ref: 0c36c79e9b58b5131d4911b05ede987ce0bb8bde
dir: /sys/src/9/bitsy/mmu.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#include "ureg.h"
#include "../port/error.h"
/*
* to avoid mmu and cash flushing, we use the pid register in the MMU
* to map all user addresses. Although there are 64 possible pids, we
* can only use 31 because there are only 32 protection domains and we
* need one for the kernel. Pid i is thus associated with domain i.
* Domain 0 is used for the kernel.
*/
/* real protection bits */
enum
{
/* level 1 descriptor bits */
L1TypeMask= (3<<0),
L1Invalid= (0<<0),
L1PageTable= (1<<0),
L1Section= (2<<0),
L1Cached= (1<<3),
L1Buffered= (1<<2),
L1DomShift= 5,
L1Domain0= (0<<L1DomShift),
L1KernelRO= (0x0<<10),
L1KernelRW= (0x1<<10),
L1UserRO= (0x2<<10),
L1UserRW= (0x3<<10),
L1SectBaseMask= (0xFFF<<20),
L1PTBaseMask= (0x3FFFFF<<10),
/* level 2 descriptor bits */
L2TypeMask= (3<<0),
L2SmallPage= (2<<0),
L2LargePage= (1<<0),
L2Cached= (1<<3),
L2Buffered= (1<<2),
L2KernelRW= (0x55<<4),
L2UserRO= (0xAA<<4),
L2UserRW= (0xFF<<4),
L2PageBaseMask= (0xFFFFF<<12),
/* domain values */
Dnoaccess= 0,
Dclient= 1,
Dmanager= 3,
};
ulong *l1table;
static int mmuinited;
/*
* We map all of memory, flash, and the zeros area with sections.
* Special use space is mapped on the fly with regmap.
*/
void
mmuinit(void)
{
ulong a, o;
ulong *t;
/* get a prototype level 1 page */
l1table = xspanalloc(16*1024, 16*1024, 0);
memset(l1table, 0, 16*1024);
/* map low mem (I really don't know why I have to do this -- presotto) */
for(o = 0; o < 1*OneMeg; o += OneMeg)
l1table[(0+o)>>20] = L1Section | L1KernelRW| L1Domain0
| L1Cached | L1Buffered
| ((0+o)&L1SectBaseMask);
/* map DRAM */
for(o = 0; o < DRAMTOP-DRAMZERO; o += OneMeg)
l1table[(DRAMZERO+o)>>20] = L1Section | L1KernelRW| L1Domain0
| L1Cached | L1Buffered
| ((PHYSDRAM0+o)&L1SectBaseMask);
/* uncached DRAM */
for(o = 0; o < UCDRAMTOP-UCDRAMZERO; o += OneMeg)
l1table[(UCDRAMZERO+o)>>20] = L1Section | L1KernelRW| L1Domain0
| ((PHYSDRAM0+o)&L1SectBaseMask);
/* map zeros area */
for(o = 0; o < NULLTOP-NULLZERO; o += OneMeg)
l1table[(NULLZERO+o)>>20] = L1Section | L1KernelRW | L1Domain0
| L1Cached | L1Buffered
| ((PHYSNULL0+o)&L1SectBaseMask);
/* map flash */
for(o = 0; o < FLASHTOP-FLASHZERO; o += OneMeg)
l1table[(FLASHZERO+o)>>20] = L1Section | L1KernelRW | L1Domain0
| ((PHYSFLASH0+o)&L1SectBaseMask);
/* map peripheral control module regs */
mapspecial(0x80000000, OneMeg);
/* map system control module regs */
mapspecial(0x90000000, OneMeg);
/*
* double map start of ram to exception vectors
*/
a = EVECTORS;
t = xspanalloc(BY2PG, 1024, 0);
memset(t, 0, BY2PG);
l1table[a>>20] = L1PageTable | L1Domain0 | (((ulong)t) & L1PTBaseMask);
t[(a&0xfffff)>>PGSHIFT] = L2SmallPage | L2KernelRW | (PHYSDRAM0 & L2PageBaseMask);
mmurestart();
mmuinited = 1;
}
void
mmurestart(void) {
/* set up the domain register to cause all domains to obey pte access bits */
putdac(Dclient);
/* point to map */
putttb((ulong)l1table);
/* enable mmu */
wbflush();
mmuinvalidate();
mmuenable();
cacheflush();
}
/*
* map on request
*/
static void*
_map(ulong pa, int len, ulong zero, ulong top, ulong l1prop, ulong l2prop)
{
ulong *t;
ulong va, i, base, end, off, entry;
int large;
ulong* rv;
rv = nil;
large = len >= 128*1024;
if(large){
base = pa & ~(OneMeg-1);
end = (pa+len-1) & ~(OneMeg-1);
} else {
base = pa & ~(BY2PG-1);
end = (pa+len-1) & ~(BY2PG-1);
}
off = pa - base;
for(va = zero; va < top && base <= end; va += OneMeg){
switch(l1table[va>>20] & L1TypeMask){
default:
/* found unused entry on level 1 table */
if(large){
if(rv == nil)
rv = (ulong*)(va+off);
l1table[va>>20] = L1Section | l1prop | L1Domain0 |
(base & L1SectBaseMask);
base += OneMeg;
continue;
} else {
/* create an L2 page table and keep going */
t = xspanalloc(BY2PG, 1024, 0);
memset(t, 0, BY2PG);
l1table[va>>20] = L1PageTable | L1Domain0 |
(((ulong)t) & L1PTBaseMask);
}
break;
case L1Section:
/* if it's already mapped in a one meg area, don't remap */
entry = l1table[va>>20];
i = entry & L1SectBaseMask;
if(pa >= i && (pa+len) <= i + OneMeg)
if((entry & ~L1SectBaseMask) == (L1Section | l1prop | L1Domain0))
return (void*)(va + (pa & (OneMeg-1)));
continue;
case L1PageTable:
if(large)
continue;
break;
}
/* here if we're using page maps instead of sections */
t = (ulong*)(l1table[va>>20] & L1PTBaseMask);
for(i = 0; i < OneMeg && base <= end; i += BY2PG){
entry = t[i>>PGSHIFT];
/* found unused entry on level 2 table */
if((entry & L2TypeMask) != L2SmallPage){
if(rv == nil)
rv = (ulong*)(va+i+off);
t[i>>PGSHIFT] = L2SmallPage | l2prop |
(base & L2PageBaseMask);
base += BY2PG;
continue;
}
}
}
/* didn't fit */
if(base <= end)
return nil;
cacheflush();
return rv;
}
/* map in i/o registers */
void*
mapspecial(ulong pa, int len)
{
return _map(pa, len, REGZERO, REGTOP, L1KernelRW, L2KernelRW);
}
/* map add on memory */
void*
mapmem(ulong pa, int len, int cached)
{
ulong l1, l2;
if(cached){
l1 = L1KernelRW|L1Cached|L1Buffered;
l2 = L2KernelRW|L2Cached|L2Buffered;
} else {
l1 = L1KernelRW;
l2 = L2KernelRW;
}
return _map(pa, len, EMEMZERO, EMEMTOP, l1, l2);
}
/* map a virtual address to a physical one */
ulong
mmu_paddr(ulong va)
{
ulong entry;
ulong *t;
entry = l1table[va>>20];
switch(entry & L1TypeMask){
case L1Section:
return (entry & L1SectBaseMask) | (va & (OneMeg-1));
case L1PageTable:
t = (ulong*)(entry & L1PTBaseMask);
va &= OneMeg-1;
entry = t[va>>PGSHIFT];
switch(entry & L1TypeMask){
case L2SmallPage:
return (entry & L2PageBaseMask) | (va & (BY2PG-1));
}
}
return 0;
}
/* map a physical address to a virtual one */
ulong
findva(ulong pa, ulong zero, ulong top)
{
int i;
ulong entry, va;
ulong start, end;
ulong *t;
for(va = zero; va < top; va += OneMeg){
/* search the L1 entry */
entry = l1table[va>>20];
switch(entry & L1TypeMask){
default:
return 0; /* no holes */
case L1Section:
start = entry & L1SectBaseMask;
end = start + OneMeg;
if(pa >= start && pa < end)
return va | (pa & (OneMeg-1));
continue;
case L1PageTable:
break;
}
/* search the L2 entry */
t = (ulong*)(l1table[va>>20] & L1PTBaseMask);
for(i = 0; i < OneMeg; i += BY2PG){
entry = t[i>>PGSHIFT];
/* found unused entry on level 2 table */
if((entry & L2TypeMask) != L2SmallPage)
break;
start = entry & L2PageBaseMask;
end = start + BY2PG;
if(pa >= start && pa < end)
return va | (BY2PG*i) | (pa & (BY2PG-1));
}
}
return 0;
}
ulong
mmu_kaddr(ulong pa)
{
ulong va;
/* try the easy stuff first (the first case is true most of the time) */
if(pa >= PHYSDRAM0 && pa <= PHYSDRAM0+(DRAMTOP-DRAMZERO))
return DRAMZERO+(pa-PHYSDRAM0);
if(pa >= PHYSFLASH0 && pa <= PHYSFLASH0+(FLASHTOP-FLASHZERO))
return FLASHZERO+(pa-PHYSFLASH0);
if(pa >= PHYSNULL0 && pa <= PHYSNULL0+(NULLTOP-NULLZERO))
return NULLZERO+(pa-PHYSNULL0);
if(!mmuinited)
return 0; /* this shouldn't happen */
/* walk the map for the special regs and extended memory */
va = findva(pa, EMEMZERO, EMEMTOP);
if(va != 0)
return va;
return findva(pa, REGZERO, REGTOP);
}
/*
* Return the number of bytes that can be accessed via KADDR(pa).
* If pa is not a valid argument to KADDR, return 0.
*/
ulong
cankaddr(ulong pa)
{
/*
* Is this enough?
* We'll find out if anyone still has one
* of these...
*/
if(pa >= PHYSDRAM0 && pa <= PHYSDRAM0+(DRAMTOP-DRAMZERO))
return PHYSDRAM0+(DRAMTOP-DRAMZERO) - pa;
return 0;
}
/*
* table to map fault.c bits to physical bits
*/
static ulong mmubits[16] =
{
[PTEVALID] L2SmallPage|L2Cached|L2Buffered|L2UserRO,
[PTEVALID|PTEWRITE] L2SmallPage|L2Cached|L2Buffered|L2UserRW,
[PTEVALID|PTEUNCACHED] L2SmallPage|L2UserRO,
[PTEVALID|PTEUNCACHED|PTEWRITE] L2SmallPage|L2UserRW,
[PTEKERNEL|PTEVALID] L2SmallPage|L2Cached|L2Buffered|L2KernelRW,
[PTEKERNEL|PTEVALID|PTEWRITE] L2SmallPage|L2Cached|L2Buffered|L2KernelRW,
[PTEKERNEL|PTEVALID|PTEUNCACHED] L2SmallPage|L2KernelRW,
[PTEKERNEL|PTEVALID|PTEUNCACHED|PTEWRITE] L2SmallPage|L2KernelRW,
};
/*
* add an entry to the current map
*/
void
putmmu(uintptr va, uintptr pa, Page *pg)
{
Page *l2pg;
ulong *t, *l1p, *l2p;
int s;
s = splhi();
/* clear out the current entry */
mmuinvalidateaddr(va);
l2pg = up->l1page[va>>20];
if(l2pg == nil){
l2pg = up->mmufree;
if(l2pg != nil){
up->mmufree = l2pg->next;
} else {
splx(s);
l2pg = newpage(0, 0, 0);
splhi();
}
l2pg->va = VA(kmap(l2pg));
up->l1page[va>>20] = l2pg;
memset((uchar*)(l2pg->va), 0, BY2PG);
}
/* always point L1 entry to L2 page, can't hurt */
l1p = &l1table[va>>20];
*l1p = L1PageTable | L1Domain0 | (l2pg->pa & L1PTBaseMask);
up->l1table[va>>20] = *l1p;
t = (ulong*)l2pg->va;
/* set L2 entry */
l2p = &t[(va & (OneMeg-1))>>PGSHIFT];
*l2p = mmubits[pa & (PTEKERNEL|PTEVALID|PTEUNCACHED|PTEWRITE)]
| (pa & ~(PTEKERNEL|PTEVALID|PTEUNCACHED|PTEWRITE));
/* write back dirty entries - we need this because the pio() in
* fault.c is writing via a different virt addr and won't clean
* its changes out of the dcache. Page coloring doesn't work
* on this mmu because the virtual cache is set associative
* rather than direct mapped.
*/
cachewb();
if(pg->txtflush){
icacheinvalidate();
pg->txtflush = 0;
}
splx(s);
}
/*
* free up all page tables for this proc
*/
void
mmuptefree(Proc *p)
{
Page *pg;
int i;
for(i = 0; i < Nmeg; i++){
pg = p->l1page[i];
if(pg == nil)
continue;
p->l1page[i] = nil;
pg->next = p->mmufree;
p->mmufree = pg;
}
memset(p->l1table, 0, sizeof(p->l1table));
}
/*
* this is called with palloc locked so the pagechainhead is kosher
*/
void
mmurelease(Proc* p)
{
Page *pg, *next;
/* write back dirty cache entries before changing map */
cacheflush();
mmuptefree(p);
for(pg = p->mmufree; pg != nil; pg = next){
next = pg->next;
if(--pg->ref)
panic("mmurelease: pg->ref %d\n", pg->ref);
pagechainhead(pg);
}
if(p->mmufree != nil)
pagechaindone();
p->mmufree = nil;
memset(l1table, 0, sizeof(p->l1table));
cachewbregion((ulong)l1table, sizeof(p->l1table));
}
void
mmuswitch(Proc *p)
{
if(m->mmupid == p->pid && p->newtlb == 0)
return;
m->mmupid = p->pid;
/* write back dirty cache entries and invalidate all cache entries */
cacheflush();
if(p->newtlb){
mmuptefree(p);
p->newtlb = 0;
}
/* move in new map */
memmove(l1table, p->l1table, sizeof(p->l1table));
/* make sure map is in memory */
cachewbregion((ulong)l1table, sizeof(p->l1table));
/* lose any possible stale tlb entries */
mmuinvalidate();
}
void
flushmmu(void)
{
int s;
s = splhi();
up->newtlb = 1;
mmuswitch(up);
splx(s);
}
void
peekmmu(ulong va)
{
ulong e, d;
e = l1table[va>>20];
switch(e & L1TypeMask){
default:
iprint("l1: %#p[%#lux] = %#lux invalid\n", l1table, va>>20, e);
break;
case L1PageTable:
iprint("l1: %#p[%#lux] = %#lux pt\n", l1table, va>>20, e);
va &= OneMeg-1;
va >>= PGSHIFT;
e &= L1PTBaseMask;
d = ((ulong*)e)[va];
iprint("l2: %#lux[%#lux] = %#lux\n", e, va, d);
break;
case L1Section:
iprint("l1: %#p[%#lux] = %#lux section\n", l1table, va>>20, e);
break;
}
}
void
checkmmu(uintptr, uintptr)
{
}
void
countpagerefs(ulong*, int)
{
}