LXR qemu/cpu-exec-common.c

   1/*
   2 *  emulator main execution loop
   3 *
   4 *  Copyright (c) 2003-2005 Fabrice Bellard
   5 *
   6 * This library is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU Lesser General Public
   8 * License as published by the Free Software Foundation; either
   9 * version 2 of the License, or (at your option) any later version.
  10 *
  11 * This library is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 * Lesser General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU Lesser General Public
  17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20#include "qemu/osdep.h"
  21#include "cpu.h"
  22#include "sysemu/cpus.h"
  23#include "exec/memory-internal.h"
  24
  25bool exit_request;
  26CPUState *tcg_current_cpu;
  27
  28/* exit the current TB from a signal handler. The host registers are
  29   restored in a state compatible with the CPU emulator
  30 */
  31#if defined(CONFIG_SOFTMMU)
  32void cpu_resume_from_signal(CPUState *cpu, void *puc)
  33{
  34    /* XXX: restore cpu registers saved in host registers */
  35
  36    cpu->exception_index = -1;
  37    siglongjmp(cpu->jmp_env, 1);
  38}
  39
  40void cpu_reloading_memory_map(void)
  41{
  42    if (qemu_in_vcpu_thread()) {
  43        /* The guest can in theory prolong the RCU critical section as long
  44         * as it feels like. The major problem with this is that because it
  45         * can do multiple reconfigurations of the memory map within the
  46         * critical section, we could potentially accumulate an unbounded
  47         * collection of memory data structures awaiting reclamation.
  48         *
  49         * Because the only thing we're currently protecting with RCU is the
  50         * memory data structures, it's sufficient to break the critical section
  51         * in this callback, which we know will get called every time the
  52         * memory map is rearranged.
  53         *
  54         * (If we add anything else in the system that uses RCU to protect
  55         * its data structures, we will need to implement some other mechanism
  56         * to force TCG CPUs to exit the critical section, at which point this
  57         * part of this callback might become unnecessary.)
  58         *
  59         * This pair matches cpu_exec's rcu_read_lock()/rcu_read_unlock(), which
  60         * only protects cpu->as->dispatch. Since we know our caller is about
  61         * to reload it, it's safe to split the critical section.
  62         */
  63        rcu_read_unlock();
  64        rcu_read_lock();
  65    }
  66}
  67#endif
  68
  69#include "qemu/etrace.h"
  70
  71void cpu_loop_exit(CPUState *cpu)
  72{
  73    if (cpu->halted && qemu_etrace_mask(ETRACE_F_EXEC)) {
  74        const char *dev_name = object_get_canonical_path(OBJECT(cpu));
  75        etrace_event_u64(&qemu_etracer, cpu->cpu_index,
  76                         ETRACE_EVU64_F_PREV_VAL,
  77                         dev_name, "sleep", 1, 0);
  78    }
  79
  80
  81    cpu->current_tb = NULL;
  82    siglongjmp(cpu->jmp_env, 1);
  83}
  84
  85void cpu_loop_exit_restore(CPUState *cpu, uintptr_t pc)
  86{
  87    if (pc) {
  88        cpu_restore_state(cpu, pc);
  89    }
  90    cpu->current_tb = NULL;
  91    siglongjmp(cpu->jmp_env, 1);
  92}
  93