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         /* padding */
  82         char pad[124];
  83     };
  84 } QEMU_PACKED;
  85 typedef struct BiosLinkerLoaderEntry BiosLinkerLoaderEntry;
  86
  87 enum {
  88     BIOS_LINKER_LOADER_COMMAND_ALLOCATE     = 0x1,
  89     BIOS_LINKER_LOADER_COMMAND_ADD_POINTER  = 0x2,
  90     BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM = 0x3,
  91 };
  92
  93 enum {
  94     BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH = 0x1,
  95     BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG = 0x2,
  96 };
  97
  98 /*
  99  * BiosLinkerFileEntry:
 100  *
 101  * An internal type used for book-keeping file entries
 102  */
 103 typedef struct BiosLinkerFileEntry {
 104     char *name; /* file name */
 105     GArray *blob; /* data accosiated with @name */
 106 } BiosLinkerFileEntry;
 107
 108 /*
 109  * bios_linker_loader_init: allocate a new linker object instance.
 110  *
 111  * After initialization, linker commands can be added, and will
 112  * be stored in the linker.cmd_blob array.
 113  */
 114 BIOSLinker *bios_linker_loader_init(void)
 115 {
 116     BIOSLinker *linker = g_new(BIOSLinker, 1);
 117
 118     linker->cmd_blob = g_array_new(false, true /* clear */, 1);
 119     linker->file_list = g_array_new(false, true /* clear */,
 120                                     sizeof(BiosLinkerFileEntry));
 121     return linker;
 122 }
 123
 124 /* Free linker wrapper */
 125 void bios_linker_loader_cleanup(BIOSLinker *linker)
 126 {
 127     int i;
 128     BiosLinkerFileEntry *entry;
 129
 130     g_array_free(linker->cmd_blob, true);
 131
 132     for (i = 0; i < linker->file_list->len; i++) {
 133         entry = &g_array_index(linker->file_list, BiosLinkerFileEntry, i);
 134         g_free(entry->name);
 135     }
 136     g_array_free(linker->file_list, true);
 137     g_free(linker);
 138 }
 139
 140 static const BiosLinkerFileEntry *
 141 bios_linker_find_file(const BIOSLinker *linker, const char *name)
 142 {
 143     int i;
 144     BiosLinkerFileEntry *entry;
 145
 146     for (i = 0; i < linker->file_list->len; i++) {
 147         entry = &g_array_index(linker->file_list, BiosLinkerFileEntry, i);
 148         if (!strcmp(entry->name, name)) {
 149             return entry;
 150         }
 151     }
 152     return NULL;
 153 }
 154
 155 /*
 156  * bios_linker_loader_alloc: ask guest to load file into guest memory.
 157  *
 158  * @linker: linker object instance
 159  * @file_name: name of the file blob to be loaded
 160  * @file_blob: pointer to blob corresponding to @file_name
 161  * @alloc_align: required minimal alignment in bytes. Must be a power of 2.
 162  * @alloc_fseg: request allocation in FSEG zone (useful for the RSDP ACPI table)
 163  *
 164  * Note: this command must precede any other linker command using this file.
 165  */
 166 void bios_linker_loader_alloc(BIOSLinker *linker,
 167                               const char *file_name,
 168                               GArray *file_blob,
 169                               uint32_t alloc_align,
 170                               bool alloc_fseg)
 171 {
 172     BiosLinkerLoaderEntry entry;
 173     BiosLinkerFileEntry file = { g_strdup(file_name), file_blob};
 174
 175     assert(!(alloc_align & (alloc_align - 1)));
 176
 177     assert(!bios_linker_find_file(linker, file_name));
 178     g_array_append_val(linker->file_list, file);
 179
 180     memset(&entry, 0, sizeof entry);
 181     strncpy(entry.alloc.file, file_name, sizeof entry.alloc.file - 1);
 182     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ALLOCATE);
 183     entry.alloc.align = cpu_to_le32(alloc_align);
 184     entry.alloc.zone = alloc_fseg ? BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG :
 185                                     BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH;
 186
 187     /* Alloc entries must come first, so prepend them */
 188     g_array_prepend_vals(linker->cmd_blob, &entry, sizeof entry);
 189 }
 190
 191 /*
 192  * bios_linker_loader_add_checksum: ask guest to add checksum of ACPI
 193  * table in the specified file at the specified offset.
 194  *
 195  * Checksum calculation simply sums -X for each byte X in the range
 196  * using 8-bit math (i.e. ACPI checksum).
 197  *
 198  * @linker: linker object instance
 199  * @file: file that includes the checksum to be calculated
 200  *        and the data to be checksummed
 201  * @start_offset, @size: range of data in the file to checksum,
 202  *                       relative to the start of file blob
 203  * @checksum_offset: location of the checksum to be patched within file blob,
 204  *                   relative to the start of file blob
 205  */
 206 void bios_linker_loader_add_checksum(BIOSLinker *linker, const char *file_name,
 207                                      unsigned start_offset, unsigned size,
 208                                      unsigned checksum_offset)
 209 {
 210     BiosLinkerLoaderEntry entry;
 211     const BiosLinkerFileEntry *file = bios_linker_find_file(linker, file_name);
 212
 213     assert(file);
 214     assert(start_offset < file->blob->len);
 215     assert(start_offset + size <= file->blob->len);
 216     assert(checksum_offset >= start_offset);
 217     assert(checksum_offset + 1 <= start_offset + size);
 218
 219     *(file->blob->data + checksum_offset) = 0;
 220     memset(&entry, 0, sizeof entry);
 221     strncpy(entry.cksum.file, file_name, sizeof entry.cksum.file - 1);
 222     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM);
 223     entry.cksum.offset = cpu_to_le32(checksum_offset);
 224     entry.cksum.start = cpu_to_le32(start_offset);
 225     entry.cksum.length = cpu_to_le32(size);
 226
 227     g_array_append_vals(linker->cmd_blob, &entry, sizeof entry);
 228 }
 229
 230 /*
 231  * bios_linker_loader_add_pointer: ask guest to patch address in
 232  * destination file with a pointer to source file
 233  *
 234  * @linker: linker object instance
 235  * @dest_file: destination file that must be changed
 236  * @dst_patched_offset: location within destination file blob to be patched
 237  *                      with the pointer to @src_file+@src_offset (i.e. source
 238  *                      blob allocated in guest memory + @src_offset), in bytes
 239  * @dst_patched_offset_size: size of the pointer to be patched
 240  *                      at @dst_patched_offset in @dest_file blob, in bytes
 241  * @src_file: source file who's address must be taken
 242  * @src_offset: location within source file blob to which
 243  *              @dest_file+@dst_patched_offset will point to after
 244  *              firmware's executed ADD_POINTER command
 245  */
 246 void bios_linker_loader_add_pointer(BIOSLinker *linker,
 247                                     const char *dest_file,
 248                                     uint32_t dst_patched_offset,
 249                                     uint8_t dst_patched_size,
 250                                     const char *src_file,
 251                                     uint32_t src_offset)
 252 {
 253     uint64_t le_src_offset;
 254     BiosLinkerLoaderEntry entry;
 255     const BiosLinkerFileEntry *dst_file =
 256         bios_linker_find_file(linker, dest_file);
 257     const BiosLinkerFileEntry *source_file =
 258         bios_linker_find_file(linker, src_file);
 259
 260     assert(dst_patched_offset < dst_file->blob->len);
 261     assert(dst_patched_offset + dst_patched_size <= dst_file->blob->len);
 262     assert(src_offset < source_file->blob->len);
 263
 264     memset(&entry, 0, sizeof entry);
 265     strncpy(entry.pointer.dest_file, dest_file,
 266             sizeof entry.pointer.dest_file - 1);
 267     strncpy(entry.pointer.src_file, src_file,
 268             sizeof entry.pointer.src_file - 1);
 269     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_POINTER);
 270     entry.pointer.offset = cpu_to_le32(dst_patched_offset);
 271     entry.pointer.size = dst_patched_size;
 272     assert(dst_patched_size == 1 || dst_patched_size == 2 ||
 273            dst_patched_size == 4 || dst_patched_size == 8);
 274
 275     le_src_offset = cpu_to_le64(src_offset);
 276     memcpy(dst_file->blob->data + dst_patched_offset,
 277            &le_src_offset, dst_patched_size);
 278
 279     g_array_append_vals(linker->cmd_blob, &entry, sizeof entry);
 280 }