[POWERPC] Introduce lowmem_end_addr to distinguish from total_lowmem

total_lowmem represents the amount of low memory, not the physical
address that low memory ends at.  If the start of memory is at 0 it
happens that total_lowmem can be used as both the size and the address
that lowmem ends at (or more specifically one byte beyond the end).

To make the code a bit more clear and deal with the case when the start of
memory isn't at physical 0, we introduce lowmem_end_addr that represents
one byte beyond the last physical address in the lowmem region.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/mm/44x_mmu.c

@@ -67,7 +67,7 @@ unsigned long __init mmu_mapin_ram(void)
 
 	/* Pin in enough TLBs to cover any lowmem not covered by the
 	 * initial 256M mapping established in head_44x.S */
-	for (addr = PPC_PIN_SIZE; addr < total_lowmem;
+	for (addr = PPC_PIN_SIZE; addr < lowmem_end_addr;
 	     addr += PPC_PIN_SIZE)
 		ppc44x_pin_tlb(addr + PAGE_OFFSET, addr);
 

arch/powerpc/mm/init_32.c

@@ -146,6 +146,7 @@ void __init MMU_init(void)
 	}
 
 	total_lowmem = total_memory = lmb_end_of_DRAM() - memstart_addr;
+	lowmem_end_addr = memstart_addr + total_lowmem;
 
 #ifdef CONFIG_FSL_BOOKE
 	/* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
@@ -156,9 +157,10 @@ void __init MMU_init(void)
 
 	if (total_lowmem > __max_low_memory) {
 		total_lowmem = __max_low_memory;
+		lowmem_end_addr = memstart_addr + total_lowmem;
 #ifndef CONFIG_HIGHMEM
 		total_memory = total_lowmem;
-		lmb_enforce_memory_limit(total_lowmem);
+		lmb_enforce_memory_limit(lowmem_end_addr);
 		lmb_analyze();
 #endif /* CONFIG_HIGHMEM */
 	}

arch/powerpc/mm/init_64.c

@@ -75,6 +75,8 @@
 /* max amount of RAM to use */
 unsigned long __max_memory;
 
+phys_addr_t memstart_addr;
+
 void free_initmem(void)
 {
 	unsigned long addr;

arch/powerpc/mm/mem.c

@@ -216,9 +216,11 @@ void __init do_init_bootmem(void)
 	unsigned long total_pages;
 	int boot_mapsize;
 
-	max_pfn = total_pages = lmb_end_of_DRAM() >> PAGE_SHIFT;
+	max_pfn = lmb_end_of_DRAM() >> PAGE_SHIFT;
+	total_pages = (lmb_end_of_DRAM() - memstart_addr) >> PAGE_SHIFT;
 #ifdef CONFIG_HIGHMEM
 	total_pages = total_lowmem >> PAGE_SHIFT;
+	max_low_pfn = lowmem_end_addr >> PAGE_SHIFT;
 #endif
 
 	/*
@@ -244,18 +246,18 @@ void __init do_init_bootmem(void)
 	 * present.
 	 */
 #ifdef CONFIG_HIGHMEM
-	free_bootmem_with_active_regions(0, total_lowmem >> PAGE_SHIFT);
+	free_bootmem_with_active_regions(0, lowmem_end_addr >> PAGE_SHIFT);
 
 	/* reserve the sections we're already using */
 	for (i = 0; i < lmb.reserved.cnt; i++) {
 		unsigned long addr = lmb.reserved.region[i].base +
 				     lmb_size_bytes(&lmb.reserved, i) - 1;
-		if (addr < total_lowmem)
+		if (addr < lowmem_end_addr)
 			reserve_bootmem(lmb.reserved.region[i].base,
 					lmb_size_bytes(&lmb.reserved, i),
 					BOOTMEM_DEFAULT);
-		else if (lmb.reserved.region[i].base < total_lowmem) {
-			unsigned long adjusted_size = total_lowmem -
+		else if (lmb.reserved.region[i].base < lowmem_end_addr) {
+			unsigned long adjusted_size = lowmem_end_addr -
 				      lmb.reserved.region[i].base;
 			reserve_bootmem(lmb.reserved.region[i].base,
 					adjusted_size, BOOTMEM_DEFAULT);
@@ -325,7 +327,7 @@ void __init paging_init(void)
 	       (top_of_ram - total_ram) >> 20);
 	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
 #ifdef CONFIG_HIGHMEM
-	max_zone_pfns[ZONE_DMA] = total_lowmem >> PAGE_SHIFT;
+	max_zone_pfns[ZONE_DMA] = lowmem_end_addr >> PAGE_SHIFT;
 	max_zone_pfns[ZONE_HIGHMEM] = top_of_ram >> PAGE_SHIFT;
 #else
 	max_zone_pfns[ZONE_DMA] = top_of_ram >> PAGE_SHIFT;
@@ -380,7 +382,7 @@ void __init mem_init(void)
 	{
 		unsigned long pfn, highmem_mapnr;
 
-		highmem_mapnr = total_lowmem >> PAGE_SHIFT;
+		highmem_mapnr = lowmem_end_addr >> PAGE_SHIFT;
 		for (pfn = highmem_mapnr; pfn < max_mapnr; ++pfn) {
 			struct page *page = pfn_to_page(pfn);
 			if (lmb_is_reserved(pfn << PAGE_SHIFT))

arch/powerpc/mm/mmu_decl.h

@@ -52,6 +52,7 @@ extern unsigned long __initial_memory_limit;
 extern unsigned long total_memory;
 extern unsigned long total_lowmem;
 extern phys_addr_t memstart_addr;
+extern phys_addr_t lowmem_end_addr;
 
 /* ...and now those things that may be slightly different between processor
  * architectures.  -- Dan