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