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//===-- sanitizer_stackdepot.cc -------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is shared between AddressSanitizer and ThreadSanitizer
// run-time libraries.
//===----------------------------------------------------------------------===//
#include "sanitizer_stackdepot.h"
#include "sanitizer_common.h"
#include "sanitizer_hash.h"
#include "sanitizer_stackdepotbase.h"
namespace __sanitizer {
struct StackDepotNode {
StackDepotNode *link;
u32 id;
atomic_uint32_t hash_and_use_count; // hash_bits : 12; use_count : 20;
u32 size;
u32 tag;
uptr stack[1]; // [size]
static const u32 kTabSizeLog = SANITIZER_ANDROID ? 16 : 20;
// Lower kTabSizeLog bits are equal for all items in one bucket.
// We use these bits to store the per-stack use counter.
static const u32 kUseCountBits = kTabSizeLog;
static const u32 kMaxUseCount = 1 << kUseCountBits;
static const u32 kUseCountMask = (1 << kUseCountBits) - 1;
static const u32 kHashMask = ~kUseCountMask;
typedef StackTrace args_type;
bool eq(u32 hash, const args_type &args) const {
u32 hash_bits =
atomic_load(&hash_and_use_count, memory_order_relaxed) & kHashMask;
if ((hash & kHashMask) != hash_bits || args.size != size || args.tag != tag)
return false;
uptr i = 0;
for (; i < size; i++) {
if (stack[i] != args.trace[i]) return false;
}
return true;
}
static uptr storage_size(const args_type &args) {
return sizeof(StackDepotNode) + (args.size - 1) * sizeof(uptr);
}
static u32 hash(const args_type &args) {
MurMur2HashBuilder H(args.size * sizeof(uptr));
for (uptr i = 0; i < args.size; i++) H.add(args.trace[i]);
return H.get();
}
static bool is_valid(const args_type &args) {
return args.size > 0 && args.trace;
}
void store(const args_type &args, u32 hash) {
atomic_store(&hash_and_use_count, hash & kHashMask, memory_order_relaxed);
size = args.size;
tag = args.tag;
internal_memcpy(stack, args.trace, size * sizeof(uptr));
}
args_type load() const {
return args_type(&stack[0], size, tag);
}
StackDepotHandle get_handle() { return StackDepotHandle(this); }
typedef StackDepotHandle handle_type;
};
COMPILER_CHECK(StackDepotNode::kMaxUseCount == (u32)kStackDepotMaxUseCount);
u32 StackDepotHandle::id() { return node_->id; }
int StackDepotHandle::use_count() {
return atomic_load(&node_->hash_and_use_count, memory_order_relaxed) &
StackDepotNode::kUseCountMask;
}
void StackDepotHandle::inc_use_count_unsafe() {
u32 prev =
atomic_fetch_add(&node_->hash_and_use_count, 1, memory_order_relaxed) &
StackDepotNode::kUseCountMask;
CHECK_LT(prev + 1, StackDepotNode::kMaxUseCount);
}
// FIXME(dvyukov): this single reserved bit is used in TSan.
typedef StackDepotBase<StackDepotNode, 1, StackDepotNode::kTabSizeLog>
StackDepot;
static StackDepot theDepot;
StackDepotStats *StackDepotGetStats() {
return theDepot.GetStats();
}
u32 StackDepotPut(StackTrace stack) {
StackDepotHandle h = theDepot.Put(stack);
return h.valid() ? h.id() : 0;
}
StackDepotHandle StackDepotPut_WithHandle(StackTrace stack) {
return theDepot.Put(stack);
}
StackTrace StackDepotGet(u32 id) {
return theDepot.Get(id);
}
void StackDepotLockAll() {
theDepot.LockAll();
}
void StackDepotUnlockAll() {
theDepot.UnlockAll();
}
bool StackDepotReverseMap::IdDescPair::IdComparator(
const StackDepotReverseMap::IdDescPair &a,
const StackDepotReverseMap::IdDescPair &b) {
return a.id < b.id;
}
StackDepotReverseMap::StackDepotReverseMap() {
map_.reserve(StackDepotGetStats()->n_uniq_ids + 100);
for (int idx = 0; idx < StackDepot::kTabSize; idx++) {
atomic_uintptr_t *p = &theDepot.tab[idx];
uptr v = atomic_load(p, memory_order_consume);
StackDepotNode *s = (StackDepotNode*)(v & ~1);
for (; s; s = s->link) {
IdDescPair pair = {s->id, s};
map_.push_back(pair);
}
}
Sort(map_.data(), map_.size(), &IdDescPair::IdComparator);
}
StackTrace StackDepotReverseMap::Get(u32 id) {
if (!map_.size())
return StackTrace();
IdDescPair pair = {id, nullptr};
uptr idx =
InternalLowerBound(map_, 0, map_.size(), pair, IdDescPair::IdComparator);
if (idx > map_.size() || map_[idx].id != id)
return StackTrace();
return map_[idx].desc->load();
}
} // namespace __sanitizer
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