blob: 84c802f94a98a8464ec207d26eb61b70da2f5378 [file] [log] [blame]
// 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.
// TODO(rsc): solve "stack overflow during malloc" problem.
#include "runtime.h"
#include "malloc.h"
#include "defs.h"
MHeap mheap;
MStats mstats;
// 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*
malloc(uintptr size)
{
int32 sizeclass;
MCache *c;
uintptr npages;
MSpan *s;
void *v;
uint32 *ref;
if(m->mallocing)
throw("malloc/free - deadlock");
m->mallocing = 1;
if(size == 0)
size = 1;
if(size <= MaxSmallSize) {
// Allocate from mcache free lists.
sizeclass = SizeToClass(size);
size = class_to_size[sizeclass];
c = m->mcache;
v = MCache_Alloc(c, sizeclass, size);
if(v == nil)
throw("out of memory");
mstats.alloc += size;
} else {
// TODO(rsc): Report tracebacks for very large allocations.
// Allocate directly from heap.
npages = size >> PageShift;
if((size & PageMask) != 0)
npages++;
s = MHeap_Alloc(&mheap, npages, 0);
if(s == nil)
throw("out of memory");
mstats.alloc += npages<<PageShift;
v = (void*)(s->start << PageShift);
}
// setup for mark sweep
if(!mlookup(v, nil, nil, &ref)) {
printf("malloc %D; mlookup failed\n", (uint64)size);
throw("malloc mlookup");
}
*ref = RefNone;
m->mallocing = 0;
return v;
}
void*
mallocgc(uintptr size)
{
void *v;
v = malloc(size);
if(mstats.inuse_pages > mstats.next_gc)
gc(0);
return v;
}
// Free the object whose base pointer is v.
void
free(void *v)
{
int32 sizeclass, size;
uintptr page, tmp;
MSpan *s;
MCache *c;
uint32 *ref;
if(v == nil)
return;
if(m->mallocing)
throw("malloc/free - deadlock");
m->mallocing = 1;
if(!mlookup(v, nil, nil, &ref))
throw("free mlookup");
*ref = RefFree;
// Find size class for v.
page = (uintptr)v >> PageShift;
sizeclass = MHeapMapCache_GET(&mheap.mapcache, page, tmp);
if(sizeclass == 0) {
// Missed in cache.
s = MHeap_Lookup(&mheap, page);
if(s == nil)
throw("free - invalid pointer");
sizeclass = s->sizeclass;
if(sizeclass == 0) {
// Large object.
mstats.alloc -= s->npages<<PageShift;
sys_memclr(v, s->npages<<PageShift);
MHeap_Free(&mheap, s);
goto out;
}
MHeapMapCache_SET(&mheap.mapcache, page, sizeclass);
}
// Small object.
c = m->mcache;
size = class_to_size[sizeclass];
sys_memclr(v, size);
mstats.alloc -= size;
MCache_Free(c, v, sizeclass, size);
out:
m->mallocing = 0;
}
int32
mlookup(void *v, byte **base, uintptr *size, uint32 **ref)
{
uintptr n, nobj, i;
byte *p;
MSpan *s;
s = MHeap_LookupMaybe(&mheap, (uintptr)v>>PageShift);
if(s == nil) {
if(base)
*base = nil;
if(size)
*size = 0;
if(ref)
*ref = 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;
if(ref)
*ref = &s->gcref0;
return 1;
}
if((byte*)v >= (byte*)s->gcref) {
// pointers into the gc ref counts
// do not count as pointers.
return 0;
}
n = class_to_size[s->sizeclass];
i = ((byte*)v - p)/n;
if(base)
*base = p + i*n;
if(size)
*size = n;
nobj = (s->npages << PageShift) / (n + RefcountOverhead);
if((byte*)s->gcref < p || (byte*)(s->gcref+nobj) > p+(s->npages<<PageShift)) {
printf("odd span state=%d span=%p base=%p sizeclass=%d n=%D size=%D npages=%D\n",
s->state, s, p, s->sizeclass, (uint64)nobj, (uint64)n, (uint64)s->npages);
printf("s->base sizeclass %d v=%p base=%p gcref=%p blocksize=%D nobj=%D size=%D end=%p end=%p\n",
s->sizeclass, v, p, s->gcref, (uint64)s->npages<<PageShift,
(uint64)nobj, (uint64)n, s->gcref + nobj, p+(s->npages<<PageShift));
throw("bad gcref");
}
if(ref)
*ref = &s->gcref[i];
return 1;
}
MCache*
allocmcache(void)
{
return FixAlloc_Alloc(&mheap.cachealloc);
}
void
mallocinit(void)
{
InitSizes();
MHeap_Init(&mheap, SysAlloc);
m->mcache = allocmcache();
// See if it works.
free(malloc(1));
}
void*
SysAlloc(uintptr n)
{
mstats.sys += n;
return sys_mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, -1, 0);
}
void
SysUnused(void *v, uintptr n)
{
USED(v);
USED(n);
// TODO(rsc): call madvise MADV_DONTNEED
}
void
SysFree(void *v, uintptr n)
{
USED(v);
USED(n);
// TODO(rsc): call munmap
}
// Runtime stubs.
extern void *oldmal(uint32);
void*
mal(uint32 n)
{
//return oldmal(n);
void *v;
v = mallocgc(n);
if(0) {
byte *p;
uint32 i;
p = v;
for(i=0; i<n; i++) {
if(p[i] != 0) {
printf("mal %d => %p: byte %d is non-zero\n", n, v, i);
throw("mal");
}
}
}
//printf("mal %d %p\n", n, v); // |checkmal to check for overlapping returns.
return v;
}
// Stack allocator uses malloc/free most of the time,
// but if we're in the middle of malloc and need stack,
// we have to do something else to avoid deadlock.
// In that case, we fall back on a fixed-size free-list
// allocator, assuming that inside malloc all the stack
// frames are small, so that all the stack allocations
// will be a single size, the minimum (right now, 5k).
struct {
Lock;
FixAlloc;
} stacks;
void*
stackalloc(uint32 n)
{
void *v;
uint32 *ref;
//return oldmal(n);
if(m->mallocing || m->gcing) {
lock(&stacks);
if(stacks.size == 0)
FixAlloc_Init(&stacks, n, SysAlloc, nil, nil);
if(stacks.size != n) {
printf("stackalloc: in malloc, size=%D want %d", (uint64)stacks.size, n);
throw("stackalloc");
}
v = FixAlloc_Alloc(&stacks);
unlock(&stacks);
return v;
}
v = malloc(n);
if(!mlookup(v, nil, nil, &ref))
throw("stackalloc mlookup");
*ref = RefStack;
return v;
}
void
stackfree(void *v)
{
//return;
if(m->mallocing || m->gcing) {
lock(&stacks);
FixAlloc_Free(&stacks, v);
unlock(&stacks);
return;
}
free(v);
}