microblaze: mm: Fix lowmem max memory size limits

Use CONFIG_LOWMEM_SIZE if system has larger ram size.
For system with larger ram size, enable HIGMEM support.

Also setup limitation for memblock and use memblock
allocation in lowmem region.
Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/include/asm/page.h

@@ -135,7 +135,6 @@ extern unsigned long min_low_pfn;
 extern unsigned long max_pfn;
 
 extern unsigned long memory_start;
-extern unsigned long memory_end;
 extern unsigned long memory_size;
 
 extern int page_is_ram(unsigned long pfn);

arch/microblaze/include/asm/pgtable.h

@@ -94,8 +94,7 @@ static inline pte_t pte_mkspecial(pte_t pte)	{ return pte; }
 /* Start and end of the vmalloc area. */
 /* Make sure to map the vmalloc area above the pinned kernel memory area
    of 32Mb.  */
-#define VMALLOC_START	(CONFIG_KERNEL_START + \
-				max(32 * 1024 * 1024UL, memory_size))
+#define VMALLOC_START	(CONFIG_KERNEL_START + CONFIG_LOWMEM_SIZE)
 #define VMALLOC_END	ioremap_bot
 
 #endif /* __ASSEMBLY__ */

arch/microblaze/include/asm/uaccess.h

@@ -80,7 +80,7 @@ extern unsigned long search_exception_table(unsigned long);
 static inline int ___range_ok(unsigned long addr, unsigned long size)
 {
 	return ((addr < memory_start) ||
-		((addr + size) > memory_end));
+		((addr + size - 1) > (memory_start + memory_size - 1)));
 }
 
 #define __range_ok(addr, size) \

arch/microblaze/mm/init.c

@@ -44,9 +44,9 @@ char *klimit = _end;
  */
 unsigned long memory_start;
 EXPORT_SYMBOL(memory_start);
-unsigned long memory_end; /* due to mm/nommu.c */
 unsigned long memory_size;
 EXPORT_SYMBOL(memory_size);
+unsigned long lowmem_size;
 
 /*
  * paging_init() sets up the page tables - in fact we've already done this.
@@ -58,7 +58,7 @@ static void __init paging_init(void)
 	/* Clean every zones */
 	memset(zones_size, 0, sizeof(zones_size));
 
-	zones_size[ZONE_DMA] = max_mapnr;
+	zones_size[ZONE_DMA] = max_pfn;
 
 	free_area_init(zones_size);
 }
@@ -74,32 +74,31 @@ void __init setup_memory(void)
 	/* Find main memory where is the kernel */
 	for_each_memblock(memory, reg) {
 		memory_start = (u32)reg->base;
-		memory_end = (u32) reg->base + reg->size;
+		lowmem_size = reg->size;
 		if ((memory_start <= (u32)_text) &&
-					((u32)_text <= memory_end)) {
-			memory_size = memory_end - memory_start;
+			((u32)_text <= (memory_start + lowmem_size - 1))) {
+			memory_size = lowmem_size;
 			PAGE_OFFSET = memory_start;
-			printk(KERN_INFO "%s: Main mem: 0x%x-0x%x, "
+			printk(KERN_INFO "%s: Main mem: 0x%x, "
 				"size 0x%08x\n", __func__, (u32) memory_start,
-					(u32) memory_end, (u32) memory_size);
+					(u32) memory_size);
 			break;
 		}
 	}
 
-	if (!memory_start || !memory_end) {
-		panic("%s: Missing memory setting 0x%08x-0x%08x\n",
-			__func__, (u32) memory_start, (u32) memory_end);
+	if (!memory_start || !memory_size) {
+		panic("%s: Missing memory setting 0x%08x, size=0x%08x\n",
+			__func__, (u32) memory_start, (u32) memory_size);
 	}
 
 	/* reservation of region where is the kernel */
 	kernel_align_start = PAGE_DOWN((u32)_text);
 	/* ALIGN can be remove because _end in vmlinux.lds.S is align */
 	kernel_align_size = PAGE_UP((u32)klimit) - kernel_align_start;
-	memblock_reserve(kernel_align_start, kernel_align_size);
-	printk(KERN_INFO "%s: kernel addr=0x%08x-0x%08x size=0x%08x\n",
+	printk(KERN_INFO "%s: kernel addr:0x%08x-0x%08x size=0x%08x\n",
 		__func__, kernel_align_start, kernel_align_start
 			+ kernel_align_size, kernel_align_size);
-
+	memblock_reserve(kernel_align_start, kernel_align_size);
 #endif
 	/*
 	 * Kernel:
@@ -116,11 +115,13 @@ void __init setup_memory(void)
 	min_low_pfn = memory_start >> PAGE_SHIFT; /* minimum for allocation */
 	/* RAM is assumed contiguous */
 	num_physpages = max_mapnr = memory_size >> PAGE_SHIFT;
-	max_pfn = max_low_pfn = memory_end >> PAGE_SHIFT;
+	max_low_pfn = ((u64)memory_start + (u64)lowmem_size) >> PAGE_SHIFT;
+	max_pfn = ((u64)memory_start + (u64)memory_size) >> PAGE_SHIFT;
 
 	printk(KERN_INFO "%s: max_mapnr: %#lx\n", __func__, max_mapnr);
 	printk(KERN_INFO "%s: min_low_pfn: %#lx\n", __func__, min_low_pfn);
 	printk(KERN_INFO "%s: max_low_pfn: %#lx\n", __func__, max_low_pfn);
+	printk(KERN_INFO "%s: max_pfn: %#lx\n", __func__, max_pfn);
 
 	/*
 	 * Find an area to use for the bootmem bitmap.
@@ -134,14 +135,25 @@ void __init setup_memory(void)
 	memblock_reserve(PFN_UP(TOPHYS((u32)klimit)) << PAGE_SHIFT, map_size);
 
 	/* free bootmem is whole main memory */
-	free_bootmem(memory_start, memory_size);
+	free_bootmem(memory_start, lowmem_size);
 
 	/* reserve allocate blocks */
 	for_each_memblock(reserved, reg) {
-		pr_debug("reserved - 0x%08x-0x%08x\n",
-			 (u32) reg->base, (u32) reg->size);
-		reserve_bootmem(reg->base, reg->size, BOOTMEM_DEFAULT);
+		unsigned long top = reg->base + reg->size - 1;
+
+		pr_debug("reserved - 0x%08x-0x%08x, %lx, %lx\n",
+			 (u32) reg->base, (u32) reg->size, top,
+						memory_start + lowmem_size - 1);
+
+		if (top <= (memory_start + lowmem_size - 1)) {
+			reserve_bootmem(reg->base, reg->size, BOOTMEM_DEFAULT);
+		} else if (reg->base < (memory_start + lowmem_size - 1)) {
+			unsigned long trunc_size = memory_start + lowmem_size -
+								reg->base;
+			reserve_bootmem(reg->base, trunc_size, BOOTMEM_DEFAULT);
+		}
 	}
+
 #ifdef CONFIG_MMU
 	init_bootmem_done = 1;
 #endif
@@ -186,7 +198,8 @@ void free_initmem(void)
 
 void __init mem_init(void)
 {
-	high_memory = (void *)__va(memory_end);
+	high_memory = (void *)__va(memory_start + lowmem_size - 1);
+
 	/* this will put all memory onto the freelists */
 	totalram_pages += free_all_bootmem();
 
@@ -222,7 +235,6 @@ static void mm_cmdline_setup(void)
 		maxmem = memparse(p, &p);
 		if (maxmem && memory_size > maxmem) {
 			memory_size = maxmem;
-			memory_end = memory_start + memory_size;
 			memblock.memory.regions[0].size = memory_size;
 		}
 	}
@@ -272,9 +284,12 @@ asmlinkage void __init mmu_init(void)
 	}
 	/* Find main memory where the kernel is */
 	memory_start = (u32) memblock.memory.regions[0].base;
-	memory_end = (u32) memblock.memory.regions[0].base +
-				(u32) memblock.memory.regions[0].size;
-	memory_size = memory_end - memory_start;
+	lowmem_size = memory_size = (u32) memblock.memory.regions[0].size;
+
+	if (lowmem_size > CONFIG_LOWMEM_SIZE) {
+		lowmem_size = CONFIG_LOWMEM_SIZE;
+		memory_size = lowmem_size;
+	}
 
 	mm_cmdline_setup(); /* FIXME parse args from command line - not used */
 
@@ -307,9 +322,13 @@ asmlinkage void __init mmu_init(void)
 	ioremap_base = 0xfe000000UL;	/* for now, could be 0xfffff000 */
 #endif /* CONFIG_HIGHMEM_START_BOOL */
 	ioremap_bot = ioremap_base;
-
 	/* Initialize the context management stuff */
 	mmu_context_init();
+
+	/* Shortly after that, the entire linear mapping will be available */
+	/* This will also cause that unflatten device tree will be allocated
+	 * inside 768MB limit */
+	memblock_set_current_limit(memory_start + lowmem_size - 1);
 }
 
 /* This is only called until mem_init is done. */

arch/microblaze/mm/pgtable.c

@@ -44,11 +44,6 @@ unsigned long ioremap_base;
 unsigned long ioremap_bot;
 EXPORT_SYMBOL(ioremap_bot);
 
-/* The maximum lowmem defaults to 768Mb, but this can be configured to
- * another value.
- */
-#define MAX_LOW_MEM	CONFIG_LOWMEM_SIZE
-
 #ifndef CONFIG_SMP
 struct pgtable_cache_struct quicklists;
 #endif
@@ -171,7 +166,7 @@ void __init mapin_ram(void)
 
 	v = CONFIG_KERNEL_START;
 	p = memory_start;
-	for (s = 0; s < memory_size; s += PAGE_SIZE) {
+	for (s = 0; s < CONFIG_LOWMEM_SIZE; s += PAGE_SIZE) {
 		f = _PAGE_PRESENT | _PAGE_ACCESSED |
 				_PAGE_SHARED | _PAGE_HWEXEC;
 		if ((char *) v < _stext || (char *) v >= _etext)