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https://github.com/Motorhead1991/qemu.git
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5b78d120ff
Emscripten does not support couroutine methods currently used by QEMU but provides a coroutine implementation called "fiber". This commit introduces a coroutine backend using fiber. Note that fiber does not support submitting coroutines to other threads. Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com> Link: https://lore.kernel.org/r/006b683fd578ed6303a2dc8679094da9a7e6dfb4.1745820062.git.ktokunaga.mail@gmail.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
127 lines
3.6 KiB
C
127 lines
3.6 KiB
C
/*
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* emscripten fiber coroutine initialization code
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* based on coroutine-ucontext.c
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*
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* Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
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* Copyright (C) 2011 Kevin Wolf <kwolf@redhat.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.0 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "qemu/osdep.h"
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#include "qemu/coroutine_int.h"
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#include "qemu/coroutine-tls.h"
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#include <emscripten/fiber.h>
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typedef struct {
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Coroutine base;
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void *stack;
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size_t stack_size;
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void *asyncify_stack;
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size_t asyncify_stack_size;
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CoroutineAction action;
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emscripten_fiber_t fiber;
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} CoroutineEmscripten;
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/**
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* Per-thread coroutine bookkeeping
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*/
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QEMU_DEFINE_STATIC_CO_TLS(Coroutine *, current);
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QEMU_DEFINE_STATIC_CO_TLS(CoroutineEmscripten *, leader);
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size_t leader_asyncify_stack_size = COROUTINE_STACK_SIZE;
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static void coroutine_trampoline(void *co_)
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{
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Coroutine *co = co_;
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while (true) {
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co->entry(co->entry_arg);
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qemu_coroutine_switch(co, co->caller, COROUTINE_TERMINATE);
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}
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}
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Coroutine *qemu_coroutine_new(void)
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{
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CoroutineEmscripten *co;
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co = g_malloc0(sizeof(*co));
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co->stack_size = COROUTINE_STACK_SIZE;
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co->stack = qemu_alloc_stack(&co->stack_size);
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co->asyncify_stack_size = COROUTINE_STACK_SIZE;
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co->asyncify_stack = g_malloc0(co->asyncify_stack_size);
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emscripten_fiber_init(&co->fiber, coroutine_trampoline, &co->base,
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co->stack, co->stack_size, co->asyncify_stack,
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co->asyncify_stack_size);
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return &co->base;
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}
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void qemu_coroutine_delete(Coroutine *co_)
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{
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CoroutineEmscripten *co = DO_UPCAST(CoroutineEmscripten, base, co_);
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qemu_free_stack(co->stack, co->stack_size);
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g_free(co->asyncify_stack);
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g_free(co);
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}
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CoroutineAction qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
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CoroutineAction action)
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{
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CoroutineEmscripten *from = DO_UPCAST(CoroutineEmscripten, base, from_);
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CoroutineEmscripten *to = DO_UPCAST(CoroutineEmscripten, base, to_);
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set_current(to_);
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to->action = action;
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emscripten_fiber_swap(&from->fiber, &to->fiber);
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return from->action;
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}
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Coroutine *qemu_coroutine_self(void)
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{
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Coroutine *self = get_current();
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if (!self) {
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CoroutineEmscripten *leaderp = get_leader();
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if (!leaderp) {
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leaderp = g_malloc0(sizeof(*leaderp));
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leaderp->asyncify_stack = g_malloc0(leader_asyncify_stack_size);
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leaderp->asyncify_stack_size = leader_asyncify_stack_size;
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emscripten_fiber_init_from_current_context(
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&leaderp->fiber,
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leaderp->asyncify_stack,
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leaderp->asyncify_stack_size);
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leaderp->stack = leaderp->fiber.stack_limit;
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leaderp->stack_size =
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leaderp->fiber.stack_base - leaderp->fiber.stack_limit;
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set_leader(leaderp);
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}
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self = &leaderp->base;
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set_current(self);
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}
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return self;
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}
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bool qemu_in_coroutine(void)
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{
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Coroutine *self = get_current();
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return self && self->caller;
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}
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