minix/servers/vm/alloc.c

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/* This file is concerned with allocating and freeing arbitrary-size blocks of
* physical memory on behalf of the FORK and EXEC system calls. The key data
* structure used is the hole table, which maintains a list of holes in memory.
* It is kept sorted in order of increasing memory address. The addresses
* it contains refers to physical memory, starting at absolute address 0
* (i.e., they are not relative to the start of PM). During system
* initialization, that part of memory containing the interrupt vectors,
* kernel, and PM are "allocated" to mark them as not available and to
* remove them from the hole list.
*
* The entry points into this file are:
* alloc_mem: allocate a given sized chunk of memory
* free_mem: release a previously allocated chunk of memory
* mem_init: initialize the tables when PM start up
*/
#define _SYSTEM 1
#include <minix/com.h>
#include <minix/callnr.h>
#include <minix/type.h>
#include <minix/config.h>
#include <minix/const.h>
#include <minix/sysutil.h>
#include <minix/syslib.h>
#include <sys/mman.h>
#include <limits.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <memory.h>
#include "vm.h"
#include "proto.h"
#include "util.h"
#include "glo.h"
/* Initially, no free pages are known. */
PRIVATE phys_bytes free_pages_head = NO_MEM; /* Physical address in bytes. */
/* Used for sanity check. */
PRIVATE phys_bytes mem_low, mem_high;
#define vm_assert_range(addr, len) \
vm_assert((addr) >= mem_low); \
vm_assert((addr) + (len) - 1 <= mem_high);
struct hole {
struct hole *h_next; /* pointer to next entry on the list */
phys_clicks h_base; /* where does the hole begin? */
phys_clicks h_len; /* how big is the hole? */
int freelist;
int holelist;
};
#define NIL_HOLE (struct hole *) 0
#define _NR_HOLES (_NR_PROCS*2) /* No. of memory holes maintained by VM */
PRIVATE struct hole hole[_NR_HOLES];
PRIVATE struct hole *hole_head; /* pointer to first hole */
PRIVATE struct hole *free_slots;/* ptr to list of unused table slots */
FORWARD _PROTOTYPE( void del_slot, (struct hole *prev_ptr, struct hole *hp) );
FORWARD _PROTOTYPE( void merge, (struct hole *hp) );
FORWARD _PROTOTYPE( void free_pages, (phys_bytes addr, int pages) );
FORWARD _PROTOTYPE( phys_bytes alloc_pages, (int pages, int flags) );
#if SANITYCHECKS
FORWARD _PROTOTYPE( void holes_sanity_f, (char *fn, int line) );
#define CHECKHOLES holes_sanity_f(__FILE__, __LINE__)
#else
#define CHECKHOLES
#endif
/* Sanity check for parameters of node p. */
#define vm_assert_params(p, bytes, next) { \
vm_assert((p) != NO_MEM); \
vm_assert(!((bytes) % VM_PAGE_SIZE)); \
vm_assert(!((next) % VM_PAGE_SIZE)); \
vm_assert((bytes) > 0); \
vm_assert((p) + (bytes) > (p)); \
vm_assert((next) == NO_MEM || ((p) + (bytes) <= (next))); \
vm_assert_range((p), (bytes)); \
vm_assert_range((next), 1); \
}
/* Retrieve size of free block and pointer to next block from physical
* address (page) p.
*/
#define GET_PARAMS(p, bytes, next) { \
phys_readaddr((p), &(bytes), &(next)); \
vm_assert_params((p), (bytes), (next)); \
}
/* Write parameters to physical page p. */
#define SET_PARAMS(p, bytes, next) { \
vm_assert_params((p), (bytes), (next)); \
phys_writeaddr((p), (bytes), (next)); \
}
void availbytes(vir_bytes *bytes, vir_bytes *chunks)
{
phys_bytes p, nextp;
*bytes = 0;
*chunks = 0;
for(p = free_pages_head; p != NO_MEM; p = nextp) {
phys_bytes thissize, ret;
GET_PARAMS(p, thissize, nextp);
(*bytes) += thissize;
(*chunks)++;
if(nextp != NO_MEM) {
vm_assert(nextp > p);
vm_assert(nextp > p + thissize);
}
}
return;
}
#if SANITYCHECKS
/*===========================================================================*
* holes_sanity_f *
*===========================================================================*/
PRIVATE void holes_sanity_f(file, line)
char *file;
int line;
{
#define myassert(c) { \
if(!(c)) { \
printf("holes_sanity_f:%s:%d: %s failed\n", file, line, #c); \
util_stacktrace(); \
vm_panic("assert failed.", NO_NUM); } \
}
int h, c = 0, n = 0;
struct hole *hp;
/* Reset flags */
for(h = 0; h < _NR_HOLES; h++) {
hole[h].freelist = 0;
hole[h].holelist = 0;
}
/* Mark all holes on freelist. */
for(hp = free_slots; hp; hp = hp->h_next) {
myassert(!hp->freelist);
myassert(!hp->holelist);
hp->freelist = 1;
myassert(c < _NR_HOLES);
c++;
n++;
}
/* Mark all holes on holelist. */
c = 0;
for(hp = hole_head; hp; hp = hp->h_next) {
myassert(!hp->freelist);
myassert(!hp->holelist);
hp->holelist = 1;
myassert(c < _NR_HOLES);
c++;
n++;
}
/* Check there are exactly the right number of nodes. */
myassert(n == _NR_HOLES);
/* Make sure each slot is on exactly one of the list. */
c = 0;
for(h = 0; h < _NR_HOLES; h++) {
hp = &hole[h];
myassert(hp->holelist || hp->freelist);
myassert(!(hp->holelist && hp->freelist));
myassert(c < _NR_HOLES);
c++;
}
/* Make sure no holes overlap. */
for(hp = hole_head; hp && hp->h_next; hp = hp->h_next) {
myassert(hp->holelist);
hp->holelist = 1;
/* No holes overlap. */
myassert(hp->h_base + hp->h_len <= hp->h_next->h_base);
/* No uncoalesced holes. */
myassert(hp->h_base + hp->h_len < hp->h_next->h_base);
}
}
#endif
/*===========================================================================*
* alloc_mem_f *
*===========================================================================*/
PUBLIC phys_clicks alloc_mem_f(phys_clicks clicks, u32_t memflags)
{
/* Allocate a block of memory from the free list using first fit. The block
* consists of a sequence of contiguous bytes, whose length in clicks is
* given by 'clicks'. A pointer to the block is returned. The block is
* always on a click boundary. This procedure is called when memory is
* needed for FORK or EXEC.
*/
register struct hole *hp, *prev_ptr;
phys_clicks old_base;
int s;
if(vm_paged) {
vm_assert(CLICK_SIZE == VM_PAGE_SIZE);
return alloc_pages(clicks, memflags);
}
CHECKHOLES;
{
prev_ptr = NIL_HOLE;
hp = hole_head;
while (hp != NIL_HOLE) {
if (hp->h_len >= clicks) {
/* We found a hole that is big enough. Use it. */
old_base = hp->h_base; /* remember where it started */
hp->h_base += clicks; /* bite a piece off */
hp->h_len -= clicks; /* ditto */
/* Delete the hole if used up completely. */
if (hp->h_len == 0) del_slot(prev_ptr, hp);
/* Anything special needs to happen? */
if(memflags & PAF_CLEAR) {
if ((s= sys_memset(0, CLICK_SIZE*old_base,
CLICK_SIZE*clicks)) != OK) {
vm_panic("alloc_mem: sys_memset failed", s);
}
}
/* Return the start address of the acquired block. */
CHECKHOLES;
return(old_base);
}
prev_ptr = hp;
hp = hp->h_next;
}
}
CHECKHOLES;
return(NO_MEM);
}
/*===========================================================================*
* free_mem_f *
*===========================================================================*/
PUBLIC void free_mem_f(phys_clicks base, phys_clicks clicks)
{
/* Return a block of free memory to the hole list. The parameters tell where
* the block starts in physical memory and how big it is. The block is added
* to the hole list. If it is contiguous with an existing hole on either end,
* it is merged with the hole or holes.
*/
register struct hole *hp, *new_ptr, *prev_ptr;
CHECKHOLES;
if (clicks == 0) return;
if(vm_paged) {
vm_assert(CLICK_SIZE == VM_PAGE_SIZE);
free_pages(base, clicks);
return;
}
if ( (new_ptr = free_slots) == NIL_HOLE)
vm_panic("hole table full", NO_NUM);
new_ptr->h_base = base;
new_ptr->h_len = clicks;
free_slots = new_ptr->h_next;
hp = hole_head;
/* If this block's address is numerically less than the lowest hole currently
* available, or if no holes are currently available, put this hole on the
* front of the hole list.
*/
if (hp == NIL_HOLE || base <= hp->h_base) {
/* Block to be freed goes on front of the hole list. */
new_ptr->h_next = hp;
hole_head = new_ptr;
merge(new_ptr);
CHECKHOLES;
return;
}
/* Block to be returned does not go on front of hole list. */
prev_ptr = NIL_HOLE;
while (hp != NIL_HOLE && base > hp->h_base) {
prev_ptr = hp;
hp = hp->h_next;
}
/* We found where it goes. Insert block after 'prev_ptr'. */
new_ptr->h_next = prev_ptr->h_next;
prev_ptr->h_next = new_ptr;
merge(prev_ptr); /* sequence is 'prev_ptr', 'new_ptr', 'hp' */
CHECKHOLES;
}
/*===========================================================================*
* del_slot *
*===========================================================================*/
PRIVATE void del_slot(prev_ptr, hp)
/* pointer to hole entry just ahead of 'hp' */
register struct hole *prev_ptr;
/* pointer to hole entry to be removed */
register struct hole *hp;
{
/* Remove an entry from the hole list. This procedure is called when a
* request to allocate memory removes a hole in its entirety, thus reducing
* the numbers of holes in memory, and requiring the elimination of one
* entry in the hole list.
*/
if (hp == hole_head)
hole_head = hp->h_next;
else
prev_ptr->h_next = hp->h_next;
hp->h_next = free_slots;
hp->h_base = hp->h_len = 0;
free_slots = hp;
}
/*===========================================================================*
* merge *
*===========================================================================*/
PRIVATE void merge(hp)
register struct hole *hp; /* ptr to hole to merge with its successors */
{
/* Check for contiguous holes and merge any found. Contiguous holes can occur
* when a block of memory is freed, and it happens to abut another hole on
* either or both ends. The pointer 'hp' points to the first of a series of
* three holes that can potentially all be merged together.
*/
register struct hole *next_ptr;
/* If 'hp' points to the last hole, no merging is possible. If it does not,
* try to absorb its successor into it and free the successor's table entry.
*/
if ( (next_ptr = hp->h_next) == NIL_HOLE) return;
if (hp->h_base + hp->h_len == next_ptr->h_base) {
hp->h_len += next_ptr->h_len; /* first one gets second one's mem */
del_slot(hp, next_ptr);
} else {
hp = next_ptr;
}
/* If 'hp' now points to the last hole, return; otherwise, try to absorb its
* successor into it.
*/
if ( (next_ptr = hp->h_next) == NIL_HOLE) return;
if (hp->h_base + hp->h_len == next_ptr->h_base) {
hp->h_len += next_ptr->h_len;
del_slot(hp, next_ptr);
}
}
/*===========================================================================*
* mem_init *
*===========================================================================*/
PUBLIC void mem_init(chunks)
struct memory *chunks; /* list of free memory chunks */
{
/* Initialize hole lists. There are two lists: 'hole_head' points to a linked
* list of all the holes (unused memory) in the system; 'free_slots' points to
* a linked list of table entries that are not in use. Initially, the former
* list has one entry for each chunk of physical memory, and the second
* list links together the remaining table slots. As memory becomes more
* fragmented in the course of time (i.e., the initial big holes break up into
* smaller holes), new table slots are needed to represent them. These slots
* are taken from the list headed by 'free_slots'.
*/
int i, first = 0;
register struct hole *hp;
/* Put all holes on the free list. */
for (hp = &hole[0]; hp < &hole[_NR_HOLES]; hp++) {
hp->h_next = hp + 1;
hp->h_base = hp->h_len = 0;
}
hole[_NR_HOLES-1].h_next = NIL_HOLE;
hole_head = NIL_HOLE;
free_slots = &hole[0];
/* Use the chunks of physical memory to allocate holes. */
for (i=NR_MEMS-1; i>=0; i--) {
if (chunks[i].size > 0) {
phys_bytes from = CLICK2ABS(chunks[i].base),
to = CLICK2ABS(chunks[i].base+chunks[i].size)-1;
if(first || from < mem_low) mem_low = from;
if(first || to > mem_high) mem_high = to;
FREE_MEM(chunks[i].base, chunks[i].size);
first = 0;
}
}
CHECKHOLES;
}
/*===========================================================================*
* alloc_pages *
*===========================================================================*/
PRIVATE PUBLIC phys_bytes alloc_pages(int pages, int memflags)
{
phys_bytes bytes, p, nextp, prevp = NO_MEM;
phys_bytes prevsize = 0;
#if SANITYCHECKS
vir_bytes avail1, avail2, chunks1, chunks2;
availbytes(&avail1, &chunks1);
#endif
vm_assert(pages > 0);
bytes = CLICK2ABS(pages);
vm_assert(ABS2CLICK(bytes) == pages);
#if SANITYCHECKS
#define ALLOCRETURNCHECK \
availbytes(&avail2, &chunks2); \
vm_assert(avail1 - bytes == avail2); \
vm_assert(chunks1 == chunks2 || chunks1-1 == chunks2); \
if(verbosealloc) \
printf("memory: 0x%lx bytes in %d chunks\n", avail2, chunks2);
#else
#define ALLOCRETURNCHECK
#endif
for(p = free_pages_head; p != NO_MEM; p = nextp) {
phys_bytes thissize, ret;
GET_PARAMS(p, thissize, nextp);
if(thissize >= bytes) {
/* We found a chunk that's big enough. */
ret = p + thissize - bytes;
thissize -= bytes;
if(thissize == 0) {
/* Special case: remove this link entirely. */
if(prevp == NO_MEM)
free_pages_head = nextp;
else {
vm_assert(prevsize > 0);
SET_PARAMS(prevp, prevsize, nextp);
}
} else {
/* Remove memory from this chunk. */
SET_PARAMS(p, thissize, nextp);
}
/* Clear memory if requested. */
if(memflags & PAF_CLEAR) {
int s;
if ((s= sys_memset(0, ret, bytes)) != OK) {
vm_panic("alloc_pages: sys_memset failed", s);
}
}
/* Check if returned range is actual good memory. */
vm_assert_range(ret, bytes);
ALLOCRETURNCHECK;
/* Return it in clicks. */
return ABS2CLICK(ret);
}
prevp = p;
prevsize = thissize;
}
return NO_MEM;
}
/*===========================================================================*
* free_pages *
*===========================================================================*/
PRIVATE PUBLIC void free_pages(phys_bytes pageno, int npages)
{
phys_bytes p, origsize,
size, nextaddr, thissize, prevp = NO_MEM, pageaddr;
#if SANITYCHECKS
vir_bytes avail1, avail2, chunks1, chunks2;
availbytes(&avail1, &chunks1);
#endif
#if SANITYCHECKS
#define FREERETURNCHECK \
availbytes(&avail2, &chunks2); \
vm_assert(avail1 + origsize == avail2); \
vm_assert(chunks1 == chunks2 || chunks1+1 == chunks2 || chunks1-1 == chunks2); \
if(verbosealloc) \
printf("memory: 0x%lx bytes in %d chunks\n", avail2, chunks2);
#else
#define FREERETURNCHECK
#endif
/* Basic sanity check. */
vm_assert(npages > 0);
vm_assert(pageno != NO_MEM); /* Page number must be reasonable. */
/* Convert page and pages to bytes. */
pageaddr = CLICK2ABS(pageno);
origsize = size = npages * VM_PAGE_SIZE; /* Size in bytes. */
vm_assert(pageaddr != NO_MEM);
vm_assert(ABS2CLICK(pageaddr) == pageno);
vm_assert_range(pageaddr, size);
/* More sanity checks. */
vm_assert(ABS2CLICK(size) == npages); /* Sanity. */
vm_assert(pageaddr + size > pageaddr); /* Must not overflow. */
/* Special case: no free pages. */
if(free_pages_head == NO_MEM) {
free_pages_head = pageaddr;
SET_PARAMS(pageaddr, size, NO_MEM);
FREERETURNCHECK;
return;
}
/* Special case: the free block is before the current head. */
if(pageaddr < free_pages_head) {
phys_bytes newsize, newnext, headsize, headnext;
vm_assert(pageaddr + size <= free_pages_head);
GET_PARAMS(free_pages_head, headsize, headnext);
newsize = size;
if(pageaddr + size == free_pages_head) {
/* Special case: contiguous. */
newsize += headsize;
newnext = headnext;
} else {
newnext = free_pages_head;
}
SET_PARAMS(pageaddr, newsize, newnext);
free_pages_head = pageaddr;
FREERETURNCHECK;
return;
}
/* Find where to put the block in the free list. */
for(p = free_pages_head; p < pageaddr; p = nextaddr) {
GET_PARAMS(p, thissize, nextaddr);
if(nextaddr == NO_MEM) {
/* Special case: page is at the end of the list. */
if(p + thissize == pageaddr) {
/* Special case: contiguous. */
SET_PARAMS(p, thissize + size, NO_MEM);
FREERETURNCHECK;
} else {
SET_PARAMS(p, thissize, pageaddr);
SET_PARAMS(pageaddr, size, NO_MEM);
FREERETURNCHECK;
}
return;
}
prevp = p;
}
/* Normal case: insert page block between two others.
* The first block starts at 'prevp' and is 'thissize'.
* The second block starts at 'p' and is 'nextsize'.
* The block that has to come in between starts at
* 'pageaddr' and is size 'size'.
*/
vm_assert(p != NO_MEM);
vm_assert(prevp != NO_MEM);
vm_assert(prevp < p);
vm_assert(p == nextaddr);
#if SANITYCHECKS
{
vir_bytes prevpsize, prevpnext;
GET_PARAMS(prevp, prevpsize, prevpnext);
vm_assert(prevpsize == thissize);
vm_assert(prevpnext == p);
availbytes(&avail2, &chunks2);
vm_assert(avail1 == avail2);
}
#endif
if(prevp + thissize == pageaddr) {
/* Special case: first block is contiguous with freed one. */
phys_bytes newsize = thissize + size;
SET_PARAMS(prevp, newsize, p);
pageaddr = prevp;
size = newsize;
} else {
SET_PARAMS(prevp, thissize, pageaddr);
}
/* The block has been inserted (and possibly merged with the
* first one). Check if it has to be merged with the second one.
*/
if(pageaddr + size == p) {
phys_bytes nextsize, nextnextaddr;
/* Special case: freed block is contiguous with next one. */
GET_PARAMS(p, nextsize, nextnextaddr);
SET_PARAMS(pageaddr, size+nextsize, nextnextaddr);
FREERETURNCHECK;
} else {
SET_PARAMS(pageaddr, size, p);
FREERETURNCHECK;
}
return;
}
#define NR_DMA 16
PRIVATE struct dmatab
{
int dt_flags;
endpoint_t dt_proc;
phys_bytes dt_base;
phys_bytes dt_size;
phys_clicks dt_seg_base;
phys_clicks dt_seg_size;
} dmatab[NR_DMA];
#define DTF_INUSE 1
#define DTF_RELEASE_DMA 2
#define DTF_RELEASE_SEG 4
/*===========================================================================*
* do_adddma *
*===========================================================================*/
PUBLIC int do_adddma(message *msg)
{
endpoint_t req_proc_e, target_proc_e;
int i, proc_n;
phys_bytes base, size;
struct vmproc *vmp;
req_proc_e= msg->VMAD_REQ;
target_proc_e= msg->VMAD_EP;
base= msg->VMAD_START;
size= msg->VMAD_SIZE;
/* Find empty slot */
for (i= 0; i<NR_DMA; i++)
{
if (!(dmatab[i].dt_flags & DTF_INUSE))
break;
}
if (i >= NR_DMA)
{
printf("vm:do_adddma: dma table full\n");
for (i= 0; i<NR_DMA; i++)
{
printf("%d: flags 0x%x proc %d base 0x%x size 0x%x\n",
i, dmatab[i].dt_flags,
dmatab[i].dt_proc,
dmatab[i].dt_base,
dmatab[i].dt_size);
}
vm_panic("adddma: table full", NO_NUM);
return ENOSPC;
}
/* Find target process */
if (vm_isokendpt(target_proc_e, &proc_n) != OK)
{
printf("vm:do_adddma: endpoint %d not found\n", target_proc_e);
return EINVAL;
}
vmp= &vmproc[proc_n];
vmp->vm_flags |= VMF_HAS_DMA;
dmatab[i].dt_flags= DTF_INUSE;
dmatab[i].dt_proc= target_proc_e;
dmatab[i].dt_base= base;
dmatab[i].dt_size= size;
return OK;
}
/*===========================================================================*
* do_deldma *
*===========================================================================*/
PUBLIC int do_deldma(message *msg)
{
endpoint_t req_proc_e, target_proc_e;
int i, j, proc_n;
phys_bytes base, size;
struct vmproc *vmp;
req_proc_e= msg->VMDD_REQ;
target_proc_e= msg->VMDD_EP;
base= msg->VMDD_START;
size= msg->VMDD_SIZE;
/* Find slot */
for (i= 0; i<NR_DMA; i++)
{
if (!(dmatab[i].dt_flags & DTF_INUSE))
continue;
if (dmatab[i].dt_proc == target_proc_e &&
dmatab[i].dt_base == base &&
dmatab[i].dt_size == size)
{
break;
}
}
if (i >= NR_DMA)
{
printf("vm:do_deldma: slot not found\n");
return ESRCH;
}
if (dmatab[i].dt_flags & DTF_RELEASE_SEG)
{
/* Check if we have to release the segment */
for (j= 0; j<NR_DMA; j++)
{
if (j == i)
continue;
if (!(dmatab[j].dt_flags & DTF_INUSE))
continue;
if (!(dmatab[j].dt_flags & DTF_RELEASE_SEG))
continue;
if (dmatab[i].dt_proc == target_proc_e)
break;
}
if (j >= NR_DMA)
{
/* Last segment */
FREE_MEM(dmatab[i].dt_seg_base,
dmatab[i].dt_seg_size);
}
}
dmatab[i].dt_flags &= ~DTF_INUSE;
return OK;
}
/*===========================================================================*
* do_getdma *
*===========================================================================*/
PUBLIC int do_getdma(message *msg)
{
endpoint_t target_proc_e;
int i, proc_n;
phys_bytes base, size;
struct vmproc *vmp;
/* Find slot to report */
for (i= 0; i<NR_DMA; i++)
{
if (!(dmatab[i].dt_flags & DTF_INUSE))
continue;
if (!(dmatab[i].dt_flags & DTF_RELEASE_DMA))
continue;
printf("do_getdma: setting reply to 0x%x@0x%x proc %d\n",
dmatab[i].dt_size, dmatab[i].dt_base,
dmatab[i].dt_proc);
msg->VMGD_PROCP= dmatab[i].dt_proc;
msg->VMGD_BASEP= dmatab[i].dt_base;
msg->VMGD_SIZEP= dmatab[i].dt_size;
return OK;
}
/* Nothing */
return EAGAIN;
}
/*===========================================================================*
* release_dma *
*===========================================================================*/
PUBLIC void release_dma(struct vmproc *vmp)
{
int i, found_one;
vm_panic("release_dma not done", NO_NUM);
#if 0
found_one= FALSE;
for (i= 0; i<NR_DMA; i++)
{
if (!(dmatab[i].dt_flags & DTF_INUSE))
continue;
if (dmatab[i].dt_proc != vmp->vm_endpoint)
continue;
dmatab[i].dt_flags |= DTF_RELEASE_DMA | DTF_RELEASE_SEG;
dmatab[i].dt_seg_base= base;
dmatab[i].dt_seg_size= size;
found_one= TRUE;
}
if (!found_one)
FREE_MEM(base, size);
msg->VMRD_FOUND = found_one;
#endif
return;
}
/*===========================================================================*
* do_allocmem *
*===========================================================================*/
PUBLIC int do_allocmem(message *m)
{
phys_clicks mem, clicks;
clicks = 1 + ((vir_bytes)m->VMAM_BYTES / CLICK_SIZE);
if((mem=ALLOC_MEM(clicks, PAF_CLEAR)) == NO_MEM) {
return ENOMEM;
}
m->VMAM_MEMBASE = CLICK2ABS(mem);
#if 0
printf("VM: do_allocmem: 0x%lx clicks OK at 0x%lx\n", m->VMAM_CLICKS, mem);
#endif
return OK;
}