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d090368b0c
Summary: A new function pass (Transforms/CFGuard/CFGuard.cpp) inserts CFGuard checks on indirect function calls, using either the check mechanism (X86, ARM, AArch64) or or the dispatch mechanism (X86-64). The check mechanism requires a new calling convention for the supported targets. The dispatch mechanism adds the target as an operand bundle, which is processed by SelectionDAG. Another pass (CodeGen/CFGuardLongjmp.cpp) identifies and emits valid longjmp targets, as required by /guard:cf. This feature is enabled using the `cfguard` CC1 option. Reviewers: thakis, rnk, theraven, pcc Subscribers: ychen, hans, metalcanine, dmajor, tomrittervg, alex, mehdi_amini, mgorny, javed.absar, kristof.beyls, hiraditya, steven_wu, dexonsmith, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D65761
63 lines
2.1 KiB
C++
63 lines
2.1 KiB
C++
//===-- CodeGen/AsmPrinter/WinCFGuard.cpp - Control Flow Guard Impl ------===//
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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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// This file contains support for writing the metadata for Windows Control Flow
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// Guard, including address-taken functions, and valid longjmp targets.
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//
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//===----------------------------------------------------------------------===//
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#include "WinCFGuard.h"
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#include "llvm/CodeGen/AsmPrinter.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/CodeGen/MachineOperand.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/Metadata.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/MC/MCObjectFileInfo.h"
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#include "llvm/MC/MCStreamer.h"
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#include <vector>
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using namespace llvm;
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WinCFGuard::WinCFGuard(AsmPrinter *A) : AsmPrinterHandler(), Asm(A) {}
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WinCFGuard::~WinCFGuard() {}
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void WinCFGuard::endFunction(const MachineFunction *MF) {
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// Skip functions without any longjmp targets.
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if (MF->getLongjmpTargets().empty())
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return;
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// Copy the function's longjmp targets to a module-level list.
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LongjmpTargets.insert(LongjmpTargets.end(), MF->getLongjmpTargets().begin(),
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MF->getLongjmpTargets().end());
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}
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void WinCFGuard::endModule() {
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const Module *M = Asm->MMI->getModule();
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std::vector<const Function *> Functions;
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for (const Function &F : *M)
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if (F.hasAddressTaken())
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Functions.push_back(&F);
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if (Functions.empty() && LongjmpTargets.empty())
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return;
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auto &OS = *Asm->OutStreamer;
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OS.SwitchSection(Asm->OutContext.getObjectFileInfo()->getGFIDsSection());
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for (const Function *F : Functions)
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OS.EmitCOFFSymbolIndex(Asm->getSymbol(F));
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// Emit the symbol index of each longjmp target.
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OS.SwitchSection(Asm->OutContext.getObjectFileInfo()->getGLJMPSection());
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for (const MCSymbol *S : LongjmpTargets) {
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OS.EmitCOFFSymbolIndex(S);
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}
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}
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