pc64: allocate palloc.pages from upages

the palloc.pages array takes arround 5% of the upages which
gives us:

16GB = ~0.8GB
32GB = ~1.6GB
64GB = ~3.2GB

we only have 2GB of address space above KZERO so this will not
work for long.

instead, pageinit() was altered to accept a preallocated memory
in palloc.pages. and preallocpages() in pc64/main.c allocates the
in upages memory, mapping it in the VMAP area (which has 512GB).

the drawback is that we cannot poke at Page structures now from
/proc/n/mem as the VMAP area is not accessible from it.

sys/src/9/pc64/fns.h

@@ -146,7 +146,7 @@ int	(*_pcmspecial)(char *, ISAConf *);
 void	pcmspecialclose(int);
 void	(*_pcmspecialclose)(int);
 void	pcmunmap(int, PCMmap*);
-void	pmap(uintptr *, uintptr, uintptr, int);
+void	pmap(uintptr *, uintptr, uintptr, vlong);
 void	procrestore(Proc*);
 void	procsave(Proc*);
 void	procsetup(Proc*);

sys/src/9/pc64/main.c

@@ -231,8 +231,7 @@ confinit(void)
 	 * (probably ~300KB).
 	 */
 	kpages *= BY2PG;
-	kpages -= conf.upages*sizeof(Page)
-		+ conf.nproc*sizeof(Proc)
+	kpages -= conf.nproc*sizeof(Proc)
 		+ conf.nimage*sizeof(Image)
 		+ conf.nswap
 		+ conf.nswppo*sizeof(Page*);
@@ -250,6 +249,44 @@ confinit(void)
 	}
 }
 
+/*
+ * The palloc.pages array takes arround 5% of the amount
+ * of upages which can be a large chunk out of the 2GB
+ * window above KZERO, so we allocate the array from
+ * upages and map in the VMAP window before pageinit()
+ */
+static void
+preallocpages(void)
+{
+	Pallocmem *pm;
+	uintptr va;
+	vlong size;
+	ulong np;
+	int i;
+
+	np = 0;
+	for(i=0; i<nelem(palloc.mem); i++){
+		pm = &palloc.mem[i];
+		np += pm->npage;
+	}
+	size = (uvlong)np * BY2PG;
+	size += sizeof(Page) + BY2PG;	/* round up */
+	size = (size / (sizeof(Page) + BY2PG)) * sizeof(Page);
+	size = PGROUND(size);
+
+	np = size/BY2PG;
+	for(i=0; i<nelem(palloc.mem); i++){
+		pm = &palloc.mem[i];
+		if((pm->base + size) <= VMAPSIZE && pm->npage >= np){
+			va = VMAP + pm->base;
+			pmap(m->pml4, pm->base | PTEGLOBAL|PTEWRITE|PTEVALID, va, size);
+			palloc.pages = (Page*)va;
+			pm->base += size;
+			pm->npage -= np;
+			break;
+		}
+	}
+}
 
 void
 machinit(void)
@@ -492,6 +529,7 @@ main()
 		links();
 	conf.monitor = 1;
 	chandevreset();
+	preallocpages();
 	pageinit();
 	swapinit();
 	userinit();

sys/src/9/pc64/mem.h

@@ -56,7 +56,7 @@
 #define KTZERO		(KZERO+1*MiB+64*KiB)
 
 #define VMAP		(0xffffff0000000000ull)
-#define VMAPSIZE	(512*GiB)
+#define VMAPSIZE	(512ull*GiB)
 
 #define	KMAP		(0xfffffe8000000000ull)
 #define KMAPSIZE	(2*MiB)

sys/src/9/pc64/memory.c

@@ -371,25 +371,6 @@ sigsearch(char* signature)
 	return sigscan(KADDR(0xe0000), 0x20000, signature);
 }
 
-static void
-lowraminit(void)
-{
-	uintptr pa, x;
-
-	/*
-	 * Initialise the memory bank information for conventional memory
-	 * (i.e. less than 640KB). The base is the first location after the
-	 * bootstrap processor MMU information and the limit is obtained from
-	 * the BIOS data area.
-	 */
-	x = PADDR(PGROUND((uintptr)end));
-	pa = MemMin;
-	if(x > pa)
-		panic("kernel too big");
-	mapfree(&rmapram, x, pa-x);
-	memset(KADDR(x), 0, pa-x);		/* keep us honest */
-}
-
 typedef struct Emap Emap;
 struct Emap
 {
@@ -421,7 +402,7 @@ emapcmp(const void *va, const void *vb)
 static void
 map(uintptr base, uintptr len, int type)
 {
-	uintptr e, n, *pte, flags, maxkpa;
+	uintptr n, flags, maxkpa;
 
 	/*
 	 * Split any call crossing MemMin to make below simpler.
@@ -433,7 +414,7 @@ map(uintptr base, uintptr len, int type)
 	}
 	
 	/*
-	 * Let lowraminit and umbscan hash out the low MemMin.
+	 * Let umbscan hash out the low MemMin.
 	 */
 	if(base < MemMin)
 		return;
@@ -497,21 +478,6 @@ map(uintptr base, uintptr len, int type)
 		break;
 	}
 	
-	/*
-	 * bottom MemMin is already mapped - just twiddle flags.
-	 * (not currently used - see above)
-	 */
-	if(base < MemMin){
-		e = base+len;
-		base &= ~((uintptr)PGLSZ(1)-1);
-		for(; base<e; base+=PGLSZ(1)){
-			pte = mmuwalk(m->pml4, base+KZERO, 1, 0);
-			if(pte != 0 && *pte & PTEVALID)
-				*pte |= flags;
-		}
-		return;
-	}
-	
 	if(flags){
 		maxkpa = -KZERO;
 		if(base >= maxkpa)
@@ -595,7 +561,6 @@ meminit(void)
 	uintptr lost;
 
 	umbscan();
-	// lowraminit();
 	e820scan();
 
 	/*

sys/src/9/pc64/mmu.c

@@ -282,13 +282,13 @@ ptecount(uintptr va, int level)
 }
 
 void
-pmap(uintptr *pml4, uintptr pa, uintptr va, int size)
+pmap(uintptr *pml4, uintptr pa, uintptr va, vlong size)
 {
 	uintptr *pte, *ptee, flags;
 	int z, l;
 
 	if((size <= 0) || va < VMAP)
-		panic("pmap: pa=%#p va=%#p size=%d", pa, va, size);
+		panic("pmap: pa=%#p va=%#p size=%lld", pa, va, size);
 	flags = pa;
 	pa = PPN(pa);
 	flags -= pa;
@@ -310,7 +310,7 @@ pmap(uintptr *pml4, uintptr pa, uintptr va, int size)
 				size += z;
 				continue;
 			}
-			panic("pmap: pa=%#p va=%#p size=%d", pa, va, size);
+			panic("pmap: pa=%#p va=%#p size=%lld", pa, va, size);
 		}
 		ptee = pte + ptecount(va, l);
 		while(size > 0 && pte < ptee){

sys/src/9/port/page.c

@@ -16,16 +16,19 @@ pageinit(void)
 	Page *p;
 	Pallocmem *pm;
 	vlong m, v, u;
-	ulong np;
 
-	np = 0;
-	for(i=0; i<nelem(palloc.mem); i++){
-		pm = &palloc.mem[i];
-		np += pm->npage;
+	if(palloc.pages == nil){
+		ulong np;
+
+		np = 0;
+		for(i=0; i<nelem(palloc.mem); i++){
+			pm = &palloc.mem[i];
+			np += pm->npage;
+		}
+		palloc.pages = xalloc(np*sizeof(Page));
+		if(palloc.pages == nil)
+			panic("pageinit");
 	}
-	palloc.pages = xalloc(np*sizeof(Page));
-	if(palloc.pages == 0)
-		panic("pageinit");
 
 	color = 0;
 	palloc.head = palloc.pages;
@@ -33,6 +36,7 @@ pageinit(void)
 	for(i=0; i<nelem(palloc.mem); i++){
 		pm = &palloc.mem[i];
 		for(j=0; j<pm->npage; j++){
+			memset(p, 0, sizeof *p);
 			p->prev = p-1;
 			p->next = p+1;
 			p->pa = pm->base+j*BY2PG;