FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_trap.c
1 /*-
2 * Copyright (C) 1994, David Greenman
3 * Copyright (c) 1990, 1993
4 * The Regents of the University of California. All rights reserved.
5 * Copyright (c) 2007 The FreeBSD Foundation
6 *
7 * This code is derived from software contributed to Berkeley by
8 * the University of Utah, and William Jolitz.
9 *
10 * Portions of this software were developed by A. Joseph Koshy under
11 * sponsorship from the FreeBSD Foundation and Google, Inc.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. All advertising materials mentioning features or use of this software
22 * must display the following acknowledgement:
23 * This product includes software developed by the University of
24 * California, Berkeley and its contributors.
25 * 4. Neither the name of the University nor the names of its contributors
26 * may be used to endorse or promote products derived from this software
27 * without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * SUCH DAMAGE.
40 *
41 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91
42 */
43
44 #include <sys/cdefs.h>
45 __FBSDID("$FreeBSD: releng/10.1/sys/kern/subr_trap.c 263875 2014-03-28 15:38:38Z kib $");
46
47 #include "opt_hwpmc_hooks.h"
48 #include "opt_ktrace.h"
49 #include "opt_kdtrace.h"
50 #include "opt_sched.h"
51
52 #include <sys/param.h>
53 #include <sys/bus.h>
54 #include <sys/capability.h>
55 #include <sys/kernel.h>
56 #include <sys/lock.h>
57 #include <sys/mutex.h>
58 #include <sys/pmckern.h>
59 #include <sys/proc.h>
60 #include <sys/ktr.h>
61 #include <sys/pioctl.h>
62 #include <sys/ptrace.h>
63 #include <sys/resourcevar.h>
64 #include <sys/sched.h>
65 #include <sys/signalvar.h>
66 #include <sys/syscall.h>
67 #include <sys/syscallsubr.h>
68 #include <sys/sysent.h>
69 #include <sys/systm.h>
70 #include <sys/vmmeter.h>
71 #ifdef KTRACE
72 #include <sys/uio.h>
73 #include <sys/ktrace.h>
74 #endif
75 #include <security/audit/audit.h>
76
77 #include <machine/cpu.h>
78
79 #ifdef VIMAGE
80 #include <net/vnet.h>
81 #endif
82
83 #ifdef XEN
84 #include <vm/vm.h>
85 #include <vm/vm_param.h>
86 #include <vm/pmap.h>
87 #endif
88
89 #ifdef HWPMC_HOOKS
90 #include <sys/pmckern.h>
91 #endif
92
93 #include <security/mac/mac_framework.h>
94
95 /*
96 * Define the code needed before returning to user mode, for trap and
97 * syscall.
98 */
99 void
100 userret(struct thread *td, struct trapframe *frame)
101 {
102 struct proc *p = td->td_proc;
103
104 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
105 td->td_name);
106 KASSERT((p->p_flag & P_WEXIT) == 0,
107 ("Exiting process returns to usermode"));
108 #if 0
109 #ifdef DIAGNOSTIC
110 /* Check that we called signotify() enough. */
111 PROC_LOCK(p);
112 thread_lock(td);
113 if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
114 (td->td_flags & TDF_ASTPENDING) == 0))
115 printf("failed to set signal flags properly for ast()\n");
116 thread_unlock(td);
117 PROC_UNLOCK(p);
118 #endif
119 #endif
120 #ifdef KTRACE
121 KTRUSERRET(td);
122 #endif
123 /*
124 * If this thread tickled GEOM, we need to wait for the giggling to
125 * stop before we return to userland
126 */
127 if (td->td_pflags & TDP_GEOM)
128 g_waitidle();
129
130 /*
131 * Charge system time if profiling.
132 */
133 if (p->p_flag & P_PROFIL)
134 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
135 /*
136 * Let the scheduler adjust our priority etc.
137 */
138 sched_userret(td);
139 #ifdef XEN
140 PT_UPDATES_FLUSH();
141 #endif
142
143 /*
144 * Check for misbehavior.
145 *
146 * In case there is a callchain tracing ongoing because of
147 * hwpmc(4), skip the scheduler pinning check.
148 * hwpmc(4) subsystem, infact, will collect callchain informations
149 * at ast() checkpoint, which is past userret().
150 */
151 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning");
152 KASSERT(td->td_critnest == 0,
153 ("userret: Returning in a critical section"));
154 KASSERT(td->td_locks == 0,
155 ("userret: Returning with %d locks held", td->td_locks));
156 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
157 ("userret: Returning with pagefaults disabled"));
158 KASSERT((td->td_pflags & TDP_DEVMEMIO) == 0,
159 ("userret: Returning with /dev/mem i/o leaked"));
160 KASSERT(td->td_no_sleeping == 0,
161 ("userret: Returning with sleep disabled"));
162 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0,
163 ("userret: Returning with with pinned thread"));
164 KASSERT(td->td_vp_reserv == 0,
165 ("userret: Returning while holding vnode reservation"));
166 KASSERT((td->td_flags & TDF_SBDRY) == 0,
167 ("userret: Returning with stop signals deferred"));
168 #ifdef VIMAGE
169 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
170 VNET_ASSERT(curvnet == NULL,
171 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
172 __func__, td, p->p_pid, td->td_name, curvnet,
173 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
174 #endif
175 #ifdef RACCT
176 PROC_LOCK(p);
177 while (p->p_throttled == 1)
178 msleep(p->p_racct, &p->p_mtx, 0, "racct", 0);
179 PROC_UNLOCK(p);
180 #endif
181 }
182
183 /*
184 * Process an asynchronous software trap.
185 * This is relatively easy.
186 * This function will return with preemption disabled.
187 */
188 void
189 ast(struct trapframe *framep)
190 {
191 struct thread *td;
192 struct proc *p;
193 int flags;
194 int sig;
195
196 td = curthread;
197 p = td->td_proc;
198
199 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
200 p->p_comm);
201 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
202 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
203 mtx_assert(&Giant, MA_NOTOWNED);
204 THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
205 td->td_frame = framep;
206 td->td_pticks = 0;
207
208 /*
209 * This updates the td_flag's for the checks below in one
210 * "atomic" operation with turning off the astpending flag.
211 * If another AST is triggered while we are handling the
212 * AST's saved in flags, the astpending flag will be set and
213 * ast() will be called again.
214 */
215 thread_lock(td);
216 flags = td->td_flags;
217 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
218 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
219 thread_unlock(td);
220 PCPU_INC(cnt.v_trap);
221
222 if (td->td_ucred != p->p_ucred)
223 cred_update_thread(td);
224 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
225 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
226 td->td_profil_ticks = 0;
227 td->td_pflags &= ~TDP_OWEUPC;
228 }
229 #ifdef HWPMC_HOOKS
230 /* Handle Software PMC callchain capture. */
231 if (PMC_IS_PENDING_CALLCHAIN(td))
232 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep);
233 #endif
234 if (flags & TDF_ALRMPEND) {
235 PROC_LOCK(p);
236 kern_psignal(p, SIGVTALRM);
237 PROC_UNLOCK(p);
238 }
239 if (flags & TDF_PROFPEND) {
240 PROC_LOCK(p);
241 kern_psignal(p, SIGPROF);
242 PROC_UNLOCK(p);
243 }
244 #ifdef MAC
245 if (flags & TDF_MACPEND)
246 mac_thread_userret(td);
247 #endif
248 if (flags & TDF_NEEDRESCHED) {
249 #ifdef KTRACE
250 if (KTRPOINT(td, KTR_CSW))
251 ktrcsw(1, 1, __func__);
252 #endif
253 thread_lock(td);
254 sched_prio(td, td->td_user_pri);
255 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
256 thread_unlock(td);
257 #ifdef KTRACE
258 if (KTRPOINT(td, KTR_CSW))
259 ktrcsw(0, 1, __func__);
260 #endif
261 }
262
263 /*
264 * Check for signals. Unlocked reads of p_pendingcnt or
265 * p_siglist might cause process-directed signal to be handled
266 * later.
267 */
268 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
269 !SIGISEMPTY(p->p_siglist)) {
270 PROC_LOCK(p);
271 mtx_lock(&p->p_sigacts->ps_mtx);
272 while ((sig = cursig(td)) != 0)
273 postsig(sig);
274 mtx_unlock(&p->p_sigacts->ps_mtx);
275 PROC_UNLOCK(p);
276 }
277 /*
278 * We need to check to see if we have to exit or wait due to a
279 * single threading requirement or some other STOP condition.
280 */
281 if (flags & TDF_NEEDSUSPCHK) {
282 PROC_LOCK(p);
283 thread_suspend_check(0);
284 PROC_UNLOCK(p);
285 }
286
287 if (td->td_pflags & TDP_OLDMASK) {
288 td->td_pflags &= ~TDP_OLDMASK;
289 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
290 }
291
292 userret(td, framep);
293 }
294
295 const char *
296 syscallname(struct proc *p, u_int code)
297 {
298 static const char unknown[] = "unknown";
299 struct sysentvec *sv;
300
301 sv = p->p_sysent;
302 if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
303 return (unknown);
304 return (sv->sv_syscallnames[code]);
305 }
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