path: root/Source/JavaScriptCore/jit/ExecutableAllocator.h

/*
 * Copyright (C) 2008 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#ifndef ExecutableAllocator_h
#define ExecutableAllocator_h
#include <stddef.h> // for ptrdiff_t
#include <limits>
#include <wtf/Assertions.h>
#include <wtf/PageAllocation.h>
#include <wtf/PassRefPtr.h>
#include <wtf/RefCounted.h>
#include <wtf/UnusedParam.h>
#include <wtf/Vector.h>

#if OS(IOS)
#include <libkern/OSCacheControl.h>
#include <sys/mman.h>
#endif

#if OS(SYMBIAN)
#include <e32std.h>
#endif

#if CPU(MIPS) && OS(LINUX)
#include <sys/cachectl.h>
#endif

#if OS(WINCE)
// From pkfuncs.h (private header file from the Platform Builder)
#define CACHE_SYNC_ALL 0x07F
extern "C" __declspec(dllimport) void CacheRangeFlush(LPVOID pAddr, DWORD dwLength, DWORD dwFlags);
#endif

#if PLATFORM(BREWMP)
#include <AEEIMemCache1.h>
#include <AEEMemCache1.bid>
#include <wtf/brew/RefPtrBrew.h>
#endif

#define JIT_ALLOCATOR_PAGE_SIZE (ExecutableAllocator::pageSize)
#define JIT_ALLOCATOR_LARGE_ALLOC_SIZE (ExecutableAllocator::pageSize * 4)

#if ENABLE(ASSEMBLER_WX_EXCLUSIVE)
#define PROTECTION_FLAGS_RW (PROT_READ | PROT_WRITE)
#define PROTECTION_FLAGS_RX (PROT_READ | PROT_EXEC)
#define EXECUTABLE_POOL_WRITABLE false
#else
#define EXECUTABLE_POOL_WRITABLE true
#endif

namespace JSC {

inline size_t roundUpAllocationSize(size_t request, size_t granularity)
{
    if ((std::numeric_limits<size_t>::max() - granularity) <= request)
        CRASH(); // Allocation is too large
    
    // Round up to next page boundary
    size_t size = request + (granularity - 1);
    size = size & ~(granularity - 1);
    ASSERT(size >= request);
    return size;
}

}

#if ENABLE(JIT) && ENABLE(ASSEMBLER)

namespace JSC {

class ExecutablePool : public RefCounted<ExecutablePool> {
public:
#if ENABLE(EXECUTABLE_ALLOCATOR_DEMAND)
    typedef PageAllocation Allocation;
#else
    class Allocation {
    public:
        Allocation(void* base, size_t size)
            : m_base(base)
            , m_size(size)
        {
        }
        void* base() { return m_base; }
        size_t size() { return m_size; }
        bool operator!() const { return !m_base; }

    private:
        void* m_base;
        size_t m_size;
    };
#endif
    typedef Vector<Allocation, 2> AllocationList;

    static PassRefPtr<ExecutablePool> create(size_t n)
    {
        return adoptRef(new ExecutablePool(n));
    }

    void* alloc(size_t n)
    {
        ASSERT(m_freePtr <= m_end);

        // Round 'n' up to a multiple of word size; if all allocations are of
        // word sized quantities, then all subsequent allocations will be aligned.
        n = roundUpAllocationSize(n, sizeof(void*));

        if (static_cast<ptrdiff_t>(n) < (m_end - m_freePtr)) {
            void* result = m_freePtr;
            m_freePtr += n;
            return result;
        }

        // Insufficient space to allocate in the existing pool
        // so we need allocate into a new pool
        return poolAllocate(n);
    }
    
    void tryShrink(void* allocation, size_t oldSize, size_t newSize)
    {
        if (static_cast<char*>(allocation) + oldSize != m_freePtr)
            return;
        m_freePtr = static_cast<char*>(allocation) + roundUpAllocationSize(newSize, sizeof(void*));
    }

    ~ExecutablePool()
    {
        AllocationList::iterator end = m_pools.end();
        for (AllocationList::iterator ptr = m_pools.begin(); ptr != end; ++ptr)
            ExecutablePool::systemRelease(*ptr);
    }

    size_t available() const { return (m_pools.size() > 1) ? 0 : m_end - m_freePtr; }

private:
    static Allocation systemAlloc(size_t n);
    static void systemRelease(Allocation& alloc);

    ExecutablePool(size_t n);

    void* poolAllocate(size_t n);

    char* m_freePtr;
    char* m_end;
    AllocationList m_pools;
};

class ExecutableAllocator {
    enum ProtectionSeting { Writable, Executable };

public:
    static size_t pageSize;
    ExecutableAllocator()
    {
        if (!pageSize)
            intializePageSize();
        if (isValid())
            m_smallAllocationPool = ExecutablePool::create(JIT_ALLOCATOR_LARGE_ALLOC_SIZE);
#if !ENABLE(INTERPRETER)
        else
            CRASH();
#endif
    }

    bool isValid() const;

    static bool underMemoryPressure();

    PassRefPtr<ExecutablePool> poolForSize(size_t n)
    {
        // Try to fit in the existing small allocator
        ASSERT(m_smallAllocationPool);
        if (n < m_smallAllocationPool->available())
            return m_smallAllocationPool;

        // If the request is large, we just provide a unshared allocator
        if (n > JIT_ALLOCATOR_LARGE_ALLOC_SIZE)
            return ExecutablePool::create(n);

        // Create a new allocator
        RefPtr<ExecutablePool> pool = ExecutablePool::create(JIT_ALLOCATOR_LARGE_ALLOC_SIZE);

        // If the new allocator will result in more free space than in
        // the current small allocator, then we will use it instead
        if ((pool->available() - n) > m_smallAllocationPool->available())
            m_smallAllocationPool = pool;
        return pool.release();
    }

#if ENABLE(ASSEMBLER_WX_EXCLUSIVE)
    static void makeWritable(void* start, size_t size)
    {
        reprotectRegion(start, size, Writable);
    }

    static void makeExecutable(void* start, size_t size)
    {
        reprotectRegion(start, size, Executable);
    }
#else
    static void makeWritable(void*, size_t) {}
    static void makeExecutable(void*, size_t) {}
#endif


#if CPU(X86) || CPU(X86_64)
    static void cacheFlush(void*, size_t)
    {
    }
#elif CPU(MIPS)
    static void cacheFlush(void* code, size_t size)
    {
#if GCC_VERSION_AT_LEAST(4, 3, 0)
#if WTF_MIPS_ISA_REV(2) && !GCC_VERSION_AT_LEAST(4, 4, 3)
        int lineSize;
        asm("rdhwr %0, $1" : "=r" (lineSize));
        //
        // Modify "start" and "end" to avoid GCC 4.3.0-4.4.2 bug in
        // mips_expand_synci_loop that may execute synci one more time.
        // "start" points to the fisrt byte of the cache line.
        // "end" points to the last byte of the line before the last cache line.
        // Because size is always a multiple of 4, this is safe to set
        // "end" to the last byte.
        //
        intptr_t start = reinterpret_cast<intptr_t>(code) & (-lineSize);
        intptr_t end = ((reinterpret_cast<intptr_t>(code) + size - 1) & (-lineSize)) - 1;
        __builtin___clear_cache(reinterpret_cast<char*>(start), reinterpret_cast<char*>(end));
#else
        intptr_t end = reinterpret_cast<intptr_t>(code) + size;
        __builtin___clear_cache(reinterpret_cast<char*>(code), reinterpret_cast<char*>(end));
#endif
#else
        _flush_cache(reinterpret_cast<char*>(code), size, BCACHE);
#endif
    }
#elif CPU(ARM_THUMB2) && OS(IOS)
    static void cacheFlush(void* code, size_t size)
    {
        sys_cache_control(kCacheFunctionPrepareForExecution, code, size);
    }
#elif CPU(ARM_THUMB2) && OS(LINUX)
    static void cacheFlush(void* code, size_t size)
    {
        asm volatile (
            "push    {r7}\n"
            "mov     r0, %0\n"
            "mov     r1, %1\n"
            "movw    r7, #0x2\n"
            "movt    r7, #0xf\n"
            "movs    r2, #0x0\n"
            "svc     0x0\n"
            "pop     {r7}\n"
            :
            : "r" (code), "r" (reinterpret_cast<char*>(code) + size)
            : "r0", "r1", "r2");
    }
#elif OS(SYMBIAN)
    static void cacheFlush(void* code, size_t size)
    {
        User::IMB_Range(code, static_cast<char*>(code) + size);
    }
#elif CPU(ARM_TRADITIONAL) && OS(LINUX) && COMPILER(RVCT)
    static __asm void cacheFlush(void* code, size_t size);
#elif CPU(ARM_TRADITIONAL) && OS(LINUX) && COMPILER(GCC)
    static void cacheFlush(void* code, size_t size)
    {
        asm volatile (
            "push    {r7}\n"
            "mov     r0, %0\n"
            "mov     r1, %1\n"
            "mov     r7, #0xf0000\n"
            "add     r7, r7, #0x2\n"
            "mov     r2, #0x0\n"
            "svc     0x0\n"
            "pop     {r7}\n"
            :
            : "r" (code), "r" (reinterpret_cast<char*>(code) + size)
            : "r0", "r1", "r2");
    }
#elif OS(WINCE)
    static void cacheFlush(void* code, size_t size)
    {
        CacheRangeFlush(code, size, CACHE_SYNC_ALL);
    }
#elif PLATFORM(BREWMP)
    static void cacheFlush(void* code, size_t size)
    {
        RefPtr<IMemCache1> memCache = createRefPtrInstance<IMemCache1>(AEECLSID_MemCache1);
        IMemCache1_ClearCache(memCache.get(), reinterpret_cast<uint32>(code), size, MEMSPACE_CACHE_FLUSH, MEMSPACE_DATACACHE);
        IMemCache1_ClearCache(memCache.get(), reinterpret_cast<uint32>(code), size, MEMSPACE_CACHE_INVALIDATE, MEMSPACE_INSTCACHE);
    }
#else
    #error "The cacheFlush support is missing on this platform."
#endif
    static size_t committedByteCount();

private:

#if ENABLE(ASSEMBLER_WX_EXCLUSIVE)
    static void reprotectRegion(void*, size_t, ProtectionSeting);
#endif

    RefPtr<ExecutablePool> m_smallAllocationPool;
    static void intializePageSize();
};

inline ExecutablePool::ExecutablePool(size_t n)
{
    size_t allocSize = roundUpAllocationSize(n, JIT_ALLOCATOR_PAGE_SIZE);
    Allocation mem = systemAlloc(allocSize);
    m_pools.append(mem);
    m_freePtr = static_cast<char*>(mem.base());
    if (!m_freePtr)
        CRASH(); // Failed to allocate
    m_end = m_freePtr + allocSize;
}

inline void* ExecutablePool::poolAllocate(size_t n)
{
    size_t allocSize = roundUpAllocationSize(n, JIT_ALLOCATOR_PAGE_SIZE);
    
    Allocation result = systemAlloc(allocSize);
    if (!result.base())
        CRASH(); // Failed to allocate
    
    ASSERT(m_end >= m_freePtr);
    if ((allocSize - n) > static_cast<size_t>(m_end - m_freePtr)) {
        // Replace allocation pool
        m_freePtr = static_cast<char*>(result.base()) + n;
        m_end = static_cast<char*>(result.base()) + allocSize;
    }

    m_pools.append(result);
    return result.base();
}

}

#endif // ENABLE(JIT) && ENABLE(ASSEMBLER)

#endif // !defined(ExecutableAllocator)