2  * sigaltstack coroutine initialization code
8 **  Copyright (c) 1999-2006 Ralf S. Engelschall <rse@engelschall.com>
21  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
33 #error "SafeStack is not compatible with code run in alternate signal stacks"
37     Coroutine base;
44  * Per-thread coroutine bookkeeping
47     /** Currently executing coroutine */
48     Coroutine *current;
50     /** The default coroutine */
67         s->current = &s->leader.base;  in coroutine_get_thread_state()
92  * This is what starts the coroutine, is called from the trampoline
96 static void coroutine_bootstrap(CoroutineSigAltStack *self, Coroutine *co)  in coroutine_bootstrap()
99     if (!sigsetjmp(self->env, 0)) {  in coroutine_bootstrap()
100         siglongjmp(*(sigjmp_buf *)co->entry_arg, 1);  in coroutine_bootstrap()
104         co->entry(co->entry_arg);  in coroutine_bootstrap()
105         qemu_coroutine_switch(co, co->caller, COROUTINE_TERMINATE);  in coroutine_bootstrap()
110  * This is used as the signal handler. This is called with the brand new stack
117     Coroutine *co;  in coroutine_trampoline()
122     self = coTS->tr_handler;  in coroutine_trampoline()
123     coTS->tr_called = 1;  in coroutine_trampoline()
124     co = &self->base;  in coroutine_trampoline()
131     if (!sigsetjmp(coTS->tr_reenter, 0)) {  in coroutine_trampoline()
139      * the auto variables (which have to be auto-variables  in coroutine_trampoline()
140      * because the start of the thread happens later). Else with  in coroutine_trampoline()
148 Coroutine *qemu_coroutine_new(void)  in qemu_coroutine_new()
161     /* The way to manipulate stack is with the sigaltstack function. We  in qemu_coroutine_new()
162      * prepare a stack, with it delivering a signal to ourselves and then  in qemu_coroutine_new()
164      * This has been done keeping coroutine-ucontext as a model and with the  in qemu_coroutine_new()
165      * pth ideas (GNU Portable Threads). See coroutine-ucontext for the basics  in qemu_coroutine_new()
171     co->stack_size = COROUTINE_STACK_SIZE;  in qemu_coroutine_new()
172     co->stack = qemu_alloc_stack(&co->stack_size);  in qemu_coroutine_new()
173     co->base.entry_arg = &old_env; /* stash away our jmp_buf */  in qemu_coroutine_new()
176     coTS->tr_handler = co;  in qemu_coroutine_new()
191      * sigaction() is a process-global operation.  We must not run  in qemu_coroutine_new()
202     ss.ss_sp = co->stack;  in qemu_coroutine_new()
203     ss.ss_size = co->stack_size;  in qemu_coroutine_new()
212      * was performed. Be careful here with race conditions.  The  in qemu_coroutine_new()
216     coTS->tr_called = 0;  in qemu_coroutine_new()
220     while (!coTS->tr_called) {  in qemu_coroutine_new()
250      * redundant ping-pong pointer arithmetic is necessary to avoid  in qemu_coroutine_new()
251      * type-conversion warnings related to the `volatile' qualifier and  in qemu_coroutine_new()
255         siglongjmp(coTS->tr_reenter, 1);  in qemu_coroutine_new()
262     return &co->base;  in qemu_coroutine_new()
265 void qemu_coroutine_delete(Coroutine *co_)  in qemu_coroutine_delete()
269     qemu_free_stack(co->stack, co->stack_size);  in qemu_coroutine_delete()
273 CoroutineAction qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,  in qemu_coroutine_switch()
281     s->current = to_;  in qemu_coroutine_switch()
283     ret = sigsetjmp(from->env, 0);  in qemu_coroutine_switch()
285         siglongjmp(to->env, action);  in qemu_coroutine_switch()
290 Coroutine *qemu_coroutine_self(void)  in qemu_coroutine_self()
294     return s->current;  in qemu_coroutine_self()
301     return s && s->current->caller;  in qemu_in_coroutine()