c923d39509
In ValidateMemRefs pass, when we validate references in the form of `Symbol + Addend`, we should check `Symbol` not `Symbol + Addend` against aliasing a jump table. Recommitting with a modified test case: https://github.com/llvm/llvm-project/pull/88838 Co-authored-by: sinan <sinan.lin@linux.alibaba.com>
105 lines
3.6 KiB
C++
105 lines
3.6 KiB
C++
//===- bolt/Passes/ValidateMemRefs.cpp ------------------------------------===//
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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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#include "bolt/Passes/ValidateMemRefs.h"
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#include "bolt/Core/ParallelUtilities.h"
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#define DEBUG_TYPE "bolt-memrefs"
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namespace opts {
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extern llvm::cl::opt<llvm::bolt::JumpTableSupportLevel> JumpTables;
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}
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namespace llvm::bolt {
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std::atomic<std::uint64_t> ValidateMemRefs::ReplacedReferences{0};
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bool ValidateMemRefs::checkAndFixJTReference(BinaryFunction &BF, MCInst &Inst,
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uint32_t OperandNum,
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const MCSymbol *Sym,
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uint64_t Offset) {
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BinaryContext &BC = BF.getBinaryContext();
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auto L = BC.scopeLock();
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BinaryData *BD = BC.getBinaryDataByName(Sym->getName());
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if (!BD)
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return false;
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JumpTable *JT = BC.getJumpTableContainingAddress(BD->getAddress());
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if (!JT)
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return false;
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const bool IsLegitAccess = llvm::is_contained(JT->Parents, &BF);
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if (IsLegitAccess)
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return true;
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// Accessing a jump table in another function. This is not a
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// legitimate jump table access, we need to replace the reference to
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// the jump table label with a regular rodata reference. Get a
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// non-JT reference by fetching the symbol 1 byte before the JT
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// label.
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MCSymbol *NewSym = BC.getOrCreateGlobalSymbol(BD->getAddress() - 1, "DATAat");
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BC.MIB->setOperandToSymbolRef(Inst, OperandNum, NewSym, Offset + 1, &*BC.Ctx,
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0);
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LLVM_DEBUG(dbgs() << "BOLT-DEBUG: replaced reference @" << BF.getPrintName()
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<< " from " << BD->getName() << " to " << NewSym->getName()
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<< " + 1\n");
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++ReplacedReferences;
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return true;
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}
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void ValidateMemRefs::runOnFunction(BinaryFunction &BF) {
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MCPlusBuilder *MIB = BF.getBinaryContext().MIB.get();
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for (BinaryBasicBlock &BB : BF) {
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for (MCInst &Inst : BB) {
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for (int I = 0, E = MCPlus::getNumPrimeOperands(Inst); I != E; ++I) {
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const MCOperand &Operand = Inst.getOperand(I);
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if (!Operand.isExpr())
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continue;
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const auto [Sym, Offset] = MIB->getTargetSymbolInfo(Operand.getExpr());
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if (!Sym)
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continue;
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checkAndFixJTReference(BF, Inst, I, Sym, Offset);
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}
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}
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}
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}
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Error ValidateMemRefs::runOnFunctions(BinaryContext &BC) {
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if (!BC.isX86())
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return Error::success();
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// Skip validation if not moving JT
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if (opts::JumpTables == JTS_NONE || opts::JumpTables == JTS_BASIC)
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return Error::success();
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ParallelUtilities::WorkFuncWithAllocTy ProcessFunction =
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[&](BinaryFunction &BF, MCPlusBuilder::AllocatorIdTy AllocId) {
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runOnFunction(BF);
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};
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ParallelUtilities::PredicateTy SkipPredicate = [&](const BinaryFunction &BF) {
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return !BF.hasCFG();
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};
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LLVM_DEBUG(dbgs() << "BOLT-DEBUG: starting memrefs validation pass\n");
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ParallelUtilities::runOnEachFunctionWithUniqueAllocId(
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BC, ParallelUtilities::SchedulingPolicy::SP_INST_LINEAR, ProcessFunction,
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SkipPredicate, "validate-mem-refs", /*ForceSequential=*/true);
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LLVM_DEBUG(dbgs() << "BOLT-DEBUG: memrefs validation is concluded\n");
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if (!ReplacedReferences)
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return Error::success();
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BC.outs() << "BOLT-INFO: validate-mem-refs updated " << ReplacedReferences
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<< " object references\n";
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return Error::success();
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}
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} // namespace llvm::bolt
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