Skip to content

Commit

Permalink
[asan] Separate calculation of ShadowBytes from calculating ASanStack…
Browse files Browse the repository at this point in the history 
…FrameLayout

Summary: No functional changes, just refactoring to make D23947 simpler.

Reviewers: eugenis

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D23954

llvm-svn: 279982
  • Loading branch information
@vitalybuka
vitalybuka committed Aug 29, 2016
1 parent ac644fa commit db331d8
Show file tree
Hide file tree
Showing 4 changed files with 115 additions and 79 deletions.
24 changes: 17 additions & 7 deletions llvm/include/llvm/Transforms/Utils/ASanStackFrameLayout.h
View file
Expand Up @@ -42,26 +42,36 @@ struct ASanStackVariableDescription {

// Output data struct for ComputeASanStackFrameLayout.
struct ASanStackFrameLayout {
size_t Granularity;
// Frame description, see DescribeAddressIfStack in ASan runtime.
SmallString<64> DescriptionString;
// The contents of the shadow memory for the stack frame that we need
// to set at function entry.
SmallVector<uint8_t, 64> ShadowBytes;
size_t FrameAlignment; // Alignment for the entire frame.
size_t FrameSize; // Size of the frame in bytes.
};

void ComputeASanStackFrameLayout(
ASanStackFrameLayout ComputeASanStackFrameLayout(
// The array of stack variables. The elements may get reordered and changed.
SmallVectorImpl<ASanStackVariableDescription> &Vars,
// AddressSanitizer's shadow granularity. Usually 8, may also be 16, 32, 64.
size_t Granularity,
// The minimal size of the left-most redzone (header).
// At least 4 pointer sizes, power of 2, and >= Granularity.
// The resulting FrameSize should be multiple of MinHeaderSize.
size_t MinHeaderSize,
// The result is put here.
ASanStackFrameLayout *Layout);
size_t MinHeaderSize);

// 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>
GetShadowBytes(const SmallVectorImpl<ASanStackVariableDescription> &Vars,
const ASanStackFrameLayout &Layout);

// Returns shadow bytes with marked red zones and after scope. This shadow
// represents the state if the stack frame when all local variables are outside
// of the own scope.
SmallVector<uint8_t, 64> GetShadowBytesAfterScope(
// The array of stack variables. The elements may get reordered and changed.
const SmallVectorImpl<ASanStackVariableDescription> &Vars,
const ASanStackFrameLayout &Layout);

} // llvm namespace

Expand Down
10 changes: 6 additions & 4 deletions llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
View file
Expand Up @@ -2180,8 +2180,10 @@ void FunctionStackPoisoner::processStaticAllocas() {
// 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;
ASanStackFrameLayout L;
ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize, &L);
const ASanStackFrameLayout &L =
ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
const SmallVector<uint8_t, 64> &ShadowBytes =
GetShadowBytesAfterScope(SVD, L);
DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
uint64_t LocalStackSize = L.FrameSize;
bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
Expand Down Expand Up @@ -2278,12 +2280,12 @@ void FunctionStackPoisoner::processStaticAllocas() {

// Poison the stack redzones at the entry.
Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
poisonStackFrame(L.ShadowBytes, IRB, ShadowBase, true);
poisonStackFrame(ShadowBytes, IRB, ShadowBase, true);

auto UnpoisonStack = [&](IRBuilder<> &IRB) {
// Do this always as poisonAlloca can be disabled with
// detect_stack_use_after_scope=0.
poisonStackFrame(L.ShadowBytes, IRB, ShadowBase, false);
poisonStackFrame(ShadowBytes, IRB, ShadowBase, false);
if (!StaticAllocaPoisonCallVec.empty()) {
// If we poisoned some allocas in llvm.lifetime analysis,
// unpoison whole stack frame now.
Expand Down
80 changes: 51 additions & 29 deletions llvm/lib/Transforms/Utils/ASanStackFrameLayout.cpp
View file
Expand Up @@ -47,15 +47,14 @@ static size_t VarAndRedzoneSize(size_t Size, size_t Alignment) {
return alignTo(Res, Alignment);
}

void
ASanStackFrameLayout
ComputeASanStackFrameLayout(SmallVectorImpl<ASanStackVariableDescription> &Vars,
size_t Granularity, size_t MinHeaderSize,
ASanStackFrameLayout *Layout) {
size_t Granularity, size_t MinHeaderSize) {
assert(Granularity >= 8 && Granularity <= 64 &&
(Granularity & (Granularity - 1)) == 0);
assert(MinHeaderSize >= 16 && (MinHeaderSize & (MinHeaderSize - 1)) == 0 &&
MinHeaderSize >= Granularity);
size_t NumVars = Vars.size();
const size_t NumVars = Vars.size();
assert(NumVars > 0);
for (size_t i = 0; i < NumVars; i++)
Vars[i].Alignment = std::max(Vars[i].Alignment, kMinAlignment);
Expand All @@ -64,21 +63,21 @@ ComputeASanStackFrameLayout(SmallVectorImpl<ASanStackVariableDescription> &Vars,
SmallString<2048> StackDescriptionStorage;
raw_svector_ostream StackDescription(StackDescriptionStorage);
StackDescription << NumVars;
Layout->FrameAlignment = std::max(Granularity, Vars[0].Alignment);
SmallVector<uint8_t, 64> &SB(Layout->ShadowBytes);
SB.clear();

ASanStackFrameLayout Layout;
Layout.Granularity = Granularity;
Layout.FrameAlignment = std::max(Granularity, Vars[0].Alignment);
size_t Offset = std::max(std::max(MinHeaderSize, Granularity),
Vars[0].Alignment);
assert((Offset % Granularity) == 0);
SB.insert(SB.end(), Offset / Granularity, kAsanStackLeftRedzoneMagic);
for (size_t i = 0; i < NumVars; i++) {
bool IsLast = i == NumVars - 1;
size_t Alignment = std::max(Granularity, Vars[i].Alignment);
(void)Alignment; // Used only in asserts.
size_t Size = Vars[i].Size;
const char *Name = Vars[i].Name;
assert((Alignment & (Alignment - 1)) == 0);
assert(Layout->FrameAlignment >= Alignment);
assert(Layout.FrameAlignment >= Alignment);
assert((Offset % Alignment) == 0);
assert(Size > 0);
assert(Vars[i].LifetimeSize <= Size);
Expand All @@ -87,31 +86,54 @@ ComputeASanStackFrameLayout(SmallVectorImpl<ASanStackVariableDescription> &Vars,
size_t NextAlignment = IsLast ? Granularity
: std::max(Granularity, Vars[i + 1].Alignment);
size_t SizeWithRedzone = VarAndRedzoneSize(Vars[i].Size, NextAlignment);
size_t LifetimeShadowSize =
(Vars[i].LifetimeSize + Granularity - 1) / Granularity;
SB.insert(SB.end(), LifetimeShadowSize, kAsanStackUseAfterScopeMagic);
if (Size / Granularity >= LifetimeShadowSize) {
SB.insert(SB.end(), Size / Granularity - LifetimeShadowSize, 0);
if (Size % Granularity)
SB.insert(SB.end(), Size % Granularity);
}
SB.insert(SB.end(), (SizeWithRedzone - Size) / Granularity,
IsLast ? kAsanStackRightRedzoneMagic
: kAsanStackMidRedzoneMagic);
Vars[i].Offset = Offset;
Offset += SizeWithRedzone;
assert(Offset == SB.size() * Granularity);
}
if (Offset % MinHeaderSize) {
size_t ExtraRedzone = MinHeaderSize - (Offset % MinHeaderSize);
SB.insert(SB.end(), ExtraRedzone / Granularity,
kAsanStackRightRedzoneMagic);
Offset += ExtraRedzone;
Offset += MinHeaderSize - (Offset % MinHeaderSize);
}
Layout.DescriptionString = StackDescription.str();
Layout.FrameSize = Offset;
assert((Layout.FrameSize % MinHeaderSize) == 0);

return Layout;
}

SmallVector<uint8_t, 64>
GetShadowBytes(const SmallVectorImpl<ASanStackVariableDescription> &Vars,
const ASanStackFrameLayout &Layout) {
SmallVector<uint8_t, 64> SB;
SB.clear();
const size_t NumVars = Vars.size();
assert(NumVars > 0);
const size_t Granularity = Layout.Granularity;
SB.resize(Vars[0].Offset / Granularity, kAsanStackLeftRedzoneMagic);
for (const auto &Var : Vars) {
SB.resize(Var.Offset / Granularity, kAsanStackMidRedzoneMagic);

SB.resize(SB.size() + Var.Size / Granularity, 0);
if (Var.Size % Granularity)
SB.push_back(Var.Size % Granularity);
}
Layout->DescriptionString = StackDescription.str();
Layout->FrameSize = Offset;
assert((Layout->FrameSize % MinHeaderSize) == 0);
assert(Layout->FrameSize / Granularity == Layout->ShadowBytes.size());
SB.resize(Layout.FrameSize / Granularity, kAsanStackRightRedzoneMagic);
return SB;
}

SmallVector<uint8_t, 64> GetShadowBytesAfterScope(
const SmallVectorImpl<ASanStackVariableDescription> &Vars,
const ASanStackFrameLayout &Layout) {
SmallVector<uint8_t, 64> SB = GetShadowBytes(Vars, Layout);
const size_t Granularity = Layout.Granularity;

for (const auto &Var : Vars) {
const size_t LifetimeShadowSize =
(Var.LifetimeSize + Granularity - 1) / Granularity;
const size_t Offset = Var.Offset / Granularity;
std::fill(SB.begin() + Offset, SB.begin() + Offset + LifetimeShadowSize,
kAsanStackUseAfterScopeMagic);
}

return SB;
}

} // llvm namespace
80 changes: 41 additions & 39 deletions llvm/unittests/Transforms/Utils/ASanStackFrameLayoutTest.cpp
View file
Expand Up @@ -30,21 +30,20 @@ ShadowBytesToString(ArrayRef<uint8_t> ShadowBytes) {
return os.str();
}

static void TestLayout(SmallVector<ASanStackVariableDescription, 10> Vars,
size_t Granularity, size_t MinHeaderSize,
const std::string &ExpectedDescr,
const std::string &ExpectedShadow) {
ASanStackFrameLayout L;
ComputeASanStackFrameLayout(Vars, Granularity, MinHeaderSize, &L);
EXPECT_EQ(ExpectedDescr, L.DescriptionString);
EXPECT_EQ(ExpectedShadow, ShadowBytesToString(L.ShadowBytes));
}
// Use macro to preserve line information in EXPECT_EQ output.
#define TEST_LAYOUT(V, Granularity, MinHeaderSize, ExpectedDescr, \
ExpectedShadow, ExpectedShadowAfterScope) \
{ \
SmallVector<ASanStackVariableDescription, 10> Vars = V; \
ASanStackFrameLayout L = \
ComputeASanStackFrameLayout(Vars, Granularity, MinHeaderSize); \
EXPECT_EQ(ExpectedDescr, L.DescriptionString); \
EXPECT_EQ(ExpectedShadow, ShadowBytesToString(GetShadowBytes(Vars, L))); \
EXPECT_EQ(ExpectedShadowAfterScope, \
ShadowBytesToString(GetShadowBytesAfterScope(Vars, L))); \
}

TEST(ASanStackFrameLayout, Test) {
#define VEC1(a) SmallVector<ASanStackVariableDescription, 10>(1, a)
#define VEC(a) \
SmallVector<ASanStackVariableDescription, 10>(a, a + sizeof(a) / sizeof(a[0]))

#define VAR(name, size, lifetime, alignment) \
ASanStackVariableDescription name##size##_##alignment = { \
#name #size "_" #alignment, \
Expand All @@ -64,41 +63,44 @@ TEST(ASanStackFrameLayout, Test) {
VAR(a, 7, 0, 1);
VAR(a, 8, 8, 1);
VAR(a, 9, 0, 1);
VAR(a, 16, 0, 1);
VAR(a, 16, 16, 1);
VAR(a, 41, 9, 1);
VAR(a, 105, 103, 1);

TestLayout(VEC1(a1_1), 8, 16, "1 16 1 4 a1_1", "LL1R");
TestLayout(VEC1(a1_1), 64, 64, "1 64 1 4 a1_1", "L1");
TestLayout(VEC1(p1_32), 8, 32, "1 32 1 5 p1_32", "LLLL1RRR");
TestLayout(VEC1(p1_32), 8, 64, "1 64 1 5 p1_32", "LLLLLLLL1RRRRRRR");
TEST_LAYOUT({a1_1}, 8, 16, "1 16 1 4 a1_1", "LL1R", "LL1R");
TEST_LAYOUT({a1_1}, 64, 64, "1 64 1 4 a1_1", "L1", "L1");
TEST_LAYOUT({p1_32}, 8, 32, "1 32 1 5 p1_32", "LLLL1RRR", "LLLL1RRR");
TEST_LAYOUT({p1_32}, 8, 64, "1 64 1 5 p1_32", "LLLLLLLL1RRRRRRR",
"LLLLLLLL1RRRRRRR");

TestLayout(VEC1(a1_1), 8, 32, "1 32 1 4 a1_1", "LLLL1RRR");
TestLayout(VEC1(a2_1), 8, 32, "1 32 2 4 a2_1", "LLLL2RRR");
TestLayout(VEC1(a3_1), 8, 32, "1 32 3 4 a3_1", "LLLL3RRR");
TestLayout(VEC1(a4_1), 8, 32, "1 32 4 4 a4_1", "LLLL4RRR");
TestLayout(VEC1(a7_1), 8, 32, "1 32 7 4 a7_1", "LLLL7RRR");
TestLayout(VEC1(a8_1), 8, 32, "1 32 8 4 a8_1", "LLLLSRRR");
TestLayout(VEC1(a9_1), 8, 32, "1 32 9 4 a9_1", "LLLL01RR");
TestLayout(VEC1(a16_1), 8, 32, "1 32 16 5 a16_1", "LLLL00RR");
TestLayout(VEC1(p1_256), 8, 32, "1 256 1 6 p1_256",
"LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL1RRR");
TestLayout(VEC1(a41_1), 8, 32, "1 32 41 5 a41_1", "LLLLSS0001RRRRRR");
TestLayout(VEC1(a105_1), 8, 32, "1 32 105 6 a105_1",
"LLLLSSSSSSSSSSSSS1RRRRRR");
TEST_LAYOUT({a1_1}, 8, 32, "1 32 1 4 a1_1", "LLLL1RRR", "LLLL1RRR");
TEST_LAYOUT({a2_1}, 8, 32, "1 32 2 4 a2_1", "LLLL2RRR", "LLLL2RRR");
TEST_LAYOUT({a3_1}, 8, 32, "1 32 3 4 a3_1", "LLLL3RRR", "LLLL3RRR");
TEST_LAYOUT({a4_1}, 8, 32, "1 32 4 4 a4_1", "LLLL4RRR", "LLLL4RRR");
TEST_LAYOUT({a7_1}, 8, 32, "1 32 7 4 a7_1", "LLLL7RRR", "LLLL7RRR");
TEST_LAYOUT({a8_1}, 8, 32, "1 32 8 4 a8_1", "LLLL0RRR", "LLLLSRRR");
TEST_LAYOUT({a9_1}, 8, 32, "1 32 9 4 a9_1", "LLLL01RR", "LLLL01RR");
TEST_LAYOUT({a16_1}, 8, 32, "1 32 16 5 a16_1", "LLLL00RR", "LLLLSSRR");
TEST_LAYOUT({p1_256}, 8, 32, "1 256 1 6 p1_256",
"LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL1RRR",
"LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL1RRR");
TEST_LAYOUT({a41_1}, 8, 32, "1 32 41 5 a41_1", "LLLL000001RRRRRR",
"LLLLSS0001RRRRRR");
TEST_LAYOUT({a105_1}, 8, 32, "1 32 105 6 a105_1", "LLLL00000000000001RRRRRR",
"LLLLSSSSSSSSSSSSS1RRRRRR");

{
ASanStackVariableDescription t[] = {a1_1, p1_256};
TestLayout(VEC(t), 8, 32, "2 256 1 6 p1_256 272 1 4 a1_1",
"LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL1M1R");
SmallVector<ASanStackVariableDescription, 10> t = {a1_1, p1_256};
TEST_LAYOUT(t, 8, 32, "2 256 1 6 p1_256 272 1 4 a1_1",
"LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL1M1R",
"LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL1M1R");
}

{
ASanStackVariableDescription t[] = {a1_1, a16_1, a41_1};
TestLayout(VEC(t), 8, 32, "3 32 1 4 a1_1 48 16 5 a16_1 80 41 5 a41_1",
"LLLL1M00MMSS0001RRRR");
SmallVector<ASanStackVariableDescription, 10> t = {a1_1, a16_1, a41_1};
TEST_LAYOUT(t, 8, 32, "3 32 1 4 a1_1 48 16 5 a16_1 80 41 5 a41_1",
"LLLL1M00MM000001RRRR", "LLLL1MSSMMSS0001RRRR");
}
#undef VEC1
#undef VEC
#undef VAR
#undef TEST_LAYOUT
}

0 comments on commit db331d8

Please sign in to comment.