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[ASan] Collect unmangled names of global variables in Clang to print …
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…them in error reports.

Currently ASan instrumentation pass creates a string with global name
for each instrumented global (to include global names in the error report). Global
name is already mangled at this point, and we may not be able to demangle it
at runtime (e.g. there is no __cxa_demangle on Android).

Instead, create a string with fully qualified global name in Clang, and pass it
to ASan instrumentation pass in llvm.asan.globals metadata. If there is no metadata
for some global, ASan will use the original algorithm.

This fixes https://code.google.com/p/address-sanitizer/issues/detail?id=264.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212872 91177308-0d34-0410-b5e6-96231b3b80d8
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@vonosmas
vonosmas committed Jul 12, 2014
1 parent cc6a418 commit b2d2590
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Showing 4 changed files with 39 additions and 20 deletions.
29 changes: 20 additions & 9 deletions lib/Transforms/Instrumentation/AddressSanitizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -216,8 +216,11 @@ namespace {
class GlobalsMetadata {
public:
struct Entry {
Entry() : SourceLoc(nullptr), IsDynInit(false), IsBlacklisted(false) {}
Entry()
: SourceLoc(nullptr), Name(nullptr), IsDynInit(false),
IsBlacklisted(false) {}
GlobalVariable *SourceLoc;
GlobalVariable *Name;
bool IsDynInit;
bool IsBlacklisted;
};
Expand All @@ -232,7 +235,7 @@ class GlobalsMetadata {
return;
for (auto MDN : Globals->operands()) {
// Metadata node contains the global and the fields of "Entry".
assert(MDN->getNumOperands() == 4);
assert(MDN->getNumOperands() == 5);
Value *V = MDN->getOperand(0);
// The optimizer may optimize away a global entirely.
if (!V)
Expand All @@ -246,9 +249,14 @@ class GlobalsMetadata {
E.SourceLoc = GVLoc;
addSourceLocationGlobal(GVLoc);
}
ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(2));
if (Value *Name = MDN->getOperand(2)) {
GlobalVariable *GVName = cast<GlobalVariable>(Name);
E.Name = GVName;
InstrumentationGlobals.insert(GVName);
}
ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(3));
E.IsDynInit |= IsDynInit->isOne();
ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(3));
ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(4));
E.IsBlacklisted |= IsBlacklisted->isOne();
}
}
Expand Down Expand Up @@ -1049,6 +1057,14 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
for (size_t i = 0; i < n; i++) {
static const uint64_t kMaxGlobalRedzone = 1 << 18;
GlobalVariable *G = GlobalsToChange[i];

auto MD = GlobalsMD.get(G);
// Create string holding the global name unless it was provided by
// the metadata.
GlobalVariable *Name =
MD.Name ? MD.Name : createPrivateGlobalForString(M, G->getName(),
/*AllowMerging*/ true);

PointerType *PtrTy = cast<PointerType>(G->getType());
Type *Ty = PtrTy->getElementType();
uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
Expand All @@ -1070,9 +1086,6 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
NewTy, G->getInitializer(),
Constant::getNullValue(RightRedZoneTy), NULL);

GlobalVariable *Name =
createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);

// Create a new global variable with enough space for a redzone.
GlobalValue::LinkageTypes Linkage = G->getLinkage();
if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
Expand All @@ -1092,8 +1105,6 @@ bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
NewGlobal->takeName(G);
G->eraseFromParent();

auto MD = GlobalsMD.get(G);

Initializers[i] = ConstantStruct::get(
GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
ConstantInt::get(IntptrTy, SizeInBytes),
Expand Down
20 changes: 14 additions & 6 deletions test/Instrumentation/AddressSanitizer/global_metadata.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -18,12 +18,20 @@ target triple = "x86_64-unknown-linux-gnu"
@.asan_loc_descr2 = private unnamed_addr constant { [22 x i8]*, i32, i32 } { [22 x i8]* @.str1, i32 12, i32 14 }
@.asan_loc_descr4 = private unnamed_addr constant { [22 x i8]*, i32, i32 } { [22 x i8]* @.str1, i32 14, i32 25 }

; Global names:
@.str2 = private unnamed_addr constant [7 x i8] c"global\00", align 1
@.str3 = private unnamed_addr constant [16 x i8] c"dyn_init_global\00", align 1
@.str4 = private unnamed_addr constant [11 x i8] c"static_var\00", align 1
@.str5 = private unnamed_addr constant [17 x i8] c"<string literal>\00", align 1

; Check that globals were instrumented, but sanitizer location descriptors weren't:
; CHECK: @global = global { i32, [60 x i8] } zeroinitializer, align 32
; CHECK: @.str = internal unnamed_addr constant { [14 x i8], [50 x i8] } { [14 x i8] c"Hello, world!\00", [50 x i8] zeroinitializer }, align 32
; CHECK: @.asan_loc_descr = private unnamed_addr constant { [22 x i8]*, i32, i32 } { [22 x i8]* @.str1, i32 5, i32 5 }
; CHECK: @.str2 = private unnamed_addr constant [7 x i8] c"global\00", align 1

; Check that location decriptors were passed into __asan_register_globals:
; Check that location decriptors and global names were passed into __asan_register_globals:
; CHECK: i64 ptrtoint ([7 x i8]* @.str2 to i64)
; CHECK: i64 ptrtoint ({ [22 x i8]*, i32, i32 }* @.asan_loc_descr to i64)

; Function Attrs: nounwind sanitize_address
Expand Down Expand Up @@ -55,9 +63,9 @@ attributes #1 = { nounwind sanitize_address "less-precise-fpmad"="false" "no-fra
!llvm.asan.globals = !{!0, !1, !2, !3, !4}
!llvm.ident = !{!5}

!0 = metadata !{i32* @global, { [22 x i8]*, i32, i32 }* @.asan_loc_descr, i1 false, i1 false}
!1 = metadata !{i32* @dyn_init_global, { [22 x i8]*, i32, i32 }* @.asan_loc_descr1, i1 true, i1 false}
!2 = metadata !{i32* @blacklisted_global, null, i1 false, i1 true}
!3 = metadata !{i32* @_ZZ4funcvE10static_var, { [22 x i8]*, i32, i32 }* @.asan_loc_descr2, i1 false, i1 false}
!4 = metadata !{[14 x i8]* @.str, { [22 x i8]*, i32, i32 }* @.asan_loc_descr4, i1 false, i1 false}
!0 = metadata !{i32* @global, { [22 x i8]*, i32, i32 }* @.asan_loc_descr, [7 x i8]* @.str2, i1 false, i1 false}
!1 = metadata !{i32* @dyn_init_global, { [22 x i8]*, i32, i32 }* @.asan_loc_descr1, [16 x i8]* @.str3, i1 true, i1 false}
!2 = metadata !{i32* @blacklisted_global, null, null, i1 false, i1 true}
!3 = metadata !{i32* @_ZZ4funcvE10static_var, { [22 x i8]*, i32, i32 }* @.asan_loc_descr2, [11 x i8]* @.str4, i1 false, i1 false}
!4 = metadata !{[14 x i8]* @.str, { [22 x i8]*, i32, i32 }* @.asan_loc_descr4, [17 x i8]* @.str5, i1 false, i1 false}
!5 = metadata !{metadata !"clang version 3.5.0 (211282)"}
2 changes: 1 addition & 1 deletion test/Instrumentation/AddressSanitizer/instrument_global.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -69,7 +69,7 @@ entry:


!llvm.asan.globals = !{!0}
!0 = metadata !{[10 x i32]* @GlobDy, null, i1 true, i1 false}
!0 = metadata !{[10 x i32]* @GlobDy, null, null, i1 true, i1 false}

; CHECK-LABEL: define internal void @asan.module_ctor
; CHECK-NOT: ret
Expand Down
8 changes: 4 additions & 4 deletions test/Instrumentation/AddressSanitizer/instrument_initializer_metadata.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -7,10 +7,10 @@ target triple = "x86_64-unknown-linux-gnu"
@YYY = global i32 0, align 4 ; W/o dynamic initializer.
; Clang will emit the following metadata identifying @xxx as dynamically
; initialized.
!0 = metadata !{i32* @xxx, null, i1 true, i1 false}
!1 = metadata !{i32* @XXX, null, i1 true, i1 false}
!2 = metadata !{i32* @yyy, null, i1 false, i1 false}
!3 = metadata !{i32* @YYY, null, i1 false, i1 false}
!0 = metadata !{i32* @xxx, null, null, i1 true, i1 false}
!1 = metadata !{i32* @XXX, null, null, i1 true, i1 false}
!2 = metadata !{i32* @yyy, null, null, i1 false, i1 false}
!3 = metadata !{i32* @YYY, null, null, i1 false, i1 false}
!llvm.asan.globals = !{!0, !1, !2, !3}

define i32 @initializer() uwtable {
Expand Down

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