qemu

FORK: QEMU emulator
git clone https://git.neptards.moe/neptards/qemu.git
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coroutine-win32.c (3321B)

      1 /*
      2  * Win32 coroutine initialization code
      3  *
      4  * Copyright (c) 2011 Kevin Wolf <kwolf@redhat.com>
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining a copy
      7  * of this software and associated documentation files (the "Software"), to deal
      8  * in the Software without restriction, including without limitation the rights
      9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     10  * copies of the Software, and to permit persons to whom the Software is
     11  * furnished to do so, subject to the following conditions:
     12  *
     13  * The above copyright notice and this permission notice shall be included in
     14  * all copies or substantial portions of the Software.
     15  *
     16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
     19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
     22  * THE SOFTWARE.
     23  */
     24 
     25 #include "qemu/osdep.h"
     26 #include "qemu/coroutine_int.h"
     27 #include "qemu/coroutine-tls.h"
     28 
     29 typedef struct
     30 {
     31     Coroutine base;
     32 
     33     LPVOID fiber;
     34     CoroutineAction action;
     35 } CoroutineWin32;
     36 
     37 QEMU_DEFINE_STATIC_CO_TLS(CoroutineWin32, leader);
     38 QEMU_DEFINE_STATIC_CO_TLS(Coroutine *, current);
     39 
     40 /* This function is marked noinline to prevent GCC from inlining it
     41  * into coroutine_trampoline(). If we allow it to do that then it
     42  * hoists the code to get the address of the TLS variable "current"
     43  * out of the while() loop. This is an invalid transformation because
     44  * the SwitchToFiber() call may be called when running thread A but
     45  * return in thread B, and so we might be in a different thread
     46  * context each time round the loop.
     47  */
     48 CoroutineAction __attribute__((noinline))
     49 qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
     50                       CoroutineAction action)
     51 {
     52     CoroutineWin32 *from = DO_UPCAST(CoroutineWin32, base, from_);
     53     CoroutineWin32 *to = DO_UPCAST(CoroutineWin32, base, to_);
     54 
     55     set_current(to_);
     56 
     57     to->action = action;
     58     SwitchToFiber(to->fiber);
     59     return from->action;
     60 }
     61 
     62 static void CALLBACK coroutine_trampoline(void *co_)
     63 {
     64     Coroutine *co = co_;
     65 
     66     while (true) {
     67         co->entry(co->entry_arg);
     68         qemu_coroutine_switch(co, co->caller, COROUTINE_TERMINATE);
     69     }
     70 }
     71 
     72 Coroutine *qemu_coroutine_new(void)
     73 {
     74     const size_t stack_size = COROUTINE_STACK_SIZE;
     75     CoroutineWin32 *co;
     76 
     77     co = g_malloc0(sizeof(*co));
     78     co->fiber = CreateFiber(stack_size, coroutine_trampoline, &co->base);
     79     return &co->base;
     80 }
     81 
     82 void qemu_coroutine_delete(Coroutine *co_)
     83 {
     84     CoroutineWin32 *co = DO_UPCAST(CoroutineWin32, base, co_);
     85 
     86     DeleteFiber(co->fiber);
     87     g_free(co);
     88 }
     89 
     90 Coroutine *qemu_coroutine_self(void)
     91 {
     92     Coroutine *current = get_current();
     93 
     94     if (!current) {
     95         CoroutineWin32 *leader = get_ptr_leader();
     96 
     97         current = &leader->base;
     98         set_current(current);
     99         leader->fiber = ConvertThreadToFiber(NULL);
    100     }
    101     return current;
    102 }
    103 
    104 bool qemu_in_coroutine(void)
    105 {
    106     Coroutine *current = get_current();
    107 
    108     return current && current->caller;
    109 }