pmap.c

早期freebsd实现

struct pte *pmap_pte(pmap, va)
	register pmap_t	pmap;
	vm_offset_t va;
{

#ifdef DEBUGx
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_pte(%x, %x) ->\n", pmap, va);
#endif
	if (pmap && pmap_pde_v(pmap_pde(pmap, va))) {

		/* are we current address space or kernel? */
		if (pmap->pm_pdir[PTDPTDI].pd_pfnum == PTDpde.pd_pfnum
			|| pmap == kernel_pmap)
			return ((struct pte *) vtopte(va));

		/* otherwise, we are alternate address space */
		else {
			if (pmap->pm_pdir[PTDPTDI].pd_pfnum
				!= APTDpde.pd_pfnum) {
				APTDpde = pmap->pm_pdir[PTDPTDI];
				tlbflush();
			}
			return((struct pte *) avtopte(va));
		}
	}
	return(0);
}

/*
 *	Routine:	pmap_extract
 *	Function:
 *		Extract the physical page address associated
 *		with the given map/virtual_address pair.
 */

vm_offset_t
pmap_extract(pmap, va)
	register pmap_t	pmap;
	vm_offset_t va;
{
	register vm_offset_t pa;

#ifdef DEBUGx
	if (pmapdebug & PDB_FOLLOW)
		pg("pmap_extract(%x, %x) -> ", pmap, va);
#endif
	pa = 0;
	if (pmap && pmap_pde_v(pmap_pde(pmap, va))) {
		pa = *(int *) pmap_pte(pmap, va);
	}
	if (pa)
		pa = (pa & PG_FRAME) | (va & ~PG_FRAME);
#ifdef DEBUGx
	if (pmapdebug & PDB_FOLLOW)
		printf("%x\n", pa);
#endif
	return(pa);
}

/*
 *	Copy the range specified by src_addr/len
 *	from the source map to the range dst_addr/len
 *	in the destination map.
 *
 *	This routine is only advisory and need not do anything.
 */
void pmap_copy(dst_pmap, src_pmap, dst_addr, len, src_addr)
	pmap_t		dst_pmap;
	pmap_t		src_pmap;
	vm_offset_t	dst_addr;
	vm_size_t	len;
	vm_offset_t	src_addr;
{
#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_copy(%x, %x, %x, %x, %x)",
		       dst_pmap, src_pmap, dst_addr, len, src_addr);
#endif
}

/*
 *	Require that all active physical maps contain no
 *	incorrect entries NOW.  [This update includes
 *	forcing updates of any address map caching.]
 *
 *	Generally used to insure that a thread about
 *	to run will see a semantically correct world.
 */
void pmap_update()
{
#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_update()");
#endif
	tlbflush();
}

/*
 *	Routine:	pmap_collect
 *	Function:
 *		Garbage collects the physical map system for
 *		pages which are no longer used.
 *		Success need not be guaranteed -- that is, there
 *		may well be pages which are not referenced, but
 *		others may be collected.
 *	Usage:
 *		Called by the pageout daemon when pages are scarce.
 * [ needs to be written -wfj ]
 */
void
pmap_collect(pmap)
	pmap_t		pmap;
{
	register vm_offset_t pa;
	register pv_entry_t pv;
	register int *pte;
	vm_offset_t kpa;
	int s;

#ifdef DEBUG
	int *pde;
	int opmapdebug;
	printf("pmap_collect(%x) ", pmap);
#endif
	if (pmap != kernel_pmap)
		return;

}

/* [ macro again?, should I force kstack into user map here? -wfj ] */
void
pmap_activate(pmap, pcbp)
	register pmap_t pmap;
	struct pcb *pcbp;
{
int x;
#ifdef DEBUG
	if (pmapdebug & (PDB_FOLLOW|PDB_PDRTAB))
		pg("pmap_activate(%x, %x) ", pmap, pcbp);
#endif
	PMAP_ACTIVATE(pmap, pcbp);
/*printf("pde ");
for(x=0x3f6; x < 0x3fA; x++)
	printf("%x ", pmap->pm_pdir[x]);*/
/*pads(pmap);*/
/*pg(" pcb_cr3 %x", pcbp->pcb_cr3);*/
}

/*
 *	pmap_zero_page zeros the specified (machine independent)
 *	page by mapping the page into virtual memory and using
 *	bzero to clear its contents, one machine dependent page
 *	at a time.
 */
void
pmap_zero_page(phys)
	register vm_offset_t	phys;
{
	register int ix;

#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_zero_page(%x)", phys);
#endif
	phys >>= PG_SHIFT;
	ix = 0;
	do {
		clearseg(phys++);
	} while (++ix != i386pagesperpage);
}

/*
 *	pmap_copy_page copies the specified (machine independent)
 *	page by mapping the page into virtual memory and using
 *	bcopy to copy the page, one machine dependent page at a
 *	time.
 */
void
pmap_copy_page(src, dst)
	register vm_offset_t	src, dst;
{
	register int ix;

#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_copy_page(%x, %x)", src, dst);
#endif
	src >>= PG_SHIFT;
	dst >>= PG_SHIFT;
	ix = 0;
	do {
		physcopyseg(src++, dst++);
	} while (++ix != i386pagesperpage);
}


/*
 *	Routine:	pmap_pageable
 *	Function:
 *		Make the specified pages (by pmap, offset)
 *		pageable (or not) as requested.
 *
 *		A page which is not pageable may not take
 *		a fault; therefore, its page table entry
 *		must remain valid for the duration.
 *
 *		This routine is merely advisory; pmap_enter
 *		will specify that these pages are to be wired
 *		down (or not) as appropriate.
 */
void
pmap_pageable(pmap, sva, eva, pageable)
	pmap_t		pmap;
	vm_offset_t	sva, eva;
	boolean_t	pageable;
{
#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_pageable(%x, %x, %x, %x)",
		       pmap, sva, eva, pageable);
#endif
	/*
	 * If we are making a PT page pageable then all valid
	 * mappings must be gone from that page.  Hence it should
	 * be all zeros and there is no need to clean it.
	 * Assumptions:
	 *	- we are called with only one page at a time
	 *	- PT pages have only one pv_table entry
	 */
	if (pmap == kernel_pmap && pageable && sva + PAGE_SIZE == eva) {
		register pv_entry_t pv;
		register vm_offset_t pa;

#ifdef DEBUG
		if ((pmapdebug & (PDB_FOLLOW|PDB_PTPAGE)) == PDB_PTPAGE)
			printf("pmap_pageable(%x, %x, %x, %x)",
			       pmap, sva, eva, pageable);
#endif
		/*if (!pmap_pde_v(pmap_pde(pmap, sva)))
			return;*/
		if(pmap_pte(pmap, sva) == 0)
			return;
		pa = pmap_pte_pa(pmap_pte(pmap, sva));
		if (pa < vm_first_phys || pa >= vm_last_phys)
			return;
		pv = pa_to_pvh(pa);
		/*if (!ispt(pv->pv_va))
			return;*/
#ifdef DEBUG
		if (pv->pv_va != sva || pv->pv_next) {
			pg("pmap_pageable: bad PT page va %x next %x\n",
			       pv->pv_va, pv->pv_next);
			return;
		}
#endif
		/*
		 * Mark it unmodified to avoid pageout
		 */
		pmap_clear_modify(pa);
#ifdef needsomethinglikethis
		if (pmapdebug & PDB_PTPAGE)
			pg("pmap_pageable: PT page %x(%x) unmodified\n",
			       sva, *(int *)pmap_pte(pmap, sva));
		if (pmapdebug & PDB_WIRING)
			pmap_check_wiring("pageable", sva);
#endif
	}
}

/*
 *	Clear the modify bits on the specified physical page.
 */

void
pmap_clear_modify(pa)
	vm_offset_t	pa;
{
#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_clear_modify(%x)", pa);
#endif
	pmap_changebit(pa, PG_M, FALSE);
}

/*
 *	pmap_clear_reference:
 *
 *	Clear the reference bit on the specified physical page.
 */

void pmap_clear_reference(pa)
	vm_offset_t	pa;
{
#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_clear_reference(%x)", pa);
#endif
	pmap_changebit(pa, PG_U, FALSE);
}

/*
 *	pmap_is_referenced:
 *
 *	Return whether or not the specified physical page is referenced
 *	by any physical maps.
 */

boolean_t
pmap_is_referenced(pa)
	vm_offset_t	pa;
{
#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW) {
		boolean_t rv = pmap_testbit(pa, PG_U);
		printf("pmap_is_referenced(%x) -> %c", pa, "FT"[rv]);
		return(rv);
	}
#endif
	return(pmap_testbit(pa, PG_U));
}

/*
 *	pmap_is_modified:
 *
 *	Return whether or not the specified physical page is modified
 *	by any physical maps.
 */

boolean_t
pmap_is_modified(pa)
	vm_offset_t	pa;
{
#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW) {
		boolean_t rv = pmap_testbit(pa, PG_M);
		printf("pmap_is_modified(%x) -> %c", pa, "FT"[rv]);
		return(rv);
	}
#endif
	return(pmap_testbit(pa, PG_M));
}

vm_offset_t
pmap_phys_address(ppn)
	int ppn;
{
	return(i386_ptob(ppn));
}

/*
 * Miscellaneous support routines follow
 */

i386_protection_init()
{
	register int *kp, prot;

	kp = protection_codes;
	for (prot = 0; prot < 8; prot++) {
		switch (prot) {
		case VM_PROT_NONE | VM_PROT_NONE | VM_PROT_NONE:
			*kp++ = 0;
			break;
		case VM_PROT_READ | VM_PROT_NONE | VM_PROT_NONE:
		case VM_PROT_READ | VM_PROT_NONE | VM_PROT_EXECUTE:
		case VM_PROT_NONE | VM_PROT_NONE | VM_PROT_EXECUTE:
			*kp++ = PG_RO;
			break;
		case VM_PROT_NONE | VM_PROT_WRITE | VM_PROT_NONE:
		case VM_PROT_NONE | VM_PROT_WRITE | VM_PROT_EXECUTE:
		case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_NONE:
		case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE:
			*kp++ = PG_RW;
			break;
		}
	}
}

static
boolean_t
pmap_testbit(pa, bit)
	register vm_offset_t pa;
	int bit;
{
	register pv_entry_t pv;
	register int *pte, ix;
	int s;

	if (pa < vm_first_phys || pa >= vm_last_phys)
		return(FALSE);

	pv = pa_to_pvh(pa);
	s = splimp();
	/*
	 * Check saved info first
	 */
	if (pmap_attributes[pa_index(pa)] & bit) {
		splx(s);
		return(TRUE);
	}
	/*
	 * Not found, check current mappings returning
	 * immediately if found.
	 */
	if (pv->pv_pmap != NULL) {
		for (; pv; pv = pv->pv_next) {
			pte = (int *) pmap_pte(pv->pv_pmap, pv->pv_va);
			ix = 0;
			do {
				if (*pte++ & bit) {
					splx(s);
					return(TRUE);
				}
			} while (++ix != i386pagesperpage);
		}
	}
	splx(s);
	return(FALSE);
}

pmap_changebit(pa, bit, setem)
	register vm_offset_t pa;
	int bit;
	boolean_t setem;
{
	register pv_entry_t pv;
	register int *pte, npte, ix;
	vm_offset_t va;
	int s;
	boolean_t firstpage = TRUE;

#ifdef DEBUG
	if (pmapdebug & PDB_BITS)
		printf("pmap_changebit(%x, %x, %s)",
		       pa, bit, setem ? "set" : "clear");
#endif
	if (pa < vm_first_phys || pa >= vm_last_phys)
		return;

	pv = pa_to_pvh(pa);
	s = splimp();
	/*
	 * Clear saved attributes (modify, reference)
	 */
	if (!setem)
		pmap_attributes[pa_index(pa)] &= ~bit;
	/*
	 * Loop over all current mappings setting/clearing as appropos
	 * If setting RO do we need to clear the VAC?
	 */
	if (pv->pv_pmap != NULL) {
#ifdef DEBUG
		int toflush = 0;
#endif
		for (; pv; pv = pv->pv_next) {
#ifdef DEBUG
			toflush |= (pv->pv_pmap == kernel_pmap) ? 2 : 1;
#endif
			va = pv->pv_va;

                        /*
                         * XXX don't write protect pager mappings
                         */
                        if (bit == PG_RO) {
                                extern vm_offset_t pager_sva, pager_eva;

                                if (va >= pager_sva && va < pager_eva)
                                        continue;
                        }

			pte = (int *) pmap_pte(pv->pv_pmap, va);
			ix = 0;
			do {
				if (setem)
					npte = *pte | bit;
				else
					npte = *pte & ~bit;
				if (*pte != npte) {
					*pte = npte;
					/*TBIS(va);*/
				}
				va += I386_PAGE_SIZE;
				pte++;
			} while (++ix != i386pagesperpage);

			if (pv->pv_pmap == &curproc->p_vmspace->vm_pmap)
				pmap_activate(pv->pv_pmap, (struct pcb *)curproc->p_addr);
		}
#ifdef somethinglikethis
		if (setem && bit == PG_RO && (pmapvacflush & PVF_PROTECT)) {
			if ((pmapvacflush & PVF_TOTAL) || toflush == 3)
				DCIA();
			else if (toflush == 2)
				DCIS();
			else
				DCIU();
		}
#endif
	}
	splx(s);
}

#ifdef DEBUG
pmap_pvdump(pa)
	vm_offset_t pa;
{
	register pv_entry_t pv;

	printf("pa %x", pa);
	for (pv = pa_to_pvh(pa); pv; pv = pv->pv_next) {
		printf(" -> pmap %x, va %x, flags %x",
		       pv->pv_pmap, pv->pv_va, pv->pv_flags);
		pads(pv->pv_pmap);
	}
	printf(" ");
}

#ifdef notyet
pmap_check_wiring(str, va)
	char *str;
	vm_offset_t va;
{
	vm_map_entry_t entry;
	register int count, *pte;

	va = trunc_page(va);
	if (!pmap_pde_v(pmap_pde(kernel_pmap, va)) ||
	    !pmap_pte_v(pmap_pte(kernel_pmap, va)))
		return;

	if (!vm_map_lookup_entry(pt_map, va, &entry)) {
		pg("wired_check: entry for %x not found\n", va);
		return;
	}
	count = 0;
	for (pte = (int *)va; pte < (int *)(va+PAGE_SIZE); pte++)
		if (*pte)
			count++;
	if (entry->wired_count != count)
		pg("*%s*: %x: w%d/a%d\n",
		       str, va, entry->wired_count, count);
}
#endif

/* print address space of pmap*/
pads(pm) pmap_t pm; {
	unsigned va, i, j;
	struct pte *ptep;

	if(pm == kernel_pmap) return;
	for (i = 0; i < 1024; i++) 
		if(pm->pm_pdir[i].pd_v)
			for (j = 0; j < 1024 ; j++) {
				va = (i<<22)+(j<<12);
				if (pm == kernel_pmap && va < 0xfe000000)
						continue;
				if (pm != kernel_pmap && va > UPT_MAX_ADDRESS)
						continue;
				ptep = pmap_pte(pm, va);
				if(pmap_pte_v(ptep)) 
					printf("%x:%x ", va, *(int *)ptep); 
			} ;
				
}
#endif