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("$FreeBSD$");
46
47 #include "opt_hwpmc_hooks.h"
48 #include "opt_ktrace.h"
49 #include "opt_sched.h"
50
51 #include <sys/param.h>
52 #include <sys/bus.h>
53 #include <sys/capsicum.h>
54 #include <sys/kernel.h>
55 #include <sys/lock.h>
56 #include <sys/mutex.h>
57 #include <sys/pmckern.h>
58 #include <sys/proc.h>
59 #include <sys/ktr.h>
60 #include <sys/pioctl.h>
61 #include <sys/ptrace.h>
62 #include <sys/racct.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 HWPMC_HOOKS
84 #include <sys/pmckern.h>
85 #endif
86
87 #include <security/mac/mac_framework.h>
88
89 void (*softdep_ast_cleanup)(struct thread *);
90
91 /*
92 * Define the code needed before returning to user mode, for trap and
93 * syscall.
94 */
95 void
96 userret(struct thread *td, struct trapframe *frame)
97 {
98 struct proc *p = td->td_proc;
99
100 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
101 td->td_name);
102 KASSERT((p->p_flag & P_WEXIT) == 0,
103 ("Exiting process returns to usermode"));
104 #ifdef DIAGNOSTIC
105 /*
106 * Check that we called signotify() enough. For
107 * multi-threaded processes, where signal distribution might
108 * change due to other threads changing sigmask, the check is
109 * racy and cannot be performed reliably.
110 * If current process is vfork child, indicated by P_PPWAIT, then
111 * issignal() ignores stops, so we block the check to avoid
112 * classifying pending signals.
113 */
114 if (p->p_numthreads == 1) {
115 PROC_LOCK(p);
116 thread_lock(td);
117 if ((p->p_flag & P_PPWAIT) == 0) {
118 KASSERT(!SIGPENDING(td) || (td->td_flags &
119 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
120 (TDF_NEEDSIGCHK | TDF_ASTPENDING),
121 ("failed to set signal flags for ast p %p "
122 "td %p fl %x", p, td, td->td_flags));
123 }
124 thread_unlock(td);
125 PROC_UNLOCK(p);
126 }
127 #endif
128 #ifdef KTRACE
129 KTRUSERRET(td);
130 #endif
131 td_softdep_cleanup(td);
132 MPASS(td->td_su == NULL);
133
134 /*
135 * If this thread tickled GEOM, we need to wait for the giggling to
136 * stop before we return to userland
137 */
138 if (td->td_pflags & TDP_GEOM)
139 g_waitidle();
140
141 /*
142 * Charge system time if profiling.
143 */
144 if (p->p_flag & P_PROFIL)
145 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
146 /*
147 * Let the scheduler adjust our priority etc.
148 */
149 sched_userret(td);
150
151 /*
152 * Check for misbehavior.
153 *
154 * In case there is a callchain tracing ongoing because of
155 * hwpmc(4), skip the scheduler pinning check.
156 * hwpmc(4) subsystem, infact, will collect callchain informations
157 * at ast() checkpoint, which is past userret().
158 */
159 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning");
160 KASSERT(td->td_critnest == 0,
161 ("userret: Returning in a critical section"));
162 KASSERT(td->td_locks == 0,
163 ("userret: Returning with %d locks held", td->td_locks));
164 KASSERT(td->td_rw_rlocks == 0,
165 ("userret: Returning with %d rwlocks held in read mode",
166 td->td_rw_rlocks));
167 KASSERT(td->td_lk_slocks == 0,
168 ("userret: Returning with %d lockmanager locks held in shared mode",
169 td->td_lk_slocks));
170 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
171 ("userret: Returning with pagefaults disabled"));
172 KASSERT(td->td_no_sleeping == 0,
173 ("userret: Returning with sleep disabled"));
174 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0,
175 ("userret: Returning with with pinned thread"));
176 KASSERT(td->td_vp_reserv == 0,
177 ("userret: Returning while holding vnode reservation"));
178 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0,
179 ("userret: Returning with stop signals deferred"));
180 KASSERT(td->td_su == NULL,
181 ("userret: Returning with SU cleanup request not handled"));
182 KASSERT(td->td_vslock_sz == 0,
183 ("userret: Returning with vslock-wired space"));
184 #ifdef VIMAGE
185 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
186 VNET_ASSERT(curvnet == NULL,
187 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
188 __func__, td, p->p_pid, td->td_name, curvnet,
189 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
190 #endif
191 #ifdef RACCT
192 if (racct_enable && p->p_throttled != 0) {
193 PROC_LOCK(p);
194 while (p->p_throttled != 0) {
195 msleep(p->p_racct, &p->p_mtx, 0, "racct",
196 p->p_throttled < 0 ? 0 : p->p_throttled);
197 if (p->p_throttled > 0)
198 p->p_throttled = 0;
199 }
200 PROC_UNLOCK(p);
201 }
202 #endif
203 }
204
205 /*
206 * Process an asynchronous software trap.
207 * This is relatively easy.
208 * This function will return with preemption disabled.
209 */
210 void
211 ast(struct trapframe *framep)
212 {
213 struct thread *td;
214 struct proc *p;
215 int flags;
216 int sig;
217
218 td = curthread;
219 p = td->td_proc;
220
221 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
222 p->p_comm);
223 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
224 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
225 mtx_assert(&Giant, MA_NOTOWNED);
226 THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
227 td->td_frame = framep;
228 td->td_pticks = 0;
229
230 /*
231 * This updates the td_flag's for the checks below in one
232 * "atomic" operation with turning off the astpending flag.
233 * If another AST is triggered while we are handling the
234 * AST's saved in flags, the astpending flag will be set and
235 * ast() will be called again.
236 */
237 thread_lock(td);
238 flags = td->td_flags;
239 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
240 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
241 thread_unlock(td);
242 PCPU_INC(cnt.v_trap);
243
244 if (td->td_cowgen != p->p_cowgen)
245 thread_cow_update(td);
246 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
247 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
248 td->td_profil_ticks = 0;
249 td->td_pflags &= ~TDP_OWEUPC;
250 }
251 #ifdef HWPMC_HOOKS
252 /* Handle Software PMC callchain capture. */
253 if (PMC_IS_PENDING_CALLCHAIN(td))
254 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep);
255 #endif
256 if (flags & TDF_ALRMPEND) {
257 PROC_LOCK(p);
258 kern_psignal(p, SIGVTALRM);
259 PROC_UNLOCK(p);
260 }
261 if (flags & TDF_PROFPEND) {
262 PROC_LOCK(p);
263 kern_psignal(p, SIGPROF);
264 PROC_UNLOCK(p);
265 }
266 #ifdef MAC
267 if (flags & TDF_MACPEND)
268 mac_thread_userret(td);
269 #endif
270 if (flags & TDF_NEEDRESCHED) {
271 #ifdef KTRACE
272 if (KTRPOINT(td, KTR_CSW))
273 ktrcsw(1, 1, __func__);
274 #endif
275 thread_lock(td);
276 sched_prio(td, td->td_user_pri);
277 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
278 thread_unlock(td);
279 #ifdef KTRACE
280 if (KTRPOINT(td, KTR_CSW))
281 ktrcsw(0, 1, __func__);
282 #endif
283 }
284
285 #ifdef DIAGNOSTIC
286 if (p->p_numthreads == 1 && (flags & TDF_NEEDSIGCHK) == 0) {
287 PROC_LOCK(p);
288 thread_lock(td);
289 /*
290 * Note that TDF_NEEDSIGCHK should be re-read from
291 * td_flags, since signal might have been delivered
292 * after we cleared td_flags above. This is one of
293 * the reason for looping check for AST condition.
294 * See comment in userret() about P_PPWAIT.
295 */
296 if ((p->p_flag & P_PPWAIT) == 0) {
297 KASSERT(!SIGPENDING(td) || (td->td_flags &
298 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
299 (TDF_NEEDSIGCHK | TDF_ASTPENDING),
300 ("failed2 to set signal flags for ast p %p td %p "
301 "fl %x %x", p, td, flags, td->td_flags));
302 }
303 thread_unlock(td);
304 PROC_UNLOCK(p);
305 }
306 #endif
307
308 /*
309 * Check for signals. Unlocked reads of p_pendingcnt or
310 * p_siglist might cause process-directed signal to be handled
311 * later.
312 */
313 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
314 !SIGISEMPTY(p->p_siglist)) {
315 PROC_LOCK(p);
316 mtx_lock(&p->p_sigacts->ps_mtx);
317 while ((sig = cursig(td)) != 0)
318 postsig(sig);
319 mtx_unlock(&p->p_sigacts->ps_mtx);
320 PROC_UNLOCK(p);
321 }
322 /*
323 * We need to check to see if we have to exit or wait due to a
324 * single threading requirement or some other STOP condition.
325 */
326 if (flags & TDF_NEEDSUSPCHK) {
327 PROC_LOCK(p);
328 thread_suspend_check(0);
329 PROC_UNLOCK(p);
330 }
331
332 if (td->td_pflags & TDP_OLDMASK) {
333 td->td_pflags &= ~TDP_OLDMASK;
334 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
335 }
336
337 userret(td, framep);
338 }
339
340 const char *
341 syscallname(struct proc *p, u_int code)
342 {
343 static const char unknown[] = "unknown";
344 struct sysentvec *sv;
345
346 sv = p->p_sysent;
347 if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
348 return (unknown);
349 return (sv->sv_syscallnames[code]);
350 }
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