ref: 83246e296ea433b65b9d295b5e08fedd39ff1ab7
dir: /os/pc64/mmu.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#define DP if(1){}else print
/*
* Simple segment descriptors with no translation.
*/
#define EXECSEGM(p) { 0, SEGL|SEGP|SEGPL(p)|SEGEXEC }
#define DATASEGM(p) { 0, SEGB|SEGG|SEGP|SEGPL(p)|SEGDATA|SEGW }
Segdesc gdt[NGDT] =
{
[NULLSEG] { 0, 0}, /* null descriptor */
[KESEG] EXECSEGM(0), /* code - kernel privilege for all */
[KDSEG] DATASEGM(0), /* data - kernel privilege for all */
};
enum {
/* level */
PML4E = 3,
PDPE = 2,
PDE = 1,
PTE = 0,
};
static void
loadptr(u16int lim, uintptr off, void (*load)(void*))
{
u64int b[2], *o;
u16int *s;
o = &b[1];
s = ((u16int*)o)-1;
*s = lim;
*o = off;
(*load)(s);
}
static void
taskswitch(uintptr stack)
{
Tss *tss;
tss = m->tss;
tss->rsp0[0] = (u32)stack;
tss->rsp0[1] = stack >> 32;
tss->rsp1[0] = (u32)stack;
tss->rsp1[1] = stack >> 32;
tss->rsp2[0] = (u32)stack;
tss->rsp2[1] = stack >> 32;
mmuflushtlb();
}
void
mmuinit(void)
{
uintptr x;
int i;
/* move kernelro here to mimic 9front? */
m->tss = mallocz(sizeof(Tss), 1);
if(m->tss == nil){
print("mmuinit: no memory for Tss");
panic("mmuinit: no memory for Tss");
}
m->tss->iomap = 0xDFFF;
/* the IST is not used by the interrupt descriptors.
* Putting the existing stack address instead of
* leaving the fields empty.
*/
for(i=0; i<14; i+=2){
x = (uintptr)m + MACHSIZE;
m->tss->ist[i] = x;
m->tss->ist[i+1] = x>>32;
}
/*
* We used to keep the GDT in the Mach structure, but it
* turns out that that slows down access to the rest of the
* page. Since the Mach structure is accessed quite often,
* it pays off anywhere from a factor of 1.25 to 2 on real
* hardware to separate them (the AMDs are more sensitive
* than Intels in this regard). Under VMware it pays off
* a factor of about 10 to 100.
*/
memmove(m->gdt, gdt, sizeof gdt);
x = (uintptr)m->tss;
m->gdt[TSSSEG+0].d0 = (x<<16)|(sizeof(Tss)-1);
m->gdt[TSSSEG+0].d1 = (x&0xFF000000)|((x>>16)&0xFF)|SEGTSS|SEGPL(0)|SEGP;
m->gdt[TSSSEG+1].d0 = x>>32;
m->gdt[TSSSEG+1].d1 = 0;
loadptr(sizeof(gdt)-1, (uintptr)m->gdt, lgdt);
loadptr(sizeof(Segdesc)*512-1, (uintptr)IDTADDR, lidt);
taskswitch((uintptr)m + MACHSIZE);
ltr(TSSSEL);
wrmsr(FSbase, 0ull);
wrmsr(GSbase, (u64)&machp[m->machno]);
/* SWAPGS is not needed for inferno.
* leaving it the same as GSbase if unintentional SWAPGS's are used
*/
wrmsr(KernelGSbase, (u64)&machp[m->machno]);
/* pre allocate pages */
Confmem *cm;
ulong np, nt;
np = 0;
for(i=0; i<nelem(conf.mem); i++){
cm = &conf.mem[i];
if(cm->npage == 0)
continue;
DP("i %d base 0x%p npage 0x%d\n", i, cm->base, cm->npage);
pmap(cm->base, PTEGLOBAL|PTEWRITE|PTENOEXEC|PTEVALID, cm->npage*BY2PG);
}
}
int
mmukmapsync(uintptr va)
{
return 0;
}
uintptr
mmukmap(uintptr pa, uintptr va, int size)
{
return 0;
}
void*
vmap(uintptr pa, int size)
{
return 0;
}
void
vunmap(void *va, int size)
{
}
s32
segflush(void*, u32)
{
return 0;
}
static uintptr*
mmucreate(uintptr *table, uintptr pa, int level, int index)
{
uintptr *page, flags;
MMU *p;
DP("mmucreate table 0x%p pa 0x%p level %d index %d\n",
table, pa, level, index);
flags = PTEWRITE|PTEVALID;
page = (uintptr*)rampage();
DP("mmucreate new page 0x%p PTSZ 0x%x %d BY2PG 0x%zx %zd\n",
page, PTSZ, PTSZ, BY2PG, BY2PG);
memset(page, 0, PTSZ);
table[index] = PADDR(page) | flags;
return page;
}
/* not bothering with 1GiB or 2MiB pages yet */
uintptr*
mmuwalk(uintptr* table, uintptr pa, int level, int create)
{
uintptr pte, flags;
int i, x;
DP("mmuwalk table 0x%p pa 0x%p level %d create %d\n",
table, pa, level, create);
flags = PTEWRITE | PTEVALID;
x = PTLX(pa, 3);
DP("\tpml4 index %d\n", x);
for(i = 2; i >= level; i--){
pte = table[x];
if(pte & PTEVALID){
pte = PPN(pte);
table = (void*)pte;
} else {
if(!create)
return 0;
table = mmucreate(table, pa, i, x);
}
x = PTLX(pa, i);
DP("\tlevel %d index %d\n", i, x);
}
return &table[x];
}
static int
ptecount(uintptr pa, s32 level)
{
return (1<<PTSHIFT) - (pa & PGLSZ(level+1)-1) / PGLSZ(level);
}
/* splits a 2 MiB page table entry into a table of 4096 pages
* probably not useful for inferno
*/
static void
ptesplit(uintptr* table, uintptr va)
{
uintptr *pte, pa, off;
pte = mmuwalk(table, va, 1, 0);
if(pte == nil || (*pte & PTESIZE) == 0 || (va & PGLSZ(1)-1) == 0)
return;
table = (uintptr*)rampage();
va &= -PGLSZ(1);
pa = *pte & ~PTESIZE;
for(off = 0; off < PGLSZ(1); off += PGLSZ(0))
table[PTLX(va + off, 0)] = pa + off;
*pte = PADDR(table) | PTEVALID|PTEWRITE;
invlpg(va);
}
void
pmap(uintptr pa, u64 flags, s64 size)
{
uintptr *pte, *ptee;
s32 z, l;
if(size <= 0)
panic("pmap: pa=%#p size=%lld", pa, size);
DP("pmap pa 0x%p-0x%zux flags 0x%llux size %llud 0x%llux\n",
pa, (uintptr)pa+size, flags, size, size);
pa = PPN(pa);
DP("\tpa 0x%p\n", pa);
while(size > 0){
/* reducing complexity, use 4096 byte pages all through */
l = 0;
z = PGLSZ(0);
pte = mmuwalk((uintptr*)PML4ADDR, pa, l, 1);
if(pte == nil){
panic("pmap: pa=%#p size=%lld", pa, size);
}
ptee = pte + ptecount(pa, l);
while(size > 0 && pte < ptee){
*pte++ = pa | flags;
pa += z;
size -= z;
}
}
}
void
punmap(uintptr pa, vlong size)
{
uintptr *pte;
int l;
pa = PPN(pa);
while(size > 0){
if((pa % PGLSZ(1)) != 0 || size < PGLSZ(1))
ptesplit((uintptr*)PML4ADDR, pa);
l = 0;
pte = mmuwalk((uintptr*)PML4ADDR,pa, l, 0);
if(pte == nil && (pa % PGLSZ(1)) == 0 && size >= PGLSZ(1))
pte = mmuwalk((uintptr*)PML4ADDR, pa, ++l, 0);
if(pte){
*pte = 0;
invlpg(pa);
}
pa += PGLSZ(l);
size -= PGLSZ(l);
}
}
/*
* mark pages as write combining (used for framebuffer)
*/
void
patwc(void *a, int n)
{
uintptr *pte, mask, attr, pa;
int z, l;
vlong v;
/* check if pat is usable */
if((MACHP(0)->cpuiddx & Pat) == 0
|| rdmsr(0x277, &v) == -1
|| ((v >> PATWC*8) & 7) != 1)
return;
/* set the bits for all pages in range */
for(pa = (uintptr)a; n > 0; n -= z, pa += z){
l = 0;
pte = mmuwalk((uintptr*)PML4ADDR, pa, l, 0);
if(pte == 0)
pte = mmuwalk((uintptr*)PML4ADDR, pa, ++l, 0);
if(pte == 0 || (*pte & PTEVALID) == 0)
panic("patwc: pa=%#p", pa);
z = PGLSZ(l);
z -= pa & (z-1);
mask = l == 0 ? 3<<3 | 1<<7 : 3<<3 | 1<<12;
attr = (((PATWC&3)<<3) | ((PATWC&4)<<5) | ((PATWC&4)<<10));
*pte = (*pte & ~mask) | (attr & mask);
}
}