pmap.c

早期freebsd实现

	 */
	if (!pmap->pm_segtab) {
		/* change entries in kernel pmap */
#ifdef DIAGNOSTIC
		if (va < VM_MIN_KERNEL_ADDRESS || va >= virtual_end)
			panic("pmap_change_wiring");
#endif
		pte = kvtopte(va);
	} else {
		if (!(pte = pmap_segmap(pmap, va)))
			return;
		pte += (va >> PGSHIFT) & (NPTEPG - 1);
	}

	i = pmaxpagesperpage;
	if (!(pte->pt_entry & PG_WIRED) && p)
		pmap->pm_stats.wired_count += i;
	else if ((pte->pt_entry & PG_WIRED) && !p)
		pmap->pm_stats.wired_count -= i;
	do {
		if (pte->pt_entry & PG_V)
			pte->pt_entry = (pte->pt_entry & ~PG_WIRED) | p;
		pte++;
	} while (--i != 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 DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_extract(%x, %x) -> ", pmap, va);
#endif

	if (!pmap->pm_segtab) {
#ifdef DIAGNOSTIC
		if (va < VM_MIN_KERNEL_ADDRESS || va >= virtual_end)
			panic("pmap_extract");
#endif
		pa = kvtopte(va)->pt_entry & PG_FRAME;
	} else {
		register pt_entry_t *pte;

		if (!(pte = pmap_segmap(pmap, va)))
			pa = 0;
		else {
			pte += (va >> PGSHIFT) & (NPTEPG - 1);
			pa = pte->pt_entry & PG_FRAME;
		}
	}
	if (pa)
		pa |= va & PGOFSET;

#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_extract: pa %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)\n",
		       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()\n");
#endif
}

/*
 *	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.
 */
void
pmap_collect(pmap)
	pmap_t pmap;
{

#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_collect(%x)\n", pmap);
#endif
}

/*
 *	pmap_zero_page zeros the specified (machine independent)
 *	page.
 */
void
pmap_zero_page(phys)
	vm_offset_t phys;
{
	register int *p, *end;

#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_zero_page(%x)\n", phys);
#endif
	p = (int *)MACH_PHYS_TO_CACHED(phys);
	end = p + PAGE_SIZE / sizeof(int);
	do {
		p[0] = 0;
		p[1] = 0;
		p[2] = 0;
		p[3] = 0;
		p += 4;
	} while (p != end);
}

/*
 *	pmap_copy_page copies the specified (machine independent)
 *	page.
 */
void
pmap_copy_page(src, dst)
	vm_offset_t src, dst;
{
	register int *s, *d, *end;
	register int tmp0, tmp1, tmp2, tmp3;

#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_copy_page(%x, %x)\n", src, dst);
#endif
	s = (int *)MACH_PHYS_TO_CACHED(src);
	d = (int *)MACH_PHYS_TO_CACHED(dst);
	end = s + PAGE_SIZE / sizeof(int);
	do {
		tmp0 = s[0];
		tmp1 = s[1];
		tmp2 = s[2];
		tmp3 = s[3];
		d[0] = tmp0;
		d[1] = tmp1;
		d[2] = tmp2;
		d[3] = tmp3;
		s += 4;
		d += 4;
	} while (s != end);
}

/*
 *	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)\n",
		       pmap, sva, eva, pageable);
#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)\n", pa);
#endif
#ifdef ATTR
	pmap_attributes[atop(pa)] &= ~PMAP_ATTR_MOD;
#endif
}

/*
 *	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)\n", pa);
#endif
#ifdef ATTR
	pmap_attributes[atop(pa)] &= ~PMAP_ATTR_REF;
#endif
}

/*
 *	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 ATTR
	return (pmap_attributes[atop(pa)] & PMAP_ATTR_REF);
#else
	return (FALSE);
#endif
}

/*
 *	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 ATTR
	return (pmap_attributes[atop(pa)] & PMAP_ATTR_MOD);
#else
	return (FALSE);
#endif
}

vm_offset_t
pmap_phys_address(ppn)
	int ppn;
{

#ifdef DEBUG
	if (pmapdebug & PDB_FOLLOW)
		printf("pmap_phys_address(%x)\n", ppn);
#endif
	return (pmax_ptob(ppn));
}

/*
 * Miscellaneous support routines
 */

/*
 * Allocate a hardware PID and return it.
 * It takes almost as much or more time to search the TLB for a
 * specific PID and flush those entries as it does to flush the entire TLB.
 * Therefore, when we allocate a new PID, we just take the next number. When
 * we run out of numbers, we flush the TLB, increment the generation count
 * and start over. PID zero is reserved for kernel use.
 * This is called only by switch().
 */
int
pmap_alloc_tlbpid(p)
	register struct proc *p;
{
	register pmap_t pmap;
	register int id;

	pmap = &p->p_vmspace->vm_pmap;
	if (pmap->pm_tlbgen != tlbpid_gen) {
		id = tlbpid_cnt;
		if (id == VMMACH_NUM_PIDS) {
			MachTLBFlush();
			/* reserve tlbpid_gen == 0 to alway mean invalid */
			if (++tlbpid_gen == 0)
				tlbpid_gen = 1;
			id = 1;
		}
		tlbpid_cnt = id + 1;
		pmap->pm_tlbpid = id;
		pmap->pm_tlbgen = tlbpid_gen;
	} else
		id = pmap->pm_tlbpid;

#ifdef DEBUG
	if (pmapdebug & (PDB_FOLLOW|PDB_TLBPID)) {
		if (curproc)
			printf("pmap_alloc_tlbpid: curproc %d '%s' ",
				curproc->p_pid, curproc->p_comm);
		else
			printf("pmap_alloc_tlbpid: curproc <none> ");
		printf("segtab %x tlbpid %d pid %d '%s'\n",
			pmap->pm_segtab, id, p->p_pid, p->p_comm);
	}
#endif
	return (id);
}

/*
 * Remove a physical to virtual address translation.
 */
void
pmap_remove_pv(pmap, va, pa)
	pmap_t pmap;
	vm_offset_t va, pa;
{
	register pv_entry_t pv, npv;
	int s;

#ifdef DEBUG
	if (pmapdebug & (PDB_FOLLOW|PDB_PVENTRY))
		printf("pmap_remove_pv(%x, %x, %x)\n", pmap, va, pa);
#endif
	/*
	 * Remove page from the PV table (raise IPL since we
	 * may be called at interrupt time).
	 */
	if (!IS_VM_PHYSADDR(pa))
		return;
	pv = pa_to_pvh(pa);
	s = splimp();
	/*
	 * If it is the first entry on the list, it is actually
	 * in the header and we must copy the following entry up
	 * to the header.  Otherwise we must search the list for
	 * the entry.  In either case we free the now unused entry.
	 */
	if (pmap == pv->pv_pmap && va == pv->pv_va) {
		npv = pv->pv_next;
		if (npv) {
			*pv = *npv;
			free((caddr_t)npv, M_VMPVENT);
		} else
			pv->pv_pmap = NULL;
#ifdef DEBUG
		remove_stats.pvfirst++;
#endif
	} else {
		for (npv = pv->pv_next; npv; pv = npv, npv = npv->pv_next) {
#ifdef DEBUG
			remove_stats.pvsearch++;
#endif
			if (pmap == npv->pv_pmap && va == npv->pv_va)
				goto fnd;
		}
#ifdef DIAGNOSTIC
		printf("pmap_remove_pv(%x, %x, %x) not found\n", pmap, va, pa);
		panic("pmap_remove_pv");
#endif
	fnd:
		pv->pv_next = npv->pv_next;
		free((caddr_t)npv, M_VMPVENT);
	}
	splx(s);
}

/*
 *	vm_page_alloc1:
 *
 *	Allocate and return a memory cell with no associated object.
 */
vm_page_t
vm_page_alloc1()
{
	register vm_page_t	mem;
	int		spl;

	spl = splimp();				/* XXX */
	simple_lock(&vm_page_queue_free_lock);
	if (vm_page_queue_free.tqh_first == NULL) {
		simple_unlock(&vm_page_queue_free_lock);
		splx(spl);
		return (NULL);
	}

	mem = vm_page_queue_free.tqh_first;
	TAILQ_REMOVE(&vm_page_queue_free, mem, pageq);

	cnt.v_free_count--;
	simple_unlock(&vm_page_queue_free_lock);
	splx(spl);

	mem->flags = PG_BUSY | PG_CLEAN | PG_FAKE;
	mem->wire_count = 0;

	/*
	 *	Decide if we should poke the pageout daemon.
	 *	We do this if the free count is less than the low
	 *	water mark, or if the free count is less than the high
	 *	water mark (but above the low water mark) and the inactive
	 *	count is less than its target.
	 *
	 *	We don't have the counts locked ... if they change a little,
	 *	it doesn't really matter.
	 */

	if (cnt.v_free_count < cnt.v_free_min ||
	    (cnt.v_free_count < cnt.v_free_target &&
	     cnt.v_inactive_count < cnt.v_inactive_target))
		thread_wakeup((int)&vm_pages_needed);
	return (mem);
}

/*
 *	vm_page_free1:
 *
 *	Returns the given page to the free list,
 *	disassociating it with any VM object.
 *
 *	Object and page must be locked prior to entry.
 */
void
vm_page_free1(mem)
	register vm_page_t	mem;
{

	if (mem->flags & PG_ACTIVE) {
		TAILQ_REMOVE(&vm_page_queue_active, mem, pageq);
		mem->flags &= ~PG_ACTIVE;
		cnt.v_active_count--;
	}

	if (mem->flags & PG_INACTIVE) {
		TAILQ_REMOVE(&vm_page_queue_inactive, mem, pageq);
		mem->flags &= ~PG_INACTIVE;
		cnt.v_inactive_count--;
	}

	if (!(mem->flags & PG_FICTITIOUS)) {
		int	spl;

		spl = splimp();
		simple_lock(&vm_page_queue_free_lock);
		TAILQ_INSERT_TAIL(&vm_page_queue_free, mem, pageq);

		cnt.v_free_count++;
		simple_unlock(&vm_page_queue_free_lock);
		splx(spl);
	}
}