js/src/wasm/WasmModule.h
author Luke Wagner <luke@mozilla.com>
Mon, 20 Aug 2018 11:42:46 -0500
changeset 487551 6129cb421151f9a4f6032a3a2e48a71209850711
parent 486036 ac7bd965f86b3ae24921f35072eeea2204c82bba
child 490468 603f0c6003b3ec81be847304b71124fcda216c20
permissions -rw-r--r--
Bug 1482932 - Baldr: replace unaligned access trap with out of bounds trap (r=lth)

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 *
 * Copyright 2015 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.
 */

#ifndef wasm_module_h
#define wasm_module_h

#include "jit/shared/Assembler-shared.h"
#include "js/TypeDecls.h"
#include "threading/ConditionVariable.h"
#include "threading/Mutex.h"
#include "vm/MutexIDs.h"
#include "wasm/WasmCode.h"
#include "wasm/WasmTable.h"
#include "wasm/WasmValidate.h"

namespace js {
namespace wasm {

struct CompileArgs;

// LinkData contains all the metadata necessary to patch all the locations
// that depend on the absolute address of a ModuleSegment.
//
// LinkData is built incrementally by ModuleGenerator and then stored immutably
// in Module. LinkData is distinct from Metadata in that LinkData is owned and
// destroyed by the Module since it is not needed after instantiation; Metadata
// is needed at runtime.

struct LinkDataTierCacheablePod
{
    uint32_t trapOffset = 0;

    LinkDataTierCacheablePod() = default;
};

struct LinkDataTier : LinkDataTierCacheablePod
{
    const Tier tier;

    explicit LinkDataTier(Tier tier) : tier(tier) {}

    LinkDataTierCacheablePod& pod() { return *this; }
    const LinkDataTierCacheablePod& pod() const { return *this; }

    struct InternalLink {
        uint32_t patchAtOffset;
        uint32_t targetOffset;
#ifdef JS_CODELABEL_LINKMODE
        uint32_t mode;
#endif
    };
    typedef Vector<InternalLink, 0, SystemAllocPolicy> InternalLinkVector;

    struct SymbolicLinkArray : EnumeratedArray<SymbolicAddress, SymbolicAddress::Limit, Uint32Vector> {
        WASM_DECLARE_SERIALIZABLE(SymbolicLinkArray)
    };

    InternalLinkVector  internalLinks;
    SymbolicLinkArray   symbolicLinks;

    WASM_DECLARE_SERIALIZABLE(LinkData)
};

typedef UniquePtr<LinkDataTier> UniqueLinkDataTier;

class LinkData
{
    UniqueLinkDataTier         tier1_; // Always present
    mutable UniqueLinkDataTier tier2_; // Access only if hasTier2() is true

  public:
    LinkData() {}
    explicit LinkData(UniqueLinkDataTier tier) : tier1_(std::move(tier)) {}

    void setTier2(UniqueLinkDataTier linkData) const;
    const LinkDataTier& tier(Tier tier) const;

    WASM_DECLARE_SERIALIZABLE(LinkData)
};

// Module represents a compiled wasm module and primarily provides two
// operations: instantiation and serialization. A Module can be instantiated any
// number of times to produce new Instance objects. A Module can be serialized
// any number of times such that the serialized bytes can be deserialized later
// to produce a new, equivalent Module.
//
// Fully linked-and-instantiated code (represented by Code and its owned
// ModuleSegment) can be shared between instances, provided none of those
// instances are being debugged. If patchable code is needed then each instance
// must have its own Code. Module eagerly creates a new Code and gives it to the
// first instance; it then instantiates new Code objects from a copy of the
// unlinked code that it keeps around for that purpose.

class Module : public JS::WasmModule
{
    const Assumptions       assumptions_;
    const SharedCode        code_;
    const UniqueConstBytes  unlinkedCodeForDebugging_;
    const LinkData          linkData_;
    const ImportVector      imports_;
    const ExportVector      exports_;
    const DataSegmentVector dataSegments_;
    const ElemSegmentVector elemSegments_;
    const StructTypeVector  structTypes_;
    const SharedBytes       bytecode_;

    // This flag is only used for testing purposes and is racily updated as soon
    // as tier-2 compilation finishes (in success or failure).

    mutable Atomic<bool>    testingTier2Active_;

    // `codeIsBusy_` is set to false initially and then to true when `code_` is
    // already being used for an instance and can't be shared because it may be
    // patched by the debugger. Subsequent instances must then create copies
    // by linking the `unlinkedCodeForDebugging_`.

    mutable Atomic<bool>    codeIsBusy_;

    bool instantiateFunctions(JSContext* cx, Handle<FunctionVector> funcImports) const;
    bool instantiateMemory(JSContext* cx, MutableHandleWasmMemoryObject memory) const;
    bool instantiateTable(JSContext* cx,
                          MutableHandleWasmTableObject table,
                          SharedTableVector* tables) const;
    bool instantiateGlobals(JSContext* cx, HandleValVector globalImportValues,
                            WasmGlobalObjectVector& globalObjs) const;
    bool initSegments(JSContext* cx,
                      HandleWasmInstanceObject instance,
                      Handle<FunctionVector> funcImports,
                      HandleWasmMemoryObject memory,
                      HandleValVector globalImportValues) const;

    class Tier2GeneratorTaskImpl;

  public:
    Module(Assumptions&& assumptions,
           const Code& code,
           UniqueConstBytes unlinkedCodeForDebugging,
           LinkData&& linkData,
           ImportVector&& imports,
           ExportVector&& exports,
           DataSegmentVector&& dataSegments,
           ElemSegmentVector&& elemSegments,
           StructTypeVector&& structTypes,
           const ShareableBytes& bytecode)
      : assumptions_(std::move(assumptions)),
        code_(&code),
        unlinkedCodeForDebugging_(std::move(unlinkedCodeForDebugging)),
        linkData_(std::move(linkData)),
        imports_(std::move(imports)),
        exports_(std::move(exports)),
        dataSegments_(std::move(dataSegments)),
        elemSegments_(std::move(elemSegments)),
        structTypes_(std::move(structTypes)),
        bytecode_(&bytecode),
        testingTier2Active_(false),
        codeIsBusy_(false)
    {
        MOZ_ASSERT_IF(metadata().debugEnabled, unlinkedCodeForDebugging_);
    }
    ~Module() override { /* Note: can be called on any thread */ }

    const Code& code() const { return *code_; }
    const ModuleSegment& moduleSegment(Tier t) const { return code_->segment(t); }
    const Metadata& metadata() const { return code_->metadata(); }
    const MetadataTier& metadata(Tier t) const { return code_->metadata(t); }
    const LinkData& linkData() const { return linkData_; }
    const LinkDataTier& linkData(Tier t) const { return linkData_.tier(t); }
    const ImportVector& imports() const { return imports_; }
    const ExportVector& exports() const { return exports_; }
    const ShareableBytes& bytecode() const { return *bytecode_; }
    uint32_t codeLength(Tier t) const { return code_->segment(t).length(); }

    // Instantiate this module with the given imports:

    bool instantiate(JSContext* cx,
                     Handle<FunctionVector> funcImports,
                     HandleWasmTableObject tableImport,
                     HandleWasmMemoryObject memoryImport,
                     HandleValVector globalImportValues,
                     WasmGlobalObjectVector& globalObjs,
                     HandleObject instanceProto,
                     MutableHandleWasmInstanceObject instanceObj) const;

    // Tier-2 compilation may be initiated after the Module is constructed at
    // most once. When tier-2 compilation completes, ModuleGenerator calls
    // finishTier2() from a helper thread, passing tier-variant data which will
    // be installed and made visible.

    void startTier2(const CompileArgs& args);
    bool finishTier2(UniqueLinkDataTier linkData2, UniqueCodeTier tier2, ModuleEnvironment* env2);

    void testingBlockOnTier2Complete() const;
    bool testingTier2Active() const { return testingTier2Active_; }

    // Currently dead, but will be ressurrected with shell tests (bug 1330661)
    // and HTTP cache integration.

    size_t compiledSerializedSize() const;
    void compiledSerialize(uint8_t* compiledBegin, size_t compiledSize) const;

    static bool assumptionsMatch(const Assumptions& current, const uint8_t* compiledBegin,
                                 size_t remain);
    static RefPtr<Module> deserialize(const uint8_t* bytecodeBegin, size_t bytecodeSize,
                                      const uint8_t* compiledBegin, size_t compiledSize,
                                      Metadata* maybeMetadata = nullptr);

    // JS API and JS::WasmModule implementation:

    JSObject* createObject(JSContext* cx) override;

    // about:memory reporting:

    void addSizeOfMisc(MallocSizeOf mallocSizeOf,
                       Metadata::SeenSet* seenMetadata,
                       ShareableBytes::SeenSet* seenBytes,
                       Code::SeenSet* seenCode,
                       size_t* code, size_t* data) const;

    // Generated code analysis support:

    bool extractCode(JSContext* cx, Tier tier, MutableHandleValue vp) const;
};

typedef RefPtr<Module> SharedModule;

// JS API implementations:

SharedModule
DeserializeModule(PRFileDesc* bytecode, JS::BuildIdCharVector&& buildId, UniqueChars filename,
                  unsigned line);

} // namespace wasm
} // namespace js

#endif // wasm_module_h