain) const {
   MI->setDesc(get(table[Domain-1]));
 }
 
-/// insertNoop - Insert a noop into the instruction stream at the specified
-/// point.
-void X86InstrInfo::insertNoop(MachineBasicBlock &MBB,
-                              MachineBasicBlock::iterator MI) const {
-  DebugLoc DL;
-  BuildMI(MBB, MI, DL, get(X86::NOOP));
-}
-
-/// insertNoop - Insert a randomly chosen type of noop into the instruction
-/// stream at the specified point to introduce fine-grained diversity.
-void X86InstrInfo::insertNoop(MachineBasicBlock &MBB,
-                              MachineBasicBlock::iterator MI,
-                              RandomNumberGenerator &RNG) const {
-  // This set of Noop instructions was carefully chosen so that
-  // misaligned parses of these instructions do not introduce new,
-  // useful ROP gadgets. The ASM instructions noted are for misaligned
-  // parses of the noop in 32 and 64 bits.
-  enum {
-    NOP,    // 90
-    MOV_BP, // 89 ed, 48 89 ed -- IN EAX, IN AL (privileged)
-    MOV_SP, // 89 e4, 48 89 e4 -- IN AL, IN EAX (privileged)
-    LEA_SI, // 8d 36, 48 8d 36 -- SS segment override, NULL
-            // prefix (does not add new gadget)
-    LEA_DI, // 8d 3f, 48 8d 3f -- AAS (bcd->hex), invalid
-    MAX_NOPS
-  };
-
-  static const unsigned NopRegs[MAX_NOPS][2] = {
-      {0, 0},
-      {X86::EBP, X86::RBP},
-      {X86::ESP, X86::RSP},
-      {X86::ESI, X86::RSI},
-      {X86::EDI, X86::RDI},
-  };
-
-  std::uniform_int_distribution<unsigned> Distribution(0, MAX_NOPS - 1);
-
-  unsigned Type = Distribution(RNG);
-
-  DebugLoc DL;
-  bool is64Bit = Subtarget.is64Bit();
-  unsigned Reg = NopRegs[Type][is64Bit];
-
-  switch (Type) {
-  case NOP:
-    BuildMI(MBB, MI, DL, get(X86::NOOP));
-    break;
-  case MOV_BP:
-  case MOV_SP:
-    copyPhysReg(MBB, MI, DL, Reg, Reg, false);
-    break;
-  case LEA_SI:
-  case LEA_DI: {
-    unsigned opc = is64Bit ? X86::LEA64r : X86::LEA32r;
-    addRegOffset(BuildMI(MBB, MI, DL, get(opc), Reg), Reg, false, 0);
-    break;
-  }
-  }
-}
-
 /// getNoopForMachoTarget - Return the noop instruction to use for a noop.
 void X86InstrInfo::getNoopForMachoTarget(MCInst &NopInst) const {
   NopInst.setOpcode(X86::NOOP);
diff --git a/llvm/lib/Target/X86/X86InstrInfo.h b/llvm/lib/Target/X86/X86InstrInfo.h
index eecc673..5662e86 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.h
+++ b/llvm/lib/Target/X86/X86InstrInfo.h
@@ -361,13 +361,6 @@ public:
   bool shouldScheduleAdjacent(MachineInstr* First,
                               MachineInstr *Second) const override;
 
-  void insertNoop(MachineBasicBlock &MBB,
-                  MachineBasicBlock::iterator MI) const override;
-
-  void insertNoop(MachineBasicBlock &MBB,
-                  MachineBasicBlock::iterator MI,
-                  RandomNumberGenerator &RNG) const override;
-
   void getNoopForMachoTarget(MCInst &NopInst) const override;
 
   bool