summaryrefslogtreecommitdiffstats
path: root/sys/compat/linux/linux_emul.c
blob: 16e6033c1b62a032e29433b8e3a78ef7d8046cbc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
/*-
 * Copyright (c) 2006 Roman Divacky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer
 *    in this position and unchanged.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_compat.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/imgact.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/sx.h>
#include <sys/proc.h>
#include <sys/syscallsubr.h>
#include <sys/sysproto.h>
#include <sys/unistd.h>

#ifdef COMPAT_LINUX32
#include <machine/../linux32/linux.h>
#include <machine/../linux32/linux32_proto.h>
#else
#include <machine/../linux/linux.h>
#include <machine/../linux/linux_proto.h>
#endif

#include <compat/linux/linux_emul.h>
#include <compat/linux/linux_futex.h>

struct sx	emul_shared_lock;
struct mtx	emul_lock;

/* this returns locked reference to the emuldata entry (if found) */
struct linux_emuldata *
em_find(struct proc *p, int locked)
{
	struct linux_emuldata *em;

	if (locked == EMUL_DOLOCK)
		EMUL_LOCK(&emul_lock);

	em = p->p_emuldata;

	if (em == NULL && locked == EMUL_DOLOCK)
		EMUL_UNLOCK(&emul_lock);

	return (em);
}

int
linux_proc_init(struct thread *td, pid_t child, int flags)
{
	struct linux_emuldata *em, *p_em;
	struct proc *p;

	if (child != 0) {
		/* non-exec call */
		em = malloc(sizeof *em, M_LINUX, M_WAITOK | M_ZERO);
		em->pid = child;
		em->pdeath_signal = 0;
		em->robust_futexes = NULL;
		if (flags & LINUX_CLONE_THREAD) {
			/* handled later in the code */
		} else {
			struct linux_emuldata_shared *s;

			s = malloc(sizeof *s, M_LINUX, M_WAITOK | M_ZERO);
			s->refs = 1;
			s->group_pid = child;

			LIST_INIT(&s->threads);
			em->shared = s;
		}
	} else {
		/* lookup the old one */
		em = em_find(td->td_proc, EMUL_DOLOCK);
		KASSERT(em != NULL, ("proc_init: emuldata not found in exec case.\n"));
	}

	em->child_clear_tid = NULL;
	em->child_set_tid = NULL;

	/*
	 * allocate the shared struct only in clone()/fork cases in the case
	 * of clone() td = calling proc and child = pid of the newly created
	 * proc
	 */
	if (child != 0) {
		if (flags & LINUX_CLONE_THREAD) {
			/* lookup the parent */
			/* 
			 * we dont have to lock the p_em because
			 * its waiting for us in linux_clone so
			 * there is no chance of it changing the
			 * p_em->shared address
			 */
			p_em = em_find(td->td_proc, EMUL_DONTLOCK);
			KASSERT(p_em != NULL, ("proc_init: parent emuldata not found for CLONE_THREAD\n"));
			em->shared = p_em->shared;
			EMUL_SHARED_WLOCK(&emul_shared_lock);
			em->shared->refs++;
			EMUL_SHARED_WUNLOCK(&emul_shared_lock);
		} else {
			/*
			 * handled earlier to avoid malloc(M_WAITOK) with
			 * rwlock held
			 */
		}
	}
	if (child != 0) {
		EMUL_SHARED_WLOCK(&emul_shared_lock);
		LIST_INSERT_HEAD(&em->shared->threads, em, threads);
		EMUL_SHARED_WUNLOCK(&emul_shared_lock);

		p = pfind(child);
		KASSERT(p != NULL, ("process not found in proc_init\n"));
		p->p_emuldata = em;
		PROC_UNLOCK(p);
	} else
		EMUL_UNLOCK(&emul_lock);

	return (0);
}

void
linux_proc_exit(void *arg __unused, struct proc *p)
{
	struct linux_emuldata *em;
	int error;
	struct thread *td = FIRST_THREAD_IN_PROC(p);
	int *child_clear_tid;
	struct proc *q, *nq;

	if (__predict_true(p->p_sysent != &elf_linux_sysvec))
		return;

	release_futexes(p);

	/* find the emuldata */
	em = em_find(p, EMUL_DOLOCK);

	KASSERT(em != NULL, ("proc_exit: emuldata not found.\n"));

	/* reparent all procs that are not a thread leader to initproc */
	if (em->shared->group_pid != p->p_pid) {
		child_clear_tid = em->child_clear_tid;
		EMUL_UNLOCK(&emul_lock);
		sx_xlock(&proctree_lock);
		wakeup(initproc);
		PROC_LOCK(p);
		proc_reparent(p, initproc);
		p->p_sigparent = SIGCHLD;
		PROC_UNLOCK(p);
		sx_xunlock(&proctree_lock);
	} else {
		child_clear_tid = em->child_clear_tid;
		EMUL_UNLOCK(&emul_lock);	
	}

	EMUL_SHARED_WLOCK(&emul_shared_lock);
	LIST_REMOVE(em, threads);

	em->shared->refs--;
	if (em->shared->refs == 0) {
		EMUL_SHARED_WUNLOCK(&emul_shared_lock);
		free(em->shared, M_LINUX);
	} else	
		EMUL_SHARED_WUNLOCK(&emul_shared_lock);

	if (child_clear_tid != NULL) {
		struct linux_sys_futex_args cup;
		int null = 0;

		error = copyout(&null, child_clear_tid, sizeof(null));
		if (error) {
			free(em, M_LINUX);
			return;
		}

		/* futexes stuff */
		cup.uaddr = child_clear_tid;
		cup.op = LINUX_FUTEX_WAKE;
		cup.val = 0x7fffffff;	/* Awake everyone */
		cup.timeout = NULL;
		cup.uaddr2 = NULL;
		cup.val3 = 0;
		error = linux_sys_futex(FIRST_THREAD_IN_PROC(p), &cup);
		/*
		 * this cannot happen at the moment and if this happens it
		 * probably means there is a user space bug
		 */
		if (error)
			printf(LMSG("futex stuff in proc_exit failed.\n"));
	}

	/* clean the stuff up */
	free(em, M_LINUX);

	/* this is a little weird but rewritten from exit1() */
	sx_xlock(&proctree_lock);
	q = LIST_FIRST(&p->p_children);
	for (; q != NULL; q = nq) {
		nq = LIST_NEXT(q, p_sibling);
		if (q->p_flag & P_WEXIT)
			continue;
		if (__predict_false(q->p_sysent != &elf_linux_sysvec))
			continue;
		em = em_find(q, EMUL_DOLOCK);
		KASSERT(em != NULL, ("linux_reparent: emuldata not found: %i\n", q->p_pid));
		if (em->pdeath_signal != 0) {
			PROC_LOCK(q);
			psignal(q, em->pdeath_signal);
			PROC_UNLOCK(q);
		}
		EMUL_UNLOCK(&emul_lock);
	}
	sx_xunlock(&proctree_lock);
}

/*
 * This is used in a case of transition from FreeBSD binary execing to linux binary
 * in this case we create linux emuldata proc entry with the pid of the currently running
 * process.
 */
void 
linux_proc_exec(void *arg __unused, struct proc *p, struct image_params *imgp)
{
	if (__predict_false(imgp->sysent == &elf_linux_sysvec
	    && p->p_sysent != &elf_linux_sysvec))
		linux_proc_init(FIRST_THREAD_IN_PROC(p), p->p_pid, 0);
	if (__predict_false(imgp->sysent != &elf_linux_sysvec
	    && p->p_sysent == &elf_linux_sysvec)) {
		struct linux_emuldata *em;

		/* 
		 * XXX:There's a race because here we assign p->p_emuldata NULL
		 * but the process is still counted as linux one for a short
 		 * time so some other process might reference it and try to
 		 * access its p->p_emuldata and panicing on a NULL reference.
		 */
		em = em_find(p, EMUL_DONTLOCK);

		KASSERT(em != NULL, ("proc_exec: emuldata not found.\n"));

		EMUL_SHARED_WLOCK(&emul_shared_lock);
		LIST_REMOVE(em, threads);

		PROC_LOCK(p);
		p->p_emuldata = NULL;
		PROC_UNLOCK(p);

		em->shared->refs--;
		if (em->shared->refs == 0) {
			EMUL_SHARED_WUNLOCK(&emul_shared_lock);
			free(em->shared, M_LINUX);
		} else
			EMUL_SHARED_WUNLOCK(&emul_shared_lock);

		free(em, M_LINUX);
	}
}

void
linux_schedtail(void *arg __unused, struct proc *p)
{
	struct linux_emuldata *em;
	int error = 0;
	int *child_set_tid;

	if (__predict_true(p->p_sysent != &elf_linux_sysvec))
		return;

	/* find the emuldata */
	em = em_find(p, EMUL_DOLOCK);

	KASSERT(em != NULL, ("linux_schedtail: emuldata not found.\n"));
	child_set_tid = em->child_set_tid;
	EMUL_UNLOCK(&emul_lock);

	if (child_set_tid != NULL)
		error = copyout(&p->p_pid, (int *)child_set_tid,
		    sizeof(p->p_pid));

	return;
}

int
linux_set_tid_address(struct thread *td, struct linux_set_tid_address_args *args)
{
	struct linux_emuldata *em;

#ifdef DEBUG
	if (ldebug(set_tid_address))
		printf(ARGS(set_tid_address, "%p"), args->tidptr);
#endif

	/* find the emuldata */
	em = em_find(td->td_proc, EMUL_DOLOCK);

	KASSERT(em != NULL, ("set_tid_address: emuldata not found.\n"));

	em->child_clear_tid = args->tidptr;
	td->td_retval[0] = td->td_proc->p_pid;

	EMUL_UNLOCK(&emul_lock);
	return 0;
}
OpenPOWER on IntegriCloud