payloads/libpayload/gdb/commands.c

   1 /*
   2  * Copyright 2014 Google Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of
   7  * the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but without any warranty; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <arch/cache.h>
  16 #include <gdb.h>
  17 #include <libpayload.h>
  18
  19 static void gdb_get_last_signal(struct gdb_message *command,
  20                                 int offset, struct gdb_message *reply)
  21 {
  22         gdb_message_add_string(reply, "S");
  23         gdb_message_encode_bytes(reply, &gdb_state.signal, 1);
  24 }
  25
  26 static void gdb_read_general_registers(struct gdb_message *command,
  27                                        int offset, struct gdb_message *reply)
  28 {
  29         gdb_arch_encode_regs(reply);
  30 }
  31
  32 static void gdb_write_general_registers(struct gdb_message *command,
  33                                         int offset, struct gdb_message *reply)
  34 {
  35         gdb_arch_decode_regs(offset, command);
  36         gdb_message_add_string(reply, "OK");
  37 }
  38
  39 static void gdb_read_memory(struct gdb_message *command,
  40                             int offset, struct gdb_message *reply)
  41 {
  42         int tok = gdb_message_tokenize(command, &offset);
  43         uintptr_t addr = gdb_message_decode_int(command, tok, offset - 1 - tok);
  44         size_t length = gdb_message_decode_int(command, offset,
  45                                                command->used - offset);
  46
  47         gdb_message_encode_bytes(reply, (void *)addr, length);
  48 }
  49
  50 static void gdb_write_memory(struct gdb_message *command,
  51                              int offset, struct gdb_message *reply)
  52 {
  53         int tok = gdb_message_tokenize(command, &offset);
  54         uintptr_t addr = gdb_message_decode_int(command, tok, offset - 1 - tok);
  55         tok = gdb_message_tokenize(command, &offset);
  56         size_t length = gdb_message_decode_int(command, tok, offset - 1 - tok);
  57
  58         die_if(length * 2 != command->used - offset, "Invalid length field in "
  59                "GDB command: %.*s", command->used, command->buf);
  60
  61         gdb_message_decode_bytes(command, offset, (void *)addr, length);
  62         cache_sync_instructions();
  63         gdb_message_add_string(reply, "OK");
  64 }
  65
  66 static void gdb_continue(struct gdb_message *command,
  67                          int offset, struct gdb_message *reply)
  68 {
  69         /* Disable single step if it's still on. */
  70         gdb_arch_set_single_step(0);
  71
  72         /* No need to support the extension that passes in new EIP/PC. */
  73         if (command->used > offset)
  74                 gdb_message_add_string(reply, "E00");
  75         else
  76                 gdb_state.resumed = 1;
  77 }
  78
  79 static void gdb_single_step(struct gdb_message *command,
  80                             int offset, struct gdb_message *reply)
  81 {
  82         if (command->used > offset || gdb_arch_set_single_step(1))
  83                 gdb_message_add_string(reply, "E00");
  84         else
  85                 gdb_state.resumed = 1;
  86 }
  87
  88 struct gdb_command gdb_commands[] = {
  89         { "?", &gdb_get_last_signal },
  90         { "g", &gdb_read_general_registers },
  91         { "G", &gdb_write_general_registers },
  92         { "m", &gdb_read_memory },
  93         { "M", &gdb_write_memory },
  94         { "c", &gdb_continue },
  95         { "s", &gdb_single_step }
  96 };
  97 const int gdb_command_count = ARRAY_SIZE(gdb_commands);