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qemu/cpus.c
Jan Kiszka 3c638d0690 Rework debug exception processing for gdb use 
Guest debugging is currently broken under CONFIG_IOTHREAD. The reason is
inconsistent or even lacking signaling the debug events from the source
VCPU to the main loop and the gdbstub.

This patch addresses the issue by pushing this signaling into a
CPUDebugExcpHandler: cpu_debug_handler is registered as first handler,
thus will be executed last after potential breakpoint emulation
handlers. It sets informs the gdbstub about the debug event source,
requests a debug exit of the main loop and stops the current VCPU. This
mechanism works both for TCG and KVM, with and without IO-thread.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
2010-07-22 05:52:09 +02:00

862 lines
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/*
* QEMU System Emulator
*
* Copyright (c) 2003-2008 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/* Needed early for CONFIG_BSD etc. */
#include "config-host.h"
#include "monitor.h"
#include "sysemu.h"
#include "gdbstub.h"
#include "dma.h"
#include "kvm.h"
#include "exec-all.h"
#include "cpus.h"
#ifdef SIGRTMIN
#define SIG_IPI (SIGRTMIN+4)
#else
#define SIG_IPI SIGUSR1
#endif
static CPUState *next_cpu;
/***********************************************************/
void hw_error(const char *fmt, ...)
{
va_list ap;
CPUState *env;
va_start(ap, fmt);
fprintf(stderr, "qemu: hardware error: ");
vfprintf(stderr, fmt, ap);
fprintf(stderr, "\n");
for(env = first_cpu; env != NULL; env = env->next_cpu) {
fprintf(stderr, "CPU #%d:\n", env->cpu_index);
#ifdef TARGET_I386
cpu_dump_state(env, stderr, fprintf, X86_DUMP_FPU);
#else
cpu_dump_state(env, stderr, fprintf, 0);
#endif
}
va_end(ap);
abort();
}
void cpu_synchronize_all_states(void)
{
CPUState *cpu;
for (cpu = first_cpu; cpu; cpu = cpu->next_cpu) {
cpu_synchronize_state(cpu);
}
}
void cpu_synchronize_all_post_reset(void)
{
CPUState *cpu;
for (cpu = first_cpu; cpu; cpu = cpu->next_cpu) {
cpu_synchronize_post_reset(cpu);
}
}
void cpu_synchronize_all_post_init(void)
{
CPUState *cpu;
for (cpu = first_cpu; cpu; cpu = cpu->next_cpu) {
cpu_synchronize_post_init(cpu);
}
}
int cpu_is_stopped(CPUState *env)
{
return !vm_running || env->stopped;
}
static void do_vm_stop(int reason)
{
if (vm_running) {
cpu_disable_ticks();
vm_running = 0;
pause_all_vcpus();
vm_state_notify(0, reason);
monitor_protocol_event(QEVENT_STOP, NULL);
}
}
static int cpu_can_run(CPUState *env)
{
if (env->stop)
return 0;
if (env->stopped || !vm_running)
return 0;
return 1;
}
static int cpu_has_work(CPUState *env)
{
if (env->stop)
return 1;
if (env->queued_work_first)
return 1;
if (env->stopped || !vm_running)
return 0;
if (!env->halted)
return 1;
if (qemu_cpu_has_work(env))
return 1;
return 0;
}
static int any_cpu_has_work(void)
{
CPUState *env;
for (env = first_cpu; env != NULL; env = env->next_cpu)
if (cpu_has_work(env))
return 1;
return 0;
}
static void cpu_debug_handler(CPUState *env)
{
gdb_set_stop_cpu(env);
debug_requested = EXCP_DEBUG;
vm_stop(EXCP_DEBUG);
}
#ifndef _WIN32
static int io_thread_fd = -1;
static void qemu_event_increment(void)
{
/* Write 8 bytes to be compatible with eventfd. */
static const uint64_t val = 1;
ssize_t ret;
if (io_thread_fd == -1)
return;
do {
ret = write(io_thread_fd, &val, sizeof(val));
} while (ret < 0 && errno == EINTR);
/* EAGAIN is fine, a read must be pending. */
if (ret < 0 && errno != EAGAIN) {
fprintf(stderr, "qemu_event_increment: write() filed: %s\n",
strerror(errno));
exit (1);
}
}
static void qemu_event_read(void *opaque)
{
int fd = (unsigned long)opaque;
ssize_t len;
char buffer[512];
/* Drain the notify pipe. For eventfd, only 8 bytes will be read. */
do {
len = read(fd, buffer, sizeof(buffer));
} while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
}
static int qemu_event_init(void)
{
int err;
int fds[2];
err = qemu_eventfd(fds);
if (err == -1)
return -errno;
err = fcntl_setfl(fds[0], O_NONBLOCK);
if (err < 0)
goto fail;
err = fcntl_setfl(fds[1], O_NONBLOCK);
if (err < 0)
goto fail;
qemu_set_fd_handler2(fds[0], NULL, qemu_event_read, NULL,
(void *)(unsigned long)fds[0]);
io_thread_fd = fds[1];
return 0;
fail:
close(fds[0]);
close(fds[1]);
return err;
}
#else
HANDLE qemu_event_handle;
static void dummy_event_handler(void *opaque)
{
}
static int qemu_event_init(void)
{
qemu_event_handle = CreateEvent(NULL, FALSE, FALSE, NULL);
if (!qemu_event_handle) {
fprintf(stderr, "Failed CreateEvent: %ld\n", GetLastError());
return -1;
}
qemu_add_wait_object(qemu_event_handle, dummy_event_handler, NULL);
return 0;
}
static void qemu_event_increment(void)
{
if (!SetEvent(qemu_event_handle)) {
fprintf(stderr, "qemu_event_increment: SetEvent failed: %ld\n",
GetLastError());
exit (1);
}
}
#endif
#ifndef CONFIG_IOTHREAD
int qemu_init_main_loop(void)
{
cpu_set_debug_excp_handler(cpu_debug_handler);
return qemu_event_init();
}
void qemu_main_loop_start(void)
{
}
void qemu_init_vcpu(void *_env)
{
CPUState *env = _env;
env->nr_cores = smp_cores;
env->nr_threads = smp_threads;
if (kvm_enabled())
kvm_init_vcpu(env);
return;
}
int qemu_cpu_self(void *env)
{
return 1;
}
void run_on_cpu(CPUState *env, void (*func)(void *data), void *data)
{
func(data);
}
void resume_all_vcpus(void)
{
}
void pause_all_vcpus(void)
{
}
void qemu_cpu_kick(void *env)
{
return;
}
void qemu_notify_event(void)
{
CPUState *env = cpu_single_env;
qemu_event_increment ();
if (env) {
cpu_exit(env);
}
if (next_cpu && env != next_cpu) {
cpu_exit(next_cpu);
}
}
void qemu_mutex_lock_iothread(void) {}
void qemu_mutex_unlock_iothread(void) {}
void vm_stop(int reason)
{
do_vm_stop(reason);
}
#else /* CONFIG_IOTHREAD */
#include "qemu-thread.h"
QemuMutex qemu_global_mutex;
static QemuMutex qemu_fair_mutex;
static QemuThread io_thread;
static QemuThread *tcg_cpu_thread;
static QemuCond *tcg_halt_cond;
static int qemu_system_ready;
/* cpu creation */
static QemuCond qemu_cpu_cond;
/* system init */
static QemuCond qemu_system_cond;
static QemuCond qemu_pause_cond;
static QemuCond qemu_work_cond;
static void tcg_init_ipi(void);
static void kvm_init_ipi(CPUState *env);
static void unblock_io_signals(void);
int qemu_init_main_loop(void)
{
int ret;
cpu_set_debug_excp_handler(cpu_debug_handler);
ret = qemu_event_init();
if (ret)
return ret;
qemu_cond_init(&qemu_pause_cond);
qemu_cond_init(&qemu_system_cond);
qemu_mutex_init(&qemu_fair_mutex);
qemu_mutex_init(&qemu_global_mutex);
qemu_mutex_lock(&qemu_global_mutex);
unblock_io_signals();
qemu_thread_self(&io_thread);
return 0;
}
void qemu_main_loop_start(void)
{
qemu_system_ready = 1;
qemu_cond_broadcast(&qemu_system_cond);
}
void run_on_cpu(CPUState *env, void (*func)(void *data), void *data)
{
struct qemu_work_item wi;
if (qemu_cpu_self(env)) {
func(data);
return;
}
wi.func = func;
wi.data = data;
if (!env->queued_work_first)
env->queued_work_first = &wi;
else
env->queued_work_last->next = &wi;
env->queued_work_last = &wi;
wi.next = NULL;
wi.done = false;
qemu_cpu_kick(env);
while (!wi.done) {
CPUState *self_env = cpu_single_env;
qemu_cond_wait(&qemu_work_cond, &qemu_global_mutex);
cpu_single_env = self_env;
}
}
static void flush_queued_work(CPUState *env)
{
struct qemu_work_item *wi;
if (!env->queued_work_first)
return;
while ((wi = env->queued_work_first)) {
env->queued_work_first = wi->next;
wi->func(wi->data);
wi->done = true;
}
env->queued_work_last = NULL;
qemu_cond_broadcast(&qemu_work_cond);
}
static void qemu_wait_io_event_common(CPUState *env)
{
if (env->stop) {
env->stop = 0;
env->stopped = 1;
qemu_cond_signal(&qemu_pause_cond);
}
flush_queued_work(env);
}
static void qemu_tcg_wait_io_event(void)
{
CPUState *env;
while (!any_cpu_has_work())
qemu_cond_timedwait(tcg_halt_cond, &qemu_global_mutex, 1000);
qemu_mutex_unlock(&qemu_global_mutex);
/*
* Users of qemu_global_mutex can be starved, having no chance
* to acquire it since this path will get to it first.
* So use another lock to provide fairness.
*/
qemu_mutex_lock(&qemu_fair_mutex);
qemu_mutex_unlock(&qemu_fair_mutex);
qemu_mutex_lock(&qemu_global_mutex);
for (env = first_cpu; env != NULL; env = env->next_cpu) {
qemu_wait_io_event_common(env);
}
}
static void qemu_kvm_eat_signal(CPUState *env, int timeout)
{
struct timespec ts;
int r, e;
siginfo_t siginfo;
sigset_t waitset;
ts.tv_sec = timeout / 1000;
ts.tv_nsec = (timeout % 1000) * 1000000;
sigemptyset(&waitset);
sigaddset(&waitset, SIG_IPI);
qemu_mutex_unlock(&qemu_global_mutex);
r = sigtimedwait(&waitset, &siginfo, &ts);
e = errno;
qemu_mutex_lock(&qemu_global_mutex);
if (r == -1 && !(e == EAGAIN || e == EINTR)) {
fprintf(stderr, "sigtimedwait: %s\n", strerror(e));
exit(1);
}
}
static void qemu_kvm_wait_io_event(CPUState *env)
{
while (!cpu_has_work(env))
qemu_cond_timedwait(env->halt_cond, &qemu_global_mutex, 1000);
qemu_kvm_eat_signal(env, 0);
qemu_wait_io_event_common(env);
}
static int qemu_cpu_exec(CPUState *env);
static void *kvm_cpu_thread_fn(void *arg)
{
CPUState *env = arg;
qemu_mutex_lock(&qemu_global_mutex);
qemu_thread_self(env->thread);
if (kvm_enabled())
kvm_init_vcpu(env);
kvm_init_ipi(env);
/* signal CPU creation */
env->created = 1;
qemu_cond_signal(&qemu_cpu_cond);
/* and wait for machine initialization */
while (!qemu_system_ready)
qemu_cond_timedwait(&qemu_system_cond, &qemu_global_mutex, 100);
while (1) {
if (cpu_can_run(env))
qemu_cpu_exec(env);
qemu_kvm_wait_io_event(env);
}
return NULL;
}
static void *tcg_cpu_thread_fn(void *arg)
{
CPUState *env = arg;
tcg_init_ipi();
qemu_thread_self(env->thread);
/* signal CPU creation */
qemu_mutex_lock(&qemu_global_mutex);
for (env = first_cpu; env != NULL; env = env->next_cpu)
env->created = 1;
qemu_cond_signal(&qemu_cpu_cond);
/* and wait for machine initialization */
while (!qemu_system_ready)
qemu_cond_timedwait(&qemu_system_cond, &qemu_global_mutex, 100);
while (1) {
cpu_exec_all();
qemu_tcg_wait_io_event();
}
return NULL;
}
void qemu_cpu_kick(void *_env)
{
CPUState *env = _env;
qemu_cond_broadcast(env->halt_cond);
qemu_thread_signal(env->thread, SIG_IPI);
}
int qemu_cpu_self(void *_env)
{
CPUState *env = _env;
QemuThread this;
qemu_thread_self(&this);
return qemu_thread_equal(&this, env->thread);
}
static void cpu_signal(int sig)
{
if (cpu_single_env)
cpu_exit(cpu_single_env);
exit_request = 1;
}
static void tcg_init_ipi(void)
{
sigset_t set;
struct sigaction sigact;
memset(&sigact, 0, sizeof(sigact));
sigact.sa_handler = cpu_signal;
sigaction(SIG_IPI, &sigact, NULL);
sigemptyset(&set);
sigaddset(&set, SIG_IPI);
pthread_sigmask(SIG_UNBLOCK, &set, NULL);
}
static void dummy_signal(int sig)
{
}
static void kvm_init_ipi(CPUState *env)
{
int r;
sigset_t set;
struct sigaction sigact;
memset(&sigact, 0, sizeof(sigact));
sigact.sa_handler = dummy_signal;
sigaction(SIG_IPI, &sigact, NULL);
pthread_sigmask(SIG_BLOCK, NULL, &set);
sigdelset(&set, SIG_IPI);
r = kvm_set_signal_mask(env, &set);
if (r) {
fprintf(stderr, "kvm_set_signal_mask: %s\n", strerror(r));
exit(1);
}
}
static void unblock_io_signals(void)
{
sigset_t set;
sigemptyset(&set);
sigaddset(&set, SIGUSR2);
sigaddset(&set, SIGIO);
sigaddset(&set, SIGALRM);
pthread_sigmask(SIG_UNBLOCK, &set, NULL);
sigemptyset(&set);
sigaddset(&set, SIG_IPI);
pthread_sigmask(SIG_BLOCK, &set, NULL);
}
void qemu_mutex_lock_iothread(void)
{
if (kvm_enabled()) {
qemu_mutex_lock(&qemu_fair_mutex);
qemu_mutex_lock(&qemu_global_mutex);
qemu_mutex_unlock(&qemu_fair_mutex);
} else {
qemu_mutex_lock(&qemu_fair_mutex);
if (qemu_mutex_trylock(&qemu_global_mutex)) {
qemu_thread_signal(tcg_cpu_thread, SIG_IPI);
qemu_mutex_lock(&qemu_global_mutex);
}
qemu_mutex_unlock(&qemu_fair_mutex);
}
}
void qemu_mutex_unlock_iothread(void)
{
qemu_mutex_unlock(&qemu_global_mutex);
}
static int all_vcpus_paused(void)
{
CPUState *penv = first_cpu;
while (penv) {
if (!penv->stopped)
return 0;
penv = (CPUState *)penv->next_cpu;
}
return 1;
}
void pause_all_vcpus(void)
{
CPUState *penv = first_cpu;
while (penv) {
penv->stop = 1;
qemu_cpu_kick(penv);
penv = (CPUState *)penv->next_cpu;
}
while (!all_vcpus_paused()) {
qemu_cond_timedwait(&qemu_pause_cond, &qemu_global_mutex, 100);
penv = first_cpu;
while (penv) {
qemu_cpu_kick(penv);
penv = (CPUState *)penv->next_cpu;
}
}
}
void resume_all_vcpus(void)
{
CPUState *penv = first_cpu;
while (penv) {
penv->stop = 0;
penv->stopped = 0;
qemu_cpu_kick(penv);
penv = (CPUState *)penv->next_cpu;
}
}
static void tcg_init_vcpu(void *_env)
{
CPUState *env = _env;
/* share a single thread for all cpus with TCG */
if (!tcg_cpu_thread) {
env->thread = qemu_mallocz(sizeof(QemuThread));
env->halt_cond = qemu_mallocz(sizeof(QemuCond));
qemu_cond_init(env->halt_cond);
qemu_thread_create(env->thread, tcg_cpu_thread_fn, env);
while (env->created == 0)
qemu_cond_timedwait(&qemu_cpu_cond, &qemu_global_mutex, 100);
tcg_cpu_thread = env->thread;
tcg_halt_cond = env->halt_cond;
} else {
env->thread = tcg_cpu_thread;
env->halt_cond = tcg_halt_cond;
}
}
static void kvm_start_vcpu(CPUState *env)
{
env->thread = qemu_mallocz(sizeof(QemuThread));
env->halt_cond = qemu_mallocz(sizeof(QemuCond));
qemu_cond_init(env->halt_cond);
qemu_thread_create(env->thread, kvm_cpu_thread_fn, env);
while (env->created == 0)
qemu_cond_timedwait(&qemu_cpu_cond, &qemu_global_mutex, 100);
}
void qemu_init_vcpu(void *_env)
{
CPUState *env = _env;
env->nr_cores = smp_cores;
env->nr_threads = smp_threads;
if (kvm_enabled())
kvm_start_vcpu(env);
else
tcg_init_vcpu(env);
}
void qemu_notify_event(void)
{
qemu_event_increment();
}
static void qemu_system_vmstop_request(int reason)
{
vmstop_requested = reason;
qemu_notify_event();
}
void vm_stop(int reason)
{
QemuThread me;
qemu_thread_self(&me);
if (!qemu_thread_equal(&me, &io_thread)) {
qemu_system_vmstop_request(reason);
/*
* FIXME: should not return to device code in case
* vm_stop() has been requested.
*/
if (cpu_single_env) {
cpu_exit(cpu_single_env);
cpu_single_env->stop = 1;
}
return;
}
do_vm_stop(reason);
}
#endif
static int qemu_cpu_exec(CPUState *env)
{
int ret;
#ifdef CONFIG_PROFILER
int64_t ti;
#endif
#ifdef CONFIG_PROFILER
ti = profile_getclock();
#endif
if (use_icount) {
int64_t count;
int decr;
qemu_icount -= (env->icount_decr.u16.low + env->icount_extra);
env->icount_decr.u16.low = 0;
env->icount_extra = 0;
count = qemu_icount_round (qemu_next_deadline());
qemu_icount += count;
decr = (count > 0xffff) ? 0xffff : count;
count -= decr;
env->icount_decr.u16.low = decr;
env->icount_extra = count;
}
ret = cpu_exec(env);
#ifdef CONFIG_PROFILER
qemu_time += profile_getclock() - ti;
#endif
if (use_icount) {
/* Fold pending instructions back into the
instruction counter, and clear the interrupt flag. */
qemu_icount -= (env->icount_decr.u16.low
+ env->icount_extra);
env->icount_decr.u32 = 0;
env->icount_extra = 0;
}
return ret;
}
bool cpu_exec_all(void)
{
if (next_cpu == NULL)
next_cpu = first_cpu;
for (; next_cpu != NULL && !exit_request; next_cpu = next_cpu->next_cpu) {
CPUState *env = next_cpu;
qemu_clock_enable(vm_clock,
(env->singlestep_enabled & SSTEP_NOTIMER) == 0);
if (qemu_alarm_pending())
break;
if (cpu_can_run(env)) {
if (qemu_cpu_exec(env) == EXCP_DEBUG) {
break;
}
} else if (env->stop) {
break;
}
}
exit_request = 0;
return any_cpu_has_work();
}
void set_numa_modes(void)
{
CPUState *env;
int i;
for (env = first_cpu; env != NULL; env = env->next_cpu) {
for (i = 0; i < nb_numa_nodes; i++) {
if (node_cpumask[i] & (1 << env->cpu_index)) {
env->numa_node = i;
}
}
}
}
void set_cpu_log(const char *optarg)
{
int mask;
const CPULogItem *item;
mask = cpu_str_to_log_mask(optarg);
if (!mask) {
printf("Log items (comma separated):\n");
for (item = cpu_log_items; item->mask != 0; item++) {
printf("%-10s %s\n", item->name, item->help);
}
exit(1);
}
cpu_set_log(mask);
}
/* Return the virtual CPU time, based on the instruction counter. */
int64_t cpu_get_icount(void)
{
int64_t icount;
CPUState *env = cpu_single_env;;
icount = qemu_icount;
if (env) {
if (!can_do_io(env)) {
fprintf(stderr, "Bad clock read\n");
}
icount -= (env->icount_decr.u16.low + env->icount_extra);
}
return qemu_icount_bias + (icount << icount_time_shift);
}
void list_cpus(FILE *f, int (*cpu_fprintf)(FILE *f, const char *fmt, ...),
const char *optarg)
{
/* XXX: implement xxx_cpu_list for targets that still miss it */
#if defined(cpu_list_id)
cpu_list_id(f, cpu_fprintf, optarg);
#elif defined(cpu_list)
cpu_list(f, cpu_fprintf); /* deprecated */
#endif
}
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