xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/SanitizerMetadata.cpp (revision e9e8876a4d6afc1ad5315faaa191b25121a813d7)
1 //===--- SanitizerMetadata.cpp - Ignored entities for sanitizers ----------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Class which emits metadata consumed by sanitizer instrumentation passes.
10 //
11 //===----------------------------------------------------------------------===//
12 #include "SanitizerMetadata.h"
13 #include "CodeGenModule.h"
14 #include "clang/AST/Attr.h"
15 #include "clang/AST/Type.h"
16 #include "clang/Basic/SourceManager.h"
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/IR/Constants.h"
19 
20 using namespace clang;
21 using namespace CodeGen;
22 
23 SanitizerMetadata::SanitizerMetadata(CodeGenModule &CGM) : CGM(CGM) {}
24 
25 static bool isAsanHwasanOrMemTag(const SanitizerSet& SS) {
26   return SS.hasOneOf(SanitizerKind::Address | SanitizerKind::KernelAddress |
27                      SanitizerKind::HWAddress | SanitizerKind::KernelHWAddress |
28                      SanitizerKind::MemTag);
29 }
30 
31 void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
32                                            SourceLocation Loc, StringRef Name,
33                                            QualType Ty, bool IsDynInit,
34                                            bool IsExcluded) {
35   if (!isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize))
36     return;
37   IsDynInit &= !CGM.isInNoSanitizeList(GV, Loc, Ty, "init");
38   IsExcluded |= CGM.isInNoSanitizeList(GV, Loc, Ty);
39 
40   llvm::Metadata *LocDescr = nullptr;
41   llvm::Metadata *GlobalName = nullptr;
42   llvm::LLVMContext &VMContext = CGM.getLLVMContext();
43   if (!IsExcluded) {
44     // Don't generate source location and global name if it is on
45     // the NoSanitizeList - it won't be instrumented anyway.
46     LocDescr = getLocationMetadata(Loc);
47     if (!Name.empty())
48       GlobalName = llvm::MDString::get(VMContext, Name);
49   }
50 
51   llvm::Metadata *GlobalMetadata[] = {
52       llvm::ConstantAsMetadata::get(GV), LocDescr, GlobalName,
53       llvm::ConstantAsMetadata::get(
54           llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext), IsDynInit)),
55       llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
56           llvm::Type::getInt1Ty(VMContext), IsExcluded))};
57 
58   llvm::MDNode *ThisGlobal = llvm::MDNode::get(VMContext, GlobalMetadata);
59   llvm::NamedMDNode *AsanGlobals =
60       CGM.getModule().getOrInsertNamedMetadata("llvm.asan.globals");
61   AsanGlobals->addOperand(ThisGlobal);
62 }
63 
64 void SanitizerMetadata::reportGlobalToASan(llvm::GlobalVariable *GV,
65                                            const VarDecl &D, bool IsDynInit) {
66   if (!isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize))
67     return;
68   std::string QualName;
69   llvm::raw_string_ostream OS(QualName);
70   D.printQualifiedName(OS);
71 
72   bool IsExcluded = false;
73   for (auto Attr : D.specific_attrs<NoSanitizeAttr>())
74     if (Attr->getMask() & SanitizerKind::Address)
75       IsExcluded = true;
76   reportGlobalToASan(GV, D.getLocation(), OS.str(), D.getType(), IsDynInit,
77                      IsExcluded);
78 }
79 
80 void SanitizerMetadata::disableSanitizerForGlobal(llvm::GlobalVariable *GV) {
81   // For now, just make sure the global is not modified by the ASan
82   // instrumentation.
83   if (isAsanHwasanOrMemTag(CGM.getLangOpts().Sanitize))
84     reportGlobalToASan(GV, SourceLocation(), "", QualType(), false, true);
85 }
86 
87 void SanitizerMetadata::disableSanitizerForInstruction(llvm::Instruction *I) {
88   I->setMetadata(CGM.getModule().getMDKindID("nosanitize"),
89                  llvm::MDNode::get(CGM.getLLVMContext(), None));
90 }
91 
92 llvm::MDNode *SanitizerMetadata::getLocationMetadata(SourceLocation Loc) {
93   PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc);
94   if (!PLoc.isValid())
95     return nullptr;
96   llvm::LLVMContext &VMContext = CGM.getLLVMContext();
97   llvm::Metadata *LocMetadata[] = {
98       llvm::MDString::get(VMContext, PLoc.getFilename()),
99       llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
100           llvm::Type::getInt32Ty(VMContext), PLoc.getLine())),
101       llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
102           llvm::Type::getInt32Ty(VMContext), PLoc.getColumn())),
103   };
104   return llvm::MDNode::get(VMContext, LocMetadata);
105 }
106