ARM: mm: use physical addresses in highmem sanity checks

This patch modifies the highmem sanity checking code to use physical addresses
instead.  This change eliminates the wrap-around problems associated with the
original virtual address based checks, and this simplifies the code a bit.

The one constraint imposed here is that low physical memory must be mapped in
a monotonically increasing fashion if there are multiple banks of memory,
i.e., x < y must => pa(x) < pa(y).

Signed-off-by: Cyril Chemparathy <cyril@ti.com>
Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Subash Patel <subash.rp@samsung.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm/mm/mmu.c

@@ -988,6 +988,7 @@ phys_addr_t arm_lowmem_limit __initdata = 0;
 void __init sanity_check_meminfo(void)
 {
 	int i, j, highmem = 0;
+	phys_addr_t vmalloc_limit = __pa(vmalloc_min - 1) + 1;
 
 	for (i = 0, j = 0; i < meminfo.nr_banks; i++) {
 		struct membank *bank = &meminfo.bank[j];
@@ -997,8 +998,7 @@ void __init sanity_check_meminfo(void)
 			highmem = 1;
 
 #ifdef CONFIG_HIGHMEM
-		if (__va(bank->start) >= vmalloc_min ||
-		    __va(bank->start) < (void *)PAGE_OFFSET)
+		if (bank->start >= vmalloc_limit)
 			highmem = 1;
 
 		bank->highmem = highmem;
@@ -1007,8 +1007,8 @@ void __init sanity_check_meminfo(void)
 		 * Split those memory banks which are partially overlapping
 		 * the vmalloc area greatly simplifying things later.
 		 */
-		if (!highmem && __va(bank->start) < vmalloc_min &&
-		    bank->size > vmalloc_min - __va(bank->start)) {
+		if (!highmem && bank->start < vmalloc_limit &&
+		    bank->size > vmalloc_limit - bank->start) {
 			if (meminfo.nr_banks >= NR_BANKS) {
 				printk(KERN_CRIT "NR_BANKS too low, "
 						 "ignoring high memory\n");
@@ -1017,12 +1017,12 @@ void __init sanity_check_meminfo(void)
 					(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;
+				bank[1].size -= vmalloc_limit - bank->start;
+				bank[1].start = vmalloc_limit;
 				bank[1].highmem = highmem = 1;
 				j++;
 			}
-			bank->size = vmalloc_min - __va(bank->start);
+			bank->size = vmalloc_limit - bank->start;
 		}
 #else
 		bank->highmem = highmem;
@@ -1042,8 +1042,7 @@ void __init sanity_check_meminfo(void)
 		 * Check whether this memory bank would entirely overlap
 		 * the vmalloc area.
 		 */
-		if (__va(bank->start) >= vmalloc_min ||
-		    __va(bank->start) < (void *)PAGE_OFFSET) {
+		if (bank->start >= vmalloc_limit) {
 			printk(KERN_NOTICE "Ignoring RAM at %.8llx-%.8llx "
 			       "(vmalloc region overlap).\n",
 			       (unsigned long long)bank->start,
@@ -1055,9 +1054,8 @@ void __init sanity_check_meminfo(void)
 		 * Check whether this memory bank would partially overlap
 		 * the vmalloc area.
 		 */
-		if (__va(bank->start + bank->size - 1) >= vmalloc_min ||
-		    __va(bank->start + bank->size - 1) <= __va(bank->start)) {
-			unsigned long newsize = vmalloc_min - __va(bank->start);
+		if (bank->start + bank->size > vmalloc_limit)
+			unsigned long newsize = vmalloc_limit - bank->start;
 			printk(KERN_NOTICE "Truncating RAM at %.8llx-%.8llx "
 			       "to -%.8llx (vmalloc region overlap).\n",
 			       (unsigned long long)bank->start,