ref: 83246e296ea433b65b9d295b5e08fedd39ff1ab7
dir: /os/pc/memory.c/
/*
* Size memory and create the kernel page-tables on the fly while doing so.
* Called from main(), this code should only be run by the bootstrap processor.
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#define MEMDEBUG 0
enum {
MemUPA = 0, /* unbacked physical address */
MemRAM = 1, /* physical memory */
MemUMB = 2, /* upper memory block (<16MB) */
NMemType = 3,
KB = 1024,
MemMinMB = 4, /* minimum physical memory (<=4MB) */
MemMaxMB = 768, /* maximum physical memory to check */
NMemBase = 10,
};
typedef struct {
u32 size;
uintptr addr;
} Map;
typedef struct {
char* name;
Map* map;
Map* mapend;
Lock;
} RMap;
static Map mapupa[16];
static RMap rmapupa = {
"unallocated unbacked physical memory",
mapupa,
&mapupa[nelem(mapupa)-1],
};
static Map xmapupa[16];
static RMap xrmapupa = {
"unbacked physical memory",
xmapupa,
&xmapupa[nelem(xmapupa)-1],
};
static Map mapram[16];
static RMap rmapram = {
"physical memory",
mapram,
&mapram[nelem(mapram)-1],
};
static Map mapumb[64];
static RMap rmapumb = {
"upper memory block",
mapumb,
&mapumb[nelem(mapumb)-1],
};
static Map mapumbrw[16];
static RMap rmapumbrw = {
"UMB device memory",
mapumbrw,
&mapumbrw[nelem(mapumbrw)-1],
};
void
mapprint(RMap *rmap)
{
Map *mp;
print("%s\n", rmap->name);
for(mp = rmap->map; mp->size; mp++)
print("\t%8.8zuX %8.8uX %8.8zuX\n", mp->addr, mp->size, mp->addr+mp->size);
}
void
memdebug(void)
{
uintptr maxpa, maxpa1, maxpa2;
if(MEMDEBUG == 0)
return;
maxpa = (nvramread(0x18)<<8)|nvramread(0x17);
maxpa1 = (nvramread(0x31)<<8)|nvramread(0x30);
maxpa2 = (nvramread(0x16)<<8)|nvramread(0x15);
print("maxpa = %zuX -> %zuX, maxpa1 = %zuX maxpa2 = %zuX\n",
maxpa, MB+maxpa*KB, maxpa1, maxpa2);
mapprint(&rmapram);
mapprint(&rmapumb);
mapprint(&rmapumbrw);
mapprint(&rmapupa);
}
void
mapfree(RMap* rmap, uintptr addr, ulong size)
{
Map *mp;
uintptr t;
if(size <= 0)
return;
lock(rmap);
for(mp = rmap->map; mp->addr <= addr && mp->size; mp++)
;
if(mp > rmap->map && (mp-1)->addr+(mp-1)->size == addr){
(mp-1)->size += size;
if(addr+size == mp->addr){
(mp-1)->size += mp->size;
while(mp->size){
mp++;
(mp-1)->addr = mp->addr;
(mp-1)->size = mp->size;
}
}
}
else{
if(addr+size == mp->addr && mp->size){
mp->addr -= size;
mp->size += size;
}
else do{
if(mp >= rmap->mapend){
print("mapfree: %s: losing 0x%zuX, %ld\n",
rmap->name, addr, size);
break;
}
t = mp->addr;
mp->addr = addr;
addr = t;
t = mp->size;
mp->size = size;
mp++;
}while(size = t);
}
unlock(rmap);
}
uintptr
mapalloc(RMap* rmap, uintptr addr, int size, int align)
{
Map *mp;
uintptr maddr, oaddr;
lock(rmap);
for(mp = rmap->map; mp->size; mp++){
maddr = mp->addr;
if(addr){
/*
* A specific address range has been given:
* if the current map entry is greater then
* the address is not in the map;
* if the current map entry does not overlap
* the beginning of the requested range then
* continue on to the next map entry;
* if the current map entry does not entirely
* contain the requested range then the range
* is not in the map.
*/
if(maddr > addr)
break;
if(mp->size < addr - maddr) /* maddr+mp->size < addr, but no overflow */
continue;
if(addr - maddr > mp->size - size) /* addr+size > maddr+mp->size, but no overflow */
break;
maddr = addr;
}
if(align > 0)
maddr = ((maddr+align-1)/align)*align;
if(mp->addr+mp->size-maddr < size)
continue;
oaddr = mp->addr;
mp->addr = maddr+size;
mp->size -= maddr-oaddr+size;
if(mp->size == 0){
do{
mp++;
(mp-1)->addr = mp->addr;
}while((mp-1)->size = mp->size);
}
unlock(rmap);
if(oaddr != maddr)
mapfree(rmap, oaddr, maddr-oaddr);
return maddr;
}
unlock(rmap);
return 0;
}
static void
umbscan(void)
{
uchar *p;
/*
* Scan the Upper Memory Blocks (0xA0000->0xF0000) for pieces
* which aren't used; they can be used later for devices which
* want to allocate some virtual address space.
* Check for two things:
* 1) device BIOS ROM. This should start with a two-byte header
* of 0x55 0xAA, followed by a byte giving the size of the ROM
* in 512-byte chunks. These ROM's must start on a 2KB boundary.
* 2) device memory. This is read-write.
* There are some assumptions: there's VGA memory at 0xA0000 and
* the VGA BIOS ROM is at 0xC0000. Also, if there's no ROM signature
* at 0xE0000 then the whole 64KB up to 0xF0000 is theoretically up
* for grabs; check anyway.
*/
p = KADDR(0xD0000);
while(p < (uchar*)KADDR(0xE0000)){
/*
* Test for 0x55 0xAA before poking obtrusively,
* some machines (e.g. Thinkpad X20) seem to map
* something dynamic here (cardbus?) causing weird
* problems if it is changed.
*/
if(p[0] == 0x55 && p[1] == 0xAA){
p += p[2]*512;
continue;
}
p[0] = 0xCC;
p[2*KB-1] = 0xCC;
if(p[0] != 0xCC || p[2*KB-1] != 0xCC){
p[0] = 0x55;
p[1] = 0xAA;
p[2] = 4;
if(p[0] == 0x55 && p[1] == 0xAA){
p += p[2]*512;
continue;
}
if(p[0] == 0xFF && p[1] == 0xFF)
mapfree(&rmapumb, PADDR(p), 2*KB);
}
else
mapfree(&rmapumbrw, PADDR(p), 2*KB);
p += 2*KB;
}
p = KADDR(0xE0000);
if(p[0] != 0x55 || p[1] != 0xAA){
p[0] = 0xCC;
p[64*KB-1] = 0xCC;
if(p[0] != 0xCC && p[64*KB-1] != 0xCC)
mapfree(&rmapumb, PADDR(p), 64*KB);
}
}
static void
ramscan(uintptr maxmem)
{
uintptr *k0, kzero, map, maxpa, pa, *pte, *table, *va, x, n;
int nvalid[NMemType];
uchar *bda;
/*
* The bootstrap code has has created a prototype page
* table which maps the first MemMinMB of physical memory to KZERO.
* The page directory is at m->pdb and the first page of
* free memory is after the per-processor MMU information.
*/
/*
* Initialise the memory bank information for conventional memory
* (i.e. less than 640KB). The base is the first location after the
* bootstrap processor MMU information and the limit is obtained from
* the BIOS data area.
*/
x = PADDR(CPU0MACH+BY2PG);
bda = (uchar*)KADDR(0x400);
n = ((bda[0x14]<<8)|bda[0x13])*KB-x;
mapfree(&rmapram, x, n);
// memset(KADDR(x), 0, n); /* keep us honest */
x = PADDR(PGROUND((uintptr)end));
pa = MemMinMB*MB;
mapfree(&rmapram, x, pa-x);
// memset(KADDR(x), 0, pa-x); /* keep us honest */
/*
* Check if the extended memory size can be obtained from the CMOS.
* If it's 0 then it's either not known or >= 64MB. Always check
* at least 24MB in case there's a memory gap (up to 8MB) below 16MB;
* in this case the memory from the gap is remapped to the top of
* memory.
* The value in CMOS is supposed to be the number of KB above 1MB.
*/
if(maxmem == 0){
x = (nvramread(0x18)<<8)|nvramread(0x17);
if(x == 0 || x >= (63*KB))
maxpa = MemMaxMB*MB;
else
maxpa = MB+x*KB;
if(maxpa < 24*MB)
maxpa = 24*MB;
maxmem = MemMaxMB*MB;
}
else
maxpa = maxmem;
/*
* March up memory from MemMinMB to maxpa 1MB at a time,
* mapping the first page and checking the page can
* be written and read correctly. The page tables are created here
* on the fly, allocating from low memory as necessary.
*/
k0 = (uintptr*)KADDR(0);
kzero = *k0;
map = 0;
x = 0x12345678;
memset(nvalid, 0, sizeof(nvalid));
while(pa < maxpa){
/*
* Map the page. Use mapalloc(&rmapram, ...) to make
* the page table if necessary, it will be returned to the
* pool later if it isn't needed.
*/
va = KADDR(pa);
table = &m->pdb[PDX(va)];
if(*table == 0){
if(map == 0 && (map = mapalloc(&rmapram, 0, BY2PG, BY2PG)) == 0)
break;
memset(KADDR(map), 0, BY2PG);
*table = map|PTEWRITE|PTEVALID;
memset(nvalid, 0, sizeof(nvalid));
}
table = KADDR(PPN(*table));
pte = &table[PTX(va)];
*pte = pa|PTEWRITE|PTEUNCACHED|PTEVALID;
mmuflushtlb(PADDR(m->pdb));
/*
* Write a pattern to the page and write a different
* pattern to a possible mirror at KZER0. If the data
* reads back correctly the chunk is some type of RAM (possibly
* a linearly-mapped VGA framebuffer, for instance...) and
* can be cleared and added to the memory pool. If not, the
* chunk is marked uncached and added to the UMB pool if <16MB
* or is marked invalid and added to the UPA pool.
*/
*va = x;
*k0 = ~x;
if(*va == x){
nvalid[MemRAM] += MB/BY2PG;
mapfree(&rmapram, pa, MB);
do{
*pte++ = pa|PTEWRITE|PTEVALID;
pa += BY2PG;
}while(pa % MB);
// TODO mmuflushtlb(PADDR(m->pdb));
/* memset(va, 0, MB); so damn slow to memset all of memory */
}
else if(pa < 16*MB){
nvalid[MemUMB] += MB/BY2PG;
mapfree(&rmapumb, pa, MB);
do{
*pte++ = pa|PTEWRITE|PTEUNCACHED|PTEVALID;
pa += BY2PG;
}while(pa % MB);
}
else{
nvalid[MemUPA] += MB/BY2PG;
mapfree(&rmapupa, pa, MB);
*pte = 0;
pa += MB;
}
/*
* Done with this 4MB chunk, review the options:
* 1) not physical memory and >=16MB - invalidate the PDB entry;
* 2) physical memory - use the 4MB page extension if possible;
* 3) not physical memory and <16MB - use the 4MB page extension
* if possible;
* 4) mixed or no 4MB page extension - commit the already
* initialised space for the page table.
*/
if((pa % (4*MB)) == 0){
table = &m->pdb[PDX(va)];
if(nvalid[MemUPA] == (4*MB)/BY2PG)
*table = 0;
else if(nvalid[MemRAM] == (4*MB)/BY2PG && (m->cpuiddx & 0x08))
*table = (pa - 4*MB)|PTESIZE|PTEWRITE|PTEVALID;
else if(nvalid[MemUMB] == (4*MB)/BY2PG && (m->cpuiddx & 0x08))
*table = (pa - 4*MB)|PTESIZE|PTEWRITE|PTEUNCACHED|PTEVALID;
else
map = 0;
}
// TODO mmuflushtlb(PADDR(m->pdb));
x += 0x3141526;
}
/*
* If we didn't reach the end of the 4MB chunk, that part won't
* be mapped. Commit the already initialised space for the page table.
*/
if(pa % (4*MB))
map = 0;
if(map)
mapfree(&rmapram, map, BY2PG);
if(pa < maxmem)
mapfree(&rmapupa, pa, maxmem-pa);
if(maxmem < 0xFFE00000)
mapfree(&rmapupa, maxmem, 0x00000000-maxmem);
if(MEMDEBUG)
print("maxmem %zuX %zuX\n", maxmem, 0x00000000-maxmem);
*k0 = kzero;
}
void
meminit(uintptr maxmem)
{
Map *mp, *xmp;
uintptr pa, *pte;
/*
* Set special attributes for memory between 640KB and 1MB:
* VGA memory is writethrough;
* BIOS ROM's/UMB's are uncached;
* then scan for useful memory.
*/
for(pa = 0xA0000; pa < 0xC0000; pa += BY2PG){
pte = mmuwalk(m->pdb, (uintptr)KADDR(pa), 2, 0);
*pte |= PTEWT;
}
for(pa = 0xC0000; pa < 0x100000; pa += BY2PG){
pte = mmuwalk(m->pdb, (uintptr)KADDR(pa), 2, 0);
*pte |= PTEUNCACHED;
}
mmuflushtlb(PADDR(m->pdb));
umbscan();
ramscan(maxmem);
/*
* Set the conf entries describing two banks of allocatable memory.
* Grab the first and largest entries in rmapram as left by ramscan().
*
* It would be nice to have more than 2 memory banks describable in conf.
*/
mp = rmapram.map;
conf.base0 = mp->addr;
conf.npage0 = mp->size/BY2PG;
mp++;
for(xmp = 0; mp->size; mp++){
if(xmp == 0 || mp->size > xmp->size)
xmp = mp;
}
if(xmp){
conf.base1 = xmp->addr;
conf.npage1 = xmp->size/BY2PG;
}
if(MEMDEBUG)
memdebug();
}
uintptr
umbmalloc(uintptr addr, int size, int align)
{
uintptr a;
if(a = mapalloc(&rmapumb, addr, size, align))
return (uintptr)KADDR(a);
return 0;
}
void
umbfree(uintptr addr, int size)
{
mapfree(&rmapumb, PADDR(addr), size);
}
uintptr
umbrwmalloc(uintptr addr, int size, int align)
{
uintptr a;
uchar *p;
if(a = mapalloc(&rmapumbrw, addr, size, align))
return(uintptr)KADDR(a);
/*
* Perhaps the memory wasn't visible before
* the interface is initialised, so try again.
*/
if((a = umbmalloc(addr, size, align)) == 0)
return 0;
p = (uchar*)a;
p[0] = 0xCC;
p[size-1] = 0xCC;
if(p[0] == 0xCC && p[size-1] == 0xCC)
return a;
umbfree(a, size);
return 0;
}
void
umbrwfree(uintptr addr, int size)
{
mapfree(&rmapumbrw, PADDR(addr), size);
}
uintptr
upamalloc(uintptr pa, int size, int align)
{
uintptr a, ae;
if(a = mapalloc(&xrmapupa, pa, size, align))
return a;
if((a = mapalloc(&rmapupa, pa, size, align)) == 0){
memdebug();
return 0;
}
/*
* Upamalloc is a request to map a range of physical addresses.
* Therefore, if pa is 0 mapalloc will choose the base address.
* Note, however, mmukmap is always asked to give a 1-to-1 mapping
* of va to pa.
*/
ae = mmukmap(a, a, size);
/*
* Should check here that it was all delivered
* and put it back and barf if not.
*/
USED(ae);
/*
* Be very careful this returns a PHYSICAL address
* mapped 1-to-1 with the virtual address.
* If a < KZERO it's probably not a good idea to
* try KADDR(a)...
*/
return a;
}
void
upafree(uintptr pa, int size)
{
mapfree(&xrmapupa, pa, size);
}
void
upareserve(uintptr pa, int size)
{
uintptr a;
a = mapalloc(&rmapupa, pa, size, 0);
if(a != pa){
/*
* This can happen when we're using the E820
* map, which might have already reserved some
* of the regions claimed by the pci devices.
*/
// print("upareserve: cannot reserve pa=%#.8lux size=%d\n", pa, size);
if(a != 0)
mapfree(&rmapupa, a, size);
}
}