Peter Crosthwaite | 5abf949 | 2015-09-10 22:39:31 -0700 | [diff] [blame] | 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 | |
Peter Maydell | 7b31bbc | 2016-01-26 18:16:56 +0000 | [diff] [blame] | 20 | #include "qemu/osdep.h" |
Peter Crosthwaite | 5abf949 | 2015-09-10 22:39:31 -0700 | [diff] [blame] | 21 | #include "cpu.h" |
| 22 | #include "sysemu/cpus.h" |
Paolo Bonzini | 63c9155 | 2016-03-15 13:18:37 +0100 | [diff] [blame] | 23 | #include "exec/exec-all.h" |
Peter Crosthwaite | 5abf949 | 2015-09-10 22:39:31 -0700 | [diff] [blame] | 24 | #include "exec/memory-internal.h" |
| 25 | |
Peter Maydell | 6886b98 | 2016-05-17 15:18:04 +0100 | [diff] [blame] | 26 | /* exit the current TB, but without causing any exception to be raised */ |
| 27 | void cpu_loop_exit_noexc(CPUState *cpu) |
Peter Crosthwaite | 5abf949 | 2015-09-10 22:39:31 -0700 | [diff] [blame] | 28 | { |
| 29 | /* XXX: restore cpu registers saved in host registers */ |
| 30 | |
| 31 | cpu->exception_index = -1; |
| 32 | siglongjmp(cpu->jmp_env, 1); |
| 33 | } |
| 34 | |
Peter Maydell | f213e72 | 2016-05-17 15:18:03 +0100 | [diff] [blame] | 35 | #if defined(CONFIG_SOFTMMU) |
Peter Maydell | 32857f4 | 2015-10-01 15:29:50 +0100 | [diff] [blame] | 36 | void cpu_reloading_memory_map(void) |
Peter Crosthwaite | 5abf949 | 2015-09-10 22:39:31 -0700 | [diff] [blame] | 37 | { |
Alex Bennée | 8539093 | 2017-03-22 16:11:13 +0000 | [diff] [blame] | 38 | if (qemu_in_vcpu_thread() && current_cpu->running) { |
Peter Maydell | 53f8a5e | 2015-10-01 15:29:49 +0100 | [diff] [blame] | 39 | /* The guest can in theory prolong the RCU critical section as long |
| 40 | * as it feels like. The major problem with this is that because it |
| 41 | * can do multiple reconfigurations of the memory map within the |
| 42 | * critical section, we could potentially accumulate an unbounded |
| 43 | * collection of memory data structures awaiting reclamation. |
Peter Crosthwaite | 5abf949 | 2015-09-10 22:39:31 -0700 | [diff] [blame] | 44 | * |
Peter Maydell | 53f8a5e | 2015-10-01 15:29:49 +0100 | [diff] [blame] | 45 | * Because the only thing we're currently protecting with RCU is the |
| 46 | * memory data structures, it's sufficient to break the critical section |
| 47 | * in this callback, which we know will get called every time the |
| 48 | * memory map is rearranged. |
| 49 | * |
| 50 | * (If we add anything else in the system that uses RCU to protect |
| 51 | * its data structures, we will need to implement some other mechanism |
| 52 | * to force TCG CPUs to exit the critical section, at which point this |
| 53 | * part of this callback might become unnecessary.) |
Peter Crosthwaite | 5abf949 | 2015-09-10 22:39:31 -0700 | [diff] [blame] | 54 | * |
| 55 | * This pair matches cpu_exec's rcu_read_lock()/rcu_read_unlock(), which |
Peter Maydell | 32857f4 | 2015-10-01 15:29:50 +0100 | [diff] [blame] | 56 | * only protects cpu->as->dispatch. Since we know our caller is about |
| 57 | * to reload it, it's safe to split the critical section. |
Peter Crosthwaite | 5abf949 | 2015-09-10 22:39:31 -0700 | [diff] [blame] | 58 | */ |
| 59 | rcu_read_unlock(); |
| 60 | rcu_read_lock(); |
| 61 | } |
Peter Crosthwaite | 5abf949 | 2015-09-10 22:39:31 -0700 | [diff] [blame] | 62 | } |
| 63 | #endif |
| 64 | |
| 65 | void cpu_loop_exit(CPUState *cpu) |
| 66 | { |
Peter Crosthwaite | 5abf949 | 2015-09-10 22:39:31 -0700 | [diff] [blame] | 67 | siglongjmp(cpu->jmp_env, 1); |
| 68 | } |
| 69 | |
| 70 | void cpu_loop_exit_restore(CPUState *cpu, uintptr_t pc) |
| 71 | { |
| 72 | if (pc) { |
| 73 | cpu_restore_state(cpu, pc); |
| 74 | } |
Peter Crosthwaite | 5abf949 | 2015-09-10 22:39:31 -0700 | [diff] [blame] | 75 | siglongjmp(cpu->jmp_env, 1); |
| 76 | } |
Richard Henderson | fdbc2b5 | 2016-06-29 22:12:55 -0700 | [diff] [blame] | 77 | |
| 78 | void cpu_loop_exit_atomic(CPUState *cpu, uintptr_t pc) |
| 79 | { |
| 80 | cpu->exception_index = EXCP_ATOMIC; |
| 81 | cpu_loop_exit_restore(cpu, pc); |
| 82 | } |