[ARM] split highmem into its own memory bank

Doing so will greatly simplify the bootmem initialization code as each
bank is therefore entirely lowmem or highmem with no crossing between
those zones.

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/mmu.c

@@ -651,44 +651,62 @@ __early_param("vmalloc=", early_vmalloc);
 
 #define VMALLOC_MIN	(void *)(VMALLOC_END - vmalloc_reserve)
 
-static int __init check_membank_valid(struct membank *mb)
-{
-	/*
-	 * Check whether this memory region would entirely overlap
-	 * the vmalloc area.
-	 */
-	if (phys_to_virt(mb->start) >= VMALLOC_MIN) {
-		printk(KERN_NOTICE "Ignoring RAM at %.8lx-%.8lx "
-			"(vmalloc region overlap).\n",
-			mb->start, mb->start + mb->size - 1);
-		return 0;
-	}
-
-	/*
-	 * Check whether this memory region would partially overlap
-	 * the vmalloc area.
-	 */
-	if (phys_to_virt(mb->start + mb->size) < phys_to_virt(mb->start) ||
-	    phys_to_virt(mb->start + mb->size) > VMALLOC_MIN) {
-		unsigned long newsize = VMALLOC_MIN - phys_to_virt(mb->start);
-
-		printk(KERN_NOTICE "Truncating RAM at %.8lx-%.8lx "
-			"to -%.8lx (vmalloc region overlap).\n",
-			mb->start, mb->start + mb->size - 1,
-			mb->start + newsize - 1);
-		mb->size = newsize;
-	}
-
-	return 1;
-}
-
 static void __init sanity_check_meminfo(void)
 {
 	int i, j;
 
 	for (i = 0, j = 0; i < meminfo.nr_banks; i++) {
-		if (check_membank_valid(&meminfo.bank[i]))
-			meminfo.bank[j++] = meminfo.bank[i];
+		struct membank *bank = &meminfo.bank[j];
+		*bank = meminfo.bank[i];
+
+#ifdef CONFIG_HIGHMEM
+		/*
+		 * Split those memory banks which are partially overlapping
+		 * the vmalloc area greatly simplifying things later.
+		 */
+		if (__va(bank->start) < VMALLOC_MIN &&
+		    bank->size > VMALLOC_MIN - __va(bank->start)) {
+			if (meminfo.nr_banks >= NR_BANKS) {
+				printk(KERN_CRIT "NR_BANKS too low, "
+						 "ignoring high memory\n");
+			} else {
+				memmove(bank + 1, bank,
+					(meminfo.nr_banks - i) * sizeof(*bank));
+				meminfo.nr_banks++;
+				i++;
+				bank[1].size -= VMALLOC_MIN - __va(bank->start);
+				bank[1].start = __pa(VMALLOC_MIN - 1) + 1;
+				j++;
+			}
+			bank->size = VMALLOC_MIN - __va(bank->start);
+		}
+#else
+		/*
+		 * Check whether this memory bank would entirely overlap
+		 * the vmalloc area.
+		 */
+		if (__va(bank->start) >= VMALLOC_MIN) {
+			printk(KERN_NOTICE "Ignoring RAM at %.8lx-%.8lx "
+			       "(vmalloc region overlap).\n",
+			       bank->start, bank->start + bank->size - 1);
+			continue;
+		}
+
+		/*
+		 * Check whether this memory bank would partially overlap
+		 * the vmalloc area.
+		 */
+		if (__va(bank->start + bank->size) > VMALLOC_MIN ||
+		    __va(bank->start + bank->size) < __va(bank->start)) {
+			unsigned long newsize = VMALLOC_MIN - __va(bank->start);
+			printk(KERN_NOTICE "Truncating RAM at %.8lx-%.8lx "
+			       "to -%.8lx (vmalloc region overlap).\n",
+			       bank->start, bank->start + bank->size - 1,
+			       bank->start + newsize - 1);
+			bank->size = newsize;
+		}
+#endif
+		j++;
 	}
 	meminfo.nr_banks = j;
 }