FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_trap.c
1 /*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (C) 1994, David Greenman
5 * Copyright (c) 1990, 1993
6 * The Regents of the University of California. All rights reserved.
7 * Copyright (c) 2007 The FreeBSD Foundation
8 *
9 * This code is derived from software contributed to Berkeley by
10 * the University of Utah, and William Jolitz.
11 *
12 * Portions of this software were developed by A. Joseph Koshy under
13 * sponsorship from the FreeBSD Foundation and Google, Inc.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
18 * 1. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 * 3. All advertising materials mentioning features or use of this software
24 * must display the following acknowledgement:
25 * This product includes software developed by the University of
26 * California, Berkeley and its contributors.
27 * 4. Neither the name of the University nor the names of its contributors
28 * may be used to endorse or promote products derived from this software
29 * without specific prior written permission.
30 *
31 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
32 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
33 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
34 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
35 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
39 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
40 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
41 * SUCH DAMAGE.
42 *
43 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91
44 */
45
46 #include <sys/cdefs.h>
47 __FBSDID("$FreeBSD: releng/12.0/sys/kern/subr_trap.c 334595 2018-06-04 01:10:23Z mmacy $");
48
49 #include "opt_hwpmc_hooks.h"
50 #include "opt_ktrace.h"
51 #include "opt_sched.h"
52
53 #include <sys/param.h>
54 #include <sys/bus.h>
55 #include <sys/capsicum.h>
56 #include <sys/kernel.h>
57 #include <sys/lock.h>
58 #include <sys/mutex.h>
59 #include <sys/pmckern.h>
60 #include <sys/proc.h>
61 #include <sys/ktr.h>
62 #include <sys/pioctl.h>
63 #include <sys/ptrace.h>
64 #include <sys/racct.h>
65 #include <sys/resourcevar.h>
66 #include <sys/sched.h>
67 #include <sys/signalvar.h>
68 #include <sys/syscall.h>
69 #include <sys/syscallsubr.h>
70 #include <sys/sysent.h>
71 #include <sys/systm.h>
72 #include <sys/vmmeter.h>
73 #ifdef KTRACE
74 #include <sys/uio.h>
75 #include <sys/ktrace.h>
76 #endif
77 #include <security/audit/audit.h>
78
79 #include <machine/cpu.h>
80
81 #ifdef VIMAGE
82 #include <net/vnet.h>
83 #endif
84
85 #ifdef HWPMC_HOOKS
86 #include <sys/pmckern.h>
87 #endif
88
89 #include <security/mac/mac_framework.h>
90
91 void (*softdep_ast_cleanup)(struct thread *);
92
93 /*
94 * Define the code needed before returning to user mode, for trap and
95 * syscall.
96 */
97 void
98 userret(struct thread *td, struct trapframe *frame)
99 {
100 struct proc *p = td->td_proc;
101
102 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
103 td->td_name);
104 KASSERT((p->p_flag & P_WEXIT) == 0,
105 ("Exiting process returns to usermode"));
106 #ifdef DIAGNOSTIC
107 /*
108 * Check that we called signotify() enough. For
109 * multi-threaded processes, where signal distribution might
110 * change due to other threads changing sigmask, the check is
111 * racy and cannot be performed reliably.
112 * If current process is vfork child, indicated by P_PPWAIT, then
113 * issignal() ignores stops, so we block the check to avoid
114 * classifying pending signals.
115 */
116 if (p->p_numthreads == 1) {
117 PROC_LOCK(p);
118 thread_lock(td);
119 if ((p->p_flag & P_PPWAIT) == 0) {
120 KASSERT(!SIGPENDING(td) || (td->td_flags &
121 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
122 (TDF_NEEDSIGCHK | TDF_ASTPENDING),
123 ("failed to set signal flags for ast p %p "
124 "td %p fl %x", p, td, td->td_flags));
125 }
126 thread_unlock(td);
127 PROC_UNLOCK(p);
128 }
129 #endif
130 #ifdef KTRACE
131 KTRUSERRET(td);
132 #endif
133 td_softdep_cleanup(td);
134 MPASS(td->td_su == NULL);
135
136 /*
137 * If this thread tickled GEOM, we need to wait for the giggling to
138 * stop before we return to userland
139 */
140 if (td->td_pflags & TDP_GEOM)
141 g_waitidle();
142
143 /*
144 * Charge system time if profiling.
145 */
146 if (p->p_flag & P_PROFIL)
147 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
148
149 #ifdef HWPMC_HOOKS
150 if (PMC_THREAD_HAS_SAMPLES(td))
151 PMC_CALL_HOOK(td, PMC_FN_THR_USERRET, NULL);
152 #endif
153 /*
154 * Let the scheduler adjust our priority etc.
155 */
156 sched_userret(td);
157
158 /*
159 * Check for misbehavior.
160 *
161 * In case there is a callchain tracing ongoing because of
162 * hwpmc(4), skip the scheduler pinning check.
163 * hwpmc(4) subsystem, infact, will collect callchain informations
164 * at ast() checkpoint, which is past userret().
165 */
166 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning");
167 KASSERT(td->td_critnest == 0,
168 ("userret: Returning in a critical section"));
169 KASSERT(td->td_epochnest == 0,
170 ("userret: Returning in an epoch section"));
171 KASSERT(td->td_locks == 0,
172 ("userret: Returning with %d locks held", td->td_locks));
173 KASSERT(td->td_rw_rlocks == 0,
174 ("userret: Returning with %d rwlocks held in read mode",
175 td->td_rw_rlocks));
176 KASSERT(td->td_sx_slocks == 0,
177 ("userret: Returning with %d sx locks held in shared mode",
178 td->td_sx_slocks));
179 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
180 ("userret: Returning with pagefaults disabled"));
181 KASSERT(td->td_no_sleeping == 0,
182 ("userret: Returning with sleep disabled"));
183 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0,
184 ("userret: Returning with with pinned thread"));
185 KASSERT(td->td_vp_reserv == 0,
186 ("userret: Returning while holding vnode reservation"));
187 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0,
188 ("userret: Returning with stop signals deferred"));
189 KASSERT(td->td_su == NULL,
190 ("userret: Returning with SU cleanup request not handled"));
191 KASSERT(td->td_vslock_sz == 0,
192 ("userret: Returning with vslock-wired space"));
193 #ifdef VIMAGE
194 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
195 VNET_ASSERT(curvnet == NULL,
196 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
197 __func__, td, p->p_pid, td->td_name, curvnet,
198 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
199 #endif
200 #ifdef RACCT
201 if (racct_enable && p->p_throttled != 0) {
202 PROC_LOCK(p);
203 while (p->p_throttled != 0) {
204 msleep(p->p_racct, &p->p_mtx, 0, "racct",
205 p->p_throttled < 0 ? 0 : p->p_throttled);
206 if (p->p_throttled > 0)
207 p->p_throttled = 0;
208 }
209 PROC_UNLOCK(p);
210 }
211 #endif
212 }
213
214 /*
215 * Process an asynchronous software trap.
216 * This is relatively easy.
217 * This function will return with preemption disabled.
218 */
219 void
220 ast(struct trapframe *framep)
221 {
222 struct thread *td;
223 struct proc *p;
224 int flags;
225 int sig;
226
227 td = curthread;
228 p = td->td_proc;
229
230 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
231 p->p_comm);
232 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
233 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
234 mtx_assert(&Giant, MA_NOTOWNED);
235 THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
236 td->td_frame = framep;
237 td->td_pticks = 0;
238
239 /*
240 * This updates the td_flag's for the checks below in one
241 * "atomic" operation with turning off the astpending flag.
242 * If another AST is triggered while we are handling the
243 * AST's saved in flags, the astpending flag will be set and
244 * ast() will be called again.
245 */
246 thread_lock(td);
247 flags = td->td_flags;
248 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
249 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
250 thread_unlock(td);
251 VM_CNT_INC(v_trap);
252
253 if (td->td_cowgen != p->p_cowgen)
254 thread_cow_update(td);
255 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
256 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
257 td->td_profil_ticks = 0;
258 td->td_pflags &= ~TDP_OWEUPC;
259 }
260 #ifdef HWPMC_HOOKS
261 /* Handle Software PMC callchain capture. */
262 if (PMC_IS_PENDING_CALLCHAIN(td))
263 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep);
264 #endif
265 if (flags & TDF_ALRMPEND) {
266 PROC_LOCK(p);
267 kern_psignal(p, SIGVTALRM);
268 PROC_UNLOCK(p);
269 }
270 if (flags & TDF_PROFPEND) {
271 PROC_LOCK(p);
272 kern_psignal(p, SIGPROF);
273 PROC_UNLOCK(p);
274 }
275 #ifdef MAC
276 if (flags & TDF_MACPEND)
277 mac_thread_userret(td);
278 #endif
279 if (flags & TDF_NEEDRESCHED) {
280 #ifdef KTRACE
281 if (KTRPOINT(td, KTR_CSW))
282 ktrcsw(1, 1, __func__);
283 #endif
284 thread_lock(td);
285 sched_prio(td, td->td_user_pri);
286 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
287 thread_unlock(td);
288 #ifdef KTRACE
289 if (KTRPOINT(td, KTR_CSW))
290 ktrcsw(0, 1, __func__);
291 #endif
292 }
293
294 #ifdef DIAGNOSTIC
295 if (p->p_numthreads == 1 && (flags & TDF_NEEDSIGCHK) == 0) {
296 PROC_LOCK(p);
297 thread_lock(td);
298 /*
299 * Note that TDF_NEEDSIGCHK should be re-read from
300 * td_flags, since signal might have been delivered
301 * after we cleared td_flags above. This is one of
302 * the reason for looping check for AST condition.
303 * See comment in userret() about P_PPWAIT.
304 */
305 if ((p->p_flag & P_PPWAIT) == 0) {
306 KASSERT(!SIGPENDING(td) || (td->td_flags &
307 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
308 (TDF_NEEDSIGCHK | TDF_ASTPENDING),
309 ("failed2 to set signal flags for ast p %p td %p "
310 "fl %x %x", p, td, flags, td->td_flags));
311 }
312 thread_unlock(td);
313 PROC_UNLOCK(p);
314 }
315 #endif
316
317 /*
318 * Check for signals. Unlocked reads of p_pendingcnt or
319 * p_siglist might cause process-directed signal to be handled
320 * later.
321 */
322 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
323 !SIGISEMPTY(p->p_siglist)) {
324 PROC_LOCK(p);
325 mtx_lock(&p->p_sigacts->ps_mtx);
326 while ((sig = cursig(td)) != 0) {
327 KASSERT(sig >= 0, ("sig %d", sig));
328 postsig(sig);
329 }
330 mtx_unlock(&p->p_sigacts->ps_mtx);
331 PROC_UNLOCK(p);
332 }
333 /*
334 * We need to check to see if we have to exit or wait due to a
335 * single threading requirement or some other STOP condition.
336 */
337 if (flags & TDF_NEEDSUSPCHK) {
338 PROC_LOCK(p);
339 thread_suspend_check(0);
340 PROC_UNLOCK(p);
341 }
342
343 if (td->td_pflags & TDP_OLDMASK) {
344 td->td_pflags &= ~TDP_OLDMASK;
345 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
346 }
347
348 userret(td, framep);
349 }
350
351 const char *
352 syscallname(struct proc *p, u_int code)
353 {
354 static const char unknown[] = "unknown";
355 struct sysentvec *sv;
356
357 sv = p->p_sysent;
358 if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
359 return (unknown);
360 return (sv->sv_syscallnames[code]);
361 }
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