ExecutableAllocator.h [plain text]
#ifndef ExecutableAllocator_h
#define ExecutableAllocator_h
#include <stddef.h> // for ptrdiff_t
#include <limits>
#include <wtf/Assertions.h>
#include <wtf/PassRefPtr.h>
#include <wtf/RefCounted.h>
#include <wtf/UnusedParam.h>
#include <wtf/Vector.h>
#if OS(IPHONE_OS)
#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)
#define CACHE_SYNC_ALL 0x07F
extern "C" __declspec(dllimport) void CacheRangeFlush(LPVOID pAddr, DWORD dwLength, DWORD dwFlags);
#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 INITIAL_PROTECTION_FLAGS PROTECTION_FLAGS_RX
#else
#define INITIAL_PROTECTION_FLAGS (PROT_READ | PROT_WRITE | PROT_EXEC)
#endif
namespace JSC {
inline size_t roundUpAllocationSize(size_t request, size_t granularity)
{
if ((std::numeric_limits<size_t>::max() - granularity) <= request)
CRASH();
size_t size = request + (granularity - 1);
size = size & ~(granularity - 1);
ASSERT(size >= request);
return size;
}
}
#if ENABLE(ASSEMBLER)
namespace JSC {
class ExecutablePool : public RefCounted<ExecutablePool> {
private:
struct Allocation {
char* pages;
size_t size;
#if OS(SYMBIAN)
RChunk* chunk;
#endif
};
typedef Vector<Allocation, 2> AllocationList;
public:
static PassRefPtr<ExecutablePool> create(size_t n)
{
return adoptRef(new ExecutablePool(n));
}
void* alloc(size_t n)
{
ASSERT(m_freePtr <= m_end);
n = roundUpAllocationSize(n, sizeof(void*));
if (static_cast<ptrdiff_t>(n) < (m_end - m_freePtr)) {
void* result = m_freePtr;
m_freePtr += n;
return result;
}
return poolAllocate(n);
}
~ExecutablePool()
{
AllocationList::const_iterator end = m_pools.end();
for (AllocationList::const_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(const 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();
m_smallAllocationPool = ExecutablePool::create(JIT_ALLOCATOR_LARGE_ALLOC_SIZE);
}
PassRefPtr<ExecutablePool> poolForSize(size_t n)
{
if (n < m_smallAllocationPool->available())
return m_smallAllocationPool;
if (n > JIT_ALLOCATOR_LARGE_ALLOC_SIZE)
return ExecutablePool::create(n);
RefPtr<ExecutablePool> pool = ExecutablePool::create(JIT_ALLOCATOR_LARGE_ALLOC_SIZE);
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 COMPILER(GCC) && (GCC_VERSION >= 40300)
#if WTF_MIPS_ISA_REV(2) && (GCC_VERSION < 40403)
int lineSize;
asm("rdhwr %0, $1" : "=r" (lineSize));
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(IPHONE_OS)
static void cacheFlush(void* code, size_t size)
{
sys_dcache_flush(code, size);
sys_icache_invalidate(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);
}
#else
#error "The cacheFlush support is missing on this platform."
#endif
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 = mem.pages;
if (!m_freePtr)
CRASH(); 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.pages)
CRASH();
ASSERT(m_end >= m_freePtr);
if ((allocSize - n) > static_cast<size_t>(m_end - m_freePtr)) {
m_freePtr = result.pages + n;
m_end = result.pages + allocSize;
}
m_pools.append(result);
return result.pages;
}
}
#endif // ENABLE(ASSEMBLER)
#endif // !defined(ExecutableAllocator)