/* ---------------------------------------------------------------------------- Copyright (c) 2018, Microsoft Research, Daan Leijen This is free software; you can redistribute it and/or modify it under the terms of the MIT license. A copy of the license can be found in the file "LICENSE" at the root of this distribution. -----------------------------------------------------------------------------*/ #ifndef _DEFAULT_SOURCE #define _DEFAULT_SOURCE // ensure mmap flags are defined #endif #include "mimalloc.h" #include "mimalloc-internal.h" #include // memset #include #if defined(_WIN32) #include #else #include // mmap #include // sysconf #endif /* ----------------------------------------------------------- Initialization. On windows initializes support for aligned allocation and large OS pages (if MIMALLOC_LARGE_OS_PAGES is true). ----------------------------------------------------------- */ bool _mi_os_decommit(void* addr, size_t size, mi_stats_t* stats); uintptr_t _mi_align_up(uintptr_t sz, size_t alignment) { uintptr_t x = (sz / alignment) * alignment; if (x < sz) x += alignment; if (x < sz) return 0; // overflow return x; } static void* mi_align_up_ptr(void* p, size_t alignment) { return (void*)_mi_align_up((uintptr_t)p, alignment); } static uintptr_t _mi_align_down(uintptr_t sz, size_t alignment) { return (sz / alignment) * alignment; } static void* mi_align_down_ptr(void* p, size_t alignment) { return (void*)_mi_align_down((uintptr_t)p, alignment); } // page size (initialized properly in `os_init`) static size_t os_page_size = 4096; // minimal allocation granularity static size_t os_alloc_granularity = 4096; // if non-zero, use large page allocation static size_t large_os_page_size = 0; // OS (small) page size size_t _mi_os_page_size() { return os_page_size; } // if large OS pages are supported (2 or 4MiB), then return the size, otherwise return the small page size (4KiB) size_t _mi_os_large_page_size() { return (large_os_page_size != 0 ? large_os_page_size : _mi_os_page_size()); } static bool use_large_os_page(size_t size, size_t alignment) { // if we have access, check the size and alignment requirements if (large_os_page_size == 0) return false; return ((size % large_os_page_size) == 0 && (alignment % large_os_page_size) == 0); } // round to a good allocation size static size_t mi_os_good_alloc_size(size_t size, size_t alignment) { UNUSED(alignment); if (size >= (SIZE_MAX - os_alloc_granularity)) return size; // possible overflow? return _mi_align_up(size, os_alloc_granularity); } #if defined(_WIN32) // We use VirtualAlloc2 for aligned allocation, but it is only supported on Windows 10 and Windows Server 2016. // So, we need to look it up dynamically to run on older systems. (use __stdcall for 32-bit compatibility) typedef PVOID(__stdcall *VirtualAlloc2Ptr)(HANDLE, PVOID, SIZE_T, ULONG, ULONG, MEM_EXTENDED_PARAMETER*, ULONG); static VirtualAlloc2Ptr pVirtualAlloc2 = NULL; void _mi_os_init(void) { // get the page size SYSTEM_INFO si; GetSystemInfo(&si); if (si.dwPageSize > 0) os_page_size = si.dwPageSize; if (si.dwAllocationGranularity > 0) os_alloc_granularity = si.dwAllocationGranularity; // get the VirtualAlloc2 function HINSTANCE hDll; hDll = LoadLibrary("kernelbase.dll"); if (hDll != NULL) { // use VirtualAlloc2FromApp as it is available to Windows store apps pVirtualAlloc2 = (VirtualAlloc2Ptr)GetProcAddress(hDll, "VirtualAlloc2FromApp"); FreeLibrary(hDll); } // Try to see if large OS pages are supported unsigned long err = 0; bool ok = mi_option_is_enabled(mi_option_large_os_pages); if (ok) { // To use large pages on Windows, we first need access permission // Set "Lock pages in memory" permission in the group policy editor // HANDLE token = NULL; ok = OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, &token); if (ok) { TOKEN_PRIVILEGES tp; ok = LookupPrivilegeValue(NULL, "SeLockMemoryPrivilege", &tp.Privileges[0].Luid); if (ok) { tp.PrivilegeCount = 1; tp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED; ok = AdjustTokenPrivileges(token, FALSE, &tp, 0, (PTOKEN_PRIVILEGES)NULL, 0); if (ok) { err = GetLastError(); ok = (err == ERROR_SUCCESS); if (ok) { large_os_page_size = GetLargePageMinimum(); } } } CloseHandle(token); } if (!ok) { if (err == 0) err = GetLastError(); _mi_warning_message("cannot enable large OS page support, error %lu\n", err); } } } #else void _mi_os_init() { // get the page size long result = sysconf(_SC_PAGESIZE); if (result > 0) { os_page_size = (size_t)result; os_alloc_granularity = os_page_size; } if (mi_option_is_enabled(mi_option_large_os_pages)) { large_os_page_size = (1UL << 21); // 2MiB } } #endif /* ----------------------------------------------------------- Raw allocation on Windows (VirtualAlloc) and Unix's (mmap). ----------------------------------------------------------- */ static bool mi_os_mem_free(void* addr, size_t size, mi_stats_t* stats) { if (addr == NULL || size == 0) return true; bool err = false; #if defined(_WIN32) err = (VirtualFree(addr, 0, MEM_RELEASE) == 0); #else err = (munmap(addr, size) == -1); #endif _mi_stat_decrease(&stats->committed, size); // TODO: what if never committed? _mi_stat_decrease(&stats->reserved, size); if (err) { #pragma warning(suppress:4996) _mi_warning_message("munmap failed: %s, addr 0x%8li, size %lu\n", strerror(errno), (size_t)addr, size); return false; } else { return true; } } #ifdef _WIN32 static void* mi_win_virtual_allocx(void* addr, size_t size, size_t try_alignment, DWORD flags) { #if defined(MEM_EXTENDED_PARAMETER_TYPE_BITS) if (try_alignment > 0 && (try_alignment % _mi_os_page_size()) == 0 && pVirtualAlloc2 != NULL) { // on modern Windows try use VirtualAlloc2 MEM_ADDRESS_REQUIREMENTS reqs = { 0 }; reqs.Alignment = try_alignment; MEM_EXTENDED_PARAMETER param = { 0 }; param.Type = MemExtendedParameterAddressRequirements; param.Pointer = &reqs; return (*pVirtualAlloc2)(addr, NULL, size, flags, PAGE_READWRITE, ¶m, 1); } #endif return VirtualAlloc(addr, size, flags, PAGE_READWRITE); } static void* mi_win_virtual_alloc(void* addr, size_t size, size_t try_alignment, DWORD flags) { void* p = NULL; if (use_large_os_page(size, try_alignment)) { p = mi_win_virtual_allocx(addr, size, try_alignment, MEM_LARGE_PAGES | flags); // fall back to non-large page allocation on error (`p == NULL`). } if (p == NULL) { p = mi_win_virtual_allocx(addr, size, try_alignment, flags); } return p; } #else static void* mi_unix_mmap(size_t size, size_t try_alignment, int protect_flags) { void* p = NULL; #if !defined(MAP_ANONYMOUS) #define MAP_ANONYMOUS MAP_ANON #endif int flags = MAP_PRIVATE | MAP_ANONYMOUS; #if defined(MAP_ALIGNED) // BSD if (try_alignment > 0) { size_t n = _mi_bsr(try_alignment); if (((size_t)1 << n) == try_alignment && n >= 12 && n <= 30) { // alignment is a power of 2 and 4096 <= alignment <= 1GiB flags |= MAP_ALIGNED(n); } } #endif #if defined(PROT_MAX) protect_flags |= PROT_MAX(PROT_READ | PROT_WRITE); // BSD #endif if (large_os_page_size > 0 && use_large_os_page(size, try_alignment)) { int lflags = flags; #ifdef MAP_ALIGNED_SUPER lflags |= MAP_ALIGNED_SUPER; #endif #ifdef MAP_HUGETLB lflags |= MAP_HUGETLB; #endif #ifdef MAP_HUGE_2MB lflags |= MAP_HUGE_2MB; #endif if (lflags != flags) { // try large page allocation // TODO: if always failing due to permissions or no huge pages, try to avoid repeatedly trying? // Should we check this in _mi_os_init? (as on Windows) p = mmap(NULL, size, protect_flags, lflags, -1, 0); if (p == MAP_FAILED) p = NULL; // fall back to regular mmap if large is exhausted or no permission } } if (p == NULL) { p = mmap(NULL, size, protect_flags, flags, -1, 0); if (p == MAP_FAILED) p = NULL; } return p; } #endif // Primitive allocation from the OS. // Note: the `alignment` is just a hint and the returned pointer is not guaranteed to be aligned. static void* mi_os_mem_alloc(size_t size, size_t try_alignment, bool commit, mi_stats_t* stats) { mi_assert_internal(size > 0 && (size % _mi_os_page_size()) == 0); if (size == 0) return NULL; void* p = NULL; #if defined(_WIN32) int flags = MEM_RESERVE; if (commit) flags |= MEM_COMMIT; p = mi_win_virtual_alloc(NULL, size, try_alignment, flags); #else int protect_flags = (commit ? (PROT_WRITE | PROT_READ) : PROT_NONE); p = mi_unix_mmap(size, try_alignment, protect_flags); #endif _mi_stat_increase(&stats->mmap_calls, 1); if (p != NULL) { _mi_stat_increase(&stats->reserved, size); if (commit) _mi_stat_increase(&stats->committed, size); } return p; } // Primitive aligned allocation from the OS. // This function guarantees the allocated memory is aligned. static void* mi_os_mem_alloc_aligned(size_t size, size_t alignment, bool commit, mi_stats_t* stats) { mi_assert_internal(alignment >= _mi_os_page_size() && ((alignment & (alignment - 1)) == 0)); mi_assert_internal(size > 0 && (size % _mi_os_page_size()) == 0); if (!(alignment >= _mi_os_page_size() && ((alignment & (alignment - 1)) == 0))) return NULL; size = _mi_align_up(size, _mi_os_page_size()); // try first with a hint (this will be aligned directly on Win 10+ or BSD) void* p = mi_os_mem_alloc(size, alignment, commit, stats); if (p == NULL) return NULL; // if not aligned, free it, overallocate, and unmap around it if (((uintptr_t)p % alignment != 0)) { mi_os_mem_free(p, size, stats); if (size >= (SIZE_MAX - alignment)) return NULL; // overflow size_t over_size = size + alignment; #if _WIN32 // over-allocate and than re-allocate exactly at an aligned address in there. // this may fail due to threads allocating at the same time so we // retry this at most 3 times before giving up. // (we can not decommit around the overallocation on Windows, because we can only // free the original pointer, not one pointing inside the area) int flags = MEM_RESERVE; if (commit) flags |= MEM_COMMIT; for (int tries = 0; tries < 3; tries++) { // over-allocate to determine a virtual memory range p = mi_os_mem_alloc(over_size, alignment, commit, stats); if (p == NULL) return NULL; // error if (((uintptr_t)p % alignment) == 0) { // if p happens to be aligned, just decommit the left-over area _mi_os_decommit((uint8_t*)p + size, over_size - size, stats); break; } else { // otherwise free and allocate at an aligned address in there mi_os_mem_free(p, over_size, stats); void* aligned_p = mi_align_up_ptr(p, alignment); p = mi_win_virtual_alloc(aligned_p, size, alignment, flags); if (p == aligned_p) break; // success! if (p != NULL) { // should not happen? mi_os_mem_free(p, size, stats); p = NULL; } } } #else // overallocate... p = mi_os_mem_alloc(over_size, alignment, commit, stats); if (p == NULL) return NULL; // and selectively unmap parts around the over-allocated area. void* aligned_p = mi_align_up_ptr(p, alignment); size_t pre_size = (uint8_t*)aligned_p - (uint8_t*)p; size_t mid_size = _mi_align_up(size, _mi_os_page_size()); size_t post_size = over_size - pre_size - mid_size; mi_assert_internal(pre_size < over_size && post_size < over_size && mid_size >= size); if (pre_size > 0) mi_os_mem_free(p, pre_size, stats); if (post_size > 0) mi_os_mem_free((uint8_t*)aligned_p + mid_size, post_size, stats); // we can return the aligned pointer on `mmap` systems p = aligned_p; #endif } mi_assert_internal(p == NULL || (p != NULL && ((uintptr_t)p % alignment) == 0)); return p; } /* ----------------------------------------------------------- OS API: alloc, free, alloc_aligned ----------------------------------------------------------- */ void* _mi_os_alloc(size_t size, mi_stats_t* stats) { if (size == 0) return NULL; size = mi_os_good_alloc_size(size, 0); return mi_os_mem_alloc(size, 0, true, stats); } void _mi_os_free(void* p, size_t size, mi_stats_t* stats) { if (size == 0 || p == NULL) return; size = mi_os_good_alloc_size(size, 0); mi_os_mem_free(p, size, stats); } void* _mi_os_alloc_aligned(size_t size, size_t alignment, bool commit, mi_os_tld_t* tld) { if (size == 0) return NULL; size = mi_os_good_alloc_size(size, alignment); alignment = _mi_align_up(alignment, _mi_os_page_size()); return mi_os_mem_alloc_aligned(size, alignment, commit, tld->stats); } /* ----------------------------------------------------------- OS memory API: reset, commit, decommit, protect, unprotect. ----------------------------------------------------------- */ // OS page align within a given area, either conservative (pages inside the area only), // or not (straddling pages outside the area is possible) static void* mi_os_page_align_areax(bool conservative, void* addr, size_t size, size_t* newsize) { mi_assert(addr != NULL && size > 0); if (newsize != NULL) *newsize = 0; if (size == 0 || addr == NULL) return NULL; // page align conservatively within the range void* start = (conservative ? mi_align_up_ptr(addr, _mi_os_page_size()) : mi_align_down_ptr(addr, _mi_os_page_size())); void* end = (conservative ? mi_align_down_ptr((uint8_t*)addr + size, _mi_os_page_size()) : mi_align_up_ptr((uint8_t*)addr + size, _mi_os_page_size())); ptrdiff_t diff = (uint8_t*)end - (uint8_t*)start; if (diff <= 0) return NULL; mi_assert_internal((size_t)diff <= size); if (newsize != NULL) *newsize = (size_t)diff; return start; } static void* mi_os_page_align_area_conservative(void* addr, size_t size, size_t* newsize) { return mi_os_page_align_areax(true, addr, size, newsize); } // Signal to the OS that the address range is no longer in use // but may be used later again. This will release physical memory // pages and reduce swapping while keeping the memory committed. // We page align to a conservative area inside the range to reset. bool _mi_os_reset(void* addr, size_t size, mi_stats_t* stats) { // page align conservatively within the range size_t csize; void* start = mi_os_page_align_area_conservative(addr, size, &csize); if (csize == 0) return true; _mi_stat_increase(&stats->reset, csize); #if defined(_WIN32) // Testing shows that for us (on `malloc-large`) MEM_RESET is 2x faster than DiscardVirtualMemory // (but this is for an access pattern that immediately reuses the memory) /* DWORD ok = DiscardVirtualMemory(start, csize); return (ok != 0); */ void* p = VirtualAlloc(start, csize, MEM_RESET, PAGE_READWRITE); mi_assert(p == start); if (p != start) return false; /* // VirtualUnlock removes the memory eagerly from the current working set (which MEM_RESET does lazily on demand) // TODO: put this behind an option? DWORD ok = VirtualUnlock(start, csize); if (ok != 0) return false; */ return true; #else #if defined(MADV_FREE) static int advice = MADV_FREE; int err = madvise(start, csize, advice); if (err != 0 && errno == EINVAL && advice == MADV_FREE) { // if MADV_FREE is not supported, fall back to MADV_DONTNEED from now on advice = MADV_DONTNEED; err = madvise(start, csize, advice); } #else int err = madvise(start, csize, MADV_DONTNEED); #endif if (err != 0) { _mi_warning_message("madvise reset error: start: 0x%8p, csize: 0x%8zux, errno: %i\n", start, csize, errno); } //mi_assert(err == 0); return (err == 0); #endif } // Protect a region in memory to be not accessible. static bool mi_os_protectx(void* addr, size_t size, bool protect) { // page align conservatively within the range size_t csize = 0; void* start = mi_os_page_align_area_conservative(addr, size, &csize); if (csize == 0) return false; int err = 0; #ifdef _WIN32 DWORD oldprotect = 0; BOOL ok = VirtualProtect(start, csize, protect ? PAGE_NOACCESS : PAGE_READWRITE, &oldprotect); err = (ok ? 0 : GetLastError()); #else err = mprotect(start, csize, protect ? PROT_NONE : (PROT_READ | PROT_WRITE)); #endif if (err != 0) { _mi_warning_message("mprotect error: start: 0x%8p, csize: 0x%8zux, err: %i\n", start, csize, err); } return (err == 0); } bool _mi_os_protect(void* addr, size_t size) { return mi_os_protectx(addr, size, true); } bool _mi_os_unprotect(void* addr, size_t size) { return mi_os_protectx(addr, size, false); } // Commit/Decommit memory. Commit is aligned liberal, while decommit is aligned conservative. static bool mi_os_commitx(void* addr, size_t size, bool commit, mi_stats_t* stats) { // page align in the range, commit liberally, decommit conservative size_t csize; void* start = mi_os_page_align_areax(!commit, addr, size, &csize); if (csize == 0) return true; int err = 0; if (commit) { _mi_stat_increase(&stats->committed, csize); _mi_stat_increase(&stats->commit_calls, 1); } else { _mi_stat_decrease(&stats->committed, csize); } #if defined(_WIN32) if (commit) { void* p = VirtualAlloc(start, csize, MEM_COMMIT, PAGE_READWRITE); err = (p == start ? 0 : GetLastError()); } else { BOOL ok = VirtualFree(start, csize, MEM_DECOMMIT); err = (ok ? 0 : GetLastError()); } #else err = mprotect(start, csize, (commit ? (PROT_READ | PROT_WRITE) : PROT_NONE)); #endif if (err != 0) { _mi_warning_message("commit/decommit error: start: 0x%8p, csize: 0x%8zux, err: %i\n", start, csize, err); } mi_assert_internal(err == 0); return (err == 0); } bool _mi_os_commit(void* addr, size_t size, mi_stats_t* stats) { return mi_os_commitx(addr, size, true, stats); } bool _mi_os_decommit(void* addr, size_t size, mi_stats_t* stats) { return mi_os_commitx(addr, size, false, stats); } bool _mi_os_shrink(void* p, size_t oldsize, size_t newsize, mi_stats_t* stats) { // page align conservatively within the range mi_assert_internal(oldsize > newsize && p != NULL); if (oldsize < newsize || p == NULL) return false; if (oldsize == newsize) return true; // oldsize and newsize should be page aligned or we cannot shrink precisely void* addr = (uint8_t*)p + newsize; size_t size = 0; void* start = mi_os_page_align_area_conservative(addr, oldsize - newsize, &size); if (size == 0 || start != addr) return false; #ifdef _WIN32 // we cannot shrink on windows, but we can decommit return _mi_os_decommit(start, size, stats); #else return mi_os_mem_free(start, size, stats); #endif }