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[asan] Simplify calculation of stack frame layout extraction calculation of stack description into separate function.

Browse Source 
Reviewers: eugenis

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D25754

llvm-svn: 284547
This commit is contained in:
Vitaly Buka 2016-10-18 23:29:52 +00:00
parent c8fcecb754
commit 53f2da3ddf
4 changed files with 55 additions and 56 deletions
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8
include/llvm/Transforms/Utils/ASanStackFrameLayout.h
View File

@ -43,9 +43,7 @@ struct ASanStackVariableDescription {
// Output data struct for ComputeASanStackFrameLayout.
struct ASanStackFrameLayout {
size_t Granularity;
// Frame description, see DescribeAddressIfStack in ASan runtime.
SmallString<64> DescriptionString;
size_t Granularity; // Shadow granularity.
size_t FrameAlignment; // Alignment for the entire frame.
size_t FrameSize; // Size of the frame in bytes.
};
@ -60,6 +58,10 @@ ASanStackFrameLayout ComputeASanStackFrameLayout(
// The resulting FrameSize should be multiple of MinHeaderSize.
size_t MinHeaderSize);
// Compute frame description, see DescribeAddressIfStack in ASan runtime.
SmallString<64> ComputeASanStackFrameDescription(
const SmallVectorImpl<ASanStackVariableDescription> &Vars);
// Returns shadow bytes with marked red zones. This shadow represents the state
// if the stack frame when all local variables are inside of the own scope.
SmallVector<uint8_t, 64>

66
lib/Transforms/Instrumentation/AddressSanitizer.cpp
View File

@ -2246,26 +2246,6 @@ void FunctionStackPoisoner::processStaticAllocas() {
// If we have a call to llvm.localescape, keep it in the entry block.
if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
// Find static allocas with lifetime analysis.
DenseMap<const AllocaInst *,
std::pair<const ASanStackVariableDescription *, unsigned>>
AllocaToSVDMap;
for (const auto &APC : StaticAllocaPoisonCallVec) {
assert(APC.InsBefore);
assert(APC.AI);
assert(ASan.isInterestingAlloca(*APC.AI));
assert(APC.AI->isStaticAlloca());
auto &Pair = AllocaToSVDMap[APC.AI];
if (const DILocation *FnLoc = EntryDebugLocation.get()) {
if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
if (LifetimeLoc->getFile() == FnLoc->getFile())
if (unsigned Line = LifetimeLoc->getLine())
Pair.second = std::min(Pair.second ? Pair.second : Line, Line);
}
}
}
SmallVector<ASanStackVariableDescription, 16> SVD;
SVD.reserve(AllocaVec.size());
for (AllocaInst *AI : AllocaVec) {
@ -2276,20 +2256,40 @@ void FunctionStackPoisoner::processStaticAllocas() {
AI,
0,
0};
auto It = AllocaToSVDMap.find(AI);
if (It != AllocaToSVDMap.end()) {
D.LifetimeSize = D.Size;
D.Line = It->second.second;
}
SVD.push_back(D);
}
// Minimal header size (left redzone) is 4 pointers,
// i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
size_t MinHeaderSize = ASan.LongSize / 2;
const ASanStackFrameLayout &L =
ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
// Build AllocaToSVDMap for ASanStackVariableDescription lookup.
DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
for (auto &Desc : SVD)
AllocaToSVDMap[Desc.AI] = &Desc;
// Update SVD with information from lifetime intrinsics.
for (const auto &APC : StaticAllocaPoisonCallVec) {
assert(APC.InsBefore);
assert(APC.AI);
assert(ASan.isInterestingAlloca(*APC.AI));
assert(APC.AI->isStaticAlloca());
ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
Desc.LifetimeSize = Desc.Size;
if (const DILocation *FnLoc = EntryDebugLocation.get()) {
if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
if (LifetimeLoc->getFile() == FnLoc->getFile())
if (unsigned Line = LifetimeLoc->getLine())
Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
}
}
}
auto DescriptionString = ComputeASanStackFrameDescription(SVD);
DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
uint64_t LocalStackSize = L.FrameSize;
bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
LocalStackSize <= kMaxStackMallocSize;
@ -2372,7 +2372,7 @@ void FunctionStackPoisoner::processStaticAllocas() {
ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
IntptrPtrTy);
GlobalVariable *StackDescriptionGlobal =
createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
createPrivateGlobalForString(*F.getParent(), DescriptionString,
/*AllowMerging*/ true);
Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
IRB.CreateStore(Description, BasePlus1);
@ -2392,21 +2392,11 @@ void FunctionStackPoisoner::processStaticAllocas() {
copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
if (!StaticAllocaPoisonCallVec.empty()) {
// Complete AllocaToSVDMap
for (const auto &Desc : SVD) {
auto It = AllocaToSVDMap.find(Desc.AI);
if (It != AllocaToSVDMap.end()) {
It->second.first = &Desc;
}
}
const auto &ShadowInScope = GetShadowBytes(SVD, L);
// Poison static allocas near lifetime intrinsics.
for (const auto &APC : StaticAllocaPoisonCallVec) {
// Must be already set.
assert(AllocaToSVDMap[APC.AI].first);
const auto &Desc = *AllocaToSVDMap[APC.AI].first;
const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
assert(Desc.Offset % L.Granularity == 0);
size_t Begin = Desc.Offset / L.Granularity;
size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;

34
lib/Transforms/Utils/ASanStackFrameLayout.cpp
View File

@ -61,9 +61,6 @@ ComputeASanStackFrameLayout(SmallVectorImpl<ASanStackVariableDescription> &Vars,
Vars[i].Alignment = std::max(Vars[i].Alignment, kMinAlignment);
std::stable_sort(Vars.begin(), Vars.end(), CompareVars);
SmallString<2048> StackDescriptionStorage;
raw_svector_ostream StackDescription(StackDescriptionStorage);
StackDescription << NumVars;
ASanStackFrameLayout Layout;
Layout.Granularity = Granularity;
@ -76,34 +73,42 @@ ComputeASanStackFrameLayout(SmallVectorImpl<ASanStackVariableDescription> &Vars,
size_t Alignment = std::max(Granularity, Vars[i].Alignment);
(void)Alignment; // Used only in asserts.
size_t Size = Vars[i].Size;
std::string Name = Vars[i].Name;
assert((Alignment & (Alignment - 1)) == 0);
assert(Layout.FrameAlignment >= Alignment);
assert((Offset % Alignment) == 0);
assert(Size > 0);
assert(Vars[i].LifetimeSize <= Size);
if (Vars[i].Line) {
Name += ":";
Name += std::to_string(Vars[i].Line);
}
StackDescription << " " << Offset << " " << Size << " " << Name.size()
<< " " << Name;
size_t NextAlignment = IsLast ? Granularity
: std::max(Granularity, Vars[i + 1].Alignment);
size_t SizeWithRedzone = VarAndRedzoneSize(Vars[i].Size, NextAlignment);
size_t SizeWithRedzone = VarAndRedzoneSize(Size, NextAlignment);
Vars[i].Offset = Offset;
Offset += SizeWithRedzone;
}
if (Offset % MinHeaderSize) {
Offset += MinHeaderSize - (Offset % MinHeaderSize);
}
Layout.DescriptionString = StackDescription.str();
Layout.FrameSize = Offset;
assert((Layout.FrameSize % MinHeaderSize) == 0);
return Layout;
}
SmallString<64> ComputeASanStackFrameDescription(
const SmallVectorImpl<ASanStackVariableDescription> &Vars) {
SmallString<2048> StackDescriptionStorage;
raw_svector_ostream StackDescription(StackDescriptionStorage);
StackDescription << Vars.size();
for (const auto &Var : Vars) {
std::string Name = Var.Name;
if (Var.Line) {
Name += ":";
Name += std::to_string(Var.Line);
}
StackDescription << " " << Var.Offset << " " << Var.Size << " "
<< Name.size() << " " << Name;
}
return StackDescription.str();
}
SmallVector<uint8_t, 64>
GetShadowBytes(const SmallVectorImpl<ASanStackVariableDescription> &Vars,
const ASanStackFrameLayout &Layout) {
@ -130,6 +135,7 @@ SmallVector<uint8_t, 64> GetShadowBytesAfterScope(
const size_t Granularity = Layout.Granularity;
for (const auto &Var : Vars) {
assert(Var.LifetimeSize <= Var.Size);
const size_t LifetimeShadowSize =
(Var.LifetimeSize + Granularity - 1) / Granularity;
const size_t Offset = Var.Offset / Granularity;

3
unittests/Transforms/Utils/ASanStackFrameLayoutTest.cpp
View File

@ -37,7 +37,8 @@ ShadowBytesToString(ArrayRef<uint8_t> ShadowBytes) {
SmallVector<ASanStackVariableDescription, 10> Vars = V; \
ASanStackFrameLayout L = \
ComputeASanStackFrameLayout(Vars, Granularity, MinHeaderSize); \
EXPECT_STREQ(ExpectedDescr, L.DescriptionString.c_str()); \
EXPECT_STREQ(ExpectedDescr, \
ComputeASanStackFrameDescription(Vars).c_str()); \
EXPECT_EQ(ExpectedShadow, ShadowBytesToString(GetShadowBytes(Vars, L))); \
EXPECT_EQ(ExpectedShadowAfterScope, \
ShadowBytesToString(GetShadowBytesAfterScope(Vars, L))); \