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Diffstat (limited to 'lib/sanitizer_common/sanitizer_stackdepot.cc')
| -rw-r--r-- | lib/sanitizer_common/sanitizer_stackdepot.cc | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/lib/sanitizer_common/sanitizer_stackdepot.cc b/lib/sanitizer_common/sanitizer_stackdepot.cc new file mode 100644 index 000000000000..08e5238325e5 --- /dev/null +++ b/lib/sanitizer_common/sanitizer_stackdepot.cc @@ -0,0 +1,204 @@ +//===-- sanitizer_stackdepot.cc -------------------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file is shared between AddressSanitizer and ThreadSanitizer +// run-time libraries. +//===----------------------------------------------------------------------===// + +#include "sanitizer_stackdepot.h" +#include "sanitizer_common.h" +#include "sanitizer_internal_defs.h" +#include "sanitizer_mutex.h" +#include "sanitizer_atomic.h" + +namespace __sanitizer { + +const int kTabSize = 1024 * 1024; // Hash table size. +const int kPartBits = 8; +const int kPartShift = sizeof(u32) * 8 - kPartBits - 1; +const int kPartCount = 1 << kPartBits; // Number of subparts in the table. +const int kPartSize = kTabSize / kPartCount; +const int kMaxId = 1 << kPartShift; + +struct StackDesc { + StackDesc *link; + u32 id; + u32 hash; + uptr size; + uptr stack[1]; // [size] +}; + +static struct { + StaticSpinMutex mtx; // Protects alloc of new blocks for region allocator. + atomic_uintptr_t region_pos; // Region allocator for StackDesc's. + atomic_uintptr_t region_end; + atomic_uintptr_t tab[kTabSize]; // Hash table of StackDesc's. + atomic_uint32_t seq[kPartCount]; // Unique id generators. +} depot; + +static StackDepotStats stats; + +StackDepotStats *StackDepotGetStats() { + return &stats; +} + +static u32 hash(const uptr *stack, uptr size) { + // murmur2 + const u32 m = 0x5bd1e995; + const u32 seed = 0x9747b28c; + const u32 r = 24; + u32 h = seed ^ (size * sizeof(uptr)); + for (uptr i = 0; i < size; i++) { + u32 k = stack[i]; + k *= m; + k ^= k >> r; + k *= m; + h *= m; + h ^= k; + } + h ^= h >> 13; + h *= m; + h ^= h >> 15; + return h; +} + +static StackDesc *tryallocDesc(uptr memsz) { + // Optimisic lock-free allocation, essentially try to bump the region ptr. + for (;;) { + uptr cmp = atomic_load(&depot.region_pos, memory_order_acquire); + uptr end = atomic_load(&depot.region_end, memory_order_acquire); + if (cmp == 0 || cmp + memsz > end) + return 0; + if (atomic_compare_exchange_weak( + &depot.region_pos, &cmp, cmp + memsz, + memory_order_acquire)) + return (StackDesc*)cmp; + } +} + +static StackDesc *allocDesc(uptr size) { + // First, try to allocate optimisitically. + uptr memsz = sizeof(StackDesc) + (size - 1) * sizeof(uptr); + StackDesc *s = tryallocDesc(memsz); + if (s) + return s; + // If failed, lock, retry and alloc new superblock. + SpinMutexLock l(&depot.mtx); + for (;;) { + s = tryallocDesc(memsz); + if (s) + return s; + atomic_store(&depot.region_pos, 0, memory_order_relaxed); + uptr allocsz = 64 * 1024; + if (allocsz < memsz) + allocsz = memsz; + uptr mem = (uptr)MmapOrDie(allocsz, "stack depot"); + stats.mapped += allocsz; + atomic_store(&depot.region_end, mem + allocsz, memory_order_release); + atomic_store(&depot.region_pos, mem, memory_order_release); + } +} + +static u32 find(StackDesc *s, const uptr *stack, uptr size, u32 hash) { + // Searches linked list s for the stack, returns its id. + for (; s; s = s->link) { + if (s->hash == hash && s->size == size) { + uptr i = 0; + for (; i < size; i++) { + if (stack[i] != s->stack[i]) + break; + } + if (i == size) + return s->id; + } + } + return 0; +} + +static StackDesc *lock(atomic_uintptr_t *p) { + // Uses the pointer lsb as mutex. + for (int i = 0;; i++) { + uptr cmp = atomic_load(p, memory_order_relaxed); + if ((cmp & 1) == 0 + && atomic_compare_exchange_weak(p, &cmp, cmp | 1, + memory_order_acquire)) + return (StackDesc*)cmp; + if (i < 10) + proc_yield(10); + else + internal_sched_yield(); + } +} + +static void unlock(atomic_uintptr_t *p, StackDesc *s) { + DCHECK_EQ((uptr)s & 1, 0); + atomic_store(p, (uptr)s, memory_order_release); +} + +u32 StackDepotPut(const uptr *stack, uptr size) { + if (stack == 0 || size == 0) + return 0; + uptr h = hash(stack, size); + atomic_uintptr_t *p = &depot.tab[h % kTabSize]; + uptr v = atomic_load(p, memory_order_consume); + StackDesc *s = (StackDesc*)(v & ~1); + // First, try to find the existing stack. + u32 id = find(s, stack, size, h); + if (id) + return id; + // If failed, lock, retry and insert new. + StackDesc *s2 = lock(p); + if (s2 != s) { + id = find(s2, stack, size, h); + if (id) { + unlock(p, s2); + return id; + } + } + uptr part = (h % kTabSize) / kPartSize; + id = atomic_fetch_add(&depot.seq[part], 1, memory_order_relaxed) + 1; + stats.n_uniq_ids++; + CHECK_LT(id, kMaxId); + id |= part << kPartShift; + CHECK_NE(id, 0); + CHECK_EQ(id & (1u << 31), 0); + s = allocDesc(size); + s->id = id; + s->hash = h; + s->size = size; + internal_memcpy(s->stack, stack, size * sizeof(uptr)); + s->link = s2; + unlock(p, s); + return id; +} + +const uptr *StackDepotGet(u32 id, uptr *size) { + if (id == 0) + return 0; + CHECK_EQ(id & (1u << 31), 0); + // High kPartBits contain part id, so we need to scan at most kPartSize lists. + uptr part = id >> kPartShift; + for (int i = 0; i != kPartSize; i++) { + uptr idx = part * kPartSize + i; + CHECK_LT(idx, kTabSize); + atomic_uintptr_t *p = &depot.tab[idx]; + uptr v = atomic_load(p, memory_order_consume); + StackDesc *s = (StackDesc*)(v & ~1); + for (; s; s = s->link) { + if (s->id == id) { + *size = s->size; + return s->stack; + } + } + } + *size = 0; + return 0; +} + +} // namespace __sanitizer |