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Diffstat (limited to 'lib/hwasan/hwasan_thread_list.h')
| -rw-r--r-- | lib/hwasan/hwasan_thread_list.h | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/lib/hwasan/hwasan_thread_list.h b/lib/hwasan/hwasan_thread_list.h new file mode 100644 index 000000000..53747b51f --- /dev/null +++ b/lib/hwasan/hwasan_thread_list.h @@ -0,0 +1,200 @@ +//===-- hwasan_thread_list.h ------------------------------------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file is a part of HWAddressSanitizer. +// +//===----------------------------------------------------------------------===// + +// HwasanThreadList is a registry for live threads, as well as an allocator for +// HwasanThread objects and their stack history ring buffers. There are +// constraints on memory layout of the shadow region and CompactRingBuffer that +// are part of the ABI contract between compiler-rt and llvm. +// +// * Start of the shadow memory region is aligned to 2**kShadowBaseAlignment. +// * All stack ring buffers are located within (2**kShadowBaseAlignment) +// sized region below and adjacent to the shadow region. +// * Each ring buffer has a size of (2**N)*4096 where N is in [0, 8), and is +// aligned to twice its size. The value of N can be different for each buffer. +// +// These constrains guarantee that, given an address A of any element of the +// ring buffer, +// A_next = (A + sizeof(uptr)) & ~((1 << (N + 13)) - 1) +// is the address of the next element of that ring buffer (with wrap-around). +// And, with K = kShadowBaseAlignment, +// S = (A | ((1 << K) - 1)) + 1 +// (align up to kShadowBaseAlignment) is the start of the shadow region. +// +// These calculations are used in compiler instrumentation to update the ring +// buffer and obtain the base address of shadow using only two inputs: address +// of the current element of the ring buffer, and N (i.e. size of the ring +// buffer). Since the value of N is very limited, we pack both inputs into a +// single thread-local word as +// (1 << (N + 56)) | A +// See the implementation of class CompactRingBuffer, which is what is stored in +// said thread-local word. +// +// Note the unusual way of aligning up the address of the shadow: +// (A | ((1 << K) - 1)) + 1 +// It is only correct if A is not already equal to the shadow base address, but +// it saves 2 instructions on AArch64. + +#include "hwasan.h" +#include "hwasan_allocator.h" +#include "hwasan_flags.h" +#include "hwasan_thread.h" + +#include "sanitizer_common/sanitizer_placement_new.h" + +namespace __hwasan { + +static uptr RingBufferSize() { + uptr desired_bytes = flags()->stack_history_size * sizeof(uptr); + // FIXME: increase the limit to 8 once this bug is fixed: + // https://bugs.llvm.org/show_bug.cgi?id=39030 + for (int shift = 1; shift < 7; ++shift) { + uptr size = 4096 * (1ULL << shift); + if (size >= desired_bytes) + return size; + } + Printf("stack history size too large: %d\n", flags()->stack_history_size); + CHECK(0); + return 0; +} + +struct ThreadListHead { + Thread *list_; + + ThreadListHead() : list_(nullptr) {} + + void Push(Thread *t) { + t->next_ = list_; + list_ = t; + } + + Thread *Pop() { + Thread *t = list_; + if (t) + list_ = t->next_; + return t; + } + + void Remove(Thread *t) { + Thread **cur = &list_; + while (*cur != t) cur = &(*cur)->next_; + CHECK(*cur && "thread not found"); + *cur = (*cur)->next_; + } + + template <class CB> + void ForEach(CB cb) { + Thread *t = list_; + while (t) { + cb(t); + t = t->next_; + } + } +}; + +struct ThreadStats { + uptr n_live_threads; + uptr total_stack_size; +}; + +class HwasanThreadList { + public: + HwasanThreadList(uptr storage, uptr size) + : free_space_(storage), + free_space_end_(storage + size), + ring_buffer_size_(RingBufferSize()) {} + + Thread *CreateCurrentThread() { + Thread *t; + { + SpinMutexLock l(&list_mutex_); + t = free_list_.Pop(); + if (t) + internal_memset((void *)t, 0, sizeof(Thread) + ring_buffer_size_); + else + t = AllocThread(); + live_list_.Push(t); + } + t->Init((uptr)(t + 1), ring_buffer_size_); + AddThreadStats(t); + return t; + } + + void ReleaseThread(Thread *t) { + // FIXME: madvise away the ring buffer? + RemoveThreadStats(t); + t->Destroy(); + SpinMutexLock l(&list_mutex_); + live_list_.Remove(t); + free_list_.Push(t); + } + + Thread *GetThreadByBufferAddress(uptr p) { + uptr align = ring_buffer_size_ * 2; + return (Thread *)(RoundDownTo(p, align) - sizeof(Thread)); + } + + uptr MemoryUsedPerThread() { + uptr res = sizeof(Thread) + ring_buffer_size_; + if (auto sz = flags()->heap_history_size) + res += HeapAllocationsRingBuffer::SizeInBytes(sz); + return res; + } + + template <class CB> + void VisitAllLiveThreads(CB cb) { + SpinMutexLock l(&list_mutex_); + live_list_.ForEach(cb); + } + + void AddThreadStats(Thread *t) { + SpinMutexLock l(&stats_mutex_); + stats_.n_live_threads++; + stats_.total_stack_size += t->stack_size(); + } + + void RemoveThreadStats(Thread *t) { + SpinMutexLock l(&stats_mutex_); + stats_.n_live_threads--; + stats_.total_stack_size -= t->stack_size(); + } + + ThreadStats GetThreadStats() { + SpinMutexLock l(&stats_mutex_); + return stats_; + } + + private: + Thread *AllocThread() { + uptr align = ring_buffer_size_ * 2; + uptr ring_buffer_start = RoundUpTo(free_space_ + sizeof(Thread), align); + free_space_ = ring_buffer_start + ring_buffer_size_; + CHECK(free_space_ <= free_space_end_ && "out of thread memory"); + return (Thread *)(ring_buffer_start - sizeof(Thread)); + } + + uptr free_space_; + uptr free_space_end_; + uptr ring_buffer_size_; + + ThreadListHead free_list_; + ThreadListHead live_list_; + SpinMutex list_mutex_; + + ThreadStats stats_; + SpinMutex stats_mutex_; +}; + +void InitThreadList(uptr storage, uptr size); +HwasanThreadList &hwasanThreadList(); + +} // namespace |