2 * gdb server stub - softmmu specific bits
4 * Debug integration depends on support from the individual
5 * accelerators so most of this involves calling the ops helpers.
7 * Copyright (c) 2003-2005 Fabrice Bellard
8 * Copyright (c) 2022 Linaro Ltd
10 * SPDX-License-Identifier: LGPL-2.0+
13 #include "qemu/osdep.h"
14 #include "qapi/error.h"
15 #include "qemu/error-report.h"
16 #include "qemu/cutils.h"
17 #include "exec/gdbstub.h"
18 #include "gdbstub/syscalls.h"
19 #include "exec/hwaddr.h"
20 #include "exec/tb-flush.h"
21 #include "sysemu/cpus.h"
22 #include "sysemu/runstate.h"
23 #include "sysemu/replay.h"
24 #include "hw/core/cpu.h"
25 #include "hw/cpu/cluster.h"
26 #include "hw/boards.h"
27 #include "chardev/char.h"
28 #include "chardev/char-fe.h"
29 #include "monitor/monitor.h"
31 #include "internals.h"
33 /* System emulation specific state */
39 GDBSystemState gdbserver_system_state;
41 static void reset_gdbserver_state(void)
43 g_free(gdbserver_state.processes);
44 gdbserver_state.processes = NULL;
45 gdbserver_state.process_num = 0;
46 gdbserver_state.allow_stop_reply = false;
50 * Return the GDB index for a given vCPU state.
52 * In system mode GDB numbers CPUs from 1 as 0 is reserved as an "any
55 int gdb_get_cpu_index(CPUState *cpu)
57 return cpu->cpu_index + 1;
61 * We check the status of the last message in the chardev receive code
63 bool gdb_got_immediate_ack(void)
69 * GDB Connection management. For system emulation we do all of this
70 * via our existing Chardev infrastructure which allows us to support
71 * network and unix sockets.
74 void gdb_put_buffer(const uint8_t *buf, int len)
77 * XXX this blocks entire thread. Rewrite to use
78 * qemu_chr_fe_write and background I/O callbacks
80 qemu_chr_fe_write_all(&gdbserver_system_state.chr, buf, len);
83 static void gdb_chr_event(void *opaque, QEMUChrEvent event)
86 GDBState *s = (GDBState *) opaque;
89 case CHR_EVENT_OPENED:
90 /* Start with first process attached, others detached */
91 for (i = 0; i < s->process_num; i++) {
92 s->processes[i].attached = !i;
95 s->c_cpu = gdb_first_attached_cpu();
98 vm_stop(RUN_STATE_PAUSED);
99 replay_gdb_attached();
108 * In softmmu mode we stop the VM and wait to send the syscall packet
109 * until notification that the CPU has stopped. This must be done
110 * because if the packet is sent now the reply from the syscall
111 * request could be received while the CPU is still in the running
112 * state, which can cause packets to be dropped and state transition
113 * 'T' packets to be sent while the syscall is still being processed.
115 void gdb_syscall_handling(const char *syscall_packet)
117 vm_stop(RUN_STATE_DEBUG);
118 qemu_cpu_kick(gdbserver_state.c_cpu);
121 static void gdb_vm_state_change(void *opaque, bool running, RunState state)
123 CPUState *cpu = gdbserver_state.c_cpu;
124 g_autoptr(GString) buf = g_string_new(NULL);
125 g_autoptr(GString) tid = g_string_new(NULL);
129 if (running || gdbserver_state.state == RS_INACTIVE) {
133 /* Is there a GDB syscall waiting to be sent? */
134 if (gdb_handled_syscall()) {
139 /* No process attached */
143 if (!gdbserver_state.allow_stop_reply) {
147 gdb_append_thread_id(cpu, tid);
150 case RUN_STATE_DEBUG:
151 if (cpu->watchpoint_hit) {
152 switch (cpu->watchpoint_hit->flags & BP_MEM_ACCESS) {
163 trace_gdbstub_hit_watchpoint(type,
164 gdb_get_cpu_index(cpu),
165 cpu->watchpoint_hit->vaddr);
166 g_string_printf(buf, "T%02xthread:%s;%swatch:%" VADDR_PRIx ";",
167 GDB_SIGNAL_TRAP, tid->str, type,
168 cpu->watchpoint_hit->vaddr);
169 cpu->watchpoint_hit = NULL;
172 trace_gdbstub_hit_break();
175 ret = GDB_SIGNAL_TRAP;
177 case RUN_STATE_PAUSED:
178 trace_gdbstub_hit_paused();
179 ret = GDB_SIGNAL_INT;
181 case RUN_STATE_SHUTDOWN:
182 trace_gdbstub_hit_shutdown();
183 ret = GDB_SIGNAL_QUIT;
185 case RUN_STATE_IO_ERROR:
186 trace_gdbstub_hit_io_error();
189 case RUN_STATE_WATCHDOG:
190 trace_gdbstub_hit_watchdog();
191 ret = GDB_SIGNAL_ALRM;
193 case RUN_STATE_INTERNAL_ERROR:
194 trace_gdbstub_hit_internal_error();
195 ret = GDB_SIGNAL_ABRT;
197 case RUN_STATE_SAVE_VM:
198 case RUN_STATE_RESTORE_VM:
200 case RUN_STATE_FINISH_MIGRATE:
201 ret = GDB_SIGNAL_XCPU;
204 trace_gdbstub_hit_unknown(state);
205 ret = GDB_SIGNAL_UNKNOWN;
208 gdb_set_stop_cpu(cpu);
209 g_string_printf(buf, "T%02xthread:%s;", ret, tid->str);
212 gdb_put_packet(buf->str);
213 gdbserver_state.allow_stop_reply = false;
215 /* disable single step if it was enabled */
216 cpu_single_step(cpu, 0);
220 static void gdb_sigterm_handler(int signal)
222 if (runstate_is_running()) {
223 vm_stop(RUN_STATE_PAUSED);
228 static int gdb_monitor_write(Chardev *chr, const uint8_t *buf, int len)
230 g_autoptr(GString) hex_buf = g_string_new("O");
231 gdb_memtohex(hex_buf, buf, len);
232 gdb_put_packet(hex_buf->str);
236 static void gdb_monitor_open(Chardev *chr, ChardevBackend *backend,
237 bool *be_opened, Error **errp)
242 static void char_gdb_class_init(ObjectClass *oc, void *data)
244 ChardevClass *cc = CHARDEV_CLASS(oc);
247 cc->open = gdb_monitor_open;
248 cc->chr_write = gdb_monitor_write;
251 #define TYPE_CHARDEV_GDB "chardev-gdb"
253 static const TypeInfo char_gdb_type_info = {
254 .name = TYPE_CHARDEV_GDB,
255 .parent = TYPE_CHARDEV,
256 .class_init = char_gdb_class_init,
259 static int gdb_chr_can_receive(void *opaque)
262 * We can handle an arbitrarily large amount of data.
263 * Pick the maximum packet size, which is as good as anything.
265 return MAX_PACKET_LENGTH;
268 static void gdb_chr_receive(void *opaque, const uint8_t *buf, int size)
272 for (i = 0; i < size; i++) {
273 gdb_read_byte(buf[i]);
277 static int find_cpu_clusters(Object *child, void *opaque)
279 if (object_dynamic_cast(child, TYPE_CPU_CLUSTER)) {
280 GDBState *s = (GDBState *) opaque;
281 CPUClusterState *cluster = CPU_CLUSTER(child);
284 s->processes = g_renew(GDBProcess, s->processes, ++s->process_num);
286 process = &s->processes[s->process_num - 1];
289 * GDB process IDs -1 and 0 are reserved. To avoid subtle errors at
290 * runtime, we enforce here that the machine does not use a cluster ID
291 * that would lead to PID 0.
293 assert(cluster->cluster_id != UINT32_MAX);
294 process->pid = cluster->cluster_id + 1;
295 process->attached = false;
296 process->target_xml[0] = '\0';
301 return object_child_foreach(child, find_cpu_clusters, opaque);
304 static int pid_order(const void *a, const void *b)
306 GDBProcess *pa = (GDBProcess *) a;
307 GDBProcess *pb = (GDBProcess *) b;
309 if (pa->pid < pb->pid) {
311 } else if (pa->pid > pb->pid) {
318 static void create_processes(GDBState *s)
320 object_child_foreach(object_get_root(), find_cpu_clusters, s);
322 if (gdbserver_state.processes) {
324 qsort(gdbserver_state.processes,
325 gdbserver_state.process_num,
326 sizeof(gdbserver_state.processes[0]),
330 gdb_create_default_process(s);
333 int gdbserver_start(const char *device)
335 trace_gdbstub_op_start(device);
337 char gdbstub_device_name[128];
342 error_report("gdbstub: meaningless to attach gdb to a "
343 "machine without any CPU.");
347 if (!gdb_supports_guest_debug()) {
348 error_report("gdbstub: current accelerator doesn't "
349 "support guest debugging");
356 if (strcmp(device, "none") != 0) {
357 if (strstart(device, "tcp:", NULL)) {
358 /* enforce required TCP attributes */
359 snprintf(gdbstub_device_name, sizeof(gdbstub_device_name),
360 "%s,wait=off,nodelay=on,server=on", device);
361 device = gdbstub_device_name;
364 else if (strcmp(device, "stdio") == 0) {
365 struct sigaction act;
367 memset(&act, 0, sizeof(act));
368 act.sa_handler = gdb_sigterm_handler;
369 sigaction(SIGINT, &act, NULL);
373 * FIXME: it's a bit weird to allow using a mux chardev here
374 * and implicitly setup a monitor. We may want to break this.
376 chr = qemu_chr_new_noreplay("gdb", device, true, NULL);
382 if (!gdbserver_state.init) {
383 gdb_init_gdbserver_state();
385 qemu_add_vm_change_state_handler(gdb_vm_state_change, NULL);
387 /* Initialize a monitor terminal for gdb */
388 mon_chr = qemu_chardev_new(NULL, TYPE_CHARDEV_GDB,
389 NULL, NULL, &error_abort);
390 monitor_init_hmp(mon_chr, false, &error_abort);
392 qemu_chr_fe_deinit(&gdbserver_system_state.chr, true);
393 mon_chr = gdbserver_system_state.mon_chr;
394 reset_gdbserver_state();
397 create_processes(&gdbserver_state);
400 qemu_chr_fe_init(&gdbserver_system_state.chr, chr, &error_abort);
401 qemu_chr_fe_set_handlers(&gdbserver_system_state.chr,
403 gdb_chr_receive, gdb_chr_event,
404 NULL, &gdbserver_state, NULL, true);
406 gdbserver_state.state = chr ? RS_IDLE : RS_INACTIVE;
407 gdbserver_system_state.mon_chr = mon_chr;
413 static void register_types(void)
415 type_register_static(&char_gdb_type_info);
418 type_init(register_types);
420 /* Tell the remote gdb that the process has exited. */
421 void gdb_exit(int code)
425 if (!gdbserver_state.init) {
429 trace_gdbstub_op_exiting((uint8_t)code);
431 if (gdbserver_state.allow_stop_reply) {
432 snprintf(buf, sizeof(buf), "W%02x", (uint8_t)code);
434 gdbserver_state.allow_stop_reply = false;
437 qemu_chr_fe_deinit(&gdbserver_system_state.chr, true);
443 static int phy_memory_mode;
445 int gdb_target_memory_rw_debug(CPUState *cpu, hwaddr addr,
446 uint8_t *buf, int len, bool is_write)
450 if (phy_memory_mode) {
452 cpu_physical_memory_write(addr, buf, len);
454 cpu_physical_memory_read(addr, buf, len);
459 cc = CPU_GET_CLASS(cpu);
460 if (cc->memory_rw_debug) {
461 return cc->memory_rw_debug(cpu, addr, buf, len, is_write);
464 return cpu_memory_rw_debug(cpu, addr, buf, len, is_write);
471 unsigned int gdb_get_max_cpus(void)
473 MachineState *ms = MACHINE(qdev_get_machine());
474 return ms->smp.max_cpus;
477 bool gdb_can_reverse(void)
479 return replay_mode == REPLAY_MODE_PLAY;
483 * Softmmu specific command helpers
486 void gdb_handle_query_qemu_phy_mem_mode(GArray *params,
489 g_string_printf(gdbserver_state.str_buf, "%d", phy_memory_mode);
493 void gdb_handle_set_qemu_phy_mem_mode(GArray *params, void *user_ctx)
496 gdb_put_packet("E22");
500 if (!get_param(params, 0)->val_ul) {
505 gdb_put_packet("OK");
508 void gdb_handle_query_rcmd(GArray *params, void *user_ctx)
510 const guint8 zero = 0;
514 gdb_put_packet("E22");
518 len = strlen(get_param(params, 0)->data);
520 gdb_put_packet("E01");
524 g_assert(gdbserver_state.mem_buf->len == 0);
526 gdb_hextomem(gdbserver_state.mem_buf, get_param(params, 0)->data, len);
527 g_byte_array_append(gdbserver_state.mem_buf, &zero, 1);
528 qemu_chr_be_write(gdbserver_system_state.mon_chr,
529 gdbserver_state.mem_buf->data,
530 gdbserver_state.mem_buf->len);
531 gdb_put_packet("OK");
535 * Execution state helpers
538 void gdb_handle_query_attached(GArray *params, void *user_ctx)
543 void gdb_continue(void)
545 if (!runstate_needs_reset()) {
546 trace_gdbstub_op_continue();
552 * Resume execution, per CPU actions.
554 int gdb_continue_partial(char *newstates)
560 if (!runstate_needs_reset()) {
561 bool step_requested = false;
563 if (newstates[cpu->cpu_index] == 's') {
564 step_requested = true;
569 if (vm_prepare_start(step_requested)) {
574 switch (newstates[cpu->cpu_index]) {
577 break; /* nothing to do here */
579 trace_gdbstub_op_stepping(cpu->cpu_index);
580 cpu_single_step(cpu, gdbserver_state.sstep_flags);
585 trace_gdbstub_op_continue_cpu(cpu->cpu_index);
596 qemu_clock_enable(QEMU_CLOCK_VIRTUAL, true);
602 * Signal Handling - in system mode we only need SIGINT and SIGTRAP; other
603 * signals are not yet supported.
611 int gdb_signal_to_target(int sig)
615 return TARGET_SIGINT;
617 return TARGET_SIGTRAP;
624 * Break/Watch point helpers
627 bool gdb_supports_guest_debug(void)
629 const AccelOpsClass *ops = cpus_get_accel();
630 if (ops->supports_guest_debug) {
631 return ops->supports_guest_debug();
636 int gdb_breakpoint_insert(CPUState *cs, int type, vaddr addr, vaddr len)
638 const AccelOpsClass *ops = cpus_get_accel();
639 if (ops->insert_breakpoint) {
640 return ops->insert_breakpoint(cs, type, addr, len);
645 int gdb_breakpoint_remove(CPUState *cs, int type, vaddr addr, vaddr len)
647 const AccelOpsClass *ops = cpus_get_accel();
648 if (ops->remove_breakpoint) {
649 return ops->remove_breakpoint(cs, type, addr, len);
654 void gdb_breakpoint_remove_all(CPUState *cs)
656 const AccelOpsClass *ops = cpus_get_accel();
657 if (ops->remove_all_breakpoints) {
658 ops->remove_all_breakpoints(cs);