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qemu/gdbstub/system.c
Philippe Mathieu-Daudé 0eaf7fb9a8 gdbstub/system: Rename 'user_ctx' argument as 'ctx' 
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20240313213339.82071-4-philmd@linaro.org>
2024-04-02 14:55:07 +02:00

665 lines
16 KiB
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/*
* gdb server stub - system specific bits
*
* Debug integration depends on support from the individual
* accelerators so most of this involves calling the ops helpers.
*
* Copyright (c) 2003-2005 Fabrice Bellard
* Copyright (c) 2022 Linaro Ltd
*
* SPDX-License-Identifier: LGPL-2.0+
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "qemu/cutils.h"
#include "exec/gdbstub.h"
#include "gdbstub/syscalls.h"
#include "exec/hwaddr.h"
#include "exec/tb-flush.h"
#include "sysemu/cpus.h"
#include "sysemu/runstate.h"
#include "sysemu/replay.h"
#include "hw/core/cpu.h"
#include "hw/cpu/cluster.h"
#include "hw/boards.h"
#include "chardev/char.h"
#include "chardev/char-fe.h"
#include "monitor/monitor.h"
#include "trace.h"
#include "internals.h"
/* System emulation specific state */
typedef struct {
CharBackend chr;
Chardev *mon_chr;
} GDBSystemState;
GDBSystemState gdbserver_system_state;
static void reset_gdbserver_state(void)
{
g_free(gdbserver_state.processes);
gdbserver_state.processes = NULL;
gdbserver_state.process_num = 0;
gdbserver_state.allow_stop_reply = false;
}
/*
* Return the GDB index for a given vCPU state.
*
* In system mode GDB numbers CPUs from 1 as 0 is reserved as an "any
* cpu" index.
*/
int gdb_get_cpu_index(CPUState *cpu)
{
return cpu->cpu_index + 1;
}
/*
* We check the status of the last message in the chardev receive code
*/
bool gdb_got_immediate_ack(void)
{
return true;
}
/*
* GDB Connection management. For system emulation we do all of this
* via our existing Chardev infrastructure which allows us to support
* network and unix sockets.
*/
void gdb_put_buffer(const uint8_t *buf, int len)
{
/*
* XXX this blocks entire thread. Rewrite to use
* qemu_chr_fe_write and background I/O callbacks
*/
qemu_chr_fe_write_all(&gdbserver_system_state.chr, buf, len);
}
static void gdb_chr_event(void *opaque, QEMUChrEvent event)
{
int i;
GDBState *s = (GDBState *) opaque;
switch (event) {
case CHR_EVENT_OPENED:
/* Start with first process attached, others detached */
for (i = 0; i < s->process_num; i++) {
s->processes[i].attached = !i;
}
s->c_cpu = gdb_first_attached_cpu();
s->g_cpu = s->c_cpu;
vm_stop(RUN_STATE_PAUSED);
replay_gdb_attached();
break;
default:
break;
}
}
/*
* In system-mode we stop the VM and wait to send the syscall packet
* until notification that the CPU has stopped. This must be done
* because if the packet is sent now the reply from the syscall
* request could be received while the CPU is still in the running
* state, which can cause packets to be dropped and state transition
* 'T' packets to be sent while the syscall is still being processed.
*/
void gdb_syscall_handling(const char *syscall_packet)
{
vm_stop(RUN_STATE_DEBUG);
qemu_cpu_kick(gdbserver_state.c_cpu);
}
static void gdb_vm_state_change(void *opaque, bool running, RunState state)
{
CPUState *cpu = gdbserver_state.c_cpu;
g_autoptr(GString) buf = g_string_new(NULL);
g_autoptr(GString) tid = g_string_new(NULL);
const char *type;
int ret;
if (running || gdbserver_state.state == RS_INACTIVE) {
return;
}
/* Is there a GDB syscall waiting to be sent? */
if (gdb_handled_syscall()) {
return;
}
if (cpu == NULL) {
/* No process attached */
return;
}
if (!gdbserver_state.allow_stop_reply) {
return;
}
gdb_append_thread_id(cpu, tid);
switch (state) {
case RUN_STATE_DEBUG:
if (cpu->watchpoint_hit) {
switch (cpu->watchpoint_hit->flags & BP_MEM_ACCESS) {
case BP_MEM_READ:
type = "r";
break;
case BP_MEM_ACCESS:
type = "a";
break;
default:
type = "";
break;
}
trace_gdbstub_hit_watchpoint(type,
gdb_get_cpu_index(cpu),
cpu->watchpoint_hit->vaddr);
g_string_printf(buf, "T%02xthread:%s;%swatch:%" VADDR_PRIx ";",
GDB_SIGNAL_TRAP, tid->str, type,
cpu->watchpoint_hit->vaddr);
cpu->watchpoint_hit = NULL;
goto send_packet;
} else {
trace_gdbstub_hit_break();
}
tb_flush(cpu);
ret = GDB_SIGNAL_TRAP;
break;
case RUN_STATE_PAUSED:
trace_gdbstub_hit_paused();
ret = GDB_SIGNAL_INT;
break;
case RUN_STATE_SHUTDOWN:
trace_gdbstub_hit_shutdown();
ret = GDB_SIGNAL_QUIT;
break;
case RUN_STATE_IO_ERROR:
trace_gdbstub_hit_io_error();
ret = GDB_SIGNAL_STOP;
break;
case RUN_STATE_WATCHDOG:
trace_gdbstub_hit_watchdog();
ret = GDB_SIGNAL_ALRM;
break;
case RUN_STATE_INTERNAL_ERROR:
trace_gdbstub_hit_internal_error();
ret = GDB_SIGNAL_ABRT;
break;
case RUN_STATE_SAVE_VM:
case RUN_STATE_RESTORE_VM:
return;
case RUN_STATE_FINISH_MIGRATE:
ret = GDB_SIGNAL_XCPU;
break;
default:
trace_gdbstub_hit_unknown(state);
ret = GDB_SIGNAL_UNKNOWN;
break;
}
gdb_set_stop_cpu(cpu);
g_string_printf(buf, "T%02xthread:%s;", ret, tid->str);
send_packet:
gdb_put_packet(buf->str);
gdbserver_state.allow_stop_reply = false;
/* disable single step if it was enabled */
cpu_single_step(cpu, 0);
}
#ifndef _WIN32
static void gdb_sigterm_handler(int signal)
{
if (runstate_is_running()) {
vm_stop(RUN_STATE_PAUSED);
}
}
#endif
static int gdb_monitor_write(Chardev *chr, const uint8_t *buf, int len)
{
g_autoptr(GString) hex_buf = g_string_new("O");
gdb_memtohex(hex_buf, buf, len);
gdb_put_packet(hex_buf->str);
return len;
}
static void gdb_monitor_open(Chardev *chr, ChardevBackend *backend,
bool *be_opened, Error **errp)
{
*be_opened = false;
}
static void char_gdb_class_init(ObjectClass *oc, void *data)
{
ChardevClass *cc = CHARDEV_CLASS(oc);
cc->internal = true;
cc->open = gdb_monitor_open;
cc->chr_write = gdb_monitor_write;
}
#define TYPE_CHARDEV_GDB "chardev-gdb"
static const TypeInfo char_gdb_type_info = {
.name = TYPE_CHARDEV_GDB,
.parent = TYPE_CHARDEV,
.class_init = char_gdb_class_init,
};
static int gdb_chr_can_receive(void *opaque)
{
/*
* We can handle an arbitrarily large amount of data.
* Pick the maximum packet size, which is as good as anything.
*/
return MAX_PACKET_LENGTH;
}
static void gdb_chr_receive(void *opaque, const uint8_t *buf, int size)
{
int i;
for (i = 0; i < size; i++) {
gdb_read_byte(buf[i]);
}
}
static int find_cpu_clusters(Object *child, void *opaque)
{
if (object_dynamic_cast(child, TYPE_CPU_CLUSTER)) {
GDBState *s = (GDBState *) opaque;
CPUClusterState *cluster = CPU_CLUSTER(child);
GDBProcess *process;
s->processes = g_renew(GDBProcess, s->processes, ++s->process_num);
process = &s->processes[s->process_num - 1];
/*
* GDB process IDs -1 and 0 are reserved. To avoid subtle errors at
* runtime, we enforce here that the machine does not use a cluster ID
* that would lead to PID 0.
*/
assert(cluster->cluster_id != UINT32_MAX);
process->pid = cluster->cluster_id + 1;
process->attached = false;
process->target_xml = NULL;
return 0;
}
return object_child_foreach(child, find_cpu_clusters, opaque);
}
static int pid_order(const void *a, const void *b)
{
GDBProcess *pa = (GDBProcess *) a;
GDBProcess *pb = (GDBProcess *) b;
if (pa->pid < pb->pid) {
return -1;
} else if (pa->pid > pb->pid) {
return 1;
} else {
return 0;
}
}
static void create_processes(GDBState *s)
{
object_child_foreach(object_get_root(), find_cpu_clusters, s);
if (gdbserver_state.processes) {
/* Sort by PID */
qsort(gdbserver_state.processes,
gdbserver_state.process_num,
sizeof(gdbserver_state.processes[0]),
pid_order);
}
gdb_create_default_process(s);
}
int gdbserver_start(const char *device)
{
Chardev *chr = NULL;
Chardev *mon_chr;
g_autoptr(GString) cs = g_string_new(device);
if (!first_cpu) {
error_report("gdbstub: meaningless to attach gdb to a "
"machine without any CPU.");
return -1;
}
if (!gdb_supports_guest_debug()) {
error_report("gdbstub: current accelerator doesn't "
"support guest debugging");
return -1;
}
if (cs->len == 0) {
return -1;
}
trace_gdbstub_op_start(cs->str);
if (g_strcmp0(cs->str, "none") != 0) {
if (g_str_has_prefix(cs->str, "tcp:")) {
/* enforce required TCP attributes */
g_string_append_printf(cs, ",wait=off,nodelay=on,server=on");
}
#ifndef _WIN32
else if (strcmp(device, "stdio") == 0) {
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_handler = gdb_sigterm_handler;
sigaction(SIGINT, &act, NULL);
}
#endif
/*
* FIXME: it's a bit weird to allow using a mux chardev here
* and implicitly setup a monitor. We may want to break this.
*/
chr = qemu_chr_new_noreplay("gdb", cs->str, true, NULL);
if (!chr) {
return -1;
}
}
if (!gdbserver_state.init) {
gdb_init_gdbserver_state();
qemu_add_vm_change_state_handler(gdb_vm_state_change, NULL);
/* Initialize a monitor terminal for gdb */
mon_chr = qemu_chardev_new(NULL, TYPE_CHARDEV_GDB,
NULL, NULL, &error_abort);
monitor_init_hmp(mon_chr, false, &error_abort);
} else {
qemu_chr_fe_deinit(&gdbserver_system_state.chr, true);
mon_chr = gdbserver_system_state.mon_chr;
reset_gdbserver_state();
}
create_processes(&gdbserver_state);
if (chr) {
qemu_chr_fe_init(&gdbserver_system_state.chr, chr, &error_abort);
qemu_chr_fe_set_handlers(&gdbserver_system_state.chr,
gdb_chr_can_receive,
gdb_chr_receive, gdb_chr_event,
NULL, &gdbserver_state, NULL, true);
}
gdbserver_state.state = chr ? RS_IDLE : RS_INACTIVE;
gdbserver_system_state.mon_chr = mon_chr;
gdb_syscall_reset();
return 0;
}
static void register_types(void)
{
type_register_static(&char_gdb_type_info);
}
type_init(register_types);
/* Tell the remote gdb that the process has exited. */
void gdb_exit(int code)
{
char buf[4];
if (!gdbserver_state.init) {
return;
}
trace_gdbstub_op_exiting((uint8_t)code);
if (gdbserver_state.allow_stop_reply) {
snprintf(buf, sizeof(buf), "W%02x", (uint8_t)code);
gdb_put_packet(buf);
gdbserver_state.allow_stop_reply = false;
}
qemu_chr_fe_deinit(&gdbserver_system_state.chr, true);
}
void gdb_qemu_exit(int code)
{
qemu_system_shutdown_request_with_code(SHUTDOWN_CAUSE_GUEST_SHUTDOWN,
code);
}
/*
* Memory access
*/
static int phy_memory_mode;
int gdb_target_memory_rw_debug(CPUState *cpu, hwaddr addr,
uint8_t *buf, int len, bool is_write)
{
CPUClass *cc;
if (phy_memory_mode) {
if (is_write) {
cpu_physical_memory_write(addr, buf, len);
} else {
cpu_physical_memory_read(addr, buf, len);
}
return 0;
}
cc = CPU_GET_CLASS(cpu);
if (cc->memory_rw_debug) {
return cc->memory_rw_debug(cpu, addr, buf, len, is_write);
}
return cpu_memory_rw_debug(cpu, addr, buf, len, is_write);
}
/*
* cpu helpers
*/
unsigned int gdb_get_max_cpus(void)
{
MachineState *ms = MACHINE(qdev_get_machine());
return ms->smp.max_cpus;
}
bool gdb_can_reverse(void)
{
return replay_mode == REPLAY_MODE_PLAY;
}
/*
* Softmmu specific command helpers
*/
void gdb_handle_query_qemu_phy_mem_mode(GArray *params,
void *ctx)
{
g_string_printf(gdbserver_state.str_buf, "%d", phy_memory_mode);
gdb_put_strbuf();
}
void gdb_handle_set_qemu_phy_mem_mode(GArray *params, void *ctx)
{
if (!params->len) {
gdb_put_packet("E22");
return;
}
if (!get_param(params, 0)->val_ul) {
phy_memory_mode = 0;
} else {
phy_memory_mode = 1;
}
gdb_put_packet("OK");
}
void gdb_handle_query_rcmd(GArray *params, void *ctx)
{
const guint8 zero = 0;
int len;
if (!params->len) {
gdb_put_packet("E22");
return;
}
len = strlen(get_param(params, 0)->data);
if (len % 2) {
gdb_put_packet("E01");
return;
}
g_assert(gdbserver_state.mem_buf->len == 0);
len = len / 2;
gdb_hextomem(gdbserver_state.mem_buf, get_param(params, 0)->data, len);
g_byte_array_append(gdbserver_state.mem_buf, &zero, 1);
qemu_chr_be_write(gdbserver_system_state.mon_chr,
gdbserver_state.mem_buf->data,
gdbserver_state.mem_buf->len);
gdb_put_packet("OK");
}
/*
* Execution state helpers
*/
void gdb_handle_query_attached(GArray *params, void *ctx)
{
gdb_put_packet("1");
}
void gdb_continue(void)
{
if (!runstate_needs_reset()) {
trace_gdbstub_op_continue();
vm_start();
}
}
/*
* Resume execution, per CPU actions.
*/
int gdb_continue_partial(char *newstates)
{
CPUState *cpu;
int res = 0;
int flag = 0;
if (!runstate_needs_reset()) {
bool step_requested = false;
CPU_FOREACH(cpu) {
if (newstates[cpu->cpu_index] == 's') {
step_requested = true;
break;
}
}
if (vm_prepare_start(step_requested)) {
return 0;
}
CPU_FOREACH(cpu) {
switch (newstates[cpu->cpu_index]) {
case 0:
case 1:
break; /* nothing to do here */
case 's':
trace_gdbstub_op_stepping(cpu->cpu_index);
cpu_single_step(cpu, gdbserver_state.sstep_flags);
cpu_resume(cpu);
flag = 1;
break;
case 'c':
trace_gdbstub_op_continue_cpu(cpu->cpu_index);
cpu_resume(cpu);
flag = 1;
break;
default:
res = -1;
break;
}
}
}
if (flag) {
qemu_clock_enable(QEMU_CLOCK_VIRTUAL, true);
}
return res;
}
/*
* Signal Handling - in system mode we only need SIGINT and SIGTRAP; other
* signals are not yet supported.
*/
enum {
TARGET_SIGINT = 2,
TARGET_SIGTRAP = 5
};
int gdb_signal_to_target(int sig)
{
switch (sig) {
case 2:
return TARGET_SIGINT;
case 5:
return TARGET_SIGTRAP;
default:
return -1;
}
}
/*
* Break/Watch point helpers
*/
bool gdb_supports_guest_debug(void)
{
const AccelOpsClass *ops = cpus_get_accel();
if (ops->supports_guest_debug) {
return ops->supports_guest_debug();
}
return false;
}
int gdb_breakpoint_insert(CPUState *cs, int type, vaddr addr, vaddr len)
{
const AccelOpsClass *ops = cpus_get_accel();
if (ops->insert_breakpoint) {
return ops->insert_breakpoint(cs, type, addr, len);
}
return -ENOSYS;
}
int gdb_breakpoint_remove(CPUState *cs, int type, vaddr addr, vaddr len)
{
const AccelOpsClass *ops = cpus_get_accel();
if (ops->remove_breakpoint) {
return ops->remove_breakpoint(cs, type, addr, len);
}
return -ENOSYS;
}
void gdb_breakpoint_remove_all(CPUState *cs)
{
const AccelOpsClass *ops = cpus_get_accel();
if (ops->remove_all_breakpoints) {
ops->remove_all_breakpoints(cs);
}
}
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