1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/stdarg.h>
4
5 #include <linux/ctype.h>
6 #include <linux/efi.h>
7 #include <linux/kernel.h>
8 #include <linux/printk.h> /* For CONSOLE_LOGLEVEL_* */
9 #include <asm/efi.h>
10 #include <asm/setup.h>
11
12 #include "efistub.h"
13
14 int efi_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
15
16 /**
17 * efi_char16_puts() - Write a UCS-2 encoded string to the console
18 * @str: UCS-2 encoded string
19 */
efi_char16_puts(efi_char16_t * str)20 void efi_char16_puts(efi_char16_t *str)
21 {
22 efi_call_proto(efi_table_attr(efi_system_table, con_out),
23 output_string, str);
24 }
25
26 static
utf8_to_utf32(const u8 ** s8)27 u32 utf8_to_utf32(const u8 **s8)
28 {
29 u32 c32;
30 u8 c0, cx;
31 size_t clen, i;
32
33 c0 = cx = *(*s8)++;
34 /*
35 * The position of the most-significant 0 bit gives us the length of
36 * a multi-octet encoding.
37 */
38 for (clen = 0; cx & 0x80; ++clen)
39 cx <<= 1;
40 /*
41 * If the 0 bit is in position 8, this is a valid single-octet
42 * encoding. If the 0 bit is in position 7 or positions 1-3, the
43 * encoding is invalid.
44 * In either case, we just return the first octet.
45 */
46 if (clen < 2 || clen > 4)
47 return c0;
48 /* Get the bits from the first octet. */
49 c32 = cx >> clen--;
50 for (i = 0; i < clen; ++i) {
51 /* Trailing octets must have 10 in most significant bits. */
52 cx = (*s8)[i] ^ 0x80;
53 if (cx & 0xc0)
54 return c0;
55 c32 = (c32 << 6) | cx;
56 }
57 /*
58 * Check for validity:
59 * - The character must be in the Unicode range.
60 * - It must not be a surrogate.
61 * - It must be encoded using the correct number of octets.
62 */
63 if (c32 > 0x10ffff ||
64 (c32 & 0xf800) == 0xd800 ||
65 clen != (c32 >= 0x80) + (c32 >= 0x800) + (c32 >= 0x10000))
66 return c0;
67 *s8 += clen;
68 return c32;
69 }
70
71 /**
72 * efi_puts() - Write a UTF-8 encoded string to the console
73 * @str: UTF-8 encoded string
74 */
efi_puts(const char * str)75 void efi_puts(const char *str)
76 {
77 efi_char16_t buf[128];
78 size_t pos = 0, lim = ARRAY_SIZE(buf);
79 const u8 *s8 = (const u8 *)str;
80 u32 c32;
81
82 while (*s8) {
83 if (*s8 == '\n')
84 buf[pos++] = L'\r';
85 c32 = utf8_to_utf32(&s8);
86 if (c32 < 0x10000) {
87 /* Characters in plane 0 use a single word. */
88 buf[pos++] = c32;
89 } else {
90 /*
91 * Characters in other planes encode into a surrogate
92 * pair.
93 */
94 buf[pos++] = (0xd800 - (0x10000 >> 10)) + (c32 >> 10);
95 buf[pos++] = 0xdc00 + (c32 & 0x3ff);
96 }
97 if (*s8 == '\0' || pos >= lim - 2) {
98 buf[pos] = L'\0';
99 efi_char16_puts(buf);
100 pos = 0;
101 }
102 }
103 }
104
105 /**
106 * efi_printk() - Print a kernel message
107 * @fmt: format string
108 *
109 * The first letter of the format string is used to determine the logging level
110 * of the message. If the level is less then the current EFI logging level, the
111 * message is suppressed. The message will be truncated to 255 bytes.
112 *
113 * Return: number of printed characters
114 */
efi_printk(const char * fmt,...)115 int efi_printk(const char *fmt, ...)
116 {
117 char printf_buf[256];
118 va_list args;
119 int printed;
120 int loglevel = printk_get_level(fmt);
121
122 switch (loglevel) {
123 case '0' ... '9':
124 loglevel -= '0';
125 break;
126 default:
127 /*
128 * Use loglevel -1 for cases where we just want to print to
129 * the screen.
130 */
131 loglevel = -1;
132 break;
133 }
134
135 if (loglevel >= efi_loglevel)
136 return 0;
137
138 if (loglevel >= 0)
139 efi_puts("EFI stub: ");
140
141 fmt = printk_skip_level(fmt);
142
143 va_start(args, fmt);
144 printed = vsnprintf(printf_buf, sizeof(printf_buf), fmt, args);
145 va_end(args);
146
147 efi_puts(printf_buf);
148 if (printed >= sizeof(printf_buf)) {
149 efi_puts("[Message truncated]\n");
150 return -1;
151 }
152
153 return printed;
154 }
155