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kernel: fix physical segment handling

ignore physical segments in mcountseg() and mfreeseg(). physical
segments are not backed by user pages, and doing putpage() on
physical segment pages in mfreeseg() is an error.

do now allow physical segemnts to be resized. the segment size
is only checked in segattach() to be within the physical segment!

ignore physical segments in portcountpagerefs() as pagenumber()
does not work on the malloced page structures of a physical segment.

get rid of Physseg.pgalloc() and Physseg.pgfree() indirection as
this was never used and if theres a need to do more efficient
allocation, it should be done in a portable way.

--- a/sys/src/9/port/fault.c

+++ b/sys/src/9/port/fault.c

@@ -200,7 +200,6 @@

 	Pte **p, *etp;

 	uintptr soff, mmuphys=0;

 	Page **pg, *old, *new;

-	Page *(*fn)(Segment*, uintptr);

 	addr &= ~(BY2PG-1);

 	soff = addr-s->base;

@@ -274,19 +273,13 @@

 		break;

 	case SG_PHYSICAL:

-		if(*pg == nil) {

-			fn = s->pseg->pgalloc;

-			if(fn)

-				*pg = (*fn)(s, addr);

-			else {

-				new = smalloc(sizeof(Page));

-				new->va = addr;

-				new->pa = s->pseg->pa+(addr-s->base);

-				new->ref = 1;

-				*pg = new;

-			}

+		if(*pg == nil){

+			new = smalloc(sizeof(Page));

+			new->va = addr;

+			new->pa = s->pseg->pa+(addr-s->base);

+			new->ref = 1;

+			*pg = new;

 		}

-

 		if (checkaddr && addr == addr2check)

 			(*checkaddr)(addr, s, *pg);

 		mmuphys = PPN((*pg)->pa) |PTEWRITE|PTEUNCACHED|PTEVALID;

--- a/sys/src/9/port/page.c

+++ b/sys/src/9/port/page.c

@@ -384,23 +384,11 @@

 void

 freepte(Segment *s, Pte *p)

 {

-	void (*fn)(Page*);

-	Page **pg, **ptop;

+	Page **pg;

 	switch(s->type&SG_TYPE) {

 	case SG_PHYSICAL:

-		fn = s->pseg->pgfree;

-		ptop = &p->pages[PTEPERTAB];

-		if(fn != nil) {

-			for(pg = p->pages; pg < ptop; pg++) {

-				if(*pg == nil)

-					continue;

-				(*fn)(*pg);

-				*pg = nil;

-			}

-			break;

-		}

-		for(pg = p->pages; pg < ptop; pg++) {

+		for(pg = p->first; pg <= p->last; pg++) {

 			if(*pg != nil) {

 				if(decref(*pg) == 0)

 					free(*pg);

@@ -409,11 +397,12 @@

 		}

 		break;

 	default:

-		for(pg = p->first; pg <= p->last; pg++)

+		for(pg = p->first; pg <= p->last; pg++) {

 			if(*pg != nil) {

 				putpage(*pg);

 				*pg = nil;

 			}

+		}

 	}

 	free(p);

 }

@@ -483,7 +472,7 @@

 		p = proctab(i);

 		for(j=0; j<NSEG; j++){

 			s = p->seg[j];

-			if(s)

+			if(s != nil)

 				s->mark = 0;

 		}

 	}

@@ -492,6 +481,8 @@

 		for(j=0; j<NSEG; j++){

 			s = p->seg[j];

 			if(s == nil || s->mark++)

+				continue;

+			if((s->type&SG_TYPE) == SG_PHYSICAL)

 				continue;

 			ns++;

 			for(k=0; k<s->mapsize; k++){

--- a/sys/src/9/port/portdat.h

+++ b/sys/src/9/port/portdat.h

@@ -359,8 +359,6 @@

 	char	*name;			/* Attach name */

 	uintptr	pa;			/* Physical address */

 	uintptr	size;			/* Maximum segment size in bytes */

-	Page	*(*pgalloc)(Segment*, uintptr);	/* Allocation if we need it */

-	void	(*pgfree)(Page*);

 };

 struct Sema

--- a/sys/src/9/port/segment.c

+++ b/sys/src/9/port/segment.c

@@ -11,9 +11,9 @@

  * Attachable segment types

  */

 static Physseg physseg[10] = {

-	{ SG_SHARED,	"shared",	0,	SEGMAXSIZE,	0, 	0 },

-	{ SG_BSS,	"memory",	0,	SEGMAXSIZE,	0,	0 },

-	{ 0,		0,		0,	0,		0,	0 },

+	{ SG_SHARED,	"shared",	0,	SEGMAXSIZE	},

+	{ SG_BSS,	"memory",	0,	SEGMAXSIZE	},

+	{ 0,		0,		0,	0		},

 };

 static Lock physseglock;

@@ -459,6 +459,9 @@

 	int i, j;

 	Page *pg;

+	if((s->type&SG_TYPE) == SG_PHYSICAL)

+		return 0;

+

 	pages = 0;

 	for(i = 0; i < s->mapsize; i++){

 		if(s->map[i] == nil)

@@ -481,6 +484,9 @@

 	int i, j, size;

 	uintptr soff;

 	Page *pg;

+

+	if((s->type&SG_TYPE) == SG_PHYSICAL)

+		return;

 	/*

 	 * We want to zero s->map[i]->page[j] and putpage(pg),

--- a/sys/src/9/port/sysproc.c

+++ b/sys/src/9/port/sysproc.c

@@ -745,6 +745,7 @@

 		case SG_TEXT:

 		case SG_DATA:

 		case SG_STACK:

+		case SG_PHYSICAL:

 			error(Ebadarg);

 		default:

 			return (uintptr)ibrk(va_arg(list, uintptr), i);