mirror of https://gitee.com/openkylin/qemu.git
102 lines
3.0 KiB
C
102 lines
3.0 KiB
C
/*
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* Win32 coroutine initialization code
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*
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* Copyright (c) 2011 Kevin Wolf <kwolf@redhat.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu-common.h"
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#include "block/coroutine_int.h"
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typedef struct
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{
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Coroutine base;
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LPVOID fiber;
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CoroutineAction action;
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} CoroutineWin32;
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static __thread CoroutineWin32 leader;
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static __thread Coroutine *current;
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/* This function is marked noinline to prevent GCC from inlining it
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* into coroutine_trampoline(). If we allow it to do that then it
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* hoists the code to get the address of the TLS variable "current"
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* out of the while() loop. This is an invalid transformation because
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* the SwitchToFiber() call may be called when running thread A but
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* return in thread B, and so we might be in a different thread
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* context each time round the loop.
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*/
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CoroutineAction __attribute__((noinline))
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qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
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CoroutineAction action)
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{
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CoroutineWin32 *from = DO_UPCAST(CoroutineWin32, base, from_);
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CoroutineWin32 *to = DO_UPCAST(CoroutineWin32, base, to_);
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current = to_;
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to->action = action;
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SwitchToFiber(to->fiber);
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return from->action;
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}
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static void CALLBACK 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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const size_t stack_size = 1 << 20;
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CoroutineWin32 *co;
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co = g_malloc0(sizeof(*co));
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co->fiber = CreateFiber(stack_size, coroutine_trampoline, &co->base);
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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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CoroutineWin32 *co = DO_UPCAST(CoroutineWin32, base, co_);
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DeleteFiber(co->fiber);
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g_free(co);
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}
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Coroutine *qemu_coroutine_self(void)
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{
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if (!current) {
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current = &leader.base;
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leader.fiber = ConvertThreadToFiber(NULL);
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}
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return current;
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}
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bool qemu_in_coroutine(void)
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{
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return current && current->caller;
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}
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