grub-core/commands/memrw.c

   1 /* memrw.c - command to read / write physical memory  */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2009  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <grub/dl.h>
  21 #include <grub/misc.h>
  22 #include <grub/extcmd.h>
  23 #include <grub/env.h>
  24 #include <grub/i18n.h>
  25
  26 GRUB_MOD_LICENSE ("GPLv3+");
  27
  28 static grub_extcmd_t cmd_read_byte, cmd_read_word, cmd_read_dword;
  29 static grub_command_t cmd_write_byte, cmd_write_word, cmd_write_dword;
  30
  31 static const struct grub_arg_option options[] =
  32   {
  33     {0, 'v', 0, N_("Save read value into variable VARNAME."),
  34      N_("VARNAME"), ARG_TYPE_STRING},
  35     {0, 0, 0, 0, 0, 0}
  36   };
  37
  38
  39 static grub_err_t
  40 grub_cmd_read (grub_extcmd_context_t ctxt, int argc, char **argv)
  41 {
  42   grub_addr_t addr;
  43   grub_uint32_t value = 0;
  44   char buf[sizeof ("XXXXXXXX")];
  45
  46   if (argc != 1)
  47     return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("one argument expected"));
  48
  49   addr = grub_strtoul (argv[0], 0, 0);
  50   switch (ctxt->extcmd->cmd->name[sizeof ("read_") - 1])
  51     {
  52     case 'd':
  53       value = *((volatile grub_uint32_t *) addr);
  54       break;
  55
  56     case 'w':
  57       value = *((volatile grub_uint16_t *) addr);
  58       break;
  59
  60     case 'b':
  61       value = *((volatile grub_uint8_t *) addr);
  62       break;
  63     }
  64
  65   if (ctxt->state[0].set)
  66     {
  67       grub_snprintf (buf, sizeof (buf), "%x", value);
  68       grub_env_set (ctxt->state[0].arg, buf);
  69     }
  70   else
  71     grub_printf ("0x%x\n", value);
  72
  73   return 0;
  74 }
  75
  76 static grub_err_t
  77 grub_cmd_write (grub_command_t cmd, int argc, char **argv)
  78 {
  79   grub_addr_t addr;
  80   grub_uint32_t value;
  81   grub_uint32_t mask = 0xffffffff;
  82
  83   if (argc != 2 && argc != 3)
  84     return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("two arguments expected"));
  85
  86   addr = grub_strtoul (argv[0], 0, 0);
  87   value = grub_strtoul (argv[1], 0, 0);
  88   if (argc == 3)
  89     mask = grub_strtoul (argv[2], 0, 0);
  90   value &= mask;
  91   switch (cmd->name[sizeof ("write_") - 1])
  92     {
  93     case 'd':
  94       if (mask != 0xffffffff)
  95         *((volatile grub_uint32_t *) addr)
  96           = (*((volatile grub_uint32_t *) addr) & ~mask) | value;
  97       else
  98         *((volatile grub_uint32_t *) addr) = value;
  99       break;
 100
 101     case 'w':
 102       if ((mask & 0xffff) != 0xffff)
 103         *((volatile grub_uint16_t *) addr)
 104           = (*((volatile grub_uint16_t *) addr) & ~mask) | value;
 105       else
 106         *((volatile grub_uint16_t *) addr) = value;
 107       break;
 108
 109     case 'b':
 110       if ((mask & 0xff) != 0xff)
 111         *((volatile grub_uint8_t *) addr)
 112           = (*((volatile grub_uint8_t *) addr) & ~mask) | value;
 113       else
 114         *((volatile grub_uint8_t *) addr) = value;
 115       break;
 116     }
 117
 118   return 0;
 119 }
 120
 121 GRUB_MOD_INIT(memrw)
 122 {
 123   cmd_read_byte =
 124     grub_register_extcmd ("read_byte", grub_cmd_read, 0,
 125                           N_("ADDR"), N_("Read 8-bit value from ADDR."),
 126                           options);
 127   cmd_read_word =
 128     grub_register_extcmd ("read_word", grub_cmd_read, 0,
 129                           N_("ADDR"), N_("Read 16-bit value from ADDR."),
 130                           options);
 131   cmd_read_dword =
 132     grub_register_extcmd ("read_dword", grub_cmd_read, 0,
 133                           N_("ADDR"), N_("Read 32-bit value from ADDR."),
 134                           options);
 135   cmd_write_byte =
 136     grub_register_command ("write_byte", grub_cmd_write,
 137                            N_("ADDR VALUE [MASK]"),
 138                            N_("Write 8-bit VALUE to ADDR."));
 139   cmd_write_word =
 140     grub_register_command ("write_word", grub_cmd_write,
 141                            N_("ADDR VALUE [MASK]"),
 142                            N_("Write 16-bit VALUE to ADDR."));
 143   cmd_write_dword =
 144     grub_register_command ("write_dword", grub_cmd_write,
 145                            N_("ADDR VALUE [MASK]"),
 146                            N_("Write 32-bit VALUE to ADDR."));
 147 }
 148
 149 GRUB_MOD_FINI(memrw)
 150 {
 151   grub_unregister_extcmd (cmd_read_byte);
 152   grub_unregister_extcmd (cmd_read_word);
 153   grub_unregister_extcmd (cmd_read_dword);
 154   grub_unregister_command (cmd_write_byte);
 155   grub_unregister_command (cmd_write_word);
 156   grub_unregister_command (cmd_write_dword);
 157 }