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 <ard.biesheuvel@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bhe@redhat.com
Cc: bhsharma@redhat.com
Cc: bp@alien8.de
Cc: eugene@hp.com
Cc: evgeny.kalugin@intel.com
Cc: jhugo@codeaurora.org
Cc: leif.lindholm@linaro.org
Cc: linux-efi@vger.kernel.org
Cc: roy.franz@cavium.com
Cc: rruigrok@codeaurora.org
Link: http://lkml.kernel.org/r/20170404160910.28115-2-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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

@@ -116,8 +116,6 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 	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;
@@ -151,6 +149,16 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 		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,
@@ -162,14 +170,6 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 		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

@@ -9,6 +9,8 @@
 #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

@@ -33,11 +33,16 @@
 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
 
@@ -424,6 +429,10 @@ efi_status_t efi_parse_options(char const *cmdline)
 	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
 	 * nothing to do.

drivers/firmware/efi/libstub/efistub.h

@@ -25,6 +25,13 @@
 #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

@@ -12,6 +12,8 @@
 #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

@@ -1435,9 +1435,6 @@ static inline int efi_runtime_map_copy(void *buf, size_t bufsz)
 
 /* 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,