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  * bios_linker_loader_init: allocate a new linker file blob array.
 100  *
 101  * After initialization, linker commands can be added, and will
 102  * be stored in the array.
 103  */
 104 GArray *bios_linker_loader_init(void)
 105 {
 106     return g_array_new(false, true /* clear */, 1);
 107 }
 108
 109 /* Free linker wrapper and return the linker array. */
 110 void *bios_linker_loader_cleanup(GArray *linker)
 111 {
 112     return g_array_free(linker, false);
 113 }
 114
 115 /*
 116  * bios_linker_loader_alloc: ask guest to load file into guest memory.
 117  *
 118  * @linker: linker file blob array
 119  * @file: file to be loaded
 120  * @alloc_align: required minimal alignment in bytes. Must be a power of 2.
 121  * @alloc_fseg: request allocation in FSEG zone (useful for the RSDP ACPI table)
 122  *
 123  * Note: this command must precede any other linker command using this file.
 124  */
 125 void bios_linker_loader_alloc(GArray *linker,
 126                               const char *file,
 127                               uint32_t alloc_align,
 128                               bool alloc_fseg)
 129 {
 130     BiosLinkerLoaderEntry entry;
 131
 132     assert(!(alloc_align & (alloc_align - 1)));
 133
 134     memset(&entry, 0, sizeof entry);
 135     strncpy(entry.alloc.file, file, sizeof entry.alloc.file - 1);
 136     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ALLOCATE);
 137     entry.alloc.align = cpu_to_le32(alloc_align);
 138     entry.alloc.zone = alloc_fseg ? BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG :
 139                                     BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH;
 140
 141     /* Alloc entries must come first, so prepend them */
 142     g_array_prepend_vals(linker, &entry, sizeof entry);
 143 }
 144
 145 /*
 146  * bios_linker_loader_add_checksum: ask guest to add checksum of file data
 147  * into (same) file at the specified pointer.
 148  *
 149  * Checksum calculation simply sums -X for each byte X in the range
 150  * using 8-bit math (i.e. ACPI checksum).
 151  *
 152  * @linker: linker file blob array
 153  * @file: file that includes the checksum to be calculated
 154  *        and the data to be checksummed
 155  * @table: @file blob contents
 156  * @start, @size: range of data to checksum
 157  * @checksum: location of the checksum to be patched within file blob
 158  *
 159  * Notes:
 160  * - checksum byte initial value must have been pushed into @table
 161  *   and reside at address @checksum.
 162  * - @size bytes must have been pushed into @table and reside at address
 163  *   @start.
 164  * - Guest calculates checksum of specified range of data, result is added to
 165  *   initial value at @checksum into copy of @file in Guest memory.
 166  * - Range might include the checksum itself.
 167  * - To avoid confusion, caller must always put 0x0 at @checksum.
 168  * - @file must be loaded into Guest memory using bios_linker_loader_alloc
 169  */
 170 void bios_linker_loader_add_checksum(GArray *linker, const char *file,
 171                                      GArray *table,
 172                                      void *start, unsigned size,
 173                                      uint8_t *checksum)
 174 {
 175     BiosLinkerLoaderEntry entry;
 176     ptrdiff_t checksum_offset = (gchar *)checksum - table->data;
 177     ptrdiff_t start_offset = (gchar *)start - table->data;
 178
 179     assert(checksum_offset >= 0);
 180     assert(start_offset >= 0);
 181     assert(checksum_offset + 1 <= table->len);
 182     assert(start_offset + size <= table->len);
 183     assert(*checksum == 0x0);
 184
 185     memset(&entry, 0, sizeof entry);
 186     strncpy(entry.cksum.file, file, sizeof entry.cksum.file - 1);
 187     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM);
 188     entry.cksum.offset = cpu_to_le32(checksum_offset);
 189     entry.cksum.start = cpu_to_le32(start_offset);
 190     entry.cksum.length = cpu_to_le32(size);
 191
 192     g_array_append_vals(linker, &entry, sizeof entry);
 193 }
 194
 195 /*
 196  * bios_linker_loader_add_pointer: ask guest to add address of source file
 197  * into destination file at the specified pointer.
 198  *
 199  * @linker: linker file blob array
 200  * @dest_file: destination file that must be changed
 201  * @src_file: source file who's address must be taken
 202  * @table: @dest_file blob contents array
 203  * @pointer: location of the pointer to be patched within destination file blob
 204  * @pointer_size: size of pointer to be patched, in bytes
 205  *
 206  * Notes:
 207  * - @pointer_size bytes must have been pushed into @table
 208  *   and reside at address @pointer.
 209  * - Guest address is added to initial value at @pointer
 210  *   into copy of @dest_file in Guest memory.
 211  *   e.g. to get start of src_file in guest memory, put 0x0 there
 212  *   to get address of a field at offset 0x10 in src_file, put 0x10 there
 213  * - Both @dest_file and @src_file must be
 214  *   loaded into Guest memory using bios_linker_loader_alloc
 215  */
 216 void bios_linker_loader_add_pointer(GArray *linker,
 217                                     const char *dest_file,
 218                                     const char *src_file,
 219                                     GArray *table, void *pointer,
 220                                     uint8_t pointer_size)
 221 {
 222     BiosLinkerLoaderEntry entry;
 223     ptrdiff_t offset = (gchar *)pointer - table->data;
 224
 225     assert(offset >= 0);
 226     assert(offset + pointer_size <= table->len);
 227
 228     memset(&entry, 0, sizeof entry);
 229     strncpy(entry.pointer.dest_file, dest_file,
 230             sizeof entry.pointer.dest_file - 1);
 231     strncpy(entry.pointer.src_file, src_file,
 232             sizeof entry.pointer.src_file - 1);
 233     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_POINTER);
 234     entry.pointer.offset = cpu_to_le32(offset);
 235     entry.pointer.size = pointer_size;
 236     assert(pointer_size == 1 || pointer_size == 2 ||
 237            pointer_size == 4 || pointer_size == 8);
 238
 239     g_array_append_vals(linker, &entry, sizeof entry);
 240 }