diff options
Diffstat (limited to 'cpu-common.c')
| -rw-r--r-- | cpu-common.c | 442 |
1 files changed, 442 insertions, 0 deletions
diff --git a/cpu-common.c b/cpu-common.c new file mode 100644 index 0000000000..45c745ecf6 --- /dev/null +++ b/cpu-common.c @@ -0,0 +1,442 @@ +/* + * CPU thread main loop - common bits for user and system mode emulation + * + * Copyright (c) 2003-2005 Fabrice Bellard + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, see <http://www.gnu.org/licenses/>. + */ + +#include "qemu/osdep.h" +#include "qemu/main-loop.h" +#include "exec/cpu-common.h" +#include "hw/core/cpu.h" +#include "sysemu/cpus.h" +#include "qemu/lockable.h" +#include "trace/trace-root.h" + +QemuMutex qemu_cpu_list_lock; +static QemuCond exclusive_cond; +static QemuCond exclusive_resume; +static QemuCond qemu_work_cond; + +/* >= 1 if a thread is inside start_exclusive/end_exclusive. Written + * under qemu_cpu_list_lock, read with atomic operations. + */ +static int pending_cpus; + +void qemu_init_cpu_list(void) +{ + /* This is needed because qemu_init_cpu_list is also called by the + * child process in a fork. */ + pending_cpus = 0; + + qemu_mutex_init(&qemu_cpu_list_lock); + qemu_cond_init(&exclusive_cond); + qemu_cond_init(&exclusive_resume); + qemu_cond_init(&qemu_work_cond); +} + +void cpu_list_lock(void) +{ + qemu_mutex_lock(&qemu_cpu_list_lock); +} + +void cpu_list_unlock(void) +{ + qemu_mutex_unlock(&qemu_cpu_list_lock); +} + +static bool cpu_index_auto_assigned; + +static int cpu_get_free_index(void) +{ + CPUState *some_cpu; + int max_cpu_index = 0; + + cpu_index_auto_assigned = true; + CPU_FOREACH(some_cpu) { + if (some_cpu->cpu_index >= max_cpu_index) { + max_cpu_index = some_cpu->cpu_index + 1; + } + } + return max_cpu_index; +} + +CPUTailQ cpus = QTAILQ_HEAD_INITIALIZER(cpus); +static unsigned int cpu_list_generation_id; + +unsigned int cpu_list_generation_id_get(void) +{ + return cpu_list_generation_id; +} + +void cpu_list_add(CPUState *cpu) +{ + QEMU_LOCK_GUARD(&qemu_cpu_list_lock); + if (cpu->cpu_index == UNASSIGNED_CPU_INDEX) { + cpu->cpu_index = cpu_get_free_index(); + assert(cpu->cpu_index != UNASSIGNED_CPU_INDEX); + } else { + assert(!cpu_index_auto_assigned); + } + QTAILQ_INSERT_TAIL_RCU(&cpus, cpu, node); + cpu_list_generation_id++; +} + +void cpu_list_remove(CPUState *cpu) +{ + QEMU_LOCK_GUARD(&qemu_cpu_list_lock); + if (!QTAILQ_IN_USE(cpu, node)) { + /* there is nothing to undo since cpu_exec_init() hasn't been called */ + return; + } + + QTAILQ_REMOVE_RCU(&cpus, cpu, node); + cpu->cpu_index = UNASSIGNED_CPU_INDEX; + cpu_list_generation_id++; +} + +CPUState *qemu_get_cpu(int index) +{ + CPUState *cpu; + + CPU_FOREACH(cpu) { + if (cpu->cpu_index == index) { + return cpu; + } + } + + return NULL; +} + +/* current CPU in the current thread. It is only valid inside cpu_exec() */ +__thread CPUState *current_cpu; + +struct qemu_work_item { + QSIMPLEQ_ENTRY(qemu_work_item) node; + run_on_cpu_func func; + run_on_cpu_data data; + bool free, exclusive, done; +}; + +static void queue_work_on_cpu(CPUState *cpu, struct qemu_work_item *wi) +{ + qemu_mutex_lock(&cpu->work_mutex); + QSIMPLEQ_INSERT_TAIL(&cpu->work_list, wi, node); + wi->done = false; + qemu_mutex_unlock(&cpu->work_mutex); + + qemu_cpu_kick(cpu); +} + +void do_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data, + QemuMutex *mutex) +{ + struct qemu_work_item wi; + + if (qemu_cpu_is_self(cpu)) { + func(cpu, data); + return; + } + + wi.func = func; + wi.data = data; + wi.done = false; + wi.free = false; + wi.exclusive = false; + + queue_work_on_cpu(cpu, &wi); + while (!qatomic_load_acquire(&wi.done)) { + CPUState *self_cpu = current_cpu; + + qemu_cond_wait(&qemu_work_cond, mutex); + current_cpu = self_cpu; + } +} + +void async_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data data) +{ + struct qemu_work_item *wi; + + wi = g_new0(struct qemu_work_item, 1); + wi->func = func; + wi->data = data; + wi->free = true; + + queue_work_on_cpu(cpu, wi); +} + +/* Wait for pending exclusive operations to complete. The CPU list lock + must be held. */ +static inline void exclusive_idle(void) +{ + while (pending_cpus) { + qemu_cond_wait(&exclusive_resume, &qemu_cpu_list_lock); + } +} + +/* Start an exclusive operation. + Must only be called from outside cpu_exec. */ +void start_exclusive(void) +{ + CPUState *other_cpu; + int running_cpus; + + if (current_cpu->exclusive_context_count) { + current_cpu->exclusive_context_count++; + return; + } + + qemu_mutex_lock(&qemu_cpu_list_lock); + exclusive_idle(); + + /* Make all other cpus stop executing. */ + qatomic_set(&pending_cpus, 1); + + /* Write pending_cpus before reading other_cpu->running. */ + smp_mb(); + running_cpus = 0; + CPU_FOREACH(other_cpu) { + if (qatomic_read(&other_cpu->running)) { + other_cpu->has_waiter = true; + running_cpus++; + qemu_cpu_kick(other_cpu); + } + } + + qatomic_set(&pending_cpus, running_cpus + 1); + while (pending_cpus > 1) { + qemu_cond_wait(&exclusive_cond, &qemu_cpu_list_lock); + } + + /* Can release mutex, no one will enter another exclusive + * section until end_exclusive resets pending_cpus to 0. + */ + qemu_mutex_unlock(&qemu_cpu_list_lock); + + current_cpu->exclusive_context_count = 1; +} + +/* Finish an exclusive operation. */ +void end_exclusive(void) +{ + current_cpu->exclusive_context_count--; + if (current_cpu->exclusive_context_count) { + return; + } + + qemu_mutex_lock(&qemu_cpu_list_lock); + qatomic_set(&pending_cpus, 0); + qemu_cond_broadcast(&exclusive_resume); + qemu_mutex_unlock(&qemu_cpu_list_lock); +} + +/* Wait for exclusive ops to finish, and begin cpu execution. */ +void cpu_exec_start(CPUState *cpu) +{ + qatomic_set(&cpu->running, true); + + /* Write cpu->running before reading pending_cpus. */ + smp_mb(); + + /* 1. start_exclusive saw cpu->running == true and pending_cpus >= 1. + * After taking the lock we'll see cpu->has_waiter == true and run---not + * for long because start_exclusive kicked us. cpu_exec_end will + * decrement pending_cpus and signal the waiter. + * + * 2. start_exclusive saw cpu->running == false but pending_cpus >= 1. + * This includes the case when an exclusive item is running now. + * Then we'll see cpu->has_waiter == false and wait for the item to + * complete. + * + * 3. pending_cpus == 0. Then start_exclusive is definitely going to + * see cpu->running == true, and it will kick the CPU. + */ + if (unlikely(qatomic_read(&pending_cpus))) { + QEMU_LOCK_GUARD(&qemu_cpu_list_lock); + if (!cpu->has_waiter) { + /* Not counted in pending_cpus, let the exclusive item + * run. Since we have the lock, just set cpu->running to true + * while holding it; no need to check pending_cpus again. + */ + qatomic_set(&cpu->running, false); + exclusive_idle(); + /* Now pending_cpus is zero. */ + qatomic_set(&cpu->running, true); + } else { + /* Counted in pending_cpus, go ahead and release the + * waiter at cpu_exec_end. + */ + } + } +} + +/* Mark cpu as not executing, and release pending exclusive ops. */ +void cpu_exec_end(CPUState *cpu) +{ + qatomic_set(&cpu->running, false); + + /* Write cpu->running before reading pending_cpus. */ + smp_mb(); + + /* 1. start_exclusive saw cpu->running == true. Then it will increment + * pending_cpus and wait for exclusive_cond. After taking the lock + * we'll see cpu->has_waiter == true. + * + * 2. start_exclusive saw cpu->running == false but here pending_cpus >= 1. + * This includes the case when an exclusive item started after setting + * cpu->running to false and before we read pending_cpus. Then we'll see + * cpu->has_waiter == false and not touch pending_cpus. The next call to + * cpu_exec_start will run exclusive_idle if still necessary, thus waiting + * for the item to complete. + * + * 3. pending_cpus == 0. Then start_exclusive is definitely going to + * see cpu->running == false, and it can ignore this CPU until the + * next cpu_exec_start. + */ + if (unlikely(qatomic_read(&pending_cpus))) { + QEMU_LOCK_GUARD(&qemu_cpu_list_lock); + if (cpu->has_waiter) { + cpu->has_waiter = false; + qatomic_set(&pending_cpus, pending_cpus - 1); + if (pending_cpus == 1) { + qemu_cond_signal(&exclusive_cond); + } + } + } +} + +void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, + run_on_cpu_data data) +{ + struct qemu_work_item *wi; + + wi = g_new0(struct qemu_work_item, 1); + wi->func = func; + wi->data = data; + wi->free = true; + wi->exclusive = true; + + queue_work_on_cpu(cpu, wi); +} + +void process_queued_cpu_work(CPUState *cpu) +{ + struct qemu_work_item *wi; + + qemu_mutex_lock(&cpu->work_mutex); + if (QSIMPLEQ_EMPTY(&cpu->work_list)) { + qemu_mutex_unlock(&cpu->work_mutex); + return; + } + while (!QSIMPLEQ_EMPTY(&cpu->work_list)) { + wi = QSIMPLEQ_FIRST(&cpu->work_list); + QSIMPLEQ_REMOVE_HEAD(&cpu->work_list, node); + qemu_mutex_unlock(&cpu->work_mutex); + if (wi->exclusive) { + /* Running work items outside the BQL avoids the following deadlock: + * 1) start_exclusive() is called with the BQL taken while another + * CPU is running; 2) cpu_exec in the other CPU tries to takes the + * BQL, so it goes to sleep; start_exclusive() is sleeping too, so + * neither CPU can proceed. + */ + qemu_mutex_unlock_iothread(); + start_exclusive(); + wi->func(cpu, wi->data); + end_exclusive(); + qemu_mutex_lock_iothread(); + } else { + wi->func(cpu, wi->data); + } + qemu_mutex_lock(&cpu->work_mutex); + if (wi->free) { + g_free(wi); + } else { + qatomic_store_release(&wi->done, true); + } + } + qemu_mutex_unlock(&cpu->work_mutex); + qemu_cond_broadcast(&qemu_work_cond); +} + +/* Add a breakpoint. */ +int cpu_breakpoint_insert(CPUState *cpu, vaddr pc, int flags, + CPUBreakpoint **breakpoint) +{ + CPUClass *cc = CPU_GET_CLASS(cpu); + CPUBreakpoint *bp; + + if (cc->gdb_adjust_breakpoint) { + pc = cc->gdb_adjust_breakpoint(cpu, pc); + } + + bp = g_malloc(sizeof(*bp)); + + bp->pc = pc; + bp->flags = flags; + + /* keep all GDB-injected breakpoints in front */ + if (flags & BP_GDB) { + QTAILQ_INSERT_HEAD(&cpu->breakpoints, bp, entry); + } else { + QTAILQ_INSERT_TAIL(&cpu->breakpoints, bp, entry); + } + + if (breakpoint) { + *breakpoint = bp; + } + + trace_breakpoint_insert(cpu->cpu_index, pc, flags); + return 0; +} + +/* Remove a specific breakpoint. */ +int cpu_breakpoint_remove(CPUState *cpu, vaddr pc, int flags) +{ + CPUClass *cc = CPU_GET_CLASS(cpu); + CPUBreakpoint *bp; + + if (cc->gdb_adjust_breakpoint) { + pc = cc->gdb_adjust_breakpoint(cpu, pc); + } + + QTAILQ_FOREACH(bp, &cpu->breakpoints, entry) { + if (bp->pc == pc && bp->flags == flags) { + cpu_breakpoint_remove_by_ref(cpu, bp); + return 0; + } + } + return -ENOENT; +} + +/* Remove a specific breakpoint by reference. */ +void cpu_breakpoint_remove_by_ref(CPUState *cpu, CPUBreakpoint *bp) +{ + QTAILQ_REMOVE(&cpu->breakpoints, bp, entry); + + trace_breakpoint_remove(cpu->cpu_index, bp->pc, bp->flags); + g_free(bp); +} + +/* Remove all matching breakpoints. */ +void cpu_breakpoint_remove_all(CPUState *cpu, int mask) +{ + CPUBreakpoint *bp, *next; + + QTAILQ_FOREACH_SAFE(bp, &cpu->breakpoints, entry, next) { + if (bp->flags & mask) { + cpu_breakpoint_remove_by_ref(cpu, bp); + } + } +} |