xref: /plan9/sys/src/9/bcm/mmu.c (revision 12009bff671a91993ae58f16dab833e809f4a6f3)

#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 {
	L1lo		= UZERO/MiB,		/* L1X(UZERO)? */
	L1hi		= (USTKTOP+MiB-1)/MiB,	/* L1X(USTKTOP+MiB-1)? */
};

void
mmuinit(void)
{
	PTE *l1, *l2;
	uintptr pa, va;

	l1 = (PTE*)PADDR(L1);
	l2 = (PTE*)PADDR(L2);

	/*
	 * map all of ram at KZERO
	 */
	va = KZERO;
	for(pa = PHYSDRAM; pa < PHYSDRAM+DRAMSIZE; pa += MiB){
		l1[L1X(va)] = pa|Dom0|L1AP(Krw)|Section|Cached|Buffered;
		va += MiB;
	}

	/*
	 * identity map first MB of ram so mmu can be enabled
	 */
	l1[L1X(PHYSDRAM)] = PHYSDRAM|Dom0|L1AP(Krw)|Section|Cached|Buffered;

	/*
	 * map i/o registers
	 */
	va = VIRTIO;
	for(pa = PHYSIO; pa < PHYSIO+IOSIZE; pa += MiB){
		l1[L1X(va)] = pa|Dom0|L1AP(Krw)|Section;
		va += MiB;
	}

	/*
	 * double map exception vectors at top of virtual memory
	 */
	va = HVECTORS;
	l1[L1X(va)] = (uintptr)l2|Dom0|Coarse;
	l2[L2X(va)] = PHYSDRAM|L2AP(Krw)|Small;
}

void
mmuinit1(void)
{
	PTE *l1;

	l1 = (PTE*)L1;
	m->mmul1 = l1;

	/*
	 * undo identity map of first MB of ram
	 */
	l1[L1X(PHYSDRAM)] = 0;
	cachedwbse(&l1[L1X(PHYSDRAM)], sizeof(PTE));
	mmuinvalidate();
}

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(UINT2PTR(page->va), 0, BY2PG);
		l1[page->daddr] = Fault;
		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 */
}

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 l1 caches */
	cacheuwbinv();

	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? */
	cachedwbse(&l1[L1X(UZERO)], (L1hi - L1lo)*sizeof(PTE));

	/* lose any possible stale tlb entries */
	mmuinvalidate();
}

void
flushmmu(void)
{
	int s;

	s = splhi();
	up->newtlb = 1;
	mmuswitch(up);
	splx(s);
}

void
mmurelease(Proc* proc)
{
	Page *page, *next;

	/* write back dirty and invalidate l1 caches */
	cacheuwbinv();

	mmul2empty(proc, 0);
	for(page = proc->mmul2cache; page != nil; page = next){
		next = page->next;
		if(--page->ref)
			panic("mmurelease: page->ref %d", page->ref);
		pagechainhead(page);
	}
	if(proc->mmul2cache && palloc.r.p)
		wakeup(&palloc.r);
	proc->mmul2cache = nil;

	mmul1empty();

	/* make sure map is in memory */
	/* could be smarter about how much? */
	cachedwbse(&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(*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(UINT2PTR(pg->va), 0, BY2PG);
		}
		pg->daddr = x;
		pg->next = up->mmul2;
		up->mmul2 = pg;

		/* force l2 page to memory */
		cachedwbse((void *)pg->va, BY2PG);

		*l1 = PPN(pg->pa)|Dom0|Coarse;
		cachedwbse(l1, sizeof *l1);

		if(x >= m->mmul1lo && x < m->mmul1hi){
			if(x+1 - m->mmul1lo < m->mmul1hi - x)
				m->mmul1lo = x+1;
			else
				m->mmul1hi = x;
		}
	}
	pte = UINT2PTR(KADDR(PPN(*l1)));

	/* protection bits are
	 *	PTERONLY|PTEVALID;
	 *	PTEWRITE|PTEVALID;
	 *	PTEWRITE|PTEUNCACHED|PTEVALID;
	 */
	x = Small;
	if(!(pa & PTEUNCACHED))
		x |= Cached|Buffered;
	if(pa & PTEWRITE)
		x |= L2AP(Urw);
	else
		x |= L2AP(Uro);
	pte[L2X(va)] = PPN(pa)|x;
	cachedwbse(&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.
	 */
	cachedwbinv();
	if(page->cachectl[0] == PG_TXTFLUSH){
		/* pio() sets PG_TXTFLUSH whenever a text pg has been written */
		cacheiinv();
		page->cachectl[0] = PG_NOFLUSH;
	}
	checkmmu(va, PPN(pa));
}

/*
 * 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(pa < PHYSDRAM + memsize)		/* assumes PHYSDRAM is 0 */
		return PHYSDRAM + memsize - pa;
	return 0;
}

uintptr
mmukmap(uintptr va, uintptr pa, usize size)
{
	int o;
	usize n;
	PTE *pte, *pte0;

	assert((va & (MiB-1)) == 0);
	o = pa & (MiB-1);
	pa -= o;
	size += o;
	pte = pte0 = &m->mmul1[L1X(va)];
	for(n = 0; n < size; n += MiB)
		if(*pte++ != Fault)
			return 0;
	pte = pte0;
	for(n = 0; n < size; n += MiB){
		*pte++ = (pa+n)|Dom0|L1AP(Krw)|Section;
		mmuinvalidateaddr(va+n);
	}
	cachedwbse(pte0, pte - pte0);
	return va + o;
}


void
checkmmu(uintptr va, uintptr pa)
{
	USED(va);
	USED(pa);
}