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Rewrite memory block allocator.
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Use a mix of linear probing and pseudo-random probing.
Workaround for 1GB MAP_32BIT limit on Linux/x64. Now 2GB with !LJ_GC64.
Enforce 128TB LJ_GC64 limit for > 47 bit memory layouts (ARM64).
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Mike Pall committed Apr 18, 2016
1 parent 101115d commit 0c6fdc1
Showing 1 changed file with 170 additions and 85 deletions.
255 changes: 170 additions & 85 deletions src/lj_alloc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -72,13 +72,56 @@

#define IS_DIRECT_BIT (SIZE_T_ONE)


/* Determine system-specific block allocation method. */
#if LJ_TARGET_WINDOWS

#define WIN32_LEAN_AND_MEAN
#include <windows.h>

#define LJ_ALLOC_VIRTUALALLOC 1

#if LJ_64 && !LJ_GC64
#define LJ_ALLOC_NTAVM 1
#endif

#else

#include <errno.h>
/* If this include fails, then rebuild with: -DLUAJIT_USE_SYSMALLOC */
#include <sys/mman.h>

#define LJ_ALLOC_MMAP 1

#if LJ_64

#define LJ_ALLOC_MMAP_PROBE 1

#if LJ_GC64
#define LJ_ALLOC_MBITS 47 /* 128 TB in LJ_GC64 mode. */
#elif LJ_TARGET_X64 && LJ_HASJIT
/* Due to limitations in the x64 compiler backend. */
#define LJ_ALLOC_MBITS 31 /* 2 GB on x64 with !LJ_GC64. */
#else
#define LJ_ALLOC_MBITS 32 /* 4 GB on other archs with !LJ_GC64. */
#endif

#endif

#if LJ_64 && !LJ_GC64 && defined(MAP_32BIT)
#define LJ_ALLOC_MMAP32 1
#endif

#if LJ_TARGET_LINUX
#define LJ_ALLOC_MREMAP 1
#endif

#endif


#if LJ_ALLOC_VIRTUALALLOC

#if LJ_ALLOC_NTAVM
/* Undocumented, but hey, that's what we all love so much about Windows. */
typedef long (*PNTAVM)(HANDLE handle, void **addr, ULONG zbits,
size_t *size, ULONG alloctype, ULONG prot);
Expand All @@ -89,14 +132,15 @@ static PNTAVM ntavm;
*/
#define NTAVM_ZEROBITS 1

static void INIT_MMAP(void)
static void init_mmap(void)
{
ntavm = (PNTAVM)GetProcAddress(GetModuleHandleA("ntdll.dll"),
"NtAllocateVirtualMemory");
}
#define INIT_MMAP() init_mmap()

/* Win64 32 bit MMAP via NtAllocateVirtualMemory. */
static LJ_AINLINE void *CALL_MMAP(size_t size)
static void *CALL_MMAP(size_t size)
{
DWORD olderr = GetLastError();
void *ptr = NULL;
Expand All @@ -107,7 +151,7 @@ static LJ_AINLINE void *CALL_MMAP(size_t size)
}

/* For direct MMAP, use MEM_TOP_DOWN to minimize interference */
static LJ_AINLINE void *DIRECT_MMAP(size_t size)
static void *DIRECT_MMAP(size_t size)
{
DWORD olderr = GetLastError();
void *ptr = NULL;
Expand All @@ -119,10 +163,8 @@ static LJ_AINLINE void *DIRECT_MMAP(size_t size)

#else

#define INIT_MMAP() ((void)0)

/* Win32 MMAP via VirtualAlloc */
static LJ_AINLINE void *CALL_MMAP(size_t size)
static void *CALL_MMAP(size_t size)
{
DWORD olderr = GetLastError();
void *ptr = VirtualAlloc(0, size, MEM_RESERVE|MEM_COMMIT, PAGE_READWRITE);
Expand All @@ -131,7 +173,7 @@ static LJ_AINLINE void *CALL_MMAP(size_t size)
}

/* For direct MMAP, use MEM_TOP_DOWN to minimize interference */
static LJ_AINLINE void *DIRECT_MMAP(size_t size)
static void *DIRECT_MMAP(size_t size)
{
DWORD olderr = GetLastError();
void *ptr = VirtualAlloc(0, size, MEM_RESERVE|MEM_COMMIT|MEM_TOP_DOWN,
Expand All @@ -143,7 +185,7 @@ static LJ_AINLINE void *DIRECT_MMAP(size_t size)
#endif

/* This function supports releasing coalesed segments */
static LJ_AINLINE int CALL_MUNMAP(void *ptr, size_t size)
static int CALL_MUNMAP(void *ptr, size_t size)
{
DWORD olderr = GetLastError();
MEMORY_BASIC_INFORMATION minfo;
Expand All @@ -163,129 +205,163 @@ static LJ_AINLINE int CALL_MUNMAP(void *ptr, size_t size)
return 0;
}

#else

#include <errno.h>
#include <sys/mman.h>
#elif LJ_ALLOC_MMAP

#define MMAP_PROT (PROT_READ|PROT_WRITE)
#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
#define MAP_ANONYMOUS MAP_ANON
#endif
#define MMAP_FLAGS (MAP_PRIVATE|MAP_ANONYMOUS)

#if LJ_64 && !LJ_GC64
/* 64 bit mode with 32 bit pointers needs special support for allocating
** memory in the lower 2GB.
*/
#if LJ_ALLOC_MMAP_PROBE

#if defined(MAP_32BIT)
#define LJ_ALLOC_MMAP_PROBE_MAX 30
#define LJ_ALLOC_MMAP_PROBE_LINEAR 5

#if defined(__sun__)
#define MMAP_REGION_START ((uintptr_t)0x1000)
#else
/* Actually this only gives us max. 1GB in current Linux kernels. */
#define MMAP_REGION_START ((uintptr_t)0)
#endif
#define LJ_ALLOC_MMAP_PROBE_LOWER ((uintptr_t)0x4000)

/* No point in a giant ifdef mess. Just try to open /dev/urandom.
** It doesn't really matter if this fails, since we get some ASLR bits from
** every unsuitable allocation, too. And we prefer linear allocation, anyway.
*/
#include <fcntl.h>
#include <unistd.h>

static LJ_AINLINE void *CALL_MMAP(size_t size)
static uintptr_t mmap_probe_seed(void)
{
uintptr_t val;
int fd = open("/dev/urandom", O_RDONLY);
if (fd != -1) {
int ok = ((size_t)read(fd, &val, sizeof(val)) == sizeof(val));
(void)close(fd);
if (ok) return val;
}
return 1; /* Punt. */
}

static void *mmap_probe(size_t size)
{
/* Hint for next allocation. Doesn't need to be thread-safe. */
static uintptr_t hint_addr = 0;
static uintptr_t hint_prng = 0;
int olderr = errno;
void *ptr = mmap((void *)MMAP_REGION_START, size, MMAP_PROT, MAP_32BIT|MMAP_FLAGS, -1, 0);
int retry;
for (retry = 0; retry < LJ_ALLOC_MMAP_PROBE_MAX; retry++) {
void *p = mmap((void *)hint_addr, size, MMAP_PROT, MMAP_FLAGS, -1, 0);
uintptr_t addr = (uintptr_t)p;
if ((addr >> LJ_ALLOC_MBITS) == 0 && addr >= LJ_ALLOC_MMAP_PROBE_LOWER) {
/* We got a suitable address. Bump the hint address. */
hint_addr = addr + size;
errno = olderr;
return p;
}
if (p != MFAIL) {
munmap(p, size);
} else if (errno == ENOMEM) {
return MFAIL;
}
if (hint_addr) {
/* First, try linear probing. */
if (retry < LJ_ALLOC_MMAP_PROBE_LINEAR) {
hint_addr += 0x1000000;
if (((hint_addr + size) >> LJ_ALLOC_MBITS) != 0)
hint_addr = 0;
continue;
} else if (retry == LJ_ALLOC_MMAP_PROBE_LINEAR) {
/* Next, try a no-hint probe to get back an ASLR address. */
hint_addr = 0;
continue;
}
}
/* Finally, try pseudo-random probing. */
if (LJ_UNLIKELY(hint_prng == 0)) {
hint_prng = mmap_probe_seed();
}
/* The unsuitable address we got has some ASLR PRNG bits. */
hint_addr ^= addr & ~((uintptr_t)(LJ_PAGESIZE-1));
do { /* The PRNG itself is very weak, but see above. */
hint_prng = hint_prng * 1103515245 + 12345;
hint_addr ^= hint_prng * (uintptr_t)LJ_PAGESIZE;
hint_addr &= (((uintptr_t)1 << LJ_ALLOC_MBITS)-1);
} while (hint_addr < LJ_ALLOC_MMAP_PROBE_LOWER);
}
errno = olderr;
return ptr;
return MFAIL;
}

#elif LJ_TARGET_OSX || LJ_TARGET_PS4 || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) || defined(__sun__) || LJ_TARGET_CYGWIN

/* OSX and FreeBSD mmap() use a naive first-fit linear search.
** That's perfect for us. Except that -pagezero_size must be set for OSX,
** otherwise the lower 4GB are blocked. And the 32GB RLIMIT_DATA needs
** to be reduced to 250MB on FreeBSD.
*/
#if LJ_TARGET_OSX || defined(__DragonFly__)
#define MMAP_REGION_START ((uintptr_t)0x10000)
#elif LJ_TARGET_PS4
#define MMAP_REGION_START ((uintptr_t)0x4000)
#else
#define MMAP_REGION_START ((uintptr_t)0x10000000)
#endif
#define MMAP_REGION_END ((uintptr_t)0x80000000)

#if (defined(__FreeBSD__) || defined(__FreeBSD_kernel__)) && !LJ_TARGET_PS4
#include <sys/resource.h>
#if LJ_ALLOC_MMAP32

#if defined(__sun__)
#define LJ_ALLOC_MMAP32_START ((uintptr_t)0x1000)
#else
#define LJ_ALLOC_MMAP32_START ((uintptr_t)0)
#endif

static LJ_AINLINE void *CALL_MMAP(size_t size)
static void *mmap_map32(size_t size)
{
int olderr = errno;
/* Hint for next allocation. Doesn't need to be thread-safe. */
static uintptr_t alloc_hint = MMAP_REGION_START;
int retry = 0;
#if (defined(__FreeBSD__) || defined(__FreeBSD_kernel__)) && !LJ_TARGET_PS4
static int rlimit_modified = 0;
if (LJ_UNLIKELY(rlimit_modified == 0)) {
struct rlimit rlim;
rlim.rlim_cur = rlim.rlim_max = MMAP_REGION_START;
setrlimit(RLIMIT_DATA, &rlim); /* Ignore result. May fail below. */
rlimit_modified = 1;
}
#if LJ_ALLOC_MMAP_PROBE
static int fallback = 0;
if (fallback)
return mmap_probe(size);
#endif
for (;;) {
void *p = mmap((void *)alloc_hint, size, MMAP_PROT, MMAP_FLAGS, -1, 0);
if ((uintptr_t)p >= MMAP_REGION_START &&
(uintptr_t)p + size < MMAP_REGION_END) {
alloc_hint = (uintptr_t)p + size;
errno = olderr;
return p;
{
int olderr = errno;
void *ptr = mmap((void *)LJ_ALLOC_MMAP32_START, size, MMAP_PROT, MAP_32BIT|MMAP_FLAGS, -1, 0);
errno = olderr;
/* This only allows 1GB on Linux. So fallback to probing to get 2GB. */
#if LJ_ALLOC_MMAP_PROBE
if (ptr == MFAIL) {
fallback = 1;
return mmap_probe(size);
}
if (p != CMFAIL) munmap(p, size);
#if defined(__sun__) || defined(__DragonFly__)
alloc_hint += 0x1000000; /* Need near-exhaustive linear scan. */
if (alloc_hint + size < MMAP_REGION_END) continue;
#endif
if (retry) break;
retry = 1;
alloc_hint = MMAP_REGION_START;
return ptr;
}
errno = olderr;
return CMFAIL;
}

#else

#error "NYI: need an equivalent of MAP_32BIT for this 64 bit OS"

#endif

#if LJ_ALLOC_MMAP32
#define CALL_MMAP(size) mmap_map32(size)
#elif LJ_ALLOC_MMAP_PROBE
#define CALL_MMAP(size) mmap_probe(size)
#else

/* 32 bit mode and GC64 mode is easy. */
static LJ_AINLINE void *CALL_MMAP(size_t size)
static void *CALL_MMAP(size_t size)
{
int olderr = errno;
void *ptr = mmap(NULL, size, MMAP_PROT, MMAP_FLAGS, -1, 0);
errno = olderr;
return ptr;
}

#endif

#define INIT_MMAP() ((void)0)
#define DIRECT_MMAP(s) CALL_MMAP(s)
#if (defined(__FreeBSD__) || defined(__FreeBSD_kernel__)) && !LJ_TARGET_PS4

#include <sys/resource.h>

static LJ_AINLINE int CALL_MUNMAP(void *ptr, size_t size)
static void init_mmap(void)
{
struct rlimit rlim;
rlim.rlim_cur = rlim.rlim_max = 0x10000;
setrlimit(RLIMIT_DATA, &rlim); /* Ignore result. May fail later. */
}
#define INIT_MMAP() init_mmap()

#endif

static int CALL_MUNMAP(void *ptr, size_t size)
{
int olderr = errno;
int ret = munmap(ptr, size);
errno = olderr;
return ret;
}

#if LJ_TARGET_LINUX
#if LJ_ALLOC_MREMAP
/* Need to define _GNU_SOURCE to get the mremap prototype. */
static LJ_AINLINE void *CALL_MREMAP_(void *ptr, size_t osz, size_t nsz,
int flags)
static void *CALL_MREMAP_(void *ptr, size_t osz, size_t nsz, int flags)
{
int olderr = errno;
ptr = mremap(ptr, osz, nsz, flags);
Expand All @@ -305,6 +381,15 @@ static LJ_AINLINE void *CALL_MREMAP_(void *ptr, size_t osz, size_t nsz,

#endif


#ifndef INIT_MMAP
#define INIT_MMAP() ((void)0)
#endif

#ifndef DIRECT_MMAP
#define DIRECT_MMAP(s) CALL_MMAP(s)
#endif

#ifndef CALL_MREMAP
#define CALL_MREMAP(addr, osz, nsz, mv) ((void)osz, MFAIL)
#endif
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