1//===- SanitizerBinaryMetadata.cpp
2//----------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9//
10// This file is a part of SanitizerBinaryMetadata.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/CodeGen/SanitizerBinaryMetadata.h"
15#include "llvm/CodeGen/MachineFrameInfo.h"
16#include "llvm/CodeGen/MachineFunction.h"
17#include "llvm/CodeGen/MachineFunctionPass.h"
18#include "llvm/CodeGen/Passes.h"
19#include "llvm/IR/IRBuilder.h"
20#include "llvm/IR/MDBuilder.h"
21#include "llvm/InitializePasses.h"
22#include "llvm/Pass.h"
23#include "llvm/Transforms/Instrumentation/SanitizerBinaryMetadata.h"
24#include <algorithm>
25
26using namespace llvm;
27
28namespace {
29// FIXME: This pass modifies Function metadata, which is not to be done in
30// MachineFunctionPass. It should probably be moved to a FunctionPass.
31class MachineSanitizerBinaryMetadataLegacy : public MachineFunctionPass {
32public:
33 static char ID;
34
35 MachineSanitizerBinaryMetadataLegacy();
36 bool runOnMachineFunction(MachineFunction &F) override;
37};
38
39struct MachineSanitizerBinaryMetadata {
40 bool run(MachineFunction &MF);
41};
42
43} // namespace
44
45INITIALIZE_PASS(MachineSanitizerBinaryMetadataLegacy, "machine-sanmd",
46 "Machine Sanitizer Binary Metadata", false, false)
47
48char MachineSanitizerBinaryMetadataLegacy::ID = 0;
49char &llvm::MachineSanitizerBinaryMetadataID =
50 MachineSanitizerBinaryMetadataLegacy::ID;
51
52MachineSanitizerBinaryMetadataLegacy::MachineSanitizerBinaryMetadataLegacy()
53 : MachineFunctionPass(ID) {
54 initializeMachineSanitizerBinaryMetadataLegacyPass(
55 Registry&: *PassRegistry::getPassRegistry());
56}
57
58bool MachineSanitizerBinaryMetadataLegacy::runOnMachineFunction(
59 MachineFunction &MF) {
60 return MachineSanitizerBinaryMetadata().run(MF);
61}
62
63PreservedAnalyses
64MachineSanitizerBinaryMetadataPass::run(MachineFunction &MF,
65 MachineFunctionAnalysisManager &MFAM) {
66 if (!MachineSanitizerBinaryMetadata().run(MF))
67 return PreservedAnalyses::all();
68
69 return getMachineFunctionPassPreservedAnalyses();
70}
71
72bool MachineSanitizerBinaryMetadata::run(MachineFunction &MF) {
73 MDNode *MD = MF.getFunction().getMetadata(KindID: LLVMContext::MD_pcsections);
74 if (!MD)
75 return false;
76 const auto &Section = *cast<MDString>(Val: MD->getOperand(I: 0));
77 if (!Section.getString().starts_with(Prefix: kSanitizerBinaryMetadataCoveredSection))
78 return false;
79 auto &AuxMDs = *cast<MDTuple>(Val: MD->getOperand(I: 1));
80 // Assume it currently only has features.
81 assert(AuxMDs.getNumOperands() == 1);
82 Constant *Features =
83 cast<ConstantAsMetadata>(Val: AuxMDs.getOperand(I: 0))->getValue();
84 if (!Features->getUniqueInteger()[kSanitizerBinaryMetadataUARBit])
85 return false;
86 // Calculate size of stack args for the function.
87 int64_t Size = 0;
88 uint64_t Align = 0;
89 const MachineFrameInfo &MFI = MF.getFrameInfo();
90 for (int i = -1; i >= (int)-MFI.getNumFixedObjects(); --i) {
91 Size = std::max(a: Size, b: MFI.getObjectOffset(ObjectIdx: i) + MFI.getObjectSize(ObjectIdx: i));
92 Align = std::max(a: Align, b: MFI.getObjectAlign(ObjectIdx: i).value());
93 }
94 Size = (Size + Align - 1) & ~(Align - 1);
95 if (!Size)
96 return false;
97 // Non-zero size, update metadata.
98 auto &F = MF.getFunction();
99 IRBuilder<> IRB(F.getContext());
100 MDBuilder MDB(F.getContext());
101 // Keep the features and append size of stack args to the metadata.
102 APInt NewFeatures = Features->getUniqueInteger();
103 NewFeatures.setBit(kSanitizerBinaryMetadataUARHasSizeBit);
104 F.setMetadata(
105 KindID: LLVMContext::MD_pcsections,
106 Node: MDB.createPCSections(Sections: {{Section.getString(),
107 {IRB.getInt(AI: NewFeatures), IRB.getInt32(C: Size)}}}));
108 return false;
109}
110