151 lines
4.1 KiB
C
151 lines
4.1 KiB
C
/*
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* Copyright 2014 Google Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but without any warranty; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <gdb.h>
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#include <libpayload.h>
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struct gdb_state gdb_state;
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static u8 reply_buf[2048];
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static u8 command_buf[2048];
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static struct gdb_message command = {
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.buf = command_buf,
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.used = 0,
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.size = sizeof(command_buf),
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};
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static struct gdb_message reply = {
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.buf = reply_buf,
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.used = 0,
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.size = sizeof(reply_buf),
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};
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void gdb_command_loop(u8 signal)
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{
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if (gdb_state.resumed) {
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/* We were just running. Send a stop reply. */
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reply.used = 0;
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gdb_message_add_string(&reply, "S");
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gdb_message_encode_bytes(&reply, &signal, 1);
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gdb_send_reply(&reply);
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}
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gdb_state.signal = signal;
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gdb_state.resumed = 0;
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gdb_state.connected = 1;
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while (1) {
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int i;
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gdb_get_command(&command);
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reply.used = 0;
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for (i = 0; i < gdb_command_count; i++) {
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int clen = strlen(gdb_commands[i].str);
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if (!strncmp(gdb_commands[i].str, (char *)command.buf,
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MIN(clen, command.used))) {
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gdb_commands[i].handler(&command, clen, &reply);
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break;
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}
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}
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/* If we're resuming, we won't send a reply until we stop. */
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if (gdb_state.resumed)
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return;
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gdb_send_reply(&reply);
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}
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}
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static void gdb_output_write(const void *buffer, size_t count)
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{
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if (!gdb_state.resumed) {
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/* Must be a die_if() in GDB (or a bug), so bail out and die. */
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gdb_exit(-1);
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video_console_init();
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puts("GDB died, redirecting its last words to the screen:\n");
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console_write(buffer, count);
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} else {
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reply.used = 0;
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reply.buf[reply.used++] = 'O';
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gdb_message_encode_bytes(&reply, buffer, count);
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gdb_send_reply(&reply);
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}
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}
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static struct console_output_driver gdb_output_driver = {
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.write = &gdb_output_write
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};
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static void gdb_init(void)
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{
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printf("Ready for GDB connection.\n");
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gdb_transport_init();
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gdb_arch_init();
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console_add_output_driver(&gdb_output_driver);
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}
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void gdb_enter(void)
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{
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if (!gdb_state.connected)
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gdb_init();
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gdb_arch_enter();
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}
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void gdb_exit(s8 exit_status)
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{
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if (!gdb_state.connected)
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return;
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reply.used = 0;
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gdb_message_add_string(&reply, "W");
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gdb_message_encode_bytes(&reply, &exit_status, 1);
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gdb_send_reply(&reply);
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console_remove_output_driver(&gdb_output_write);
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gdb_transport_teardown();
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gdb_state.connected = 0;
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printf("Detached from GDB connection.\n");
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}
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/*
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* This is a check architecture backends can run before entering the GDB command
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* loop during exception handling. If it returns true, GDB was already running
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* and must have caused an exception itself, which may happen if the GDB server
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* tells us to do something stupid (e.g. write to an unmapped address). In that
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* case, all we can do is blindly send a generic error code (since we're not
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* sure which command caused the exception) and continue serving commands. When
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* GDB eventually tells us to resume, we'll return from this function to the
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* architecture backend which will have to do a "super exception return" that
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* returns right back from the original (outermost) exception, "jumping over"
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* all the intermediate exception frames we may have accumulated since. (This is
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* the best we can do because our architecture backends generally don't support
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* "full", unlimited exception reentrancy.)
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*/
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int gdb_handle_reentrant_exception(void)
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{
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if (!gdb_state.connected || gdb_state.resumed)
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return 0; /* This is not a reentrant exception. */
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static const char error_code[] = "E22"; /* EINVAL? */
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static const struct gdb_message tmp_reply = {
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.buf = (u8 *)error_code,
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.used = sizeof(error_code),
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.size = sizeof(error_code),
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};
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gdb_send_reply(&tmp_reply);
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gdb_command_loop(gdb_state.signal); /* preserve old signal */
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return 1;
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}
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