minix/servers/vm/slaballoc.c
Ben Gras ed1af3c86c VM: full munmap
complete munmap implementation; single-page references made
a general munmap() implementation possible to write cleanly.

	. memory: let the MIOCRAMSIZE ioctl set the imgrd device
	  size (but only to 0)
	. let the ramdisk command set sizes to 0
	. use this command to set /dev/imgrd to 0 after mounting /usr
	  in /etc/rc, so the boot time ramdisk is freed (about 4MB
	  currently)
2012-09-18 13:17:52 +02:00

528 lines
12 KiB
C

#define _SYSTEM 1
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/config.h>
#include <minix/const.h>
#include <minix/ds.h>
#include <minix/endpoint.h>
#include <minix/keymap.h>
#include <minix/minlib.h>
#include <minix/type.h>
#include <minix/ipc.h>
#include <minix/sysutil.h>
#include <minix/syslib.h>
#include <minix/bitmap.h>
#include <minix/debug.h>
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <env.h>
#include <memory.h>
#include <sys/param.h>
#include "glo.h"
#include "proto.h"
#include "util.h"
#include "sanitycheck.h"
#define SLABSIZES 60
#define ITEMSPERPAGE(bytes) (DATABYTES / (bytes))
#define ELBITS (sizeof(element_t)*8)
#define BITPAT(b) (1UL << ((b) % ELBITS))
#define BITEL(f, b) (f)->sdh.usebits[(b)/ELBITS]
#define OFF(f, b) assert(!GETBIT(f, b))
#define ON(f, b) assert(GETBIT(f, b))
#if MEMPROTECT
#define SLABDATAWRITABLE(data, wr) do { \
assert(data->sdh.writable == WRITABLE_NONE); \
assert(wr != WRITABLE_NONE); \
vm_pagelock(data, 0); \
data->sdh.writable = wr; \
} while(0)
#define SLABDATAUNWRITABLE(data) do { \
assert(data->sdh.writable != WRITABLE_NONE); \
data->sdh.writable = WRITABLE_NONE; \
vm_pagelock(data, 1); \
} while(0)
#define SLABDATAUSE(data, code) do { \
SLABDATAWRITABLE(data, WRITABLE_HEADER); \
code \
SLABDATAUNWRITABLE(data); \
} while(0)
#else
#define SLABDATAWRITABLE(data, wr)
#define SLABDATAUNWRITABLE(data)
#define SLABDATAUSE(data, code) do { code } while(0)
#endif
#define GETBIT(f, b) (BITEL(f,b) & BITPAT(b))
#define SETBIT(f, b) {OFF(f,b); SLABDATAUSE(f, BITEL(f,b)|= BITPAT(b); (f)->sdh.nused++;); }
#define CLEARBIT(f, b) {ON(f, b); SLABDATAUSE(f, BITEL(f,b)&=~BITPAT(b); (f)->sdh.nused--; (f)->sdh.freeguess = (b);); }
#define OBJALIGN 8
#define MINSIZE 8
#define MAXSIZE (SLABSIZES-1+MINSIZE)
#define USEELEMENTS (1+(VM_PAGE_SIZE/MINSIZE/8))
static int pages = 0;
typedef u8_t element_t;
#define BITS_FULL (~(element_t)0)
typedef element_t elements_t[USEELEMENTS];
/* This file is too low-level to have global SANITYCHECKs everywhere,
* as the (other) data structures are often necessarily in an
* inconsistent state during a slaballoc() / slabfree(). So only do
* our own sanity checks here, with SLABSANITYCHECK.
*/
/* Special writable values. */
#define WRITABLE_NONE -2
#define WRITABLE_HEADER -1
struct sdh {
#if SANITYCHECKS
u32_t magic1;
#endif
int freeguess;
struct slabdata *next, *prev;
elements_t usebits;
phys_bytes phys;
#if SANITYCHECKS
int writable; /* data item number or WRITABLE_* */
u32_t magic2;
#endif
u16_t nused; /* Number of data items used in this slab. */
};
#define DATABYTES (VM_PAGE_SIZE-sizeof(struct sdh))
#define MAGIC1 0x1f5b842f
#define MAGIC2 0x8bb5a420
#define JUNK 0xdeadbeef
#define NOJUNK 0xc0ffee
static struct slabheader {
struct slabdata {
u8_t data[DATABYTES];
struct sdh sdh;
} *list_head;
} slabs[SLABSIZES];
static int objstats(void *, int, struct slabheader **, struct slabdata
**, int *);
#define GETSLAB(b, s) { \
int i; \
assert((b) >= MINSIZE); \
i = (b) - MINSIZE; \
assert((i) < SLABSIZES); \
assert((i) >= 0); \
s = &slabs[i]; \
}
/* move slabdata nw to slabheader sl under list number l. */
#define ADDHEAD(nw, sl) { \
SLABDATAUSE(nw, \
(nw)->sdh.next = sl->list_head; \
(nw)->sdh.prev = NULL;); \
sl->list_head = nw; \
if((nw)->sdh.next) { \
SLABDATAUSE((nw)->sdh.next, \
(nw)->sdh.next->sdh.prev = (nw);); \
} \
}
#define UNLINKNODE(node) { \
struct slabdata *next, *prev; \
prev = (node)->sdh.prev; \
next = (node)->sdh.next; \
if(prev) { SLABDATAUSE(prev, prev->sdh.next = next;); } \
if(next) { SLABDATAUSE(next, next->sdh.prev = prev;); } \
}
static struct slabdata *newslabdata()
{
struct slabdata *n;
phys_bytes p;
assert(sizeof(*n) == VM_PAGE_SIZE);
if(!(n = vm_allocpage(&p, VMP_SLAB))) {
printf("newslabdata: vm_allocpage failed\n");
return NULL;
}
memset(n->sdh.usebits, 0, sizeof(n->sdh.usebits));
pages++;
n->sdh.phys = p;
#if SANITYCHECKS
n->sdh.magic1 = MAGIC1;
n->sdh.magic2 = MAGIC2;
#endif
n->sdh.nused = 0;
n->sdh.freeguess = 0;
#if SANITYCHECKS
n->sdh.writable = WRITABLE_HEADER;
SLABDATAUNWRITABLE(n);
#endif
return n;
}
#if SANITYCHECKS
/*===========================================================================*
* checklist *
*===========================================================================*/
static int checklist(char *file, int line,
struct slabheader *s, int bytes)
{
struct slabdata *n = s->list_head;
int ch = 0;
while(n) {
int count = 0, i;
#if SANITYCHECKS
MYASSERT(n->sdh.magic1 == MAGIC1);
MYASSERT(n->sdh.magic2 == MAGIC2);
#endif
MYASSERT(usedpages_add(n->sdh.phys, VM_PAGE_SIZE) == OK);
if(n->sdh.prev)
MYASSERT(n->sdh.prev->sdh.next == n);
else
MYASSERT(s->list_head == n);
if(n->sdh.next) MYASSERT(n->sdh.next->sdh.prev == n);
for(i = 0; i < USEELEMENTS*8; i++)
if(i >= ITEMSPERPAGE(bytes))
MYASSERT(!GETBIT(n, i));
else
if(GETBIT(n,i))
count++;
MYASSERT(count == n->sdh.nused);
ch += count;
n = n->sdh.next;
}
return ch;
}
/*===========================================================================*
* void slab_sanitycheck *
*===========================================================================*/
void slab_sanitycheck(char *file, int line)
{
int s;
for(s = 0; s < SLABSIZES; s++) {
checklist(file, line, &slabs[s], s + MINSIZE);
}
}
/*===========================================================================*
* int slabsane *
*===========================================================================*/
int slabsane_f(char *file, int line, void *mem, int bytes)
{
struct slabheader *s;
struct slabdata *f;
int i;
bytes = roundup(bytes, OBJALIGN);
return (objstats(mem, bytes, &s, &f, &i) == OK);
}
#endif
#if SANITYCHECKS
static int nojunkwarning = 0;
#endif
/*===========================================================================*
* void *slaballoc *
*===========================================================================*/
void *slaballoc(int bytes)
{
int i;
int count = 0;
struct slabheader *s;
struct slabdata *newslab;
char *ret;
bytes = roundup(bytes, OBJALIGN);
SLABSANITYCHECK(SCL_FUNCTIONS);
/* Retrieve entry in slabs[]. */
GETSLAB(bytes, s);
assert(s);
if(!(newslab = s->list_head)) {
/* Make sure there is something on the freelist. */
newslab = newslabdata();
if(!newslab) return NULL;
ADDHEAD(newslab, s);
assert(newslab->sdh.nused == 0);
} else assert(newslab->sdh.nused > 0);
assert(newslab->sdh.nused < ITEMSPERPAGE(bytes));
SLABSANITYCHECK(SCL_DETAIL);
#if SANITYCHECKS
assert(newslab->sdh.magic1 == MAGIC1);
assert(newslab->sdh.magic2 == MAGIC2);
#endif
for(i = newslab->sdh.freeguess;
count < ITEMSPERPAGE(bytes); count++, i++) {
i = i % ITEMSPERPAGE(bytes);
if(!GETBIT(newslab, i))
break;
}
SLABSANITYCHECK(SCL_FUNCTIONS);
assert(count < ITEMSPERPAGE(bytes));
assert(i >= 0 && i < ITEMSPERPAGE(bytes));
SETBIT(newslab, i);
if(newslab->sdh.nused == ITEMSPERPAGE(bytes)) {
UNLINKNODE(newslab);
s->list_head = newslab->sdh.next;
}
ret = ((char *) newslab) + i*bytes;
#if SANITYCHECKS
#if MEMPROTECT
nojunkwarning++;
slabunlock(ret, bytes);
nojunkwarning--;
assert(!nojunkwarning);
#endif
*(u32_t *) ret = NOJUNK;
#if MEMPROTECT
slablock(ret, bytes);
#endif
#endif
SLABDATAUSE(newslab, newslab->sdh.freeguess = i+1;);
#if SANITYCHECKS
if(bytes >= SLABSIZES+MINSIZE) {
printf("slaballoc: odd, bytes %d?\n", bytes);
}
if(!slabsane_f(__FILE__, __LINE__, ret, bytes))
panic("slaballoc: slabsane failed");
#endif
assert(!((vir_bytes) ret % OBJALIGN));
return ret;
}
/*===========================================================================*
* int objstats *
*===========================================================================*/
static inline int objstats(void *mem, int bytes,
struct slabheader **sp, struct slabdata **fp, int *ip)
{
#if SANITYCHECKS
#define OBJSTATSCHECK(cond) \
if(!(cond)) { \
printf("VM: objstats: %s failed for ptr %p, %d bytes\n", \
#cond, mem, bytes); \
return EINVAL; \
}
#else
#define OBJSTATSCHECK(cond)
#endif
struct slabheader *s;
struct slabdata *f;
int i;
assert(!(bytes % OBJALIGN));
OBJSTATSCHECK((char *) mem >= (char *) VM_PAGE_SIZE);
#if SANITYCHECKS
if(*(u32_t *) mem == JUNK && !nojunkwarning) {
util_stacktrace();
printf("VM: WARNING: JUNK seen in slab object, likely freed\n");
}
#endif
/* Retrieve entry in slabs[]. */
GETSLAB(bytes, s);
/* Round address down to VM_PAGE_SIZE boundary to get header. */
f = (struct slabdata *) ((char *) mem - (vir_bytes) mem % VM_PAGE_SIZE);
#if SANITYCHECKS
OBJSTATSCHECK(f->sdh.magic1 == MAGIC1);
OBJSTATSCHECK(f->sdh.magic2 == MAGIC2);
#endif
/* Make sure it's in range. */
OBJSTATSCHECK((char *) mem >= (char *) f->data);
OBJSTATSCHECK((char *) mem < (char *) f->data + sizeof(f->data));
/* Get position. */
i = (char *) mem - (char *) f->data;
OBJSTATSCHECK(!(i % bytes));
i = i / bytes;
/* Make sure it is marked as allocated. */
OBJSTATSCHECK(GETBIT(f, i));
/* return values */
*ip = i;
*fp = f;
*sp = s;
return OK;
}
/*===========================================================================*
* void *slabfree *
*===========================================================================*/
void slabfree(void *mem, int bytes)
{
int i;
struct slabheader *s;
struct slabdata *f;
bytes = roundup(bytes, OBJALIGN);
SLABSANITYCHECK(SCL_FUNCTIONS);
if(objstats(mem, bytes, &s, &f, &i) != OK) {
panic("slabfree objstats failed");
}
#if SANITYCHECKS
if(*(u32_t *) mem == JUNK) {
printf("VM: WARNING: likely double free, JUNK seen\n");
}
#endif
#if SANITYCHECKS
#if MEMPROTECT
slabunlock(mem, bytes);
#endif
#if JUNKFREE
memset(mem, 0xa6, bytes);
#endif
*(u32_t *) mem = JUNK;
nojunkwarning++;
#if MEMPROTECT
slablock(mem, bytes);
#endif
nojunkwarning--;
assert(!nojunkwarning);
#endif
/* Free this data. */
CLEARBIT(f, i);
/* Check if this slab changes lists. */
if(f->sdh.nused == 0) {
UNLINKNODE(f);
if(f == s->list_head) s->list_head = f->sdh.next;
vm_freepages((vir_bytes) f, 1);
SLABSANITYCHECK(SCL_DETAIL);
} else if(f->sdh.nused == ITEMSPERPAGE(bytes)-1) {
ADDHEAD(f, s);
}
SLABSANITYCHECK(SCL_FUNCTIONS);
return;
}
/*===========================================================================*
* void *slablock *
*===========================================================================*/
void slablock(void *mem, int bytes)
{
int i;
struct slabheader *s;
struct slabdata *f;
bytes = roundup(bytes, OBJALIGN);
if(objstats(mem, bytes, &s, &f, &i) != OK)
panic("slablock objstats failed");
SLABDATAUNWRITABLE(f);
return;
}
/*===========================================================================*
* void *slabunlock *
*===========================================================================*/
void slabunlock(void *mem, int bytes)
{
int i;
struct slabheader *s;
struct slabdata *f;
bytes = roundup(bytes, OBJALIGN);
if(objstats(mem, bytes, &s, &f, &i) != OK)
panic("slabunlock objstats failed");
SLABDATAWRITABLE(f, i);
return;
}
#if SANITYCHECKS
/*===========================================================================*
* void slabstats *
*===========================================================================*/
void slabstats(void)
{
int s, totalbytes = 0;
static int n;
n++;
if(n%1000) return;
for(s = 0; s < SLABSIZES; s++) {
int b, t;
b = s + MINSIZE;
t = checklist(__FILE__, __LINE__, &slabs[s], b);
if(t > 0) {
int bytes = t * b;
printf("VMSTATS: %2d slabs: %d (%dkB)\n", b, t, bytes/1024);
totalbytes += bytes;
}
}
if(pages > 0) {
printf("VMSTATS: %dK net used in slab objects in %d pages (%dkB): %d%% utilization\n",
totalbytes/1024, pages, pages*VM_PAGE_SIZE/1024,
100 * totalbytes / (pages*VM_PAGE_SIZE));
}
}
#endif