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gcc/libgo/runtime/malloc.goc

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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// See malloc.h for overview.
//
// TODO(rsc): double-check stats.
package runtime
#include <stddef.h>
#include <errno.h>
#include <stdlib.h>
#include "go-alloc.h"
#include "runtime.h"
#include "arch.h"
#include "malloc.h"
#include "interface.h"
#include "go-type.h"
#include "race.h"
MHeap runtime_mheap;
extern MStats mstats; // defined in zruntime_def_$GOOS_$GOARCH.go
extern volatile intgo runtime_MemProfileRate
__asm__ ("runtime.MemProfileRate");
// Allocate an object of at least size bytes.
// Small objects are allocated from the per-thread cache's free lists.
// Large objects (> 32 kB) are allocated straight from the heap.
void*
runtime_mallocgc(uintptr size, uint32 flag, int32 dogc, int32 zeroed)
{
M *m;
G *g;
int32 sizeclass;
intgo rate;
MCache *c;
uintptr npages;
MSpan *s;
void *v;
m = runtime_m();
g = runtime_g();
if(g->status == Gsyscall)
dogc = 0;
if(runtime_gcwaiting && g != m->g0 && m->locks == 0 && g->status != Gsyscall) {
runtime_gosched();
m = runtime_m();
}
if(m->mallocing)
runtime_throw("malloc/free - deadlock");
m->mallocing = 1;
if(size == 0)
size = 1;
if(DebugTypeAtBlockEnd)
size += sizeof(uintptr);
c = m->mcache;
c->local_nmalloc++;
if(size <= MaxSmallSize) {
// Allocate from mcache free lists.
sizeclass = runtime_SizeToClass(size);
size = runtime_class_to_size[sizeclass];
v = runtime_MCache_Alloc(c, sizeclass, size, zeroed);
if(v == nil)
runtime_throw("out of memory");
c->local_alloc += size;
c->local_total_alloc += size;
c->local_by_size[sizeclass].nmalloc++;
} else {
// TODO(rsc): Report tracebacks for very large allocations.
// Allocate directly from heap.
npages = size >> PageShift;
if((size & PageMask) != 0)
npages++;
s = runtime_MHeap_Alloc(&runtime_mheap, npages, 0, 1, zeroed);
if(s == nil)
runtime_throw("out of memory");
size = npages<<PageShift;
c->local_alloc += size;
c->local_total_alloc += size;
v = (void*)(s->start << PageShift);
// setup for mark sweep
runtime_markspan(v, 0, 0, true);
}
if (sizeof(void*) == 4 && c->local_total_alloc >= (1<<30)) {
// purge cache stats to prevent overflow
runtime_lock(&runtime_mheap);
runtime_purgecachedstats(c);
runtime_unlock(&runtime_mheap);
}
if(!(flag & FlagNoGC))
runtime_markallocated(v, size, (flag&FlagNoPointers) != 0);
if(DebugTypeAtBlockEnd)
*(uintptr*)((uintptr)v+size-sizeof(uintptr)) = 0;
m->mallocing = 0;
if(!(flag & FlagNoProfiling) && (rate = runtime_MemProfileRate) > 0) {
if(size >= (uint32) rate)
goto profile;
if((uint32) m->mcache->next_sample > size)
m->mcache->next_sample -= size;
else {
// pick next profile time
// If you change this, also change allocmcache.
if(rate > 0x3fffffff) // make 2*rate not overflow
rate = 0x3fffffff;
m->mcache->next_sample = runtime_fastrand1() % (2*rate);
profile:
runtime_setblockspecial(v, true);
runtime_MProf_Malloc(v, size);
}
}
if(dogc && mstats.heap_alloc >= mstats.next_gc)
runtime_gc(0);
if(raceenabled) {
runtime_racemalloc(v, size, m->racepc);
m->racepc = nil;
}
return v;
}
void*
__go_alloc(uintptr size)
{
return runtime_mallocgc(size, 0, 0, 1);
}
// Free the object whose base pointer is v.
void
__go_free(void *v)
{
M *m;
int32 sizeclass;
MSpan *s;
MCache *c;
uint32 prof;
uintptr size;
if(v == nil)
return;
// If you change this also change mgc0.c:/^sweep,
// which has a copy of the guts of free.
m = runtime_m();
if(m->mallocing)
runtime_throw("malloc/free - deadlock");
m->mallocing = 1;
if(!runtime_mlookup(v, nil, nil, &s)) {
runtime_printf("free %p: not an allocated block\n", v);
runtime_throw("free runtime_mlookup");
}
prof = runtime_blockspecial(v);
if(raceenabled)
runtime_racefree(v);
// Find size class for v.
sizeclass = s->sizeclass;
c = m->mcache;
if(sizeclass == 0) {
// Large object.
size = s->npages<<PageShift;
*(uintptr*)(s->start<<PageShift) = 1; // mark as "needs to be zeroed"
// Must mark v freed before calling unmarkspan and MHeap_Free:
// they might coalesce v into other spans and change the bitmap further.
runtime_markfreed(v, size);
runtime_unmarkspan(v, 1<<PageShift);
runtime_MHeap_Free(&runtime_mheap, s, 1);
} else {
// Small object.
size = runtime_class_to_size[sizeclass];
if(size > sizeof(uintptr))
((uintptr*)v)[1] = 1; // mark as "needs to be zeroed"
// Must mark v freed before calling MCache_Free:
// it might coalesce v and other blocks into a bigger span
// and change the bitmap further.
runtime_markfreed(v, size);
c->local_by_size[sizeclass].nfree++;
runtime_MCache_Free(c, v, sizeclass, size);
}
c->local_nfree++;
c->local_alloc -= size;
if(prof)
runtime_MProf_Free(v, size);
m->mallocing = 0;
}
int32
runtime_mlookup(void *v, byte **base, uintptr *size, MSpan **sp)
{
M *m;
uintptr n, i;
byte *p;
MSpan *s;
m = runtime_m();
m->mcache->local_nlookup++;
if (sizeof(void*) == 4 && m->mcache->local_nlookup >= (1<<30)) {
// purge cache stats to prevent overflow
runtime_lock(&runtime_mheap);
runtime_purgecachedstats(m->mcache);
runtime_unlock(&runtime_mheap);
}
s = runtime_MHeap_LookupMaybe(&runtime_mheap, v);
if(sp)
*sp = s;
if(s == nil) {
runtime_checkfreed(v, 1);
if(base)
*base = nil;
if(size)
*size = 0;
return 0;
}
p = (byte*)((uintptr)s->start<<PageShift);
if(s->sizeclass == 0) {
// Large object.
if(base)
*base = p;
if(size)
*size = s->npages<<PageShift;
return 1;
}
if((byte*)v >= (byte*)s->limit) {
// pointers past the last block do not count as pointers.
return 0;
}
n = s->elemsize;
if(base) {
i = ((byte*)v - p)/n;
*base = p + i*n;
}
if(size)
*size = n;
return 1;
}
MCache*
runtime_allocmcache(void)
{
intgo rate;
MCache *c;
runtime_lock(&runtime_mheap);
c = runtime_FixAlloc_Alloc(&runtime_mheap.cachealloc);
mstats.mcache_inuse = runtime_mheap.cachealloc.inuse;
mstats.mcache_sys = runtime_mheap.cachealloc.sys;
runtime_unlock(&runtime_mheap);
runtime_memclr((byte*)c, sizeof(*c));
// Set first allocation sample size.
rate = runtime_MemProfileRate;
if(rate > 0x3fffffff) // make 2*rate not overflow
rate = 0x3fffffff;
if(rate != 0)
c->next_sample = runtime_fastrand1() % (2*rate);
return c;
}
void
runtime_freemcache(MCache *c)
{
runtime_MCache_ReleaseAll(c);
runtime_lock(&runtime_mheap);
runtime_purgecachedstats(c);
runtime_FixAlloc_Free(&runtime_mheap.cachealloc, c);
runtime_unlock(&runtime_mheap);
}
void
runtime_purgecachedstats(MCache *c)
{
// Protected by either heap or GC lock.
mstats.heap_alloc += c->local_cachealloc;
c->local_cachealloc = 0;
mstats.heap_objects += c->local_objects;
c->local_objects = 0;
mstats.nmalloc += c->local_nmalloc;
c->local_nmalloc = 0;
mstats.nfree += c->local_nfree;
c->local_nfree = 0;
mstats.nlookup += c->local_nlookup;
c->local_nlookup = 0;
mstats.alloc += c->local_alloc;
c->local_alloc= 0;
mstats.total_alloc += c->local_total_alloc;
c->local_total_alloc= 0;
}
extern uintptr runtime_sizeof_C_MStats
__asm__ ("runtime.Sizeof_C_MStats");
#define MaxArena32 (2U<<30)
void
runtime_mallocinit(void)
{
byte *p;
uintptr arena_size, bitmap_size;
extern byte end[];
byte *want;
uintptr limit;
runtime_sizeof_C_MStats = sizeof(MStats);
p = nil;
arena_size = 0;
bitmap_size = 0;
// for 64-bit build
USED(p);
USED(arena_size);
USED(bitmap_size);
runtime_InitSizes();
limit = runtime_memlimit();
// Set up the allocation arena, a contiguous area of memory where
// allocated data will be found. The arena begins with a bitmap large
// enough to hold 4 bits per allocated word.
if(sizeof(void*) == 8 && (limit == 0 || limit > (1<<30))) {
// On a 64-bit machine, allocate from a single contiguous reservation.
// 128 GB (MaxMem) should be big enough for now.
//
// The code will work with the reservation at any address, but ask
// SysReserve to use 0x000000c000000000 if possible.
// Allocating a 128 GB region takes away 37 bits, and the amd64
// doesn't let us choose the top 17 bits, so that leaves the 11 bits
// in the middle of 0x00c0 for us to choose. Choosing 0x00c0 means
// that the valid memory addresses will begin 0x00c0, 0x00c1, ..., 0x0x00df.
// In little-endian, that's c0 00, c1 00, ..., df 00. None of those are valid
// UTF-8 sequences, and they are otherwise as far away from
// ff (likely a common byte) as possible. An earlier attempt to use 0x11f8
// caused out of memory errors on OS X during thread allocations.
// These choices are both for debuggability and to reduce the
// odds of the conservative garbage collector not collecting memory
// because some non-pointer block of memory had a bit pattern
// that matched a memory address.
//
// Actually we reserve 136 GB (because the bitmap ends up being 8 GB)
// but it hardly matters: e0 00 is not valid UTF-8 either.
//
// If this fails we fall back to the 32 bit memory mechanism
arena_size = MaxMem;
bitmap_size = arena_size / (sizeof(void*)*8/4);
p = runtime_SysReserve((void*)(0x00c0ULL<<32), bitmap_size + arena_size);
}
if (p == nil) {
// On a 32-bit machine, we can't typically get away
// with a giant virtual address space reservation.
// Instead we map the memory information bitmap
// immediately after the data segment, large enough
// to handle another 2GB of mappings (256 MB),
// along with a reservation for another 512 MB of memory.
// When that gets used up, we'll start asking the kernel
// for any memory anywhere and hope it's in the 2GB
// following the bitmap (presumably the executable begins
// near the bottom of memory, so we'll have to use up
// most of memory before the kernel resorts to giving out
// memory before the beginning of the text segment).
//
// Alternatively we could reserve 512 MB bitmap, enough
// for 4GB of mappings, and then accept any memory the
// kernel threw at us, but normally that's a waste of 512 MB
// of address space, which is probably too much in a 32-bit world.
bitmap_size = MaxArena32 / (sizeof(void*)*8/4);
arena_size = 512<<20;
if(limit > 0 && arena_size+bitmap_size > limit) {
bitmap_size = (limit / 9) & ~((1<<PageShift) - 1);
arena_size = bitmap_size * 8;
}
// SysReserve treats the address we ask for, end, as a hint,
// not as an absolute requirement. If we ask for the end
// of the data segment but the operating system requires
// a little more space before we can start allocating, it will
// give out a slightly higher pointer. Except QEMU, which
// is buggy, as usual: it won't adjust the pointer upward.
// So adjust it upward a little bit ourselves: 1/4 MB to get
// away from the running binary image and then round up
// to a MB boundary.
want = (byte*)(((uintptr)end + (1<<18) + (1<<20) - 1)&~((1<<20)-1));
if(0xffffffff - (uintptr)want <= bitmap_size + arena_size)
want = 0;
p = runtime_SysReserve(want, bitmap_size + arena_size);
if(p == nil)
runtime_throw("runtime: cannot reserve arena virtual address space");
if((uintptr)p & (((uintptr)1<<PageShift)-1))
runtime_printf("runtime: SysReserve returned unaligned address %p; asked for %p", p, bitmap_size+arena_size);
}
if((uintptr)p & (((uintptr)1<<PageShift)-1))
runtime_throw("runtime: SysReserve returned unaligned address");
runtime_mheap.bitmap = p;
runtime_mheap.arena_start = p + bitmap_size;
runtime_mheap.arena_used = runtime_mheap.arena_start;
runtime_mheap.arena_end = runtime_mheap.arena_start + arena_size;
// Initialize the rest of the allocator.
runtime_MHeap_Init(&runtime_mheap, runtime_SysAlloc);
runtime_m()->mcache = runtime_allocmcache();
// See if it works.
runtime_free(runtime_malloc(1));
}
void*
runtime_MHeap_SysAlloc(MHeap *h, uintptr n)
{
byte *p;
if(n > (uintptr)(h->arena_end - h->arena_used)) {
// We are in 32-bit mode, maybe we didn't use all possible address space yet.
// Reserve some more space.
byte *new_end;
uintptr needed;
needed = (uintptr)h->arena_used + n - (uintptr)h->arena_end;
// Round wanted arena size to a multiple of 256MB.
needed = (needed + (256<<20) - 1) & ~((256<<20)-1);
new_end = h->arena_end + needed;
if(new_end <= h->arena_start + MaxArena32) {
p = runtime_SysReserve(h->arena_end, new_end - h->arena_end);
if(p == h->arena_end)
h->arena_end = new_end;
}
}
if(n <= (uintptr)(h->arena_end - h->arena_used)) {
// Keep taking from our reservation.
p = h->arena_used;
runtime_SysMap(p, n);
h->arena_used += n;
runtime_MHeap_MapBits(h);
if(raceenabled)
runtime_racemapshadow(p, n);
return p;
}
// If using 64-bit, our reservation is all we have.
if(sizeof(void*) == 8 && (uintptr)h->bitmap >= 0xffffffffU)
return nil;
// On 32-bit, once the reservation is gone we can
// try to get memory at a location chosen by the OS
// and hope that it is in the range we allocated bitmap for.
p = runtime_SysAlloc(n);
if(p == nil)
return nil;
if(p < h->arena_start || (uintptr)(p+n - h->arena_start) >= MaxArena32) {
runtime_printf("runtime: memory allocated by OS (%p) not in usable range [%p,%p)\n",
p, h->arena_start, h->arena_start+MaxArena32);
runtime_SysFree(p, n);
return nil;
}
if(p+n > h->arena_used) {
h->arena_used = p+n;
if(h->arena_used > h->arena_end)
h->arena_end = h->arena_used;
runtime_MHeap_MapBits(h);
if(raceenabled)
runtime_racemapshadow(p, n);
}
return p;
}
static Lock settype_lock;
void
runtime_settype_flush(M *mp, bool sysalloc)
{
uintptr *buf, *endbuf;
uintptr size, ofs, j, t;
uintptr ntypes, nbytes2, nbytes3;
uintptr *data2;
byte *data3;
bool sysalloc3;
void *v;
uintptr typ, p;
MSpan *s;
buf = mp->settype_buf;
endbuf = buf + mp->settype_bufsize;
runtime_lock(&settype_lock);
while(buf < endbuf) {
v = (void*)*buf;
*buf = 0;
buf++;
typ = *buf;
buf++;
// (Manually inlined copy of runtime_MHeap_Lookup)
p = (uintptr)v>>PageShift;
if(sizeof(void*) == 8)
p -= (uintptr)runtime_mheap.arena_start >> PageShift;
s = runtime_mheap.map[p];
if(s->sizeclass == 0) {
s->types.compression = MTypes_Single;
s->types.data = typ;
continue;
}
size = s->elemsize;
ofs = ((uintptr)v - (s->start<<PageShift)) / size;
switch(s->types.compression) {
case MTypes_Empty:
ntypes = (s->npages << PageShift) / size;
nbytes3 = 8*sizeof(uintptr) + 1*ntypes;
if(!sysalloc) {
data3 = runtime_mallocgc(nbytes3, FlagNoPointers, 0, 1);
} else {
data3 = runtime_SysAlloc(nbytes3);
if(0) runtime_printf("settype(0->3): SysAlloc(%x) --> %p\n", (uint32)nbytes3, data3);
}
s->types.compression = MTypes_Bytes;
s->types.sysalloc = sysalloc;
s->types.data = (uintptr)data3;
((uintptr*)data3)[1] = typ;
data3[8*sizeof(uintptr) + ofs] = 1;
break;
case MTypes_Words:
((uintptr*)s->types.data)[ofs] = typ;
break;
case MTypes_Bytes:
data3 = (byte*)s->types.data;
for(j=1; j<8; j++) {
if(((uintptr*)data3)[j] == typ) {
break;
}
if(((uintptr*)data3)[j] == 0) {
((uintptr*)data3)[j] = typ;
break;
}
}
if(j < 8) {
data3[8*sizeof(uintptr) + ofs] = j;
} else {
ntypes = (s->npages << PageShift) / size;
nbytes2 = ntypes * sizeof(uintptr);
if(!sysalloc) {
data2 = runtime_mallocgc(nbytes2, FlagNoPointers, 0, 1);
} else {
data2 = runtime_SysAlloc(nbytes2);
if(0) runtime_printf("settype.(3->2): SysAlloc(%x) --> %p\n", (uint32)nbytes2, data2);
}
sysalloc3 = s->types.sysalloc;
s->types.compression = MTypes_Words;
s->types.sysalloc = sysalloc;
s->types.data = (uintptr)data2;
// Move the contents of data3 to data2. Then deallocate data3.
for(j=0; j<ntypes; j++) {
t = data3[8*sizeof(uintptr) + j];
t = ((uintptr*)data3)[t];
data2[j] = t;
}
if(sysalloc3) {
nbytes3 = 8*sizeof(uintptr) + 1*ntypes;
if(0) runtime_printf("settype.(3->2): SysFree(%p,%x)\n", data3, (uint32)nbytes3);
runtime_SysFree(data3, nbytes3);
}
data2[ofs] = typ;
}
break;
}
}
runtime_unlock(&settype_lock);
mp->settype_bufsize = 0;
}
// It is forbidden to use this function if it is possible that
// explicit deallocation via calling runtime_free(v) may happen.
void
runtime_settype(void *v, uintptr t)
{
M *mp;
uintptr *buf;
uintptr i;
MSpan *s;
if(t == 0)
runtime_throw("settype: zero type");
mp = runtime_m();
buf = mp->settype_buf;
i = mp->settype_bufsize;
buf[i+0] = (uintptr)v;
buf[i+1] = t;
i += 2;
mp->settype_bufsize = i;
if(i == nelem(mp->settype_buf)) {
runtime_settype_flush(mp, false);
}
if(DebugTypeAtBlockEnd) {
s = runtime_MHeap_Lookup(&runtime_mheap, v);
*(uintptr*)((uintptr)v+s->elemsize-sizeof(uintptr)) = t;
}
}
void
runtime_settype_sysfree(MSpan *s)
{
uintptr ntypes, nbytes;
if(!s->types.sysalloc)
return;
nbytes = (uintptr)-1;
switch (s->types.compression) {
case MTypes_Words:
ntypes = (s->npages << PageShift) / s->elemsize;
nbytes = ntypes * sizeof(uintptr);
break;
case MTypes_Bytes:
ntypes = (s->npages << PageShift) / s->elemsize;
nbytes = 8*sizeof(uintptr) + 1*ntypes;
break;
}
if(nbytes != (uintptr)-1) {
if(0) runtime_printf("settype: SysFree(%p,%x)\n", (void*)s->types.data, (uint32)nbytes);
runtime_SysFree((void*)s->types.data, nbytes);
}
}
uintptr
runtime_gettype(void *v)
{
MSpan *s;
uintptr t, ofs;
byte *data;
s = runtime_MHeap_LookupMaybe(&runtime_mheap, v);
if(s != nil) {
t = 0;
switch(s->types.compression) {
case MTypes_Empty:
break;
case MTypes_Single:
t = s->types.data;
break;
case MTypes_Words:
ofs = (uintptr)v - (s->start<<PageShift);
t = ((uintptr*)s->types.data)[ofs/s->elemsize];
break;
case MTypes_Bytes:
ofs = (uintptr)v - (s->start<<PageShift);
data = (byte*)s->types.data;
t = data[8*sizeof(uintptr) + ofs/s->elemsize];
t = ((uintptr*)data)[t];
break;
default:
runtime_throw("runtime_gettype: invalid compression kind");
}
if(0) {
runtime_lock(&settype_lock);
runtime_printf("%p -> %d,%X\n", v, (int32)s->types.compression, (int64)t);
runtime_unlock(&settype_lock);
}
return t;
}
return 0;
}
// Runtime stubs.
void*
runtime_mal(uintptr n)
{
return runtime_mallocgc(n, 0, 1, 1);
}
void *
runtime_new(const Type *typ)
{
void *ret;
uint32 flag;
if(raceenabled)
runtime_m()->racepc = runtime_getcallerpc(&typ);
flag = typ->__code&GO_NO_POINTERS ? FlagNoPointers : 0;
ret = runtime_mallocgc(typ->__size, flag, 1, 1);
if(UseSpanType && !flag) {
if(false) {
runtime_printf("new %S: %p\n", *typ->__reflection, ret);
}
runtime_settype(ret, (uintptr)typ | TypeInfo_SingleObject);
}
return ret;
}
func GC() {
runtime_gc(1);
}
func SetFinalizer(obj Eface, finalizer Eface) {
byte *base;
uintptr size;
const FuncType *ft;
if(obj.__type_descriptor == nil) {
runtime_printf("runtime.SetFinalizer: first argument is nil interface\n");
goto throw;
}
if(obj.__type_descriptor->__code != GO_PTR) {
runtime_printf("runtime.SetFinalizer: first argument is %S, not pointer\n", *obj.__type_descriptor->__reflection);
goto throw;
}
if(!runtime_mlookup(obj.__object, &base, &size, nil) || obj.__object != base) {
runtime_printf("runtime.SetFinalizer: pointer not at beginning of allocated block\n");
goto throw;
}
ft = nil;
if(finalizer.__type_descriptor != nil) {
if(finalizer.__type_descriptor->__code != GO_FUNC)
goto badfunc;
ft = (const FuncType*)finalizer.__type_descriptor;
if(ft->__dotdotdot || ft->__in.__count != 1 || !__go_type_descriptors_equal(*(Type**)ft->__in.__values, obj.__type_descriptor))
goto badfunc;
}
if(!runtime_addfinalizer(obj.__object, finalizer.__type_descriptor != nil ? *(void**)finalizer.__object : nil, ft)) {
runtime_printf("runtime.SetFinalizer: finalizer already set\n");
goto throw;
}
return;
badfunc:
runtime_printf("runtime.SetFinalizer: second argument is %S, not func(%S)\n", *finalizer.__type_descriptor->__reflection, *obj.__type_descriptor->__reflection);
throw:
runtime_throw("runtime.SetFinalizer");
}
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