x86/mm: Use early_param_on_off() for direct_gbpages

The enabler / disabler is pretty simple, just use the
provided wrappers, this lets us easily relate the variable
to the associated Kconfig entry.

Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: JBeulich@suse.com
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: julia.lawall@lip6.fr
Link: http://lkml.kernel.org/r/1425518654-3403-5-git-send-email-mcgrof@do-not-panic.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/mm/init.c

@@ -133,7 +133,8 @@ int after_bootmem;
 
 static int page_size_mask;
 
-int direct_gbpages = IS_ENABLED(CONFIG_DIRECT_GBPAGES);
+early_param_on_off("gbpages", "nogbpages",
+		   direct_gbpages, CONFIG_DIRECT_GBPAGES);
 
 static void __init init_gbpages(void)
 {

arch/x86/mm/init_64.c

@@ -130,20 +130,6 @@ int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
 	return 0;
 }
 
-static int __init parse_direct_gbpages_off(char *arg)
-{
-	direct_gbpages = 0;
-	return 0;
-}
-early_param("nogbpages", parse_direct_gbpages_off);
-
-static int __init parse_direct_gbpages_on(char *arg)
-{
-	direct_gbpages = 1;
-	return 0;
-}
-early_param("gbpages", parse_direct_gbpages_on);
-
 /*
  * NOTE: pagetable_init alloc all the fixmap pagetables contiguous on the
  * physical space so we can cache the place of the first one and move