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Peter Crosthwaite5abf9492015-09-10 22:39:31 -07001/*
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
Peter Maydell7b31bbc2016-01-26 18:16:56 +000020#include "qemu/osdep.h"
Peter Crosthwaite5abf9492015-09-10 22:39:31 -070021#include "cpu.h"
22#include "sysemu/cpus.h"
Paolo Bonzini63c91552016-03-15 13:18:37 +010023#include "exec/exec-all.h"
Peter Crosthwaite5abf9492015-09-10 22:39:31 -070024#include "exec/memory-internal.h"
25
26bool exit_request;
27CPUState *tcg_current_cpu;
28
Peter Maydell6886b982016-05-17 15:18:04 +010029/* exit the current TB, but without causing any exception to be raised */
30void cpu_loop_exit_noexc(CPUState *cpu)
Peter Crosthwaite5abf9492015-09-10 22:39:31 -070031{
32 /* XXX: restore cpu registers saved in host registers */
33
34 cpu->exception_index = -1;
35 siglongjmp(cpu->jmp_env, 1);
36}
37
Peter Maydellf213e722016-05-17 15:18:03 +010038#if defined(CONFIG_SOFTMMU)
Peter Maydell32857f42015-10-01 15:29:50 +010039void cpu_reloading_memory_map(void)
Peter Crosthwaite5abf9492015-09-10 22:39:31 -070040{
Peter Crosthwaite5abf9492015-09-10 22:39:31 -070041 if (qemu_in_vcpu_thread()) {
Peter Maydell53f8a5e2015-10-01 15:29:49 +010042 /* 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.
Peter Crosthwaite5abf9492015-09-10 22:39:31 -070047 *
Peter Maydell53f8a5e2015-10-01 15:29:49 +010048 * 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.)
Peter Crosthwaite5abf9492015-09-10 22:39:31 -070057 *
58 * This pair matches cpu_exec's rcu_read_lock()/rcu_read_unlock(), which
Peter Maydell32857f42015-10-01 15:29:50 +010059 * only protects cpu->as->dispatch. Since we know our caller is about
60 * to reload it, it's safe to split the critical section.
Peter Crosthwaite5abf9492015-09-10 22:39:31 -070061 */
62 rcu_read_unlock();
63 rcu_read_lock();
64 }
Peter Crosthwaite5abf9492015-09-10 22:39:31 -070065}
66#endif
67
68void cpu_loop_exit(CPUState *cpu)
69{
Peter Crosthwaite5abf9492015-09-10 22:39:31 -070070 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 }
Peter Crosthwaite5abf9492015-09-10 22:39:31 -070078 siglongjmp(cpu->jmp_env, 1);
79}
Richard Hendersonfdbc2b52016-06-29 22:12:55 -070080
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}