sparc64: simplify reduce_memory() function

The reduce_memory() function clampls the available memory to a limit
defined by the "mem=" command line parameter. It takes into account the
amount of already reserved memory and excludes it from the limit
calculations.

Rather than traverse memblocks and remove them by hand, use
memblock_reserved_size() to account the reserved memory and
memblock_enforce_memory_limit() to clamp the available memory.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/mm/init_64.c

@@ -2269,19 +2269,6 @@ static unsigned long last_valid_pfn;
 static void sun4u_pgprot_init(void);
 static void sun4v_pgprot_init(void);
 
-static phys_addr_t __init available_memory(void)
-{
-	phys_addr_t available = 0ULL;
-	phys_addr_t pa_start, pa_end;
-	u64 i;
-
-	for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &pa_start,
-				&pa_end, NULL)
-		available = available + (pa_end  - pa_start);
-
-	return available;
-}
-
 #define _PAGE_CACHE_4U	(_PAGE_CP_4U | _PAGE_CV_4U)
 #define _PAGE_CACHE_4V	(_PAGE_CP_4V | _PAGE_CV_4V)
 #define __DIRTY_BITS_4U	 (_PAGE_MODIFIED_4U | _PAGE_WRITE_4U | _PAGE_W_4U)
@@ -2295,33 +2282,8 @@ static phys_addr_t __init available_memory(void)
  */
 static void __init reduce_memory(phys_addr_t limit_ram)
 {
-	phys_addr_t avail_ram = available_memory();
-	phys_addr_t pa_start, pa_end;
-	u64 i;
-
-	if (limit_ram >= avail_ram)
-		return;
-
-	for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &pa_start,
-				&pa_end, NULL) {
-		phys_addr_t region_size = pa_end - pa_start;
-		phys_addr_t clip_start = pa_start;
-
-		avail_ram = avail_ram - region_size;
-		/* Are we consuming too much? */
-		if (avail_ram < limit_ram) {
-			phys_addr_t give_back = limit_ram - avail_ram;
-
-			region_size = region_size - give_back;
-			clip_start = clip_start + give_back;
-		}
-
-		memblock_remove(clip_start, region_size);
-
-		if (avail_ram <= limit_ram)
-			break;
-		i = 0UL;
-	}
+	limit_ram += memblock_reserved_size();
+	memblock_enforce_memory_limit(limit_ram);
 }
 
 void __init paging_init(void)