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/exec-all.h"
  24#include "exec/memory-internal.h"
  25
  26bool exit_request;
  27CPUState *tcg_current_cpu;
  28
  29/* exit the current TB, but without causing any exception to be raised */
  30void cpu_loop_exit_noexc(CPUState *cpu)
  31{
  32    /* XXX: restore cpu registers saved in host registers */
  33
  34    cpu->exception_index = -1;
  35    siglongjmp(cpu->jmp_env, 1);
  36}
  37
  38#if defined(CONFIG_SOFTMMU)
  39void cpu_reloading_memory_map(void)
  40{
  41    if (qemu_in_vcpu_thread()) {
  42        /* The guest can in theory prolong the RCU critical section as long
  43         * as it feels like. The major problem with this is that because it
  44         * can do multiple reconfigurations of the memory map within the
  45         * critical section, we could potentially accumulate an unbounded
  46         * collection of memory data structures awaiting reclamation.
  47         *
  48         * Because the only thing we're currently protecting with RCU is the
  49         * memory data structures, it's sufficient to break the critical section
  50         * in this callback, which we know will get called every time the
  51         * memory map is rearranged.
  52         *
  53         * (If we add anything else in the system that uses RCU to protect
  54         * its data structures, we will need to implement some other mechanism
  55         * to force TCG CPUs to exit the critical section, at which point this
  56         * part of this callback might become unnecessary.)
  57         *
  58         * This pair matches cpu_exec's rcu_read_lock()/rcu_read_unlock(), which
  59         * only protects cpu->as->dispatch. Since we know our caller is about
  60         * to reload it, it's safe to split the critical section.
  61         */
  62        rcu_read_unlock();
  63        rcu_read_lock();
  64    }
  65}
  66#endif
  67
  68void cpu_loop_exit(CPUState *cpu)
  69{
  70    siglongjmp(cpu->jmp_env, 1);
  71}
  72
  73void cpu_loop_exit_restore(CPUState *cpu, uintptr_t pc)
  74{
  75    if (pc) {
  76        cpu_restore_state(cpu, pc);
  77    }
  78    siglongjmp(cpu->jmp_env, 1);
  79}
  80
  81void cpu_loop_exit_atomic(CPUState *cpu, uintptr_t pc)
  82{
  83    cpu->exception_index = EXCP_ATOMIC;
  84    cpu_loop_exit_restore(cpu, pc);
  85}
  86