migration/rdma: Plug memory leaks in qemu_rdma_registration_stop()
[qemu/armbru.git] / util / coroutine-ucontext.c
blobf0b66320e102ba03b81ee86bdb1f65477bfc810c
1 /*
2 * ucontext coroutine initialization code
4 * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
5 * Copyright (C) 2011 Kevin Wolf <kwolf@redhat.com>
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.0 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
21 /* XXX Is there a nicer way to disable glibc's stack check for longjmp? */
22 #ifdef _FORTIFY_SOURCE
23 #undef _FORTIFY_SOURCE
24 #endif
25 #include "qemu/osdep.h"
26 #include <ucontext.h>
27 #include "qemu/coroutine_int.h"
29 #ifdef CONFIG_VALGRIND_H
30 #include <valgrind/valgrind.h>
31 #endif
33 #if defined(__SANITIZE_ADDRESS__) || __has_feature(address_sanitizer)
34 #ifdef CONFIG_ASAN_IFACE_FIBER
35 #define CONFIG_ASAN 1
36 #include <sanitizer/asan_interface.h>
37 #endif
38 #endif
40 #ifdef CONFIG_TSAN
41 #include <sanitizer/tsan_interface.h>
42 #endif
44 typedef struct {
45 Coroutine base;
46 void *stack;
47 size_t stack_size;
48 #ifdef CONFIG_SAFESTACK
49 /* Need an unsafe stack for each coroutine */
50 void *unsafe_stack;
51 size_t unsafe_stack_size;
52 #endif
53 sigjmp_buf env;
55 void *tsan_co_fiber;
56 void *tsan_caller_fiber;
58 #ifdef CONFIG_VALGRIND_H
59 unsigned int valgrind_stack_id;
60 #endif
62 } CoroutineUContext;
64 /**
65 * Per-thread coroutine bookkeeping
67 static __thread CoroutineUContext leader;
68 static __thread Coroutine *current;
71 * va_args to makecontext() must be type 'int', so passing
72 * the pointer we need may require several int args. This
73 * union is a quick hack to let us do that
75 union cc_arg {
76 void *p;
77 int i[2];
80 /* QEMU_ALWAYS_INLINE only does so if __OPTIMIZE__, so we cannot use it. */
81 static inline __attribute__((always_inline))
82 void on_new_fiber(CoroutineUContext *co)
84 #ifdef CONFIG_TSAN
85 co->tsan_co_fiber = __tsan_create_fiber(0); /* flags: sync on switch */
86 co->tsan_caller_fiber = __tsan_get_current_fiber();
87 #endif
90 static inline __attribute__((always_inline))
91 void finish_switch_fiber(void *fake_stack_save)
93 #ifdef CONFIG_ASAN
94 const void *bottom_old;
95 size_t size_old;
97 __sanitizer_finish_switch_fiber(fake_stack_save, &bottom_old, &size_old);
99 if (!leader.stack) {
100 leader.stack = (void *)bottom_old;
101 leader.stack_size = size_old;
103 #endif
104 #ifdef CONFIG_TSAN
105 if (fake_stack_save) {
106 __tsan_release(fake_stack_save);
107 __tsan_switch_to_fiber(fake_stack_save, 0); /* 0=synchronize */
109 #endif
112 static inline __attribute__((always_inline)) void start_switch_fiber(
113 CoroutineAction action, void **fake_stack_save,
114 const void *bottom, size_t size, void *new_fiber)
116 #ifdef CONFIG_ASAN
117 __sanitizer_start_switch_fiber(
118 action == COROUTINE_TERMINATE ? NULL : fake_stack_save,
119 bottom, size);
120 #endif
121 #ifdef CONFIG_TSAN
122 void *curr_fiber =
123 __tsan_get_current_fiber();
124 __tsan_acquire(curr_fiber);
126 *fake_stack_save = curr_fiber;
127 __tsan_switch_to_fiber(new_fiber, 0); /* 0=synchronize */
128 #endif
131 static void coroutine_trampoline(int i0, int i1)
133 union cc_arg arg;
134 CoroutineUContext *self;
135 Coroutine *co;
136 void *fake_stack_save = NULL;
138 finish_switch_fiber(NULL);
140 arg.i[0] = i0;
141 arg.i[1] = i1;
142 self = arg.p;
143 co = &self->base;
145 /* Initialize longjmp environment and switch back the caller */
146 if (!sigsetjmp(self->env, 0)) {
147 start_switch_fiber(
148 COROUTINE_YIELD,
149 &fake_stack_save,
150 leader.stack,
151 leader.stack_size,
152 self->tsan_caller_fiber);
153 siglongjmp(*(sigjmp_buf *)co->entry_arg, 1);
156 finish_switch_fiber(fake_stack_save);
158 while (true) {
159 co->entry(co->entry_arg);
160 qemu_coroutine_switch(co, co->caller, COROUTINE_TERMINATE);
164 Coroutine *qemu_coroutine_new(void)
166 CoroutineUContext *co;
167 ucontext_t old_uc, uc;
168 sigjmp_buf old_env;
169 union cc_arg arg = {0};
170 void *fake_stack_save = NULL;
172 /* The ucontext functions preserve signal masks which incurs a
173 * system call overhead. sigsetjmp(buf, 0)/siglongjmp() does not
174 * preserve signal masks but only works on the current stack.
175 * Since we need a way to create and switch to a new stack, use
176 * the ucontext functions for that but sigsetjmp()/siglongjmp() for
177 * everything else.
180 if (getcontext(&uc) == -1) {
181 abort();
184 co = g_malloc0(sizeof(*co));
185 co->stack_size = COROUTINE_STACK_SIZE;
186 co->stack = qemu_alloc_stack(&co->stack_size);
187 #ifdef CONFIG_SAFESTACK
188 co->unsafe_stack_size = COROUTINE_STACK_SIZE;
189 co->unsafe_stack = qemu_alloc_stack(&co->unsafe_stack_size);
190 #endif
191 co->base.entry_arg = &old_env; /* stash away our jmp_buf */
193 uc.uc_link = &old_uc;
194 uc.uc_stack.ss_sp = co->stack;
195 uc.uc_stack.ss_size = co->stack_size;
196 uc.uc_stack.ss_flags = 0;
198 #ifdef CONFIG_VALGRIND_H
199 co->valgrind_stack_id =
200 VALGRIND_STACK_REGISTER(co->stack, co->stack + co->stack_size);
201 #endif
203 arg.p = co;
205 on_new_fiber(co);
206 makecontext(&uc, (void (*)(void))coroutine_trampoline,
207 2, arg.i[0], arg.i[1]);
209 /* swapcontext() in, siglongjmp() back out */
210 if (!sigsetjmp(old_env, 0)) {
211 start_switch_fiber(
212 COROUTINE_YIELD,
213 &fake_stack_save,
214 co->stack, co->stack_size, co->tsan_co_fiber);
216 #ifdef CONFIG_SAFESTACK
218 * Before we swap the context, set the new unsafe stack
219 * The unsafe stack grows just like the normal stack, so start from
220 * the last usable location of the memory area.
221 * NOTE: we don't have to re-set the usp afterwards because we are
222 * coming back to this context through a siglongjmp.
223 * The compiler already wrapped the corresponding sigsetjmp call with
224 * code that saves the usp on the (safe) stack before the call, and
225 * restores it right after (which is where we return with siglongjmp).
227 void *usp = co->unsafe_stack + co->unsafe_stack_size;
228 __safestack_unsafe_stack_ptr = usp;
229 #endif
231 swapcontext(&old_uc, &uc);
234 finish_switch_fiber(fake_stack_save);
236 return &co->base;
239 #ifdef CONFIG_VALGRIND_H
240 #if defined(CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE) && !defined(__clang__)
241 /* Work around an unused variable in the valgrind.h macro... */
242 #pragma GCC diagnostic push
243 #pragma GCC diagnostic ignored "-Wunused-but-set-variable"
244 #endif
245 static inline void valgrind_stack_deregister(CoroutineUContext *co)
247 VALGRIND_STACK_DEREGISTER(co->valgrind_stack_id);
249 #if defined(CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE) && !defined(__clang__)
250 #pragma GCC diagnostic pop
251 #endif
252 #endif
254 void qemu_coroutine_delete(Coroutine *co_)
256 CoroutineUContext *co = DO_UPCAST(CoroutineUContext, base, co_);
258 #ifdef CONFIG_VALGRIND_H
259 valgrind_stack_deregister(co);
260 #endif
262 qemu_free_stack(co->stack, co->stack_size);
263 #ifdef CONFIG_SAFESTACK
264 qemu_free_stack(co->unsafe_stack, co->unsafe_stack_size);
265 #endif
266 g_free(co);
269 /* This function is marked noinline to prevent GCC from inlining it
270 * into coroutine_trampoline(). If we allow it to do that then it
271 * hoists the code to get the address of the TLS variable "current"
272 * out of the while() loop. This is an invalid transformation because
273 * the sigsetjmp() call may be called when running thread A but
274 * return in thread B, and so we might be in a different thread
275 * context each time round the loop.
277 CoroutineAction __attribute__((noinline))
278 qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
279 CoroutineAction action)
281 CoroutineUContext *from = DO_UPCAST(CoroutineUContext, base, from_);
282 CoroutineUContext *to = DO_UPCAST(CoroutineUContext, base, to_);
283 int ret;
284 void *fake_stack_save = NULL;
286 current = to_;
288 ret = sigsetjmp(from->env, 0);
289 if (ret == 0) {
290 start_switch_fiber(action, &fake_stack_save,
291 to->stack, to->stack_size, to->tsan_co_fiber);
292 siglongjmp(to->env, action);
295 finish_switch_fiber(fake_stack_save);
297 return ret;
300 Coroutine *qemu_coroutine_self(void)
302 if (!current) {
303 current = &leader.base;
305 #ifdef CONFIG_TSAN
306 if (!leader.tsan_co_fiber) {
307 leader.tsan_co_fiber = __tsan_get_current_fiber();
309 #endif
310 return current;
313 bool qemu_in_coroutine(void)
315 return current && current->caller;