hw/acpi/bios-linker-loader.c

   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  */
 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 */
 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 *
 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  */
 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  */
 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  */
 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  */
 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  */
 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 }