From: Ard Biesheuvel <ardb+git@google.com>
To: linux-efi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
Vincent Mailhol <mailhol@kernel.org>,
x86@kernel.org
Subject: [PATCH v2 06/10] efi/libstub: Avoid efi_puts() for compile time constant strings
Date: Wed, 9 Sep 2026 13:55:37 +0200 [thread overview]
Message-ID: <20260909115530.1924665-18-ardb+git@google.com> (raw)
In-Reply-To: <20260909115530.1924665-12-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.
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;
}
--
2.55.0.1003.g10538fe699-goog
next prev parent reply other threads:[~2026-09-09 11:56 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-09 11:55 [PATCH v2 00/10] efi/libstub: Avoid UTF-16 conversion busywork Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 01/10] x86/boot: Drop pointless re-implementation of panic() Ard Biesheuvel
2026-09-09 19:14 ` Borislav Petkov
2026-09-09 20:43 ` Ard Biesheuvel
2026-09-10 13:12 ` Kiryl Shutsemau
2026-09-11 7:32 ` Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 02/10] lib/ucs2_string: Drop arbitrary input size limit and associated WARN() Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 03/10] lib/ucs2_string: Suppress modinfo when __DISABLE_EXPORTS is set Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 04/10] lib/ucs2_string: Split out ucs2_as_utf8_l() taking a separate limit Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 05/10] efi/libstub: Use ucs2_string library for UTF-16 to UTF-8 conversion Ard Biesheuvel
2026-09-09 11:55 ` Ard Biesheuvel [this message]
2026-09-09 11:55 ` [PATCH v2 07/10] efi/libstub: Output UTF-16 directly from vsnprintf() Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 08/10] efi/libstub: Add support for printing human readable GUIDs Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 09/10] efi/libstub: Add efi_snprintf() to construct wide strings Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 10/10] efi/libstub: add initial Boot Loader Interface support Ard Biesheuvel
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