to track page-overlapping vmaps such as acpi produces,
introduce vmapoverlap() as a temporary measure.  this
is a slightly better rearrangment of previous code to prepare
for acpi-only (no mp tables) booting.

Reference: /n/atom/patch/applied2013/vmapoverlap
Date: Thu Aug 22 23:35:32 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/nix/k10/fns.h	Thu Aug 22 23:34:00 2013
+++ /sys/src/nix/k10/fns.h	Thu Aug 22 23:34:01 2013
@@ -1,5 +1,4 @@
 #include "../port/portfns.h"
-void	aamloop(int);
 int	acpiinit(void);
 Dirtab*	addarchfile(char*, int, long(*)(Chan*, void*, long, vlong), long(*)(Chan*, void*, long, vlong));
 void	adrinit(void);
@@ -119,6 +118,7 @@
 int	userureg(Ureg*);
 void*	vmap(uintmem, usize);
 void*	vmappat(uintmem, usize, uint);
+void*	vmapoverlap(uintmem, usize);
 int	vmapsync(uintptr);
 void	vsvminit(int);
 void	vunmap(void*, usize);
--- /sys/src/nix/k10/mmu.c	Thu Aug 22 23:34:02 2013
+++ /sys/src/nix/k10/mmu.c	Thu Aug 22 23:34:03 2013
@@ -650,6 +650,51 @@
 	return vmap(pa, size);
 }
 
+/*
+ * sleezy code to deal with overlapping page-size vmaps.
+ * this is currently necessary because acpi maps overlap.
+ * please remove this by either just mapping all acpi
+ * memory (can we count on good acpi tables?), or
+ * keeping one map at a time.
+ * assume boot time, omit locks.
+ */
+typedef struct Remap Remap;
+struct Remap {
+	uintmem	map[150];
+	usize	n;
+};
+static	Remap	smap;
+
+void*
+vmapoverlap(uintmem pa0, usize size)
+{
+	int i, o;
+	uintmem pa, p;
+
+	o = pa0 - (pa0 & ~(PGSZ-1));
+	pa = pa0 - o;
+	size = ROUNDUP(size+o, PGSZ);
+
+	if(pa+size < 1ull*MiB)
+		return KADDR(pa);
+	if(pa < 1ull*MiB)
+		return nil;
+	for(p = pa; p < pa+size; p += PGSZ){
+		for(i = 0; i < smap.n; i++)
+			if(p == smap.map[i])
+				break;
+		if(i == smap.n){
+			if(smap.n == nelem(smap.map))
+				panic("smap.map too small %ld", smap.n);
+			if(vmap(p, PGSZ) == nil)
+				return nil;
+			smap.map[smap.n++] = p;
+		}
+	}
+	/* sleezy assumption, we know everything's direct mapped at KSEG2 */
+	return UINT2PTR(KSEG2 + pa0);
+}
+
 void
 vunmap(void* v, usize size)
 {
--- /sys/src/nix/k10/devacpi.c	Thu Aug 22 23:34:05 2013
+++ /sys/src/nix/k10/devacpi.c	Thu Aug 22 23:34:06 2013
@@ -424,49 +424,6 @@
 	return nil;
 }
 
-/*
- * sleezy code to deal with overlapping allocations.
- * please remove this by either just mapping all acpi
- * memory (can we count on good acpi tables?), or
- * keeping one map at a time.
- */
-typedef struct Sdtmap Sdtmap;
-struct Sdtmap {
-	uintmem	map[150];
-	uint	n;
-};
-static	Sdtmap	smap;
-
-static void*
-findmap(uintmem pa0, uint size)
-{
-	int i, o;
-	uintmem pa, p;
-
-	o = pa0 - (pa0 & ~(PGSZ-1));
-	pa = pa0 - o;
-	size = ROUNDUP(size+o, PGSZ);
-
-	if(pa+size < 1ull*MiB)
-		return KADDR(pa);
-	if(pa < 1ull*MiB)
-		return nil;
-	for(p = pa; p < pa+size; p += PGSZ){
-		for(i = 0; i < smap.n; i++)
-			if(p == smap.map[i])
-				break;
-		if(i == smap.n){
-			if(smap.n == nelem(smap.map))
-				panic("smap.map too small %d", smap.n);
-			if(vmap(p, PGSZ) == nil)
-				return nil;
-			smap.map[smap.n++] = p;
-		}
-	}
-	/* sleezy assumption, we know everything's direct mapped at KSEG2 */
-	return UINT2PTR(KSEG2 + pa0);
-}
-
 static void
 sdtunmap(void *va, usize sz)
 {
@@ -479,9 +436,9 @@
 {
 	Sdthdr* sdt;
 
-	sdt = findmap(pa, sizeof *sdt);
+	sdt = vmapoverlap(pa, sizeof *sdt);
 	if(sdt == nil){
-		DBG("acpi: findmap: nil\n");
+		DBG("acpi: vmapoverlap: nil\n");
 		return nil;
 	}
 	*n = l32get(sdt->length);
@@ -495,8 +452,8 @@
 }
 
 	sdtunmap(sdt, sizeof(Sdthdr));
-	if((sdt = findmap(pa, *n)) == nil){
-		DBG("acpi: findmap: nil\n");
+	if((sdt = vmapoverlap(pa, *n)) == nil){
+		DBG("acpi: vmapoverlap: nil\n");
 		return nil;
 	}
 	if(cksum != 0 && sdtchecksum(sdt, *n) == nil){