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.

sys/src/9/port/fault.c

@@ -200,7 +200,6 @@ fixfault(Segment *s, uintptr addr, int read, int doputmmu)
 	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 @@ fixfault(Segment *s, uintptr addr, int read, int doputmmu)
 		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;

sys/src/9/port/page.c

@@ -384,23 +384,11 @@ ptealloc(void)
 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 @@ freepte(Segment *s, Pte *p)
 		}
 		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 @@ portcountpagerefs(ulong *ref, int print)
 		p = proctab(i);
 		for(j=0; j<NSEG; j++){
 			s = p->seg[j];
-			if(s)
+			if(s != nil)
 				s->mark = 0;
 		}
 	}
@@ -493,6 +482,8 @@ portcountpagerefs(ulong *ref, int print)
 			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++){
 				pte = s->map[k];

sys/src/9/port/portdat.h

@@ -359,8 +359,6 @@ struct Physseg
 	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

sys/src/9/port/segment.c

@@ -11,9 +11,9 @@ int imagereclaim(int);
  * 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 @@ mcountseg(Segment *s)
 	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)
@@ -482,6 +485,9 @@ mfreeseg(Segment *s, uintptr start, int pages)
 	uintptr soff;
 	Page *pg;
 
+	if((s->type&SG_TYPE) == SG_PHYSICAL)
+		return;
+
 	/*
 	 * We want to zero s->map[i]->page[j] and putpage(pg),
 	 * but we have to make sure other processors flush the

sys/src/9/port/sysproc.c

@@ -745,6 +745,7 @@ syssegbrk(va_list list)
 		case SG_TEXT:
 		case SG_DATA:
 		case SG_STACK:
+		case SG_PHYSICAL:
 			error(Ebadarg);
 		default:
 			return (uintptr)ibrk(va_arg(list, uintptr), i);