mmalcomson created this revision.
mmalcomson added reviewers: eugenis, pcc, Sanitizers.
mmalcomson added a project: Sanitizers.
Herald added subscribers: llvm-commits, cfe-commits, jfb, hiraditya, srhines.
Herald added projects: clang, LLVM.
As I asked in the comments of https://reviews.llvm.org/D69199, if we're no
longer accounting for the late-binding feature then I believe we can remove
this lazy thread initialisation complexity.
I've tested with clang and gcc on linux that various threading programs work as
expected.
Remove lazy thread initialisation
This was an experiment made possible by a non-standard feature of the Android
dynamic loader.
It required introducing a flag to tell the compiler which ABI was being
targeted.
This flag is no longer needed, since the generated code now works for both
ABI's.
We leave that flag untouched for backwards compatibility. This also means that
if we need to distinguish between targeted ABI's again we can do that without
disturbing any existing workflows.
We leave a comment in the source code and mention in the help text to explain
this for any confused person reading the code in the future.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D69574
Files:
clang/include/clang/Driver/Options.td
compiler-rt/lib/hwasan/hwasan_interceptors.cpp
compiler-rt/lib/hwasan/hwasan_linux.cpp
llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
llvm/test/Instrumentation/HWAddressSanitizer/lazy-thread-init.ll
Index: llvm/test/Instrumentation/HWAddressSanitizer/lazy-thread-init.ll
===================================================================
--- llvm/test/Instrumentation/HWAddressSanitizer/lazy-thread-init.ll
+++ /dev/null
@@ -1,39 +0,0 @@
-; RUN: opt -S -hwasan < %s | FileCheck %s
-
-target triple = "aarch64--linux-android"
-
-declare i32 @bar([16 x i32]* %p)
-
-define void @alloca() sanitize_hwaddress "hwasan-abi"="interceptor" {
- ; CHECK: alloca [16 x i32]
- ; CHECK: [[A:%[^ ]*]] = call i8* @llvm.thread.pointer()
- ; CHECK: [[B:%[^ ]*]] = getelementptr i8, i8* [[A]], i32 48
- ; CHECK: [[C:%[^ ]*]] = bitcast i8* [[B]] to i64*
- ; CHECK: [[LOAD:%[^ ]*]] = load i64, i64* [[C]]
- ; CHECK: [[ICMP:%[^ ]*]] = icmp eq i64 [[LOAD]], 0
- ; CHECK: br i1 [[ICMP]], label %[[INIT:[^,]*]], label %[[CONT:[^,]*]], !prof [[PROF:![0-9]+]]
-
- ; CHECK: [[INIT]]:
- ; CHECK: call void @__hwasan_thread_enter()
- ; CHECK: [[RELOAD:%[^ ]*]] = load i64, i64* [[C]]
- ; CHECK: br label %[[CONT]]
-
- ; CHECK: [[CONT]]:
- ; CHECK: phi i64 [ [[LOAD]], %0 ], [ [[RELOAD]], %[[INIT]] ]
- ; CHECK: alloca i8
-
- %p = alloca [16 x i32]
- %size = call i32 @bar([16 x i32]* %p)
- %q = alloca i8, i32 %size
- ret void
-}
-
-define i32 @load(i32* %p) sanitize_hwaddress "hwasan-abi"="interceptor" {
- ; CHECK: [[SHADOW:%[^ ]*]] = call i8* asm "", "=r,0"([0 x i8]* @__hwasan_shadow)
- ; CHECK-NOT: icmp
- ; CHECK: call void @llvm.hwasan.check.memaccess(i8* [[SHADOW]],
- %v = load i32, i32* %p
- ret i32 %v
-}
-
-; CHECK: [[PROF]] = !{!"branch_weights", i32 1, i32 100000}
Index: llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -284,7 +284,6 @@
FunctionCallee HwasanTagMemoryFunc;
FunctionCallee HwasanGenerateTagFunc;
- FunctionCallee HwasanThreadEnterFunc;
Constant *ShadowGlobal;
@@ -473,9 +472,6 @@
HWAsanHandleVfork =
M.getOrInsertFunction("__hwasan_handle_vfork", IRB.getVoidTy(), IntptrTy);
-
- HwasanThreadEnterFunc =
- M.getOrInsertFunction("__hwasan_thread_enter", IRB.getVoidTy());
}
Value *HWAddressSanitizer::getDynamicShadowIfunc(IRBuilder<> &IRB) {
@@ -934,34 +930,13 @@
Value *SlotPtr = getHwasanThreadSlotPtr(IRB, IntptrTy);
assert(SlotPtr);
- Instruction *ThreadLong = IRB.CreateLoad(IntptrTy, SlotPtr);
-
- Function *F = IRB.GetInsertBlock()->getParent();
- if (F->getFnAttribute("hwasan-abi").getValueAsString() == "interceptor") {
- Value *ThreadLongEqZero =
- IRB.CreateICmpEQ(ThreadLong, ConstantInt::get(IntptrTy, 0));
- auto *Br = cast<BranchInst>(SplitBlockAndInsertIfThen(
- ThreadLongEqZero, cast<Instruction>(ThreadLongEqZero)->getNextNode(),
- false, MDBuilder(*C).createBranchWeights(1, 100000)));
-
- IRB.SetInsertPoint(Br);
- // FIXME: This should call a new runtime function with a custom calling
- // convention to avoid needing to spill all arguments here.
- IRB.CreateCall(HwasanThreadEnterFunc);
- LoadInst *ReloadThreadLong = IRB.CreateLoad(IntptrTy, SlotPtr);
-
- IRB.SetInsertPoint(&*Br->getSuccessor(0)->begin());
- PHINode *ThreadLongPhi = IRB.CreatePHI(IntptrTy, 2);
- ThreadLongPhi->addIncoming(ThreadLong, ThreadLong->getParent());
- ThreadLongPhi->addIncoming(ReloadThreadLong, ReloadThreadLong->getParent());
- ThreadLong = ThreadLongPhi;
- }
-
+ Value *ThreadLong = IRB.CreateLoad(IntptrTy, SlotPtr);
// Extract the address field from ThreadLong. Unnecessary on AArch64 with TBI.
Value *ThreadLongMaybeUntagged =
TargetTriple.isAArch64() ? ThreadLong : untagPointer(IRB, ThreadLong);
if (WithFrameRecord) {
+ Function *F = IRB.GetInsertBlock()->getParent();
StackBaseTag = IRB.CreateAShr(ThreadLong, 3);
// Prepare ring buffer data.
Index: compiler-rt/lib/hwasan/hwasan_linux.cpp
===================================================================
--- compiler-rt/lib/hwasan/hwasan_linux.cpp
+++ compiler-rt/lib/hwasan/hwasan_linux.cpp
@@ -354,12 +354,7 @@
#endif
Thread *GetCurrentThread() {
- uptr *ThreadLong = GetCurrentThreadLongPtr();
-#if HWASAN_WITH_INTERCEPTORS
- if (!*ThreadLong)
- __hwasan_thread_enter();
-#endif
- auto *R = (StackAllocationsRingBuffer *)ThreadLong;
+ auto *R = (StackAllocationsRingBuffer *)GetCurrentThreadLongPtr();
return hwasanThreadList().GetThreadByBufferAddress((uptr)(R->Next()));
}
Index: compiler-rt/lib/hwasan/hwasan_interceptors.cpp
===================================================================
--- compiler-rt/lib/hwasan/hwasan_interceptors.cpp
+++ compiler-rt/lib/hwasan/hwasan_interceptors.cpp
@@ -202,23 +202,33 @@
INTERCEPTOR_ALIAS(int, mallopt, int cmd, int value);
INTERCEPTOR_ALIAS(void, malloc_stats, void);
#endif
-#endif // HWASAN_WITH_INTERCEPTORS
+struct ThreadStartArg {
+ thread_callback_t callback;
+ void *param;
+};
+
+static void *HwasanThreadStartFunc(void *arg) {
+ __hwasan_thread_enter();
+ ThreadStartArg A = *reinterpret_cast<ThreadStartArg*>(arg);
+ UnmapOrDie(arg, GetPageSizeCached());
+ return A.callback(A.param);
+}
-#if HWASAN_WITH_INTERCEPTORS && !defined(__aarch64__)
-INTERCEPTOR(int, pthread_create, void *th, void *attr,
- void *(*callback)(void *), void *param) {
+INTERCEPTOR(int, pthread_create, void *th, void *attr, void *(*callback)(void*),
+ void * param) {
ScopedTaggingDisabler disabler;
+ ThreadStartArg *A = reinterpret_cast<ThreadStartArg *> (MmapOrDie(
+ GetPageSizeCached(), "pthread_create"));
+ *A = {callback, param};
int res = REAL(pthread_create)(UntagPtr(th), UntagPtr(attr),
- callback, param);
+ &HwasanThreadStartFunc, A);
return res;
}
-#endif
-#if HWASAN_WITH_INTERCEPTORS
DEFINE_REAL(int, vfork)
DECLARE_EXTERN_INTERCEPTOR_AND_WRAPPER(int, vfork)
-#endif
+#endif // HWASAN_WITH_INTERCEPTORS
#if HWASAN_WITH_INTERCEPTORS && defined(__aarch64__)
// Get and/or change the set of blocked signals.
@@ -331,9 +341,7 @@
#if defined(__linux__)
INTERCEPT_FUNCTION(vfork);
#endif // __linux__
-#if !defined(__aarch64__)
INTERCEPT_FUNCTION(pthread_create);
-#endif // __aarch64__
#endif
inited = 1;
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -1034,10 +1034,16 @@
: Flag<["-"], "fno-sanitize-address-use-odr-indicator">,
Group<f_clang_Group>,
HelpText<"Disable ODR indicator globals">;
+// Note: This flag was introduced when it was necessary to distinguish between
+// ABI for correct codegen. This is no longer needed, but the flag is
+// not removed since targeting either ABI will behave the same.
+// This way we cause no disturbance to existing scripts & code, and if we
+// want to use this flag in the future we will cause no disturbance then
+// either.
def fsanitize_hwaddress_abi_EQ
: Joined<["-"], "fsanitize-hwaddress-abi=">,
Group<f_clang_Group>,
- HelpText<"Select the HWAddressSanitizer ABI to target (interceptor or platform, default interceptor)">;
+ HelpText<"Select the HWAddressSanitizer ABI to target (interceptor or platform, default interceptor). This option is currently unused.">;
def fsanitize_recover : Flag<["-"], "fsanitize-recover">, Group<f_clang_Group>;
def fno_sanitize_recover : Flag<["-"], "fno-sanitize-recover">,
Flags<[CoreOption, DriverOption]>,
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