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  * board code must realize fw_cfg first, as a fixed device, before
 173  * another device realize function call bios_linker_loader_can_write_pointer()
 174  */
 175 bool bios_linker_loader_can_write_pointer(void)
 176 {
 177     FWCfgState *fw_cfg = fw_cfg_find();
 178     return fw_cfg && fw_cfg_dma_enabled(fw_cfg);
 179 }
 180
 181 /*
 182  * bios_linker_loader_alloc: ask guest to load file into guest memory.
 183  *
 184  * @linker: linker object instance
 185  * @file_name: name of the file blob to be loaded
 186  * @file_blob: pointer to blob corresponding to @file_name
 187  * @alloc_align: required minimal alignment in bytes. Must be a power of 2.
 188  * @alloc_fseg: request allocation in FSEG zone (useful for the RSDP ACPI table)
 189  *
 190  * Note: this command must precede any other linker command using this file.
 191  */
 192 void bios_linker_loader_alloc(BIOSLinker *linker,
 193                               const char *file_name,
 194                               GArray *file_blob,
 195                               uint32_t alloc_align,
 196                               bool alloc_fseg)
 197 {
 198     BiosLinkerLoaderEntry entry;
 199     BiosLinkerFileEntry file = { g_strdup(file_name), file_blob};
 200
 201     assert(!(alloc_align & (alloc_align - 1)));
 202
 203     assert(!bios_linker_find_file(linker, file_name));
 204     g_array_append_val(linker->file_list, file);
 205
 206     memset(&entry, 0, sizeof entry);
 207     strncpy(entry.alloc.file, file_name, sizeof entry.alloc.file - 1);
 208     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ALLOCATE);
 209     entry.alloc.align = cpu_to_le32(alloc_align);
 210     entry.alloc.zone = alloc_fseg ? BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG :
 211                                     BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH;
 212
 213     /* Alloc entries must come first, so prepend them */
 214     g_array_prepend_vals(linker->cmd_blob, &entry, sizeof entry);
 215 }
 216
 217 /*
 218  * bios_linker_loader_add_checksum: ask guest to add checksum of ACPI
 219  * table in the specified file at the specified offset.
 220  *
 221  * Checksum calculation simply sums -X for each byte X in the range
 222  * using 8-bit math (i.e. ACPI checksum).
 223  *
 224  * @linker: linker object instance
 225  * @file: file that includes the checksum to be calculated
 226  *        and the data to be checksummed
 227  * @start_offset, @size: range of data in the file to checksum,
 228  *                       relative to the start of file blob
 229  * @checksum_offset: location of the checksum to be patched within file blob,
 230  *                   relative to the start of file blob
 231  */
 232 void bios_linker_loader_add_checksum(BIOSLinker *linker, const char *file_name,
 233                                      unsigned start_offset, unsigned size,
 234                                      unsigned checksum_offset)
 235 {
 236     BiosLinkerLoaderEntry entry;
 237     const BiosLinkerFileEntry *file = bios_linker_find_file(linker, file_name);
 238
 239     assert(file);
 240     assert(start_offset < file->blob->len);
 241     assert(start_offset + size <= file->blob->len);
 242     assert(checksum_offset >= start_offset);
 243     assert(checksum_offset + 1 <= start_offset + size);
 244
 245     *(file->blob->data + checksum_offset) = 0;
 246     memset(&entry, 0, sizeof entry);
 247     strncpy(entry.cksum.file, file_name, sizeof entry.cksum.file - 1);
 248     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM);
 249     entry.cksum.offset = cpu_to_le32(checksum_offset);
 250     entry.cksum.start = cpu_to_le32(start_offset);
 251     entry.cksum.length = cpu_to_le32(size);
 252
 253     g_array_append_vals(linker->cmd_blob, &entry, sizeof entry);
 254 }
 255
 256 /*
 257  * bios_linker_loader_add_pointer: ask guest to patch address in
 258  * destination file with a pointer to source file
 259  *
 260  * @linker: linker object instance
 261  * @dest_file: destination file that must be changed
 262  * @dst_patched_offset: location within destination file blob to be patched
 263  *                      with the pointer to @src_file+@src_offset (i.e. source
 264  *                      blob allocated in guest memory + @src_offset), in bytes
 265  * @dst_patched_offset_size: size of the pointer to be patched
 266  *                      at @dst_patched_offset in @dest_file blob, in bytes
 267  * @src_file: source file who's address must be taken
 268  * @src_offset: location within source file blob to which
 269  *              @dest_file+@dst_patched_offset will point to after
 270  *              firmware's executed ADD_POINTER command
 271  */
 272 void bios_linker_loader_add_pointer(BIOSLinker *linker,
 273                                     const char *dest_file,
 274                                     uint32_t dst_patched_offset,
 275                                     uint8_t dst_patched_size,
 276                                     const char *src_file,
 277                                     uint32_t src_offset)
 278 {
 279     uint64_t le_src_offset;
 280     BiosLinkerLoaderEntry entry;
 281     const BiosLinkerFileEntry *dst_file =
 282         bios_linker_find_file(linker, dest_file);
 283     const BiosLinkerFileEntry *source_file =
 284         bios_linker_find_file(linker, src_file);
 285
 286     assert(dst_patched_offset < dst_file->blob->len);
 287     assert(dst_patched_offset + dst_patched_size <= dst_file->blob->len);
 288     assert(src_offset < source_file->blob->len);
 289
 290     memset(&entry, 0, sizeof entry);
 291     strncpy(entry.pointer.dest_file, dest_file,
 292             sizeof entry.pointer.dest_file - 1);
 293     strncpy(entry.pointer.src_file, src_file,
 294             sizeof entry.pointer.src_file - 1);
 295     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_POINTER);
 296     entry.pointer.offset = cpu_to_le32(dst_patched_offset);
 297     entry.pointer.size = dst_patched_size;
 298     assert(dst_patched_size == 1 || dst_patched_size == 2 ||
 299            dst_patched_size == 4 || dst_patched_size == 8);
 300
 301     le_src_offset = cpu_to_le64(src_offset);
 302     memcpy(dst_file->blob->data + dst_patched_offset,
 303            &le_src_offset, dst_patched_size);
 304
 305     g_array_append_vals(linker->cmd_blob, &entry, sizeof entry);
 306 }
 307
 308 /*
 309  * bios_linker_loader_write_pointer: ask guest to write a pointer to the
 310  * source file into the destination file, and write it back to QEMU via
 311  * fw_cfg DMA.
 312  *
 313  * @linker: linker object instance
 314  * @dest_file: destination file that must be written
 315  * @dst_patched_offset: location within destination file blob to be patched
 316  *                      with the pointer to @src_file, in bytes
 317  * @dst_patched_offset_size: size of the pointer to be patched
 318  *                      at @dst_patched_offset in @dest_file blob, in bytes
 319  * @src_file: source file who's address must be taken
 320  * @src_offset: location within source file blob to which
 321  *              @dest_file+@dst_patched_offset will point to after
 322  *              firmware's executed WRITE_POINTER command
 323  */
 324 void bios_linker_loader_write_pointer(BIOSLinker *linker,
 325                                     const char *dest_file,
 326                                     uint32_t dst_patched_offset,
 327                                     uint8_t dst_patched_size,
 328                                     const char *src_file,
 329                                     uint32_t src_offset)
 330 {
 331     BiosLinkerLoaderEntry entry;
 332     const BiosLinkerFileEntry *source_file =
 333         bios_linker_find_file(linker, src_file);
 334
 335     assert(source_file);
 336     assert(src_offset < source_file->blob->len);
 337     memset(&entry, 0, sizeof entry);
 338     strncpy(entry.wr_pointer.dest_file, dest_file,
 339             sizeof entry.wr_pointer.dest_file - 1);
 340     strncpy(entry.wr_pointer.src_file, src_file,
 341             sizeof entry.wr_pointer.src_file - 1);
 342     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_WRITE_POINTER);
 343     entry.wr_pointer.dst_offset = cpu_to_le32(dst_patched_offset);
 344     entry.wr_pointer.src_offset = cpu_to_le32(src_offset);
 345     entry.wr_pointer.size = dst_patched_size;
 346     assert(dst_patched_size == 1 || dst_patched_size == 2 ||
 347            dst_patched_size == 4 || dst_patched_size == 8);
 348
 349     g_array_append_vals(linker->cmd_blob, &entry, sizeof entry);
 350 }