Files
snmalloc/src/pal/pal_windows.h
2019-02-20 17:36:39 +01:00

132 lines
3.4 KiB
C++

#pragma once
#include "../ds/bits.h"
#include "../mem/allocconfig.h"
#ifdef _WIN32
# define WIN32_LEAN_AND_MEAN
# define NOMINMAX
# include <windows.h>
// VirtualAlloc2 is exposed in RS5 headers.
# ifdef NTDDI_WIN10_RS5
# if (NTDDI_VERSION >= NTDDI_WIN10_RS5) && (WINVER >= _WIN32_WINNT_WIN10)\
&& !defined(USE_SYSTEMATIC_TESTING)
# define PLATFORM_HAS_VIRTUALALLOC2
# endif
# endif
namespace snmalloc
{
class PALWindows
{
public:
static void error(const char* const str)
{
puts(str);
abort();
}
/// Notify platform that we will not be using these pages
void notify_not_using(void* p, size_t size) noexcept
{
assert(bits::is_aligned_block<OS_PAGE_SIZE>(p, size));
BOOL ok = VirtualFree(p, size, MEM_DECOMMIT);
if (!ok)
error("VirtualFree failed");
}
/// Notify platform that we will be using these pages
template<ZeroMem zero_mem>
void notify_using(void* p, size_t size) noexcept
{
assert(
bits::is_aligned_block<OS_PAGE_SIZE>(p, size) || (zero_mem == NoZero));
void* r = VirtualAlloc(p, size, MEM_COMMIT, PAGE_READWRITE);
if (r == nullptr)
error("out of memory");
}
/// OS specific function for zeroing memory
template<bool page_aligned = false>
void zero(void* p, size_t size) noexcept
{
if (page_aligned || bits::is_aligned_block<OS_PAGE_SIZE>(p, size))
{
assert(bits::is_aligned_block<OS_PAGE_SIZE>(p, size));
notify_not_using(p, size);
notify_using<YesZero>(p, size);
}
else
::memset(p, 0, size);
}
# ifdef USE_SYSTEMATIC_TESTING
size_t& systematic_bump_ptr()
{
static size_t bump_ptr = (size_t)0x4000'0000'0000;
return bump_ptr;
}
# endif
template<bool committed>
void* reserve(size_t* size, size_t align) noexcept
{
DWORD flags = MEM_RESERVE;
if (committed)
flags |= MEM_COMMIT;
# ifdef PLATFORM_HAS_VIRTUALALLOC2
// If we're on Windows 10 or newer, we can use the VirtualAlloc2
// function. The FromApp variant is useable by UWP applications and
// cannot allocate executable memory.
MEM_ADDRESS_REQUIREMENTS addressReqs = {0};
MEM_EXTENDED_PARAMETER param = {0};
addressReqs.Alignment = align;
param.Type = MemExtendedParameterAddressRequirements;
param.Pointer = &addressReqs;
return VirtualAlloc2FromApp(
nullptr, nullptr, *size, flags, PAGE_READWRITE, &param, 1);
# else
// Add align, so we can guarantee to provide at least size.
size_t request = *size + align;
// Alignment must be a power of 2.
assert(align == bits::next_pow2(align));
void* p;
# ifdef USE_SYSTEMATIC_TESTING
size_t retries = 1000;
do
{
p = VirtualAlloc(
(void*)systematic_bump_ptr(), request, flags, PAGE_READWRITE);
systematic_bump_ptr() += request;
retries--;
} while (p == nullptr && retries > 0);
# else
p = VirtualAlloc(nullptr, request, flags, PAGE_READWRITE);
# endif
uintptr_t aligned_p = bits::align_up((size_t)p, align);
if (aligned_p != (uintptr_t)p)
{
auto extra_bit = aligned_p - (uintptr_t)p;
uintptr_t end = (uintptr_t)p + request;
// Attempt to align end of the block.
VirtualAlloc((void*)end, extra_bit, flags, PAGE_READWRITE);
}
*size = request;
return p;
# endif
}
};
}
#endif