1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * EFI boot manager
4 *
5 * Copyright (c) 2017 Rob Clark
6 */
7
8 #include <common.h>
9 #include <charset.h>
10 #include <malloc.h>
11 #include <efi_loader.h>
12 #include <asm/unaligned.h>
13
14 static const struct efi_boot_services *bs;
15 static const struct efi_runtime_services *rs;
16
17 #define LOAD_OPTION_ACTIVE 0x00000001
18 #define LOAD_OPTION_FORCE_RECONNECT 0x00000002
19 #define LOAD_OPTION_HIDDEN 0x00000008
20
21 /*
22 * bootmgr implements the logic of trying to find a payload to boot
23 * based on the BootOrder + BootXXXX variables, and then loading it.
24 *
25 * TODO detecting a special key held (f9?) and displaying a boot menu
26 * like you would get on a PC would be clever.
27 *
28 * TODO if we had a way to write and persist variables after the OS
29 * has started, we'd also want to check OsIndications to see if we
30 * should do normal or recovery boot.
31 */
32
33
34 /* Parse serialized data and transform it into efi_load_option structure */
efi_deserialize_load_option(struct efi_load_option * lo,u8 * data)35 void efi_deserialize_load_option(struct efi_load_option *lo, u8 *data)
36 {
37 lo->attributes = get_unaligned_le32(data);
38 data += sizeof(u32);
39
40 lo->file_path_length = get_unaligned_le16(data);
41 data += sizeof(u16);
42
43 /* FIXME */
44 lo->label = (u16 *)data;
45 data += (u16_strlen(lo->label) + 1) * sizeof(u16);
46
47 /* FIXME */
48 lo->file_path = (struct efi_device_path *)data;
49 data += lo->file_path_length;
50
51 lo->optional_data = data;
52 }
53
54 /*
55 * Serialize efi_load_option structure into byte stream for BootXXXX.
56 * Return a size of allocated data.
57 */
efi_serialize_load_option(struct efi_load_option * lo,u8 ** data)58 unsigned long efi_serialize_load_option(struct efi_load_option *lo, u8 **data)
59 {
60 unsigned long label_len, option_len;
61 unsigned long size;
62 u8 *p;
63
64 label_len = (u16_strlen(lo->label) + 1) * sizeof(u16);
65 option_len = strlen((char *)lo->optional_data);
66
67 /* total size */
68 size = sizeof(lo->attributes);
69 size += sizeof(lo->file_path_length);
70 size += label_len;
71 size += lo->file_path_length;
72 size += option_len + 1;
73 p = malloc(size);
74 if (!p)
75 return 0;
76
77 /* copy data */
78 *data = p;
79 memcpy(p, &lo->attributes, sizeof(lo->attributes));
80 p += sizeof(lo->attributes);
81
82 memcpy(p, &lo->file_path_length, sizeof(lo->file_path_length));
83 p += sizeof(lo->file_path_length);
84
85 memcpy(p, lo->label, label_len);
86 p += label_len;
87
88 memcpy(p, lo->file_path, lo->file_path_length);
89 p += lo->file_path_length;
90
91 memcpy(p, lo->optional_data, option_len);
92 p += option_len;
93 *(char *)p = '\0';
94
95 return size;
96 }
97
98 /* free() the result */
get_var(u16 * name,const efi_guid_t * vendor,efi_uintn_t * size)99 static void *get_var(u16 *name, const efi_guid_t *vendor,
100 efi_uintn_t *size)
101 {
102 efi_guid_t *v = (efi_guid_t *)vendor;
103 efi_status_t ret;
104 void *buf = NULL;
105
106 *size = 0;
107 EFI_CALL(ret = rs->get_variable(name, v, NULL, size, buf));
108 if (ret == EFI_BUFFER_TOO_SMALL) {
109 buf = malloc(*size);
110 EFI_CALL(ret = rs->get_variable(name, v, NULL, size, buf));
111 }
112
113 if (ret != EFI_SUCCESS) {
114 free(buf);
115 *size = 0;
116 return NULL;
117 }
118
119 return buf;
120 }
121
122 /*
123 * Attempt to load load-option number 'n', returning device_path and file_path
124 * if successful. This checks that the EFI_LOAD_OPTION is active (enabled)
125 * and that the specified file to boot exists.
126 */
try_load_entry(uint16_t n,struct efi_device_path ** device_path,struct efi_device_path ** file_path)127 static void *try_load_entry(uint16_t n, struct efi_device_path **device_path,
128 struct efi_device_path **file_path)
129 {
130 struct efi_load_option lo;
131 u16 varname[] = L"Boot0000";
132 u16 hexmap[] = L"0123456789ABCDEF";
133 void *load_option, *image = NULL;
134 efi_uintn_t size;
135
136 varname[4] = hexmap[(n & 0xf000) >> 12];
137 varname[5] = hexmap[(n & 0x0f00) >> 8];
138 varname[6] = hexmap[(n & 0x00f0) >> 4];
139 varname[7] = hexmap[(n & 0x000f) >> 0];
140
141 load_option = get_var(varname, &efi_global_variable_guid, &size);
142 if (!load_option)
143 return NULL;
144
145 efi_deserialize_load_option(&lo, load_option);
146
147 if (lo.attributes & LOAD_OPTION_ACTIVE) {
148 efi_status_t ret;
149
150 debug("%s: trying to load \"%ls\" from %pD\n",
151 __func__, lo.label, lo.file_path);
152
153 ret = efi_load_image_from_path(lo.file_path, &image);
154
155 if (ret != EFI_SUCCESS)
156 goto error;
157
158 printf("Booting: %ls\n", lo.label);
159 efi_dp_split_file_path(lo.file_path, device_path, file_path);
160 }
161
162 error:
163 free(load_option);
164
165 return image;
166 }
167
168 /*
169 * Attempt to load, in the order specified by BootOrder EFI variable, the
170 * available load-options, finding and returning the first one that can
171 * be loaded successfully.
172 */
efi_bootmgr_load(struct efi_device_path ** device_path,struct efi_device_path ** file_path)173 void *efi_bootmgr_load(struct efi_device_path **device_path,
174 struct efi_device_path **file_path)
175 {
176 uint16_t *bootorder;
177 efi_uintn_t size;
178 void *image = NULL;
179 int i, num;
180
181 __efi_entry_check();
182
183 bs = systab.boottime;
184 rs = systab.runtime;
185
186 bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size);
187 if (!bootorder)
188 goto error;
189
190 num = size / sizeof(uint16_t);
191 for (i = 0; i < num; i++) {
192 debug("%s: trying to load Boot%04X\n", __func__, bootorder[i]);
193 image = try_load_entry(bootorder[i], device_path, file_path);
194 if (image)
195 break;
196 }
197
198 free(bootorder);
199
200 error:
201 __efi_exit_check();
202
203 return image;
204 }
205