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