xref: /openbmc/qemu/hw/acpi/bios-linker-loader.c (revision a050901d)
1 /* Dynamic linker/loader of ACPI tables
2  *
3  * Copyright (C) 2013 Red Hat Inc
4  *
5  * Author: Michael S. Tsirkin <mst@redhat.com>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11 
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16 
17  * You should have received a copy of the GNU General Public License along
18  * with this program; if not, see <http://www.gnu.org/licenses/>.
19  */
20 
21 #include "qemu/osdep.h"
22 #include "hw/acpi/bios-linker-loader.h"
23 #include "hw/nvram/fw_cfg.h"
24 
25 #include "qemu/bswap.h"
26 
27 /*
28  * Linker/loader is a paravirtualized interface that passes commands to guest.
29  * The commands can be used to request guest to
30  * - allocate memory chunks and initialize them from QEMU FW CFG files
31  * - link allocated chunks by storing pointer to one chunk into another
32  * - calculate ACPI checksum of part of the chunk and store into same chunk
33  */
34 #define BIOS_LINKER_LOADER_FILESZ FW_CFG_MAX_FILE_PATH
35 
36 struct BiosLinkerLoaderEntry {
37     uint32_t command;
38     union {
39         /*
40          * COMMAND_ALLOCATE - allocate a table from @alloc.file
41          * subject to @alloc.align alignment (must be power of 2)
42          * and @alloc.zone (can be HIGH or FSEG) requirements.
43          *
44          * Must appear exactly once for each file, and before
45          * this file is referenced by any other command.
46          */
47         struct {
48             char file[BIOS_LINKER_LOADER_FILESZ];
49             uint32_t align;
50             uint8_t zone;
51         } alloc;
52 
53         /*
54          * COMMAND_ADD_POINTER - patch the table (originating from
55          * @dest_file) at @pointer.offset, by adding a pointer to the table
56          * originating from @src_file. 1,2,4 or 8 byte unsigned
57          * addition is used depending on @pointer.size.
58          */
59         struct {
60             char dest_file[BIOS_LINKER_LOADER_FILESZ];
61             char src_file[BIOS_LINKER_LOADER_FILESZ];
62             uint32_t offset;
63             uint8_t size;
64         } pointer;
65 
66         /*
67          * COMMAND_ADD_CHECKSUM - calculate checksum of the range specified by
68          * @cksum_start and @cksum_length fields,
69          * and then add the value at @cksum.offset.
70          * Checksum simply sums -X for each byte X in the range
71          * using 8-bit math.
72          */
73         struct {
74             char file[BIOS_LINKER_LOADER_FILESZ];
75             uint32_t offset;
76             uint32_t start;
77             uint32_t length;
78         } cksum;
79 
80         /*
81          * COMMAND_WRITE_POINTER - write the fw_cfg file (originating from
82          * @dest_file) at @wr_pointer.offset, by adding a pointer to
83          * @src_offset within the table originating from @src_file.
84          * 1,2,4 or 8 byte unsigned addition is used depending on
85          * @wr_pointer.size.
86          */
87         struct {
88             char dest_file[BIOS_LINKER_LOADER_FILESZ];
89             char src_file[BIOS_LINKER_LOADER_FILESZ];
90             uint32_t dst_offset;
91             uint32_t src_offset;
92             uint8_t size;
93         } wr_pointer;
94 
95         /* padding */
96         char pad[124];
97     };
98 } QEMU_PACKED;
99 typedef struct BiosLinkerLoaderEntry BiosLinkerLoaderEntry;
100 
101 enum {
102     BIOS_LINKER_LOADER_COMMAND_ALLOCATE          = 0x1,
103     BIOS_LINKER_LOADER_COMMAND_ADD_POINTER       = 0x2,
104     BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM      = 0x3,
105     BIOS_LINKER_LOADER_COMMAND_WRITE_POINTER     = 0x4,
106 };
107 
108 enum {
109     BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH = 0x1,
110     BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG = 0x2,
111 };
112 
113 /*
114  * BiosLinkerFileEntry:
115  *
116  * An internal type used for book-keeping file entries
117  */
118 typedef struct BiosLinkerFileEntry {
119     char *name; /* file name */
120     GArray *blob; /* data accosiated with @name */
121 } BiosLinkerFileEntry;
122 
123 /*
124  * bios_linker_loader_init: allocate a new linker object instance.
125  *
126  * After initialization, linker commands can be added, and will
127  * be stored in the linker.cmd_blob array.
128  */
bios_linker_loader_init(void)129 BIOSLinker *bios_linker_loader_init(void)
130 {
131     BIOSLinker *linker = g_new(BIOSLinker, 1);
132 
133     linker->cmd_blob = g_array_new(false, true /* clear */, 1);
134     linker->file_list = g_array_new(false, true /* clear */,
135                                     sizeof(BiosLinkerFileEntry));
136     return linker;
137 }
138 
139 /* Free linker wrapper */
bios_linker_loader_cleanup(BIOSLinker * linker)140 void bios_linker_loader_cleanup(BIOSLinker *linker)
141 {
142     int i;
143     BiosLinkerFileEntry *entry;
144 
145     g_array_free(linker->cmd_blob, true);
146 
147     for (i = 0; i < linker->file_list->len; i++) {
148         entry = &g_array_index(linker->file_list, BiosLinkerFileEntry, i);
149         g_free(entry->name);
150     }
151     g_array_free(linker->file_list, true);
152     g_free(linker);
153 }
154 
155 static const BiosLinkerFileEntry *
bios_linker_find_file(const BIOSLinker * linker,const char * name)156 bios_linker_find_file(const BIOSLinker *linker, const char *name)
157 {
158     int i;
159     BiosLinkerFileEntry *entry;
160 
161     for (i = 0; i < linker->file_list->len; i++) {
162         entry = &g_array_index(linker->file_list, BiosLinkerFileEntry, i);
163         if (!strcmp(entry->name, name)) {
164             return entry;
165         }
166     }
167     return NULL;
168 }
169 
170 /*
171  * board code must realize fw_cfg first, as a fixed device, before
172  * another device realize function call bios_linker_loader_can_write_pointer()
173  */
bios_linker_loader_can_write_pointer(void)174 bool bios_linker_loader_can_write_pointer(void)
175 {
176     FWCfgState *fw_cfg = fw_cfg_find();
177     return fw_cfg && fw_cfg_dma_enabled(fw_cfg);
178 }
179 
180 /*
181  * bios_linker_loader_alloc: ask guest to load file into guest memory.
182  *
183  * @linker: linker object instance
184  * @file_name: name of the file blob to be loaded
185  * @file_blob: pointer to blob corresponding to @file_name
186  * @alloc_align: required minimal alignment in bytes. Must be a power of 2.
187  * @alloc_fseg: request allocation in FSEG zone (useful for the RSDP ACPI table)
188  *
189  * Note: this command must precede any other linker command using this file.
190  */
bios_linker_loader_alloc(BIOSLinker * linker,const char * file_name,GArray * file_blob,uint32_t alloc_align,bool alloc_fseg)191 void bios_linker_loader_alloc(BIOSLinker *linker,
192                               const char *file_name,
193                               GArray *file_blob,
194                               uint32_t alloc_align,
195                               bool alloc_fseg)
196 {
197     BiosLinkerLoaderEntry entry;
198     BiosLinkerFileEntry file = { g_strdup(file_name), file_blob};
199 
200     assert(!(alloc_align & (alloc_align - 1)));
201 
202     assert(!bios_linker_find_file(linker, file_name));
203     g_array_append_val(linker->file_list, file);
204 
205     memset(&entry, 0, sizeof entry);
206     strncpy(entry.alloc.file, file_name, sizeof entry.alloc.file - 1);
207     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ALLOCATE);
208     entry.alloc.align = cpu_to_le32(alloc_align);
209     entry.alloc.zone = alloc_fseg ? BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG :
210                                     BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH;
211 
212     /* Alloc entries must come first, so prepend them */
213     g_array_prepend_vals(linker->cmd_blob, &entry, sizeof entry);
214 }
215 
216 /*
217  * bios_linker_loader_add_checksum: ask guest to add checksum of ACPI
218  * table in the specified file at the specified offset.
219  *
220  * Checksum calculation simply sums -X for each byte X in the range
221  * using 8-bit math (i.e. ACPI checksum).
222  *
223  * @linker: linker object instance
224  * @file: file that includes the checksum to be calculated
225  *        and the data to be checksummed
226  * @start_offset, @size: range of data in the file to checksum,
227  *                       relative to the start of file blob
228  * @checksum_offset: location of the checksum to be patched within file blob,
229  *                   relative to the start of file blob
230  */
bios_linker_loader_add_checksum(BIOSLinker * linker,const char * file_name,unsigned start_offset,unsigned size,unsigned checksum_offset)231 void bios_linker_loader_add_checksum(BIOSLinker *linker, const char *file_name,
232                                      unsigned start_offset, unsigned size,
233                                      unsigned checksum_offset)
234 {
235     BiosLinkerLoaderEntry entry;
236     const BiosLinkerFileEntry *file = bios_linker_find_file(linker, file_name);
237 
238     assert(file);
239     assert(start_offset < file->blob->len);
240     assert(start_offset + size <= file->blob->len);
241     assert(checksum_offset >= start_offset);
242     assert(checksum_offset + 1 <= start_offset + size);
243 
244     *(file->blob->data + checksum_offset) = 0;
245     memset(&entry, 0, sizeof entry);
246     strncpy(entry.cksum.file, file_name, sizeof entry.cksum.file - 1);
247     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM);
248     entry.cksum.offset = cpu_to_le32(checksum_offset);
249     entry.cksum.start = cpu_to_le32(start_offset);
250     entry.cksum.length = cpu_to_le32(size);
251 
252     g_array_append_vals(linker->cmd_blob, &entry, sizeof entry);
253 }
254 
255 /*
256  * bios_linker_loader_add_pointer: ask guest to patch address in
257  * destination file with a pointer to source file
258  *
259  * @linker: linker object instance
260  * @dest_file: destination file that must be changed
261  * @dst_patched_offset: location within destination file blob to be patched
262  *                      with the pointer to @src_file+@src_offset (i.e. source
263  *                      blob allocated in guest memory + @src_offset), in bytes
264  * @dst_patched_offset_size: size of the pointer to be patched
265  *                      at @dst_patched_offset in @dest_file blob, in bytes
266  * @src_file: source file who's address must be taken
267  * @src_offset: location within source file blob to which
268  *              @dest_file+@dst_patched_offset will point to after
269  *              firmware's executed ADD_POINTER command
270  */
bios_linker_loader_add_pointer(BIOSLinker * linker,const char * dest_file,uint32_t dst_patched_offset,uint8_t dst_patched_size,const char * src_file,uint32_t src_offset)271 void bios_linker_loader_add_pointer(BIOSLinker *linker,
272                                     const char *dest_file,
273                                     uint32_t dst_patched_offset,
274                                     uint8_t dst_patched_size,
275                                     const char *src_file,
276                                     uint32_t src_offset)
277 {
278     uint64_t le_src_offset;
279     BiosLinkerLoaderEntry entry;
280     const BiosLinkerFileEntry *dst_file =
281         bios_linker_find_file(linker, dest_file);
282     const BiosLinkerFileEntry *source_file =
283         bios_linker_find_file(linker, src_file);
284 
285     assert(dst_file);
286     assert(source_file);
287     assert(dst_patched_offset < dst_file->blob->len);
288     assert(dst_patched_offset + dst_patched_size <= dst_file->blob->len);
289     assert(src_offset < source_file->blob->len);
290 
291     memset(&entry, 0, sizeof entry);
292     strncpy(entry.pointer.dest_file, dest_file,
293             sizeof entry.pointer.dest_file - 1);
294     strncpy(entry.pointer.src_file, src_file,
295             sizeof entry.pointer.src_file - 1);
296     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_POINTER);
297     entry.pointer.offset = cpu_to_le32(dst_patched_offset);
298     entry.pointer.size = dst_patched_size;
299     assert(dst_patched_size == 1 || dst_patched_size == 2 ||
300            dst_patched_size == 4 || dst_patched_size == 8);
301 
302     le_src_offset = cpu_to_le64(src_offset);
303     memcpy(dst_file->blob->data + dst_patched_offset,
304            &le_src_offset, dst_patched_size);
305 
306     g_array_append_vals(linker->cmd_blob, &entry, sizeof entry);
307 }
308 
309 /*
310  * bios_linker_loader_write_pointer: ask guest to write a pointer to the
311  * source file into the destination file, and write it back to QEMU via
312  * fw_cfg DMA.
313  *
314  * @linker: linker object instance
315  * @dest_file: destination file that must be written
316  * @dst_patched_offset: location within destination file blob to be patched
317  *                      with the pointer to @src_file, in bytes
318  * @dst_patched_offset_size: size of the pointer to be patched
319  *                      at @dst_patched_offset in @dest_file blob, in bytes
320  * @src_file: source file who's address must be taken
321  * @src_offset: location within source file blob to which
322  *              @dest_file+@dst_patched_offset will point to after
323  *              firmware's executed WRITE_POINTER command
324  */
bios_linker_loader_write_pointer(BIOSLinker * linker,const char * dest_file,uint32_t dst_patched_offset,uint8_t dst_patched_size,const char * src_file,uint32_t src_offset)325 void bios_linker_loader_write_pointer(BIOSLinker *linker,
326                                     const char *dest_file,
327                                     uint32_t dst_patched_offset,
328                                     uint8_t dst_patched_size,
329                                     const char *src_file,
330                                     uint32_t src_offset)
331 {
332     BiosLinkerLoaderEntry entry;
333     const BiosLinkerFileEntry *source_file =
334         bios_linker_find_file(linker, src_file);
335 
336     assert(source_file);
337     assert(src_offset < source_file->blob->len);
338     memset(&entry, 0, sizeof entry);
339     strncpy(entry.wr_pointer.dest_file, dest_file,
340             sizeof entry.wr_pointer.dest_file - 1);
341     strncpy(entry.wr_pointer.src_file, src_file,
342             sizeof entry.wr_pointer.src_file - 1);
343     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_WRITE_POINTER);
344     entry.wr_pointer.dst_offset = cpu_to_le32(dst_patched_offset);
345     entry.wr_pointer.src_offset = cpu_to_le32(src_offset);
346     entry.wr_pointer.size = dst_patched_size;
347     assert(dst_patched_size == 1 || dst_patched_size == 2 ||
348            dst_patched_size == 4 || dst_patched_size == 8);
349 
350     g_array_append_vals(linker->cmd_blob, &entry, sizeof entry);
351 }
352