intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 120 insertions, 0 deletions

diff --git a/contrib/libs/llvm12/lib/CodeGen/CFGuardLongjmp.cpp b/contrib/libs/llvm12/lib/CodeGen/CFGuardLongjmp.cpp
new file mode 100644
index 0000000000..c3bf938551
--- /dev/null
+++ b/contrib/libs/llvm12/lib/CodeGen/CFGuardLongjmp.cpp
@@ -0,0 +1,120 @@
+//===-- CFGuardLongjmp.cpp - Longjmp symbols for CFGuard --------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file contains a machine function pass to insert a symbol after each
+/// call to _setjmp and store this in the MachineFunction's LongjmpTargets
+/// vector. This will be used to emit the table of valid longjmp targets used
+/// by Control Flow Guard.
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/InitializePasses.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "cfguard-longjmp"
+
+STATISTIC(CFGuardLongjmpTargets,
+          "Number of Control Flow Guard longjmp targets");
+
+namespace {
+
+/// MachineFunction pass to insert a symbol after each call to _setjmp and store
+/// this in the MachineFunction's LongjmpTargets vector.
+class CFGuardLongjmp : public MachineFunctionPass {
+public:
+  static char ID;
+
+  CFGuardLongjmp() : MachineFunctionPass(ID) {
+    initializeCFGuardLongjmpPass(*PassRegistry::getPassRegistry());
+  }
+
+  StringRef getPassName() const override {
+    return "Control Flow Guard longjmp targets";
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+};
+
+} // end anonymous namespace
+
+char CFGuardLongjmp::ID = 0;
+
+INITIALIZE_PASS(CFGuardLongjmp, "CFGuardLongjmp",
+                "Insert symbols at valid longjmp targets for /guard:cf", false,
+                false)
+FunctionPass *llvm::createCFGuardLongjmpPass() { return new CFGuardLongjmp(); }
+
+bool CFGuardLongjmp::runOnMachineFunction(MachineFunction &MF) {
+
+  // Skip modules for which the cfguard flag is not set.
+  if (!MF.getMMI().getModule()->getModuleFlag("cfguard"))
+    return false;
+
+  // Skip functions that do not have calls to _setjmp.
+  if (!MF.getFunction().callsFunctionThatReturnsTwice())
+    return false;
+
+  SmallVector<MachineInstr *, 8> SetjmpCalls;
+
+  // Iterate over all instructions in the function and add calls to functions
+  // that return twice to the list of targets.
+  for (MachineBasicBlock &MBB : MF) {
+    for (MachineInstr &MI : MBB) {
+
+      // Skip instructions that are not calls.
+      if (!MI.isCall() || MI.getNumOperands() < 1)
+        continue;
+
+      // Iterate over operands to find calls to global functions.
+      for (MachineOperand &MO : MI.operands()) {
+        if (!MO.isGlobal())
+          continue;
+
+        auto *F = dyn_cast<Function>(MO.getGlobal());
+        if (!F)
+          continue;
+
+        // If the instruction calls a function that returns twice, add
+        // it to the list of targets.
+        if (F->hasFnAttribute(Attribute::ReturnsTwice)) {
+          SetjmpCalls.push_back(&MI);
+          break;
+        }
+      }
+    }
+  }
+
+  if (SetjmpCalls.empty())
+    return false;
+
+  unsigned SetjmpNum = 0;
+
+  // For each possible target, create a new symbol and insert it immediately
+  // after the call to setjmp. Add this symbol to the MachineFunction's list
+  // of longjmp targets.
+  for (MachineInstr *Setjmp : SetjmpCalls) {
+    SmallString<128> SymbolName;
+    raw_svector_ostream(SymbolName) << "$cfgsj_" << MF.getName() << SetjmpNum++;
+    MCSymbol *SjSymbol = MF.getContext().getOrCreateSymbol(SymbolName);
+
+    Setjmp->setPostInstrSymbol(MF, SjSymbol);
+    MF.addLongjmpTarget(SjSymbol);
+    CFGuardLongjmpTargets++;
+  }
+
+  return true;
+}