memblock, bootmem: Round pfn properly for memory and reserved regions

We need to round memory regions correctly -- specifically, we need to
round reserved region in the more expansive direction (lower limit
down, upper limit up) whereas usable memory regions need to be rounded
in the more restrictive direction (lower limit up, upper limit down).

This introduces two set of inlines:

memblock_region_memory_base_pfn()
memblock_region_memory_end_pfn()
memblock_region_reserved_base_pfn()
memblock_region_reserved_end_pfn()

Although they are antisymmetric (and therefore are technically
duplicates) the use of the different inlines explicitly documents the
programmer's intention.

The lack of proper rounding caused a bug on ARM, which was then found
to also affect other architectures.

Reported-by: Russell King <[e-mail]>
Signed-off-by: Yinghai Lu <[e-mail]>
LKML-Reference: <[e-mail]>
Cc: Jeremy Fitzhardinge <[e-mail]>
Signed-off-by: H. Peter Anvin <[e-mail]>

arch/arm/mm/init.c

···
 	 * Reserve the memblock reserved regions in bootmem.
 	 */
 	for_each_memblock(reserved, reg) {
-		phys_addr_t start = memblock_region_base_pfn(reg);
-		phys_addr_t end = memblock_region_end_pfn(reg);
+		phys_addr_t start = memblock_region_reserved_base_pfn(reg);
+		phys_addr_t end = memblock_region_reserved_end_pfn(reg);
 		if (start >= start_pfn && end <= end_pfn)
 			reserve_bootmem_node(pgdat, __pfn_to_phys(start),
 					     (end - start) << PAGE_SHIFT,
···
 	struct memblock_region *reg;
 
 	for_each_memblock(memory, reg)
-		memory_present(0, memblock_region_base_pfn(reg),
-			       memblock_region_end_pfn(reg));
+		memory_present(0, memblock_region_memory_base_pfn(reg),
+			       memblock_region_memory_end_pfn(reg));
 }
 #endif
 

arch/powerpc/mm/mem.c

···
 	int ret = -1;
 
 	for_each_memblock(memory, reg) {
-		tstart = max(start_pfn, memblock_region_base_pfn(reg));
-		tend = min(end_pfn, memblock_region_end_pfn(reg));
+		tstart = max(start_pfn, memblock_region_memory_base_pfn(reg));
+		tend = min(end_pfn, memblock_region_memory_end_pfn(reg));
 		if (tstart >= tend)
 			continue;
 		ret = (*func)(tstart, tend - tstart, arg);
···
 	/* Add active regions with valid PFNs */
 	for_each_memblock(memory, reg) {
 		unsigned long start_pfn, end_pfn;
-		start_pfn = memblock_region_base_pfn(reg);
-		end_pfn = memblock_region_end_pfn(reg);
+		start_pfn = memblock_region_memory_base_pfn(reg);
+		end_pfn = memblock_region_memory_end_pfn(reg);
 		add_active_range(0, start_pfn, end_pfn);
 	}
 
···
 
 	for_each_memblock(memory, reg) {
 		if (prev &&
-		    memblock_region_end_pfn(prev) < memblock_region_base_pfn(reg))
-			register_nosave_region(memblock_region_end_pfn(prev),
-					       memblock_region_base_pfn(reg));
+		    memblock_region_memory_end_pfn(prev) < memblock_region_memory_base_pfn(reg))
+			register_nosave_region(memblock_region_memory_end_pfn(prev),
+					       memblock_region_memory_base_pfn(reg));
 		prev = reg;
 	}
 	return 0;

arch/powerpc/mm/numa.c

···
 	       (top_of_ram - total_ram) >> 20);
 
 	for_each_memblock(memory, reg) {
-		start_pfn = memblock_region_base_pfn(reg);
-		end_pfn = memblock_region_end_pfn(reg);
+		start_pfn = memblock_region_memory_base_pfn(reg);
+		end_pfn = memblock_region_memory_end_pfn(reg);
 
 		fake_numa_create_new_node(end_pfn, &nid);
 		add_active_range(nid, start_pfn, end_pfn);

arch/sh/mm/init.c

···
 	/* Add active regions with valid PFNs. */
 	for_each_memblock(memory, reg) {
 		unsigned long start_pfn, end_pfn;
-		start_pfn = memblock_region_base_pfn(reg);
-		end_pfn = memblock_region_end_pfn(reg);
+		start_pfn = memblock_region_memory_base_pfn(reg);
+		end_pfn = memblock_region_memory_end_pfn(reg);
 		__add_active_range(0, start_pfn, end_pfn);
 	}
 

arch/sparc/mm/init_64.c

···
 		if (!reg->size)
 			continue;
 
-		start_pfn = memblock_region_base_pfn(reg);
-		end_pfn = memblock_region_end_pfn(reg);
+		start_pfn = memblock_region_memory_base_pfn(reg);
+		end_pfn = memblock_region_memory_end_pfn(reg);
 		add_active_range(0, start_pfn, end_pfn);
 	}
 

include/linux/memblock.h

···
  */
 
 /**
- * memblock_region_base_pfn - Return the lowest pfn intersecting with the region
+ * memblock_region_memory_base_pfn - Return the lowest pfn intersecting with the memory region
  * @reg: memblock_region structure
  */
-static inline unsigned long memblock_region_base_pfn(const struct memblock_region *reg)
+static inline unsigned long memblock_region_memory_base_pfn(const struct memblock_region *reg)
 {
-	return reg->base >> PAGE_SHIFT;
+	return PFN_UP(reg->base);
 }
 
 /**
- * memblock_region_last_pfn - Return the highest pfn intersecting with the region
+ * memblock_region_memory_end_pfn - Return the end_pfn this region
  * @reg: memblock_region structure
  */
-static inline unsigned long memblock_region_last_pfn(const struct memblock_region *reg)
+static inline unsigned long memblock_region_memory_end_pfn(const struct memblock_region *reg)
 {
-	return (reg->base + reg->size - 1) >> PAGE_SHIFT;
+	return PFN_DOWN(reg->base + reg->size);
 }
 
 /**
- * memblock_region_end_pfn - Return the pfn of the first page following the region
- *                      but not intersecting it
+ * memblock_region_reserved_base_pfn - Return the lowest pfn intersecting with the reserved region
  * @reg: memblock_region structure
  */
-static inline unsigned long memblock_region_end_pfn(const struct memblock_region *reg)
+static inline unsigned long memblock_region_reserved_base_pfn(const struct memblock_region *reg)
 {
-	return memblock_region_last_pfn(reg) + 1;
+	return PFN_DOWN(reg->base);
 }
 
 /**
- * memblock_region_pages - Return the number of pages covering a region
+ * memblock_region_reserved_end_pfn - Return the end_pfn this region
  * @reg: memblock_region structure
  */
-static inline unsigned long memblock_region_pages(const struct memblock_region *reg)
+static inline unsigned long memblock_region_reserved_end_pfn(const struct memblock_region *reg)
 {
-	return memblock_region_end_pfn(reg) - memblock_region_end_pfn(reg);
+	return PFN_UP(reg->base + reg->size);
 }
 
 #define for_each_memblock(memblock_type, region)					\