qemu/hw/acpi/bios-linker-loader.c
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   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
  37struct 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;
  85typedef struct BiosLinkerLoaderEntry BiosLinkerLoaderEntry;
  86
  87enum {
  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
  93enum {
  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 */
 103typedef 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 */
 114BIOSLinker *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 */
 125void 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
 140static const BiosLinkerFileEntry *
 141bios_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 */
 166void 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 */
 206void 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 */
 246void 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}
 281