summaryrefslogtreecommitdiffstats
path: root/sys/kern/subr_trap.c
blob: 8af60bc3413606f45ec8fc7eb29a0804516ea5b4 (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
/*-
 * Copyright (C) 1994, David Greenman
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 2007 The FreeBSD Foundation
 *
 * This code is derived from software contributed to Berkeley by
 * the University of Utah, and William Jolitz.
 *
 * Portions of this software were developed by A. Joseph Koshy under
 * sponsorship from the FreeBSD Foundation and Google, Inc.
 *
 * 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.
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 *
 *	from: @(#)trap.c	7.4 (Berkeley) 5/13/91
 */

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

#include "opt_hwpmc_hooks.h"
#include "opt_ktrace.h"
#include "opt_kdtrace.h"
#include "opt_sched.h"

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/capability.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/pmckern.h>
#include <sys/proc.h>
#include <sys/ktr.h>
#include <sys/pioctl.h>
#include <sys/ptrace.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/signalvar.h>
#include <sys/syscall.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/systm.h>
#include <sys/vmmeter.h>
#ifdef KTRACE
#include <sys/uio.h>
#include <sys/ktrace.h>
#endif
#include <security/audit/audit.h>

#include <machine/cpu.h>

#ifdef VIMAGE
#include <net/vnet.h>
#endif

#ifdef XEN
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#endif

#ifdef	HWPMC_HOOKS
#include <sys/pmckern.h>
#endif

#include <security/mac/mac_framework.h>

/*
 * Define the code needed before returning to user mode, for trap and
 * syscall.
 */
void
userret(struct thread *td, struct trapframe *frame)
{
	struct proc *p = td->td_proc;

	CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
            td->td_name);
	KASSERT((p->p_flag & P_WEXIT) == 0,
	    ("Exiting process returns to usermode"));
#if 0
#ifdef DIAGNOSTIC
	/* Check that we called signotify() enough. */
	PROC_LOCK(p);
	thread_lock(td);
	if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
	    (td->td_flags & TDF_ASTPENDING) == 0))
		printf("failed to set signal flags properly for ast()\n");
	thread_unlock(td);
	PROC_UNLOCK(p);
#endif
#endif
#ifdef KTRACE
	KTRUSERRET(td);
#endif
	/*
	 * If this thread tickled GEOM, we need to wait for the giggling to
	 * stop before we return to userland
	 */
	if (td->td_pflags & TDP_GEOM)
		g_waitidle();

	/*
	 * Charge system time if profiling.
	 */
	if (p->p_flag & P_PROFIL)
		addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
	/*
	 * Let the scheduler adjust our priority etc.
	 */
	sched_userret(td);
#ifdef XEN
	PT_UPDATES_FLUSH();
#endif

	/*
	 * Check for misbehavior.
	 *
	 * In case there is a callchain tracing ongoing because of
	 * hwpmc(4), skip the scheduler pinning check.
	 * hwpmc(4) subsystem, infact, will collect callchain informations
	 * at ast() checkpoint, which is past userret().
	 */
	WITNESS_WARN(WARN_PANIC, NULL, "userret: returning");
	KASSERT(td->td_critnest == 0,
	    ("userret: Returning in a critical section"));
	KASSERT(td->td_locks == 0,
	    ("userret: Returning with %d locks held", td->td_locks));
	KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
	    ("userret: Returning with pagefaults disabled"));
	KASSERT((td->td_pflags & TDP_DEVMEMIO) == 0,
	    ("userret: Returning with /dev/mem i/o leaked"));
	KASSERT(td->td_no_sleeping == 0,
	    ("userret: Returning with sleep disabled"));
	KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0,
	    ("userret: Returning with with pinned thread"));
	KASSERT(td->td_vp_reserv == 0,
	    ("userret: Returning while holding vnode reservation"));
	KASSERT((td->td_flags & TDF_SBDRY) == 0,
	    ("userret: Returning with stop signals deferred"));
#ifdef VIMAGE
	/* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
	VNET_ASSERT(curvnet == NULL,
	    ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
	    __func__, td, p->p_pid, td->td_name, curvnet,
	    (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
#endif
#ifdef	RACCT
	PROC_LOCK(p);
	while (p->p_throttled == 1)
		msleep(p->p_racct, &p->p_mtx, 0, "racct", 0);
	PROC_UNLOCK(p);
#endif
}

/*
 * Process an asynchronous software trap.
 * This is relatively easy.
 * This function will return with preemption disabled.
 */
void
ast(struct trapframe *framep)
{
	struct thread *td;
	struct proc *p;
	int flags;
	int sig;

	td = curthread;
	p = td->td_proc;

	CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
            p->p_comm);
	KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
	WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
	mtx_assert(&Giant, MA_NOTOWNED);
	THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
	td->td_frame = framep;
	td->td_pticks = 0;

	/*
	 * This updates the td_flag's for the checks below in one
	 * "atomic" operation with turning off the astpending flag.
	 * If another AST is triggered while we are handling the
	 * AST's saved in flags, the astpending flag will be set and
	 * ast() will be called again.
	 */
	thread_lock(td);
	flags = td->td_flags;
	td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
	    TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
	thread_unlock(td);
	PCPU_INC(cnt.v_trap);

	if (td->td_ucred != p->p_ucred) 
		cred_update_thread(td);
	if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
		addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
		td->td_profil_ticks = 0;
		td->td_pflags &= ~TDP_OWEUPC;
	}
#ifdef HWPMC_HOOKS
	/* Handle Software PMC callchain capture. */
	if (PMC_IS_PENDING_CALLCHAIN(td))
		PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep);
#endif
	if (flags & TDF_ALRMPEND) {
		PROC_LOCK(p);
		kern_psignal(p, SIGVTALRM);
		PROC_UNLOCK(p);
	}
	if (flags & TDF_PROFPEND) {
		PROC_LOCK(p);
		kern_psignal(p, SIGPROF);
		PROC_UNLOCK(p);
	}
#ifdef MAC
	if (flags & TDF_MACPEND)
		mac_thread_userret(td);
#endif
	if (flags & TDF_NEEDRESCHED) {
#ifdef KTRACE
		if (KTRPOINT(td, KTR_CSW))
			ktrcsw(1, 1, __func__);
#endif
		thread_lock(td);
		sched_prio(td, td->td_user_pri);
		mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
		thread_unlock(td);
#ifdef KTRACE
		if (KTRPOINT(td, KTR_CSW))
			ktrcsw(0, 1, __func__);
#endif
	}

	/*
	 * Check for signals. Unlocked reads of p_pendingcnt or
	 * p_siglist might cause process-directed signal to be handled
	 * later.
	 */
	if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
	    !SIGISEMPTY(p->p_siglist)) {
		PROC_LOCK(p);
		mtx_lock(&p->p_sigacts->ps_mtx);
		while ((sig = cursig(td)) != 0)
			postsig(sig);
		mtx_unlock(&p->p_sigacts->ps_mtx);
		PROC_UNLOCK(p);
	}
	/*
	 * We need to check to see if we have to exit or wait due to a
	 * single threading requirement or some other STOP condition.
	 */
	if (flags & TDF_NEEDSUSPCHK) {
		PROC_LOCK(p);
		thread_suspend_check(0);
		PROC_UNLOCK(p);
	}

	if (td->td_pflags & TDP_OLDMASK) {
		td->td_pflags &= ~TDP_OLDMASK;
		kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
	}

	userret(td, framep);
}

const char *
syscallname(struct proc *p, u_int code)
{
	static const char unknown[] = "unknown";
	struct sysentvec *sv;

	sv = p->p_sysent;
	if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
		return (unknown);
	return (sv->sv_syscallnames[code]);
}
OpenPOWER on IntegriCloud