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 2.1 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 "sysemu/cpus.h" 22 #include "sysemu/tcg.h" 23 #include "exec/exec-all.h" 24 #include "qemu/plugin.h" 25 #include "internal.h" 26 27 bool tcg_allowed; 28 29 /* exit the current TB, but without causing any exception to be raised */ 30 void cpu_loop_exit_noexc(CPUState *cpu) 31 { 32 cpu->exception_index = -1; 33 cpu_loop_exit(cpu); 34 } 35 36 #if defined(CONFIG_SOFTMMU) 37 void cpu_reloading_memory_map(void) 38 { 39 if (qemu_in_vcpu_thread() && current_cpu->running) { 40 /* The guest can in theory prolong the RCU critical section as long 41 * as it feels like. The major problem with this is that because it 42 * can do multiple reconfigurations of the memory map within the 43 * critical section, we could potentially accumulate an unbounded 44 * collection of memory data structures awaiting reclamation. 45 * 46 * Because the only thing we're currently protecting with RCU is the 47 * memory data structures, it's sufficient to break the critical section 48 * in this callback, which we know will get called every time the 49 * memory map is rearranged. 50 * 51 * (If we add anything else in the system that uses RCU to protect 52 * its data structures, we will need to implement some other mechanism 53 * to force TCG CPUs to exit the critical section, at which point this 54 * part of this callback might become unnecessary.) 55 * 56 * This pair matches cpu_exec's rcu_read_lock()/rcu_read_unlock(), which 57 * only protects cpu->as->dispatch. Since we know our caller is about 58 * to reload it, it's safe to split the critical section. 59 */ 60 rcu_read_unlock(); 61 rcu_read_lock(); 62 } 63 } 64 #endif 65 66 void cpu_loop_exit(CPUState *cpu) 67 { 68 /* Undo the setting in cpu_tb_exec. */ 69 cpu->can_do_io = 1; 70 /* Undo any setting in generated code. */ 71 qemu_plugin_disable_mem_helpers(cpu); 72 siglongjmp(cpu->jmp_env, 1); 73 } 74 75 void cpu_loop_exit_restore(CPUState *cpu, uintptr_t pc) 76 { 77 if (pc) { 78 cpu_restore_state(cpu, pc); 79 } 80 cpu_loop_exit(cpu); 81 } 82 83 void cpu_loop_exit_atomic(CPUState *cpu, uintptr_t pc) 84 { 85 /* Prevent looping if already executing in a serial context. */ 86 g_assert(!cpu_in_serial_context(cpu)); 87 cpu->exception_index = EXCP_ATOMIC; 88 cpu_loop_exit_restore(cpu, pc); 89 } 90