hw/i386/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-common.h"
  22 #include "bios-linker-loader.h"
  23 #include "hw/nvram/fw_cfg.h"
  24
  25 #include "qemu/bswap.h"
  26
  27 #define BIOS_LINKER_LOADER_FILESZ FW_CFG_MAX_FILE_PATH
  28
  29 struct BiosLinkerLoaderEntry {
  30     uint32_t command;
  31     union {
  32         /*
  33          * COMMAND_ALLOCATE - allocate a table from @alloc.file
  34          * subject to @alloc.align alignment (must be power of 2)
  35          * and @alloc.zone (can be HIGH or FSEG) requirements.
  36          *
  37          * Must appear exactly once for each file, and before
  38          * this file is referenced by any other command.
  39          */
  40         struct {
  41             char file[BIOS_LINKER_LOADER_FILESZ];
  42             uint32_t align;
  43             uint8_t zone;
  44         } alloc;
  45
  46         /*
  47          * COMMAND_ADD_POINTER - patch the table (originating from
  48          * @dest_file) at @pointer.offset, by adding a pointer to the table
  49          * originating from @src_file. 1,2,4 or 8 byte unsigned
  50          * addition is used depending on @pointer.size.
  51          */
  52         struct {
  53             char dest_file[BIOS_LINKER_LOADER_FILESZ];
  54             char src_file[BIOS_LINKER_LOADER_FILESZ];
  55             uint32_t offset;
  56             uint8_t size;
  57         } pointer;
  58
  59         /*
  60          * COMMAND_ADD_CHECKSUM - calculate checksum of the range specified by
  61          * @cksum_start and @cksum_length fields,
  62          * and then add the value at @cksum.offset.
  63          * Checksum simply sums -X for each byte X in the range
  64          * using 8-bit math.
  65          */
  66         struct {
  67             char file[BIOS_LINKER_LOADER_FILESZ];
  68             uint32_t offset;
  69             uint32_t start;
  70             uint32_t length;
  71         } cksum;
  72
  73         /* padding */
  74         char pad[124];
  75     };
  76 } QEMU_PACKED;
  77 typedef struct BiosLinkerLoaderEntry BiosLinkerLoaderEntry;
  78
  79 enum {
  80     BIOS_LINKER_LOADER_COMMAND_ALLOCATE     = 0x1,
  81     BIOS_LINKER_LOADER_COMMAND_ADD_POINTER  = 0x2,
  82     BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM = 0x3,
  83 };
  84
  85 enum {
  86     BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH = 0x1,
  87     BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG = 0x2,
  88 };
  89
  90 GArray *bios_linker_loader_init(void)
  91 {
  92     return g_array_new(false, true /* clear */, 1);
  93 }
  94
  95 /* Free linker wrapper and return the linker array. */
  96 void *bios_linker_loader_cleanup(GArray *linker)
  97 {
  98     return g_array_free(linker, false);
  99 }
 100
 101 void bios_linker_loader_alloc(GArray *linker,
 102                               const char *file,
 103                               uint32_t alloc_align,
 104                               bool alloc_fseg)
 105 {
 106     BiosLinkerLoaderEntry entry;
 107
 108     memset(&entry, 0, sizeof entry);
 109     strncpy(entry.alloc.file, file, sizeof entry.alloc.file - 1);
 110     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ALLOCATE);
 111     entry.alloc.align = cpu_to_le32(alloc_align);
 112     entry.alloc.zone = cpu_to_le32(alloc_fseg ?
 113                                     BIOS_LINKER_LOADER_ALLOC_ZONE_FSEG :
 114                                     BIOS_LINKER_LOADER_ALLOC_ZONE_HIGH);
 115
 116     /* Alloc entries must come first, so prepend them */
 117     g_array_prepend_vals(linker, &entry, sizeof entry);
 118 }
 119
 120 void bios_linker_loader_add_checksum(GArray *linker, const char *file,
 121                                      void *table,
 122                                      void *start, unsigned size,
 123                                      uint8_t *checksum)
 124 {
 125     BiosLinkerLoaderEntry entry;
 126
 127     memset(&entry, 0, sizeof entry);
 128     strncpy(entry.cksum.file, file, sizeof entry.cksum.file - 1);
 129     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM);
 130     entry.cksum.offset = cpu_to_le32(checksum - (uint8_t *)table);
 131     entry.cksum.start = cpu_to_le32((uint8_t *)start - (uint8_t *)table);
 132     entry.cksum.length = cpu_to_le32(size);
 133
 134     g_array_append_vals(linker, &entry, sizeof entry);
 135 }
 136
 137 void bios_linker_loader_add_pointer(GArray *linker,
 138                                     const char *dest_file,
 139                                     const char *src_file,
 140                                     GArray *table, void *pointer,
 141                                     uint8_t pointer_size)
 142 {
 143     BiosLinkerLoaderEntry entry;
 144
 145     memset(&entry, 0, sizeof entry);
 146     strncpy(entry.pointer.dest_file, dest_file,
 147             sizeof entry.pointer.dest_file - 1);
 148     strncpy(entry.pointer.src_file, src_file,
 149             sizeof entry.pointer.src_file - 1);
 150     entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_POINTER);
 151     entry.pointer.offset = cpu_to_le32((gchar *)pointer - table->data);
 152     entry.pointer.size = pointer_size;
 153     assert(pointer_size == 1 || pointer_size == 2 ||
 154            pointer_size == 4 || pointer_size == 8);
 155
 156     g_array_append_vals(linker, &entry, sizeof entry);
 157 }