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Tom Rinif739fcd2018-05-07 17:02:21 -04001// SPDX-License-Identifier: GPL-2.0+
Rob Clark9975fe92017-09-13 18:05:38 -04002/*
3 * EFI utils
4 *
5 * Copyright (c) 2017 Rob Clark
Rob Clark9975fe92017-09-13 18:05:38 -04006 */
7
8#include <common.h>
9#include <charset.h>
10#include <malloc.h>
11#include <efi_loader.h>
12
13static const struct efi_boot_services *bs;
14static const struct efi_runtime_services *rs;
15
16#define LOAD_OPTION_ACTIVE 0x00000001
17#define LOAD_OPTION_FORCE_RECONNECT 0x00000002
18#define LOAD_OPTION_HIDDEN 0x00000008
19
20/*
21 * bootmgr implements the logic of trying to find a payload to boot
22 * based on the BootOrder + BootXXXX variables, and then loading it.
23 *
24 * TODO detecting a special key held (f9?) and displaying a boot menu
25 * like you would get on a PC would be clever.
26 *
27 * TODO if we had a way to write and persist variables after the OS
28 * has started, we'd also want to check OsIndications to see if we
29 * should do normal or recovery boot.
30 */
31
32
33/*
34 * See section 3.1.3 in the v2.7 UEFI spec for more details on
35 * the layout of EFI_LOAD_OPTION. In short it is:
36 *
37 * typedef struct _EFI_LOAD_OPTION {
38 * UINT32 Attributes;
39 * UINT16 FilePathListLength;
40 * // CHAR16 Description[]; <-- variable length, NULL terminated
41 * // EFI_DEVICE_PATH_PROTOCOL FilePathList[]; <-- FilePathListLength bytes
42 * // UINT8 OptionalData[];
43 * } EFI_LOAD_OPTION;
44 */
45struct load_option {
46 u32 attributes;
47 u16 file_path_length;
48 u16 *label;
49 struct efi_device_path *file_path;
50 u8 *optional_data;
51};
52
53/* parse an EFI_LOAD_OPTION, as described above */
54static void parse_load_option(struct load_option *lo, void *ptr)
55{
56 lo->attributes = *(u32 *)ptr;
57 ptr += sizeof(u32);
58
59 lo->file_path_length = *(u16 *)ptr;
60 ptr += sizeof(u16);
61
62 lo->label = ptr;
Heinrich Schuchardt1dde0d52018-08-31 21:31:26 +020063 ptr += (u16_strlen(lo->label) + 1) * 2;
Rob Clark9975fe92017-09-13 18:05:38 -040064
65 lo->file_path = ptr;
66 ptr += lo->file_path_length;
67
68 lo->optional_data = ptr;
69}
70
71/* free() the result */
72static void *get_var(u16 *name, const efi_guid_t *vendor,
Heinrich Schuchardt45c66f92018-05-17 07:57:05 +020073 efi_uintn_t *size)
Rob Clark9975fe92017-09-13 18:05:38 -040074{
75 efi_guid_t *v = (efi_guid_t *)vendor;
76 efi_status_t ret;
77 void *buf = NULL;
78
79 *size = 0;
Heinrich Schuchardt45c66f92018-05-17 07:57:05 +020080 EFI_CALL(ret = rs->get_variable(name, v, NULL, size, buf));
Rob Clark9975fe92017-09-13 18:05:38 -040081 if (ret == EFI_BUFFER_TOO_SMALL) {
82 buf = malloc(*size);
Heinrich Schuchardt45c66f92018-05-17 07:57:05 +020083 EFI_CALL(ret = rs->get_variable(name, v, NULL, size, buf));
Rob Clark9975fe92017-09-13 18:05:38 -040084 }
85
86 if (ret != EFI_SUCCESS) {
87 free(buf);
88 *size = 0;
89 return NULL;
90 }
91
92 return buf;
93}
94
95/*
96 * Attempt to load load-option number 'n', returning device_path and file_path
97 * if successful. This checks that the EFI_LOAD_OPTION is active (enabled)
98 * and that the specified file to boot exists.
99 */
100static void *try_load_entry(uint16_t n, struct efi_device_path **device_path,
101 struct efi_device_path **file_path)
102{
103 struct load_option lo;
104 u16 varname[] = L"Boot0000";
105 u16 hexmap[] = L"0123456789ABCDEF";
106 void *load_option, *image = NULL;
Heinrich Schuchardt45c66f92018-05-17 07:57:05 +0200107 efi_uintn_t size;
Rob Clark9975fe92017-09-13 18:05:38 -0400108
109 varname[4] = hexmap[(n & 0xf000) >> 12];
110 varname[5] = hexmap[(n & 0x0f00) >> 8];
111 varname[6] = hexmap[(n & 0x00f0) >> 4];
112 varname[7] = hexmap[(n & 0x000f) >> 0];
113
114 load_option = get_var(varname, &efi_global_variable_guid, &size);
115 if (!load_option)
116 return NULL;
117
118 parse_load_option(&lo, load_option);
119
120 if (lo.attributes & LOAD_OPTION_ACTIVE) {
121 efi_status_t ret;
Rob Clark9975fe92017-09-13 18:05:38 -0400122
Heinrich Schuchardt4a8b5e72018-01-26 07:20:54 +0100123 debug("%s: trying to load \"%ls\" from %pD\n",
124 __func__, lo.label, lo.file_path);
Rob Clark9975fe92017-09-13 18:05:38 -0400125
126 ret = efi_load_image_from_path(lo.file_path, &image);
127
128 if (ret != EFI_SUCCESS)
129 goto error;
130
131 printf("Booting: %ls\n", lo.label);
132 efi_dp_split_file_path(lo.file_path, device_path, file_path);
133 }
134
135error:
136 free(load_option);
137
138 return image;
139}
140
141/*
142 * Attempt to load, in the order specified by BootOrder EFI variable, the
143 * available load-options, finding and returning the first one that can
144 * be loaded successfully.
145 */
146void *efi_bootmgr_load(struct efi_device_path **device_path,
147 struct efi_device_path **file_path)
148{
149 uint16_t *bootorder;
Heinrich Schuchardt45c66f92018-05-17 07:57:05 +0200150 efi_uintn_t size;
Rob Clark9975fe92017-09-13 18:05:38 -0400151 void *image = NULL;
152 int i, num;
153
154 __efi_entry_check();
155
156 bs = systab.boottime;
157 rs = systab.runtime;
158
159 bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size);
160 if (!bootorder)
161 goto error;
162
163 num = size / sizeof(uint16_t);
164 for (i = 0; i < num; i++) {
165 debug("%s: trying to load Boot%04X\n", __func__, bootorder[i]);
166 image = try_load_entry(bootorder[i], device_path, file_path);
167 if (image)
168 break;
169 }
170
171 free(bootorder);
172
173error:
174 __efi_exit_check();
175
176 return image;
177}