efi/libstub/arm/arm64: Disable debug prints on 'quiet' cmdline arg

The EFI stub currently prints a number of diagnostic messages that do
not carry a lot of information. Since these prints are not controlled
by 'loglevel' or other command line parameters, and since they appear on
the EFI framebuffer as well (if enabled), it would be nice if we could
turn them off.

So let's add support for the 'quiet' command line parameter in the stub,
and disable the non-error prints if it is passed.

Signed-off-by: Ard Biesheuvel <[e-mail]>
Acked-by: Mark Rutland <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Matt Fleming <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

drivers/firmware/efi/libstub/arm-stub.c

···
 	if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
 		goto fail;
 
-	pr_efi(sys_table, "Booting Linux Kernel...\n");
-
 	status = check_platform_features(sys_table);
 	if (status != EFI_SUCCESS)
 		goto fail;
···
 		goto fail;
 	}
 
+	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
+	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
+	    cmdline_size == 0)
+		efi_parse_options(CONFIG_CMDLINE);
+
+	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0)
+		efi_parse_options(cmdline_ptr);
+
+	pr_efi(sys_table, "Booting Linux Kernel...\n");
+
 	si = setup_graphics(sys_table);
 
 	status = handle_kernel_image(sys_table, image_addr, &image_size,
···
 		pr_efi_err(sys_table, "Failed to relocate kernel\n");
 		goto fail_free_cmdline;
 	}
-
-	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
-	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
-	    cmdline_size == 0)
-		efi_parse_options(CONFIG_CMDLINE);
-
-	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0)
-		efi_parse_options(cmdline_ptr);
 
 	secure_boot = efi_get_secureboot(sys_table);
 

drivers/firmware/efi/libstub/arm32-stub.c

···
 #include <linux/efi.h>
 #include <asm/efi.h>
 
+#include "efistub.h"
+
 efi_status_t check_platform_features(efi_system_table_t *sys_table_arg)
 {
 	int block;

drivers/firmware/efi/libstub/efi-stub-helper.c

···
 static unsigned long __chunk_size = EFI_READ_CHUNK_SIZE;
 
 static int __section(.data) __nokaslr;
+static int __section(.data) __quiet;
 
 int __pure nokaslr(void)
 {
 	return __nokaslr;
+}
+int __pure is_quiet(void)
+{
+	return __quiet;
 }
 
 #define EFI_MMAP_NR_SLACK_SLOTS	8
···
 	str = strstr(cmdline, "nokaslr");
 	if (str == cmdline || (str && str > cmdline && *(str - 1) == ' '))
 		__nokaslr = 1;
+
+	str = strstr(cmdline, "quiet");
+	if (str == cmdline || (str && str > cmdline && *(str - 1) == ' '))
+		__quiet = 1;
 
 	/*
 	 * If no EFI parameters were specified on the cmdline we've got

drivers/firmware/efi/libstub/efistub.h

···
 #endif
 
 extern int __pure nokaslr(void);
+extern int __pure is_quiet(void);
+
+#define pr_efi(sys_table, msg)		do {				\
+	if (!is_quiet()) efi_printk(sys_table, "EFI stub: "msg);	\
+} while (0)
+
+#define pr_efi_err(sys_table, msg) efi_printk(sys_table, "EFI stub: ERROR: "msg)
 
 void efi_char16_printk(efi_system_table_t *, efi_char16_t *);
 

drivers/firmware/efi/libstub/secureboot.c

···
 #include <linux/efi.h>
 #include <asm/efi.h>
 
+#include "efistub.h"
+
 /* BIOS variables */
 static const efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID;
 static const efi_char16_t const efi_SecureBoot_name[] = {

include/linux/efi.h

···
 
 /* prototypes shared between arch specific and generic stub code */
 
-#define pr_efi(sys_table, msg)     efi_printk(sys_table, "EFI stub: "msg)
-#define pr_efi_err(sys_table, msg) efi_printk(sys_table, "EFI stub: ERROR: "msg)
-
 void efi_printk(efi_system_table_t *sys_table_arg, char *str);
 
 void efi_free(efi_system_table_t *sys_table_arg, unsigned long size,