balloon: Don't balloon roms
[qemu.git] / util / coroutine-win32.c
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-common.h"
27 #include "qemu/coroutine_int.h"
28
29 typedef struct
30 {
31 Coroutine base;
32
33 LPVOID fiber;
34 CoroutineAction action;
35 } CoroutineWin32;
36
37 static __thread CoroutineWin32 leader;
38 static __thread 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 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 if (!current) {
93 current = &leader.base;
94 leader.fiber = ConvertThreadToFiber(NULL);
95 }
96 return current;
97 }
98
99 bool qemu_in_coroutine(void)
100 {
101 return current && current->caller;
102 }