ref: bf7e8777f391caa82705a0b64709a95672d2632c
dir: /sys/src/9/teg2/mmu.c/
/*
* arm arch v7 mmu
*
* we initially thought that we needn't flush the l2 cache since external
* devices needn't see page tables. sadly, reality does not agree with
* the manuals.
*
* we use l1 and l2 cache ops here because they are empirically needed.
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "arm.h"
#define L1X(va) FEXT((va), 20, 12)
#define L2X(va) FEXT((va), 12, 8)
enum {
Debug = 0,
L1lo = UZERO/MiB, /* L1X(UZERO)? */
#ifdef SMALL_ARM /* well under 1GB of RAM? */
L1hi = (USTKTOP+MiB-1)/MiB, /* L1X(USTKTOP+MiB-1)? */
#else
/*
* on trimslice, top of 1GB ram can't be addressible, as high
* virtual memory (0xfff.....) contains high vectors. We
* moved USTKTOP down another MB to utterly avoid KADDR(stack_base)
* mapping to high exception vectors. USTKTOP is thus
* (0x40000000 - 64*KiB - MiB), which in kernel virtual space is
* (0x100000000ull - 64*KiB - MiB), but we need the whole user
* virtual address space to be unmapped in a new process.
*/
L1hi = DRAMSIZE/MiB,
#endif
};
#define ISHOLE(type) ((type) == 0)
typedef struct Range Range;
struct Range {
uintptr startva;
uvlong endva;
uintptr startpa;
uvlong endpa;
ulong attrs;
int type; /* L1 Section or Coarse? */
};
static void mmul1empty(void);
static char *
typename(int type)
{
static char numb[20];
switch(type) {
case Coarse:
return "4KB-page table(s)";
case Section:
return "1MB section(s)";
default:
snprint(numb, sizeof numb, "type %d", type);
return numb;
}
}
static void
prl1range(Range *rp)
{
int attrs;
iprint("l1 maps va (%#8.8lux-%#llux) -> ", rp->startva, rp->endva-1);
if (rp->startva == rp->startpa)
iprint("identity-mapped");
else
iprint("pa %#8.8lux", rp->startpa);
iprint(" attrs ");
attrs = rp->attrs;
if (attrs) {
if (attrs & Cached)
iprint("C");
if (attrs & Buffered)
iprint("B");
if (attrs & L1sharable)
iprint("S1");
if (attrs & L1wralloc)
iprint("A1");
} else
iprint("\"\"");
iprint(" %s\n", typename(rp->type));
delay(100);
rp->endva = 0;
}
static void
l2dump(Range *rp, PTE pte)
{
USED(rp, pte);
}
/* dump level 1 page table at virtual addr l1 */
void
mmudump(PTE *l1)
{
int i, type, attrs;
uintptr pa;
uvlong va;
PTE pte;
Range rng;
/* dump first level of ptes */
iprint("cpu%d l1 pt @ %#p:\n", m->machno, PADDR(l1));
memset(&rng, 0, sizeof rng);
for (va = i = 0; i < 4096; i++, va += MB) {
pte = l1[i];
type = pte & (Section|Coarse);
if (type == Section)
pa = pte & ~(MB - 1);
else
pa = pte & ~(KiB - 1);
attrs = 0;
if (!ISHOLE(type) && type == Section)
attrs = pte & L1ptedramattrs;
/* if a range is open but this pte isn't part, close & open */
if (!ISHOLE(type) &&
(pa != rng.endpa || type != rng.type || attrs != rng.attrs))
if (rng.endva != 0) { /* range is open? close it */
prl1range(&rng);
rng.type = 0;
rng.attrs = 0;
}
if (ISHOLE(type)) { /* end of any open range? */
if (rng.endva != 0) /* range is open? close it */
prl1range(&rng);
} else { /* continuation or new range */
if (rng.endva == 0) { /* no open range? start one */
rng.startva = va;
rng.startpa = pa;
rng.type = type;
rng.attrs = attrs;
}
rng.endva = va + MB; /* continue the open range */
rng.endpa = pa + MB;
}
if (type == Coarse)
l2dump(&rng, pte);
}
if (rng.endva != 0) /* close any open range */
prl1range(&rng);
iprint("\n");
}
/*
* map `mbs' megabytes from virt to phys, uncached.
* device registers are sharable, except the private memory region:
* 2 4K pages, at 0x50040000 on the tegra2.
*/
void
mmumap(uintptr virt, uintptr phys, int mbs)
{
uint off;
PTE *l1;
phys &= ~(MB-1);
virt &= ~(MB-1);
l1 = KADDR(ttbget());
for (off = 0; mbs-- > 0; off += MB)
l1[L1X(virt + off)] = (phys + off) | Dom0 | L1AP(Krw) |
Section | L1sharable;
allcache->wbse(l1, L1SIZE);
mmuinvalidate();
}
/* identity map `mbs' megabytes from phys */
void
mmuidmap(uintptr phys, int mbs)
{
mmumap(phys, phys, mbs);
}
PTE *
newl2page(void)
{
PTE *p;
if ((uintptr)l2pages >= HVECTORS - BY2PG)
panic("l2pages");
p = (PTE *)l2pages;
l2pages += BY2PG;
return p;
}
/*
* replace an L1 section pte with an L2 page table and an L1 coarse pte,
* with the same attributes as the original pte and covering the same
* region of memory.
*/
static void
expand(uintptr va)
{
int x;
uintptr tva, pa;
PTE oldpte;
PTE *l1, *l2;
va &= ~(MB-1);
x = L1X(va);
l1 = &m->mmul1[x];
oldpte = *l1;
if (oldpte == Fault || (oldpte & (Coarse|Section)) != Section)
return; /* make idempotent */
/* wasteful - l2 pages only have 256 entries - fix */
/*
* it may be very early, before any memory allocators are
* configured, so do a crude allocation from the top of memory.
*/
l2 = newl2page();
memset(l2, 0, BY2PG);
/* write new L1 l2 entry back into L1 descriptors */
*l1 = PPN(PADDR(l2))|Dom0|Coarse;
/* fill l2 page with l2 ptes with equiv attrs; copy AP bits */
x = Small | oldpte & (Cached|Buffered) | (oldpte & (1<<15 | 3<<10)) >> 6;
if (oldpte & L1sharable)
x |= L2sharable;
if (oldpte & L1wralloc)
x |= L2wralloc;
pa = oldpte & ~(MiB - 1);
for(tva = va; tva < va + MiB; tva += BY2PG, pa += BY2PG)
l2[L2X(tva)] = PPN(pa) | x;
/* force l2 page to memory */
allcache->wbse(l2, BY2PG);
/* clear out the current entry */
mmuinvalidateaddr(PPN(va));
allcache->wbinvse(l1, sizeof *l1);
if ((*l1 & (Coarse|Section)) != Coarse)
panic("explode %#p", va);
}
/*
* cpu0's l1 page table has likely changed since we copied it in
* launchinit, notably to allocate uncached sections for ucalloc.
* so copy it again from cpu0's.
*/
void
mmuninit(void)
{
int s;
PTE *l1, *newl1;
s = splhi();
l1 = m->mmul1;
newl1 = mallocalign(L1SIZE, L1SIZE, 0, 0);
assert(newl1);
allcache->wbinvse((PTE *)L1, L1SIZE); /* get cpu0's up-to-date copy */
memmove(newl1, (PTE *)L1, L1SIZE);
allcache->wbse(newl1, L1SIZE);
mmuinvalidate();
coherence();
ttbput(PADDR(newl1)); /* switch */
coherence();
mmuinvalidate();
coherence();
m->mmul1 = newl1;
coherence();
mmul1empty();
coherence();
mmuinvalidate();
coherence();
// mmudump(m->mmul1); /* DEBUG */
splx(s);
free(l1);
}
/* l1 is base of my l1 descriptor table */
static PTE *
l2pteaddr(PTE *l1, uintptr va)
{
uintptr l2pa;
PTE pte;
PTE *l2;
expand(va);
pte = l1[L1X(va)];
if ((pte & (Coarse|Section)) != Coarse)
panic("l2pteaddr l1 pte %#8.8ux @ %#p not Coarse",
pte, &l1[L1X(va)]);
l2pa = pte & ~(KiB - 1);
l2 = (PTE *)KADDR(l2pa);
return &l2[L2X(va)];
}
void
mmuinit(void)
{
ulong va;
uintptr pa;
PTE *l1, *l2;
if (m->machno != 0) {
mmuninit();
return;
}
pa = ttbget();
l1 = KADDR(pa);
/* identity map most of the io space */
mmuidmap(PHYSIO, (PHYSIOEND - PHYSIO + MB - 1) / MB);
/* move the rest to more convenient addresses */
mmumap(VIRTNOR, PHYSNOR, 256); /* 0x40000000 v -> 0xd0000000 p */
mmumap(VIRTAHB, PHYSAHB, 256); /* 0xb0000000 v -> 0xc0000000 p */
/* map high vectors to start of dram, but only 4K, not 1MB */
pa -= MACHSIZE+BY2PG; /* page tables must be page aligned */
l2 = KADDR(pa);
memset(l2, 0, 1024);
m->mmul1 = l1; /* used by explode in l2pteaddr */
/* map private mem region (8K at soc.scu) without sharable bits */
va = soc.scu;
*l2pteaddr(l1, va) &= ~L2sharable;
va += BY2PG;
*l2pteaddr(l1, va) &= ~L2sharable;
/*
* below (and above!) the vectors in virtual space may be dram.
* populate the rest of l2 for the last MB.
*/
for (va = -MiB; va != 0; va += BY2PG)
l2[L2X(va)] = PADDR(va) | L2AP(Krw) | Small | L2ptedramattrs;
/* map high vectors page to 0; must match attributes of KZERO->0 map */
l2[L2X(HVECTORS)] = PHYSDRAM | L2AP(Krw) | Small | L2ptedramattrs;
coherence();
l1[L1X(HVECTORS)] = pa | Dom0 | Coarse; /* l1 -> ttb-machsize-4k */
/* make kernel text unwritable */
for(va = KTZERO; va < (ulong)etext; va += BY2PG)
*l2pteaddr(l1, va) |= L2apro;
allcache->wbinv();
mmuinvalidate();
m->mmul1 = l1;
coherence();
mmul1empty();
coherence();
// mmudump(l1); /* DEBUG */
}
static void
mmul2empty(Proc* proc, int clear)
{
PTE *l1;
Page **l2, *page;
l1 = m->mmul1;
l2 = &proc->mmul2;
for(page = *l2; page != nil; page = page->next){
if(clear)
memset((void*)page->va, 0, BY2PG);
l1[page->daddr] = Fault;
allcache->wbse(l1, sizeof *l1);
l2 = &page->next;
}
*l2 = proc->mmul2cache;
proc->mmul2cache = proc->mmul2;
proc->mmul2 = nil;
}
static void
mmul1empty(void)
{
#ifdef notdef
/* there's a bug in here */
PTE *l1;
/* clean out any user mappings still in l1 */
if(m->mmul1lo > L1lo){
if(m->mmul1lo == 1)
m->mmul1[L1lo] = Fault;
else
memset(&m->mmul1[L1lo], 0, m->mmul1lo*sizeof(PTE));
m->mmul1lo = L1lo;
}
if(m->mmul1hi < L1hi){
l1 = &m->mmul1[m->mmul1hi];
if((L1hi - m->mmul1hi) == 1)
*l1 = Fault;
else
memset(l1, 0, (L1hi - m->mmul1hi)*sizeof(PTE));
m->mmul1hi = L1hi;
}
#else
memset(&m->mmul1[L1lo], 0, (L1hi - L1lo)*sizeof(PTE));
#endif /* notdef */
allcache->wbse(&m->mmul1[L1lo], (L1hi - L1lo)*sizeof(PTE));
}
void
mmuswitch(Proc* proc)
{
int x;
PTE *l1;
Page *page;
/* do kprocs get here and if so, do they need to? */
if(m->mmupid == proc->pid && !proc->newtlb)
return;
m->mmupid = proc->pid;
/* write back dirty and invalidate caches */
l1cache->wbinv();
if(proc->newtlb){
mmul2empty(proc, 1);
proc->newtlb = 0;
}
mmul1empty();
/* move in new map */
l1 = m->mmul1;
for(page = proc->mmul2; page != nil; page = page->next){
x = page->daddr;
l1[x] = PPN(page->pa)|Dom0|Coarse;
/* know here that L1lo < x < L1hi */
if(x+1 - m->mmul1lo < m->mmul1hi - x)
m->mmul1lo = x+1;
else
m->mmul1hi = x;
}
/* make sure map is in memory */
/* could be smarter about how much? */
allcache->wbse(&l1[L1X(UZERO)], (L1hi - L1lo)*sizeof(PTE));
/* lose any possible stale tlb entries */
mmuinvalidate();
//print("mmuswitch l1lo %d l1hi %d %d\n",
// m->mmul1lo, m->mmul1hi, proc->kp);
wakewfi(); /* in case there's another runnable proc */
}
void
flushmmu(void)
{
int s;
s = splhi();
up->newtlb = 1;
mmuswitch(up);
splx(s);
}
void
mmurelease(Proc* proc)
{
/* write back dirty and invalidate caches */
l1cache->wbinv();
mmul2empty(proc, 0);
freepages(proc->mmul2cache, nil, 0);
proc->mmul2cache = nil;
mmul1empty();
/* make sure map is in memory */
/* could be smarter about how much? */
allcache->wbse(&m->mmul1[L1X(UZERO)], (L1hi - L1lo)*sizeof(PTE));
/* lose any possible stale tlb entries */
mmuinvalidate();
}
void
putmmu(uintptr va, uintptr pa, Page* page)
{
int x;
Page *pg;
PTE *l1, *pte;
x = L1X(va);
l1 = &m->mmul1[x];
if (Debug) {
iprint("putmmu(%#p, %#p, %#p) ", va, pa, page->pa);
iprint("mmul1 %#p l1 %#p *l1 %#ux x %d pid %ld\n",
m->mmul1, l1, *l1, x, up->pid);
if (*l1)
panic("putmmu: old l1 pte non-zero; stuck?");
}
if(*l1 == Fault){
/* wasteful - l2 pages only have 256 entries - fix */
if(up->mmul2cache == nil){
/* auxpg since we don't need much? memset if so */
pg = newpage(1, 0, 0);
pg->va = VA(kmap(pg));
}
else{
pg = up->mmul2cache;
up->mmul2cache = pg->next;
memset((void*)pg->va, 0, BY2PG);
}
pg->daddr = x;
pg->next = up->mmul2;
up->mmul2 = pg;
/* force l2 page to memory */
allcache->wbse((void *)pg->va, BY2PG);
*l1 = PPN(pg->pa)|Dom0|Coarse;
allcache->wbse(l1, sizeof *l1);
if (Debug)
iprint("l1 %#p *l1 %#ux x %d pid %ld\n", l1, *l1, x, up->pid);
if(x >= m->mmul1lo && x < m->mmul1hi){
if(x+1 - m->mmul1lo < m->mmul1hi - x)
m->mmul1lo = x+1;
else
m->mmul1hi = x;
}
}
pte = KADDR(PPN(*l1));
if (Debug) {
iprint("pte %#p index %ld was %#ux\n", pte, L2X(va), *(pte+L2X(va)));
if (*(pte+L2X(va)))
panic("putmmu: old l2 pte non-zero; stuck?");
}
/* protection bits are
* PTERONLY|PTEVALID;
* PTEWRITE|PTEVALID;
* PTEWRITE|PTEUNCACHED|PTEVALID;
*/
x = Small;
if(!(pa & PTEUNCACHED))
x |= L2ptedramattrs;
if(pa & PTEWRITE)
x |= L2AP(Urw);
else
x |= L2AP(Uro);
pte[L2X(va)] = PPN(pa)|x;
allcache->wbse(&pte[L2X(va)], sizeof pte[0]);
/* clear out the current entry */
mmuinvalidateaddr(PPN(va));
/* 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.
*/
l1cache->wb();
if(needtxtflush(page)){
cacheiinv();
donetxtflush(page);
}
if (Debug)
iprint("putmmu %#p %#p %#p\n", va, pa, PPN(pa)|x);
}
void*
mmuuncache(void* v, usize size)
{
int x;
PTE *pte;
uintptr va;
/*
* Simple helper for ucalloc().
* Uncache a Section, must already be
* valid in the MMU.
*/
va = (uintptr)v;
assert(!(va & (1*MiB-1)) && size == 1*MiB);
x = L1X(va);
pte = &m->mmul1[x];
if((*pte & (Section|Coarse)) != Section)
return nil;
*pte &= ~L1ptedramattrs;
*pte |= L1sharable;
mmuinvalidateaddr(va);
allcache->wbse(pte, 4);
return v;
}
uintptr
mmukmap(uintptr va, uintptr pa, usize size)
{
int x;
PTE *pte;
/*
* Stub.
*/
assert(!(va & (1*MiB-1)) && !(pa & (1*MiB-1)) && size == 1*MiB);
x = L1X(va);
pte = &m->mmul1[x];
if(*pte != Fault)
return 0;
*pte = pa|Dom0|L1AP(Krw)|Section;
mmuinvalidateaddr(va);
allcache->wbse(pte, 4);
return va;
}
uintptr
mmukunmap(uintptr va, uintptr pa, usize size)
{
int x;
PTE *pte;
/*
* Stub.
*/
assert(!(va & (1*MiB-1)) && !(pa & (1*MiB-1)) && size == 1*MiB);
x = L1X(va);
pte = &m->mmul1[x];
if(*pte != (pa|Dom0|L1AP(Krw)|Section))
return 0;
*pte = Fault;
mmuinvalidateaddr(va);
allcache->wbse(pte, 4);
return va;
}
/*
* Return the number of bytes that can be accessed via KADDR(pa).
* If pa is not a valid argument to KADDR, return 0.
*/
uintptr
cankaddr(uintptr pa)
{
if((PHYSDRAM == 0 || pa >= PHYSDRAM) && pa < PHYSDRAM+memsize)
return PHYSDRAM+memsize - pa;
return 0;
}
/* from 386 */
void*
vmap(uintptr pa, usize size)
{
uintptr pae, va;
usize o, osize;
/*
* XXX - replace with new vm stuff.
* Crock after crock - the first 4MB is mapped with 2MB pages
* so catch that and return good values because the current mmukmap
* will fail.
*/
if(pa+size < 4*MiB)
return (void*)(kseg0|pa);
osize = size;
o = pa & (BY2PG-1);
pa -= o;
size += o;
size = PGROUND(size);
va = kseg0|pa;
pae = mmukmap(va, pa, size);
if(pae == 0 || pae-size != pa)
panic("vmap(%#p, %ld) called from %#p: mmukmap fails %#p",
pa+o, osize, getcallerpc(&pa), pae);
return (void*)(va+o);
}
/* from 386 */
void
vunmap(void* v, usize size)
{
/*
* XXX - replace with new vm stuff.
* Can't do this until do real vmap for all space that
* might be used, e.g. stuff below 1MB which is currently
* mapped automagically at boot but that isn't used (or
* at least shouldn't be used) by the kernel.
upafree(PADDR(v), size);
*/
USED(v, size);
}
/*
* Notes.
* Everything is in domain 0;
* domain 0 access bits in the DAC register are set
* to Client, which means access is controlled by the
* permission values set in the PTE.
*
* L1 access control for the kernel is set to 1 (RW,
* no user mode access);
* L2 access control for the kernel is set to 1 (ditto)
* for all 4 AP sets;
* L1 user mode access is never set;
* L2 access control for user mode is set to either
* 2 (RO) or 3 (RW) depending on whether text or data,
* for all 4 AP sets.
* (To get kernel RO set AP to 0 and S bit in control
* register c1).
* Coarse L1 page-tables are used. They have 256 entries
* and so consume 1024 bytes per table.
* Small L2 page-tables are used. They have 1024 entries
* and so consume 4096 bytes per table.
*
* 4KiB. That's the size of 1) a page, 2) the
* size allocated for an L2 page-table page (note only 1KiB
* is needed per L2 page - to be dealt with later) and
* 3) the size of the area in L1 needed to hold the PTEs
* to map 1GiB of user space (0 -> 0x3fffffff, 1024 entries).
*/