x86: make TASK_SIZE_MAX usable from assembly code

For 64-bit the only thing missing was a strategic _AC, and for 32-bit we
need to use __PAGE_OFFSET instead of PAGE_OFFSET in the TASK_SIZE
definition to escape the explicit unsigned long cast.  This just works
because __PAGE_OFFSET is defined using _AC itself and thus never needs
the cast anyway.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Author: Christoph Hellwig

arch/x86/include/asm/page_32_types.h

@@ -44,8 +44,8 @@
 /*
  * User space process size: 3GB (default).
  */
-#define IA32_PAGE_OFFSET	PAGE_OFFSET
-#define TASK_SIZE		PAGE_OFFSET
+#define IA32_PAGE_OFFSET	__PAGE_OFFSET
+#define TASK_SIZE		__PAGE_OFFSET
 #define TASK_SIZE_LOW		TASK_SIZE
 #define TASK_SIZE_MAX		TASK_SIZE
 #define DEFAULT_MAP_WINDOW	TASK_SIZE

arch/x86/include/asm/page_64_types.h

@@ -76,7 +76,7 @@
  *
  * With page table isolation enabled, we map the LDT in ... [stay tuned]
  */
-#define TASK_SIZE_MAX	((1UL << __VIRTUAL_MASK_SHIFT) - PAGE_SIZE)
+#define TASK_SIZE_MAX	((_AC(1,UL) << __VIRTUAL_MASK_SHIFT) - PAGE_SIZE)
 
 #define DEFAULT_MAP_WINDOW	((1UL << 47) - PAGE_SIZE)