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efi: libstub: Enable efi_printk() in zboot decompressor
Split the efi_printk() routine into its own source file, and provide local implementations of strlen() and strnlen() so that the standalone zboot app can efi_err and efi_info etc. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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Ard Biesheuvel
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Nov 9, 2022
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,154 @@ | ||
| // SPDX-License-Identifier: GPL-2.0 | ||
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| #include <linux/stdarg.h> | ||
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| #include <linux/ctype.h> | ||
| #include <linux/efi.h> | ||
| #include <linux/kernel.h> | ||
| #include <linux/printk.h> /* For CONSOLE_LOGLEVEL_* */ | ||
| #include <asm/efi.h> | ||
| #include <asm/setup.h> | ||
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| #include "efistub.h" | ||
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| int efi_loglevel = CONSOLE_LOGLEVEL_DEFAULT; | ||
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| /** | ||
| * efi_char16_puts() - Write a UCS-2 encoded string to the console | ||
| * @str: UCS-2 encoded string | ||
| */ | ||
| void efi_char16_puts(efi_char16_t *str) | ||
| { | ||
| efi_call_proto(efi_table_attr(efi_system_table, con_out), | ||
| output_string, str); | ||
| } | ||
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| static | ||
| u32 utf8_to_utf32(const u8 **s8) | ||
| { | ||
| u32 c32; | ||
| u8 c0, cx; | ||
| size_t clen, i; | ||
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| c0 = cx = *(*s8)++; | ||
| /* | ||
| * The position of the most-significant 0 bit gives us the length of | ||
| * a multi-octet encoding. | ||
| */ | ||
| for (clen = 0; cx & 0x80; ++clen) | ||
| cx <<= 1; | ||
| /* | ||
| * If the 0 bit is in position 8, this is a valid single-octet | ||
| * encoding. If the 0 bit is in position 7 or positions 1-3, the | ||
| * encoding is invalid. | ||
| * In either case, we just return the first octet. | ||
| */ | ||
| if (clen < 2 || clen > 4) | ||
| return c0; | ||
| /* Get the bits from the first octet. */ | ||
| c32 = cx >> clen--; | ||
| for (i = 0; i < clen; ++i) { | ||
| /* Trailing octets must have 10 in most significant bits. */ | ||
| cx = (*s8)[i] ^ 0x80; | ||
| if (cx & 0xc0) | ||
| return c0; | ||
| c32 = (c32 << 6) | cx; | ||
| } | ||
| /* | ||
| * Check for validity: | ||
| * - The character must be in the Unicode range. | ||
| * - It must not be a surrogate. | ||
| * - It must be encoded using the correct number of octets. | ||
| */ | ||
| if (c32 > 0x10ffff || | ||
| (c32 & 0xf800) == 0xd800 || | ||
| clen != (c32 >= 0x80) + (c32 >= 0x800) + (c32 >= 0x10000)) | ||
| return c0; | ||
| *s8 += clen; | ||
| return c32; | ||
| } | ||
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| /** | ||
| * efi_puts() - Write a UTF-8 encoded string to the console | ||
| * @str: UTF-8 encoded string | ||
| */ | ||
| void efi_puts(const char *str) | ||
| { | ||
| efi_char16_t buf[128]; | ||
| size_t pos = 0, lim = ARRAY_SIZE(buf); | ||
| const u8 *s8 = (const u8 *)str; | ||
| u32 c32; | ||
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| while (*s8) { | ||
| if (*s8 == '\n') | ||
| buf[pos++] = L'\r'; | ||
| c32 = utf8_to_utf32(&s8); | ||
| if (c32 < 0x10000) { | ||
| /* Characters in plane 0 use a single word. */ | ||
| buf[pos++] = c32; | ||
| } else { | ||
| /* | ||
| * Characters in other planes encode into a surrogate | ||
| * pair. | ||
| */ | ||
| buf[pos++] = (0xd800 - (0x10000 >> 10)) + (c32 >> 10); | ||
| buf[pos++] = 0xdc00 + (c32 & 0x3ff); | ||
| } | ||
| if (*s8 == '\0' || pos >= lim - 2) { | ||
| buf[pos] = L'\0'; | ||
| efi_char16_puts(buf); | ||
| pos = 0; | ||
| } | ||
| } | ||
| } | ||
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| /** | ||
| * efi_printk() - Print a kernel message | ||
| * @fmt: format string | ||
| * | ||
| * The first letter of the format string is used to determine the logging level | ||
| * of the message. If the level is less then the current EFI logging level, the | ||
| * message is suppressed. The message will be truncated to 255 bytes. | ||
| * | ||
| * Return: number of printed characters | ||
| */ | ||
| int efi_printk(const char *fmt, ...) | ||
| { | ||
| char printf_buf[256]; | ||
| va_list args; | ||
| int printed; | ||
| int loglevel = printk_get_level(fmt); | ||
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| switch (loglevel) { | ||
| case '0' ... '9': | ||
| loglevel -= '0'; | ||
| break; | ||
| default: | ||
| /* | ||
| * Use loglevel -1 for cases where we just want to print to | ||
| * the screen. | ||
| */ | ||
| loglevel = -1; | ||
| break; | ||
| } | ||
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| if (loglevel >= efi_loglevel) | ||
| return 0; | ||
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| if (loglevel >= 0) | ||
| efi_puts("EFI stub: "); | ||
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| fmt = printk_skip_level(fmt); | ||
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| va_start(args, fmt); | ||
| printed = vsnprintf(printf_buf, sizeof(printf_buf), fmt, args); | ||
| va_end(args); | ||
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| efi_puts(printf_buf); | ||
| if (printed >= sizeof(printf_buf)) { | ||
| efi_puts("[Message truncated]\n"); | ||
| return -1; | ||
| } | ||
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| return printed; | ||
| } |
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