From fd0528a24958b7e8d55669cf50749776308d4c5a Mon Sep 17 00:00:00 2001 From: Arvind Sankar Date: Mon, 18 May 2020 15:06:55 -0400 Subject: [PATCH] efi/libstub: Buffer output of efi_puts Use a buffer to convert the string to UTF-16. This will reduce the number of firmware calls required to print the string from one per character to one per string in most cases. Cast the input char to unsigned char before converting to efi_char16_t to avoid sign-extension in case there are any non-ASCII characters in the input. Signed-off-by: Arvind Sankar Link: https://lore.kernel.org/r/20200518190716.751506-4-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel --- .../firmware/efi/libstub/efi-stub-helper.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index c6d7ef35e9f7..3cf506ab9ead 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -8,6 +8,7 @@ */ #include +#include #include #include "efistub.h" @@ -34,13 +35,19 @@ void efi_char16_puts(efi_char16_t *str) void efi_puts(const char *str) { - while (*str) { - efi_char16_t ch[] = { *str++, L'\0' }; + efi_char16_t buf[128]; + size_t pos = 0, lim = ARRAY_SIZE(buf); - if (ch[0] == L'\n') - efi_char16_puts(L"\r\n"); - else - efi_char16_puts(ch); + while (*str) { + if (*str == '\n') + buf[pos++] = L'\r'; + /* Cast to unsigned char to avoid sign-extension */ + buf[pos++] = (unsigned char)(*str++); + if (*str == '\0' || pos >= lim - 2) { + buf[pos] = L'\0'; + efi_char16_puts(buf); + pos = 0; + } } } -- 2.39.2