x86/efi: Add a "debug" option to the efi= cmdline

... and hide the memory regions dump behind it. Make it default-off.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/20141209095843.GA3990@pd.tnic
Acked-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

Documentation/kernel-parameters.txt

@@ -1036,14 +1036,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Format: {"off" | "on" | "skip[mbr]"}
 
 	efi=		[EFI]
-			Format: { "old_map", "nochunk", "noruntime" }
+			Format: { "old_map", "nochunk", "noruntime", "debug" }
 			old_map [X86-64]: switch to the old ioremap-based EFI
 			runtime services mapping. 32-bit still uses this one by
 			default.
 			nochunk: disable reading files in "chunks" in the EFI
 			boot stub, as chunking can cause problems with some
 			firmware implementations.
 			noruntime : disable EFI runtime services support
+			debug: enable misc debug output
 
 	efi_no_storage_paranoia [EFI; X86]
 			Using this parameter you can use more than 50% of

arch/x86/platform/efi/efi.c

@@ -491,7 +491,8 @@ void __init efi_init(void)
 	if (efi_memmap_init())
 		return;
 
-	print_efi_memmap();
+	if (efi_enabled(EFI_DBG))
+		print_efi_memmap();
 }
 
 void __init efi_late_init(void)
@@ -939,6 +940,8 @@ static int __init arch_parse_efi_cmdline(char *str)
 {
 	if (parse_option_str(str, "old_map"))
 		set_bit(EFI_OLD_MEMMAP, &efi.flags);
+	if (parse_option_str(str, "debug"))
+		set_bit(EFI_DBG, &efi.flags);
 
 	return 0;
 }

include/linux/efi.h

@@ -942,6 +942,7 @@ extern int __init efi_setup_pcdp_console(char *);
 #define EFI_64BIT		5	/* Is the firmware 64-bit? */
 #define EFI_PARAVIRT		6	/* Access is via a paravirt interface */
 #define EFI_ARCH_1		7	/* First arch-specific bit */
+#define EFI_DBG			8	/* Print additional debug info at runtime */
 
 #ifdef CONFIG_EFI
 /*