eugenis created this revision.
eugenis added reviewers: cryptoad, hctim.
Herald added projects: Sanitizers, LLVM.
Herald added a subscriber: Sanitizers.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D72674
Files:
compiler-rt/lib/gwp_asan/guarded_pool_allocator.cpp
compiler-rt/lib/gwp_asan/guarded_pool_allocator.h
compiler-rt/lib/scudo/standalone/combined.h
Index: compiler-rt/lib/scudo/standalone/combined.h
===================================================================
--- compiler-rt/lib/scudo/standalone/combined.h
+++ compiler-rt/lib/scudo/standalone/combined.h
@@ -23,12 +23,6 @@
#ifdef GWP_ASAN_HOOKS
#include "gwp_asan/guarded_pool_allocator.h"
-// GWP-ASan is declared here in order to avoid indirect call overhead. It's also
-// instantiated outside of the Allocator class, as the allocator is only
-// zero-initialised. GWP-ASan requires constant initialisation, and the Scudo
-// allocator doesn't have a constexpr constructor (see discussion here:
-// https://reviews.llvm.org/D69265#inline-624315).
-static gwp_asan::GuardedPoolAllocator GuardedAlloc;
#endif // GWP_ASAN_HOOKS
extern "C" inline void EmptyCallback() {}
@@ -589,6 +583,10 @@
u32 QuarantineMaxChunkSize; // quarantine_max_chunk_size
} Options;
+#ifdef GWP_ASAN_HOOKS
+ gwp_asan::GuardedPoolAllocator GuardedAlloc;
+#endif // GWP_ASAN_HOOKS
+
// The following might get optimized out by the compiler.
NOINLINE void performSanityChecks() {
// Verify that the header offset field can hold the maximum offset. In the
Index: compiler-rt/lib/gwp_asan/guarded_pool_allocator.h
===================================================================
--- compiler-rt/lib/gwp_asan/guarded_pool_allocator.h
+++ compiler-rt/lib/gwp_asan/guarded_pool_allocator.h
@@ -111,7 +111,7 @@
// == 1 means we "should sample this allocation".
if (GWP_ASAN_UNLIKELY(ThreadLocals.NextSampleCounter == 0))
ThreadLocals.NextSampleCounter =
- (getRandomUnsigned32() % AdjustedSampleRate) + 1;
+ (getRandomUnsigned32() % (AdjustedSampleRatePlusOne - 1)) + 1;
return GWP_ASAN_UNLIKELY(--ThreadLocals.NextSampleCounter == 0);
}
@@ -231,7 +231,7 @@
size_t NumSampledAllocations = 0;
// Pointer to the pool of guarded slots. Note that this points to the start of
// the pool (which is a guard page), not a pointer to the first guarded page.
- uintptr_t GuardedPagePool = UINTPTR_MAX;
+ uintptr_t GuardedPagePool = 0;
uintptr_t GuardedPagePoolEnd = 0;
// Pointer to the allocation metadata (allocation/deallocation stack traces),
// if any.
@@ -258,7 +258,7 @@
// where we would calculate modulo zero. This value is set UINT32_MAX, as when
// GWP-ASan is disabled, we wish to never spend wasted cycles recalculating
// the sample rate.
- uint32_t AdjustedSampleRate = UINT32_MAX;
+ uint32_t AdjustedSampleRatePlusOne = 0;
// Pack the thread local variables into a struct to ensure that they're in
// the same cache line for performance reasons. These are the most touched
Index: compiler-rt/lib/gwp_asan/guarded_pool_allocator.cpp
===================================================================
--- compiler-rt/lib/gwp_asan/guarded_pool_allocator.cpp
+++ compiler-rt/lib/gwp_asan/guarded_pool_allocator.cpp
@@ -157,9 +157,9 @@
// Multiply the sample rate by 2 to give a good, fast approximation for (1 /
// SampleRate) chance of sampling.
if (Opts.SampleRate != 1)
- AdjustedSampleRate = static_cast<uint32_t>(Opts.SampleRate) * 2;
+ AdjustedSampleRatePlusOne = static_cast<uint32_t>(Opts.SampleRate) * 2 + 1;
else
- AdjustedSampleRate = 1;
+ AdjustedSampleRatePlusOne = 2;
GuardedPagePool = reinterpret_cast<uintptr_t>(GuardedPoolMemory);
GuardedPagePoolEnd =
@@ -187,10 +187,10 @@
}
void GuardedPoolAllocator::uninitTestOnly() {
- if (GuardedPagePool != UINTPTR_MAX) {
+ if (GuardedPagePool) {
unmapMemory(reinterpret_cast<void *>(GuardedPagePool),
GuardedPagePoolEnd - GuardedPagePool);
- GuardedPagePool = UINTPTR_MAX;
+ GuardedPagePool = 0;
GuardedPagePoolEnd = 0;
}
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