[PATCH v3 5/9] efi/libstub: Avoid efi_puts() for compile time constant strings

[Ard Biesheuvel <ardb+git@google.com>]

From: Ard Biesheuvel <ardb@kernel.org>

efi_puts() performs a UTF-8 to UTF-16 conversion on its input, as the
EFI console's native character set is UTF-16.

This is pointless for compile time constant strings, since we can
simply define those as UTF-16 to begin with. This takes slightly more
space, but removes any runtime handling of those strings, simplifying
the code.

Note that efi_puts() also performs LF to CR-LF conversion, so this needs
to be taken into account as well.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 drivers/firmware/efi/libstub/gop.c    | 6 +++---
 drivers/firmware/efi/libstub/printk.c | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/efi/libstub/gop.c b/drivers/firmware/efi/libstub/gop.c
index 80dc8cfeb33e..6919e28ba92b 100644
--- a/drivers/firmware/efi/libstub/gop.c
+++ b/drivers/firmware/efi/libstub/gop.c
@@ -309,12 +309,12 @@ static u32 choose_mode_list(efi_graphics_output_protocol_t *gop)
 	efi_status_t status;
 
 	efi_printk("Available graphics modes are 0-%u\n", max_mode-1);
-	efi_puts("  * = current mode\n"
-		 "  - = unusable mode\n");
+	efi_char16_puts(L"  * = current mode\r\n"
+			 "  - = unusable mode\r\n");
 
 	choose_mode(gop, match_list, (void *)cur_mode);
 
-	efi_puts("\nPress any key to continue (or wait 10 seconds)\n");
+	efi_char16_puts(L"\r\nPress any key to continue (or wait 10 seconds)\r\n");
 	status = efi_wait_for_key(10 * EFI_USEC_PER_SEC, &key);
 	if (status != EFI_SUCCESS && status != EFI_TIMEOUT) {
 		efi_err("Unable to read key, continuing in 10 seconds\n");
diff --git a/drivers/firmware/efi/libstub/printk.c b/drivers/firmware/efi/libstub/printk.c
index bc599212c05d..f36639886d00 100644
--- a/drivers/firmware/efi/libstub/printk.c
+++ b/drivers/firmware/efi/libstub/printk.c
@@ -136,7 +136,7 @@ int efi_printk(const char *fmt, ...)
 		return 0;
 
 	if (loglevel >= 0)
-		efi_puts("EFI stub: ");
+		efi_char16_puts(L"EFI stub: ");
 
 	fmt = printk_skip_level(fmt);
 
@@ -146,7 +146,7 @@ int efi_printk(const char *fmt, ...)
 
 	efi_puts(printf_buf);
 	if (printed >= sizeof(printf_buf)) {
-		efi_puts("[Message truncated]\n");
+		efi_char16_puts(L"[Message truncated]\r\n");
 		return -1;
 	}
 
-- 
2.55.0.1032.g73a4cd73de-goog