ARC: Make vmalloc size configurable

On ARC, lower 2G of address space is translated and used for
 - user vaddr space (region 0 to 5)
 - unused kernel-user gutter (region 6)
 - kernel vaddr space (region 7)

where each region simply represents 256MB of address space.

The kernel vaddr space of 256MB is used to implement vmalloc, modules
So far this was enough, but not on EZChip system with 4K CPUs (given
that per cpu mechanism uses vmalloc for allocating chunks)

So allow VMALLOC_SIZE to be configurable by expanding down into the unused
kernel-user gutter region which at default 256M was excessive anyways.

Also use _BITUL() to fix a build error since PGDIR_SIZE cannot use "1UL"
as called from assembly code in mm/tlbex.S

Signed-off-by: Noam Camus <noamc@ezchip.com>
[vgupta: rewrote changelog, debugged bootup crash due to int vs. hex]
Acked-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h
index 1d694c1..d0a9211 100644
--- a/arch/arc/include/asm/processor.h
+++ b/arch/arc/include/asm/processor.h
@@ -97,7 +97,7 @@
 #endif /* !__ASSEMBLY__ */
 
 /*
- * System Memory Map on ARC
+ * Default System Memory Map on ARC
  *
  * ---------------------------- (lower 2G, Translated) -------------------------
  * 0x0000_0000		0x5FFF_FFFF	(user vaddr: TASK_SIZE)
@@ -109,18 +109,17 @@
  * 0xC000_0000		0xFFFF_FFFF	(peripheral uncached space)
  * -----------------------------------------------------------------------------
  */
-#define VMALLOC_START	0x70000000
 
-/*
- * 1 PGDIR_SIZE each for fixmap/pkmap, 2 PGDIR_SIZE gutter
- * See asm/highmem.h for details
- */
-#define VMALLOC_SIZE	(PAGE_OFFSET - VMALLOC_START - PGDIR_SIZE * 4)
+#define TASK_SIZE	0x60000000
+
+#define VMALLOC_START	(PAGE_OFFSET - (CONFIG_ARC_KVADDR_SIZE << 20))
+
+/* 1 PGDIR_SIZE each for fixmap/pkmap, 2 PGDIR_SIZE gutter (see asm/highmem.h) */
+#define VMALLOC_SIZE	((CONFIG_ARC_KVADDR_SIZE << 20) - PGDIR_SIZE * 4)
+
 #define VMALLOC_END	(VMALLOC_START + VMALLOC_SIZE)
 
-#define USER_KERNEL_GUTTER    0x10000000
-
-#define TASK_SIZE	(VMALLOC_START - USER_KERNEL_GUTTER)
+#define USER_KERNEL_GUTTER    (VMALLOC_START - TASK_SIZE)
 
 #define STACK_TOP       TASK_SIZE
 #define STACK_TOP_MAX   STACK_TOP