firefox-main/js/src/wasm/WasmProcess.cpp (file symbol)

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/*
* Copyright 2017 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "wasm/WasmProcess.h"
#include "mozilla/BinarySearch.h"
#include "mozilla/ScopeExit.h"
#include "gc/Memory.h"
#include "threading/ExclusiveData.h"
#include "vm/MutexIDs.h"
#include "vm/Runtime.h"
#include "wasm/WasmBuiltinModule.h"
#include "wasm/WasmBuiltins.h"
#include "wasm/WasmCode.h"
#include "wasm/WasmComponent.h"
#include "wasm/WasmInstance.h"
#include "wasm/WasmModuleTypes.h"
#include "wasm/WasmStaticTypeDefs.h"
using namespace js;
using namespace wasm;
// Per-process map from values of program-counter (pc) to CodeBlocks.
//
// Whenever a new CodeBlock is ready to use, it has to be registered so that
// we can have fast lookups from pc to CodeBlocks in numerous places. Since
// wasm compilation may be tiered, and the second tier doesn't have access to
// any JSContext/JS::Compartment/etc lying around, we have to use a process-wide
// map instead.
mozilla::Atomic<ThreadSafeCodeBlockMap*> wasm::sThreadSafeCodeBlockMap(nullptr);
struct ThreadSafeCodeBlockMap::CodeBlockPC {
const void* pc;
explicit CodeBlockPC(const void* pc) : pc(pc) {}
int operator()(const CodeBlock* cb) const {
if (cb->containsCodePC(pc)) {
return 0;
}
if (pc < cb->base()) {
return -1;
}
return 1;
}
};
ThreadSafeCodeBlockMap::ThreadSafeCodeBlockMap()
: mutatorsMutex_(mutexid::WasmCodeBlockMap),
mutableCodeBlocks_(&segments1_),
readonlyCodeBlocks_(&segments2_),
numActiveLookups_(0),
empty_(true) {}
ThreadSafeCodeBlockMap::~ThreadSafeCodeBlockMap() {
MOZ_RELEASE_ASSERT(numActiveLookups_ == 0);
segments1_.clearAndFree();
segments2_.clearAndFree();
}
void ThreadSafeCodeBlockMap::swapAndWait() {
// Both vectors are consistent for lookup at this point although their
// contents are different: there is no way for the looked up PC to be
// in the code segment that is getting registered, because the code
// segment is not even fully created yet.
// If a lookup happens before this instruction, then the
// soon-to-become-former read-only pointer is used during the lookup,
// which is valid.
mutableCodeBlocks_ = const_cast<RawCodeBlockVector*>(
readonlyCodeBlocks_.exchange(mutableCodeBlocks_));
// If a lookup happens after this instruction, then the updated vector
// is used, which is valid:
// - in case of insertion, it means the new vector contains more data,
// but it's fine since the code segment is getting registered and thus
// isn't even fully created yet, so the code can't be running.
// - in case of removal, it means the new vector contains one less
// entry, but it's fine since unregistering means the code segment
// isn't used by any live instance anymore, thus PC can't be in the
// to-be-removed code segment's range.
// A lookup could have happened on any of the two vectors. Wait for
// observers to be done using any vector before mutating.
while (numActiveLookups_ > 0) {
}
}
bool ThreadSafeCodeBlockMap::insert(const CodeBlock* cs) {
LockGuard<Mutex> lock(mutatorsMutex_);
size_t index;
MOZ_ALWAYS_FALSE(BinarySearchIf(*mutableCodeBlocks_, 0,
mutableCodeBlocks_->length(),
CodeBlockPC(cs->base()), &index));
if (!mutableCodeBlocks_->insert(mutableCodeBlocks_->begin() + index, cs)) {
return false;
}
// Set empty_ first to ensure it's seen before readonlyCodeBlocks_.
empty_ = false;
swapAndWait();
#ifdef DEBUG
size_t otherIndex;
MOZ_ALWAYS_FALSE(BinarySearchIf(*mutableCodeBlocks_, 0,
mutableCodeBlocks_->length(),
CodeBlockPC(cs->base()), &otherIndex));
MOZ_ASSERT(index == otherIndex);
#endif
// Although we could simply revert the insertion in the read-only
// vector, it is simpler to just crash and given that each CodeBlock
// consumes multiple pages, it is unlikely this insert() would OOM in
// practice
AutoEnterOOMUnsafeRegion oom;
if (!mutableCodeBlocks_->insert(mutableCodeBlocks_->begin() + index, cs)) {
oom.crash("when inserting a CodeBlock in the process-wide map");
}
return true;
}
void ThreadSafeCodeBlockMap::remove(const CodeBlock* cs) {
LockGuard<Mutex> lock(mutatorsMutex_);
size_t index;
MOZ_ALWAYS_TRUE(BinarySearchIf(*mutableCodeBlocks_, 0,
mutableCodeBlocks_->length(),
CodeBlockPC(cs->base()), &index));
mutableCodeBlocks_->erase(mutableCodeBlocks_->begin() + index);
swapAndWait();
#ifdef DEBUG
size_t otherIndex;
MOZ_ALWAYS_TRUE(BinarySearchIf(*mutableCodeBlocks_, 0,
mutableCodeBlocks_->length(),
CodeBlockPC(cs->base()), &otherIndex));
MOZ_ASSERT(index == otherIndex);
#endif
mutableCodeBlocks_->erase(mutableCodeBlocks_->begin() + index);
// Now that readonlyCodeBlocks_ is updated, we can update empty_.
empty_ = mutableCodeBlocks_->empty();
}
const CodeBlock* ThreadSafeCodeBlockMap::lookup(
const void* pc, const CodeRange** codeRange /* = nullptr */) {
auto decObserver = mozilla::MakeScopeExit([&] {
MOZ_ASSERT(numActiveLookups_ > 0);
numActiveLookups_--;
});
numActiveLookups_++;
const RawCodeBlockVector* readonly = readonlyCodeBlocks_;
size_t index;
if (!BinarySearchIf(*readonly, 0, readonly->length(), CodeBlockPC(pc),
&index)) {
if (codeRange) {
*codeRange = nullptr;
}
return nullptr;
}
// It is fine returning a raw CodeBlock*, because we assume we are
// looking up a live PC in code which is on the stack, keeping the
// CodeBlock alive.
const CodeBlock* result = (*readonly)[index];
if (codeRange) {
*codeRange = result->lookupRange(pc);
}
return result;
}
bool wasm::RegisterCodeBlock(const CodeBlock* cs) {
if (cs->length() == 0) {
return true;
}
// This function cannot race with startup/shutdown.
ThreadSafeCodeBlockMap* map = sThreadSafeCodeBlockMap;
MOZ_RELEASE_ASSERT(map);
return map->insert(cs);
}
void wasm::UnregisterCodeBlock(const CodeBlock* cs) {
if (cs->length() == 0) {
return;
}
// This function cannot race with startup/shutdown.
ThreadSafeCodeBlockMap* map = sThreadSafeCodeBlockMap;
MOZ_RELEASE_ASSERT(map);
map->remove(cs);
}
const CodeBlock* wasm::LookupCodeBlock(
const void* pc, const CodeRange** codeRange /*= nullptr */) {
ThreadSafeCodeBlockMap* map = sThreadSafeCodeBlockMap;
if (!map) {
return nullptr;
}
return map->lookup(pc, codeRange);
}
const Code* wasm::LookupCode(const void* pc,
const CodeRange** codeRange /* = nullptr */) {
const CodeBlock* found = LookupCodeBlock(pc, codeRange);
MOZ_ASSERT_IF(!found && codeRange, !*codeRange);
return found ? found->code : nullptr;
}
bool wasm::InCompiledCode(void* pc) {
if (LookupCodeBlock(pc)) {
return true;
}
const CodeRange* codeRange;
const uint8_t* codeBase;
return LookupBuiltinThunk(pc, &codeRange, &codeBase);
}
#ifdef WASM_SUPPORTS_HUGE_MEMORY
# if defined(__riscv)
// On riscv64, Sv39 is not enough for huge memory, so we require at least Sv48.
static const size_t MinAddressBitsForHugeMemory = 47;
# elif defined(__loongarch__) && (__loongarch_grlen == 64)
// On loong64 silicon, there are two addressing modes observed: 40b VA on
// Loongson 3B6000M/2K3000, and 48b VA on various other models. Only enable
// huge memory on the latter.
static const size_t MinAddressBitsForHugeMemory = 47;
# else
/*
* Some 64 bit systems greatly limit the range of available virtual memory. We
* require about 6GiB for each wasm huge memory, which can exhaust the address
* spaces of these systems quickly. In order to avoid this, we only enable huge
* memory if we observe a large enough address space.
*
* This number is conservatively chosen to continue using huge memory on our
* smallest address space system, Android on ARM64 (39 bits), along with a bit
* for error in detecting the address space limit.
*/
static const size_t MinAddressBitsForHugeMemory = 38;
# endif
/*
* In addition to the above, some systems impose an independent limit on the
* amount of virtual memory that may be used.
*/
static const size_t MinVirtualMemoryLimitForHugeMemory =
size_t(1) << MinAddressBitsForHugeMemory;
#endif
static bool sHugeMemoryEnabled32 = false;
bool wasm::IsHugeMemoryEnabled(wasm::AddressType t, wasm::PageSize sz) {
if (t == AddressType::I64 || sz != wasm::PageSize::Standard) {
// No support for huge memory with 64-bit memories or custom page sizes.
return false;
}
return sHugeMemoryEnabled32;
}
void ConfigureHugeMemory() {
#ifdef WASM_SUPPORTS_HUGE_MEMORY
MOZ_ASSERT(!sHugeMemoryEnabled32);
if (JS::Prefs::wasm_disable_huge_memory()) {
return;
}
if (gc::SystemAddressBits() < MinAddressBitsForHugeMemory) {
return;
}
if (gc::VirtualMemoryLimit() != size_t(-1) &&
gc::VirtualMemoryLimit() < MinVirtualMemoryLimitForHugeMemory) {
return;
}
sHugeMemoryEnabled32 = true;
#endif
}
#ifdef ENABLE_WASM_JSPI
const TagType* wasm::sJSPromiseTagType = nullptr;
#endif
const TagType* wasm::sWrappedJSValueTagType = nullptr;
static bool InitStaticTagTypes() {
MutableTagType type = js_new<TagType>();
if (!type || !type->initialize(StaticTypeDefs::jsExceptionTag)) {
return false;
}
MOZ_ASSERT(WrappedJSValueTagType_ValueOffset ==
type->exceptionArgOffsets()[0]);
type.forget(&sWrappedJSValueTagType);
#ifdef ENABLE_WASM_JSPI
type = js_new<TagType>();
if (!type || !type->initialize(StaticTypeDefs::jsPromiseTag)) {
return false;
}
type.forget(&sJSPromiseTagType);
#endif
return true;
}
bool wasm::Init() {
MOZ_RELEASE_ASSERT(!sThreadSafeCodeBlockMap);
// Assert invariants that should universally hold true, but cannot be checked
// at compile time.
uintptr_t pageSize = gc::SystemPageSize();
MOZ_RELEASE_ASSERT(wasm::NullPtrGuardSize <= pageSize);
MOZ_RELEASE_ASSERT(intptr_t(nullptr) == AnyRef::NullRefValue);
ConfigureHugeMemory();
AutoEnterOOMUnsafeRegion oomUnsafe;
ThreadSafeCodeBlockMap* map = js_new<ThreadSafeCodeBlockMap>();
if (!map) {
oomUnsafe.crash("js::wasm::Init");
}
if (!StaticTypeDefs::init()) {
oomUnsafe.crash("js::wasm::Init");
}
// This uses StaticTypeDefs
if (!BuiltinModuleFuncs::init()) {
oomUnsafe.crash("js::wasm::Init");
}
sThreadSafeCodeBlockMap = map;
if (!InitStaticTagTypes()) {
oomUnsafe.crash("js::wasm::Init");
}
return true;
}
void wasm::ShutDown() {
// If there are live runtimes then we are already pretty much leaking the
// world, so to avoid spurious assertions (which are valid and valuable when
// there are not live JSRuntimes), don't bother releasing anything here.
if (JSRuntime::hasLiveRuntimes()) {
return;
}
BuiltinModuleFuncs::destroy();
StaticTypeDefs::destroy();
PurgeCanonicalTypes();
#ifdef ENABLE_WASM_COMPONENTS
PurgeComponentCanonicalTypes();
#endif
#ifdef ENABLE_WASM_JSPI
if (sJSPromiseTagType) {
sJSPromiseTagType->Release();
sJSPromiseTagType = nullptr;
}
#endif
if (sWrappedJSValueTagType) {
sWrappedJSValueTagType->Release();
sWrappedJSValueTagType = nullptr;
}
// After signalling shutdown by clearing sThreadSafeCodeBlockMap, wait for
// concurrent wasm::LookupCodeBlock()s to finish.
ThreadSafeCodeBlockMap* map = sThreadSafeCodeBlockMap;
MOZ_RELEASE_ASSERT(map);
sThreadSafeCodeBlockMap = nullptr;
while (map->numActiveLookups() > 0) {
}
ReleaseBuiltinThunks();
js_delete(map);
}