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/10.2/sys/kern/subr_trap.c 284665 2015-06-21 06:28:26Z trasz $");
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/capsicum.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/racct.h>
64 #include <sys/resourcevar.h>
65 #include <sys/sched.h>
66 #include <sys/signalvar.h>
67 #include <sys/syscall.h>
68 #include <sys/syscallsubr.h>
69 #include <sys/sysent.h>
70 #include <sys/systm.h>
71 #include <sys/vmmeter.h>
72 #ifdef KTRACE
73 #include <sys/uio.h>
74 #include <sys/ktrace.h>
75 #endif
76 #include <security/audit/audit.h>
77
78 #include <machine/cpu.h>
79
80 #ifdef VIMAGE
81 #include <net/vnet.h>
82 #endif
83
84 #ifdef XEN
85 #include <vm/vm.h>
86 #include <vm/vm_param.h>
87 #include <vm/pmap.h>
88 #endif
89
90 #ifdef HWPMC_HOOKS
91 #include <sys/pmckern.h>
92 #endif
93
94 #include <security/mac/mac_framework.h>
95
96 void (*softdep_ast_cleanup)(void);
97
98 /*
99 * Define the code needed before returning to user mode, for trap and
100 * syscall.
101 */
102 void
103 userret(struct thread *td, struct trapframe *frame)
104 {
105 struct proc *p = td->td_proc;
106
107 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
108 td->td_name);
109 KASSERT((p->p_flag & P_WEXIT) == 0,
110 ("Exiting process returns to usermode"));
111 #if 0
112 #ifdef DIAGNOSTIC
113 /* Check that we called signotify() enough. */
114 PROC_LOCK(p);
115 thread_lock(td);
116 if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
117 (td->td_flags & TDF_ASTPENDING) == 0))
118 printf("failed to set signal flags properly for ast()\n");
119 thread_unlock(td);
120 PROC_UNLOCK(p);
121 #endif
122 #endif
123 #ifdef KTRACE
124 KTRUSERRET(td);
125 #endif
126 if (softdep_ast_cleanup != NULL)
127 softdep_ast_cleanup();
128
129 /*
130 * If this thread tickled GEOM, we need to wait for the giggling to
131 * stop before we return to userland
132 */
133 if (td->td_pflags & TDP_GEOM)
134 g_waitidle();
135
136 /*
137 * Charge system time if profiling.
138 */
139 if (p->p_flag & P_PROFIL)
140 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
141 /*
142 * Let the scheduler adjust our priority etc.
143 */
144 sched_userret(td);
145 #ifdef XEN
146 PT_UPDATES_FLUSH();
147 #endif
148
149 /*
150 * Check for misbehavior.
151 *
152 * In case there is a callchain tracing ongoing because of
153 * hwpmc(4), skip the scheduler pinning check.
154 * hwpmc(4) subsystem, infact, will collect callchain informations
155 * at ast() checkpoint, which is past userret().
156 */
157 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning");
158 KASSERT(td->td_critnest == 0,
159 ("userret: Returning in a critical section"));
160 KASSERT(td->td_locks == 0,
161 ("userret: Returning with %d locks held", td->td_locks));
162 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
163 ("userret: Returning with pagefaults disabled"));
164 KASSERT(td->td_no_sleeping == 0,
165 ("userret: Returning with sleep disabled"));
166 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0,
167 ("userret: Returning with with pinned thread"));
168 KASSERT(td->td_vp_reserv == 0,
169 ("userret: Returning while holding vnode reservation"));
170 KASSERT((td->td_flags & TDF_SBDRY) == 0,
171 ("userret: Returning with stop signals deferred"));
172 KASSERT(td->td_su == NULL,
173 ("userret: Returning with SU cleanup request not handled"));
174 #ifdef VIMAGE
175 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
176 VNET_ASSERT(curvnet == NULL,
177 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
178 __func__, td, p->p_pid, td->td_name, curvnet,
179 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
180 #endif
181 #ifdef RACCT
182 if (racct_enable) {
183 PROC_LOCK(p);
184 while (p->p_throttled == 1)
185 msleep(p->p_racct, &p->p_mtx, 0, "racct", 0);
186 PROC_UNLOCK(p);
187 }
188 #endif
189 }
190
191 /*
192 * Process an asynchronous software trap.
193 * This is relatively easy.
194 * This function will return with preemption disabled.
195 */
196 void
197 ast(struct trapframe *framep)
198 {
199 struct thread *td;
200 struct proc *p;
201 int flags;
202 int sig;
203
204 td = curthread;
205 p = td->td_proc;
206
207 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
208 p->p_comm);
209 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
210 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
211 mtx_assert(&Giant, MA_NOTOWNED);
212 THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
213 td->td_frame = framep;
214 td->td_pticks = 0;
215
216 /*
217 * This updates the td_flag's for the checks below in one
218 * "atomic" operation with turning off the astpending flag.
219 * If another AST is triggered while we are handling the
220 * AST's saved in flags, the astpending flag will be set and
221 * ast() will be called again.
222 */
223 thread_lock(td);
224 flags = td->td_flags;
225 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
226 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
227 thread_unlock(td);
228 PCPU_INC(cnt.v_trap);
229
230 if (td->td_ucred != p->p_ucred)
231 cred_update_thread(td);
232 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
233 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
234 td->td_profil_ticks = 0;
235 td->td_pflags &= ~TDP_OWEUPC;
236 }
237 #ifdef HWPMC_HOOKS
238 /* Handle Software PMC callchain capture. */
239 if (PMC_IS_PENDING_CALLCHAIN(td))
240 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep);
241 #endif
242 if (flags & TDF_ALRMPEND) {
243 PROC_LOCK(p);
244 kern_psignal(p, SIGVTALRM);
245 PROC_UNLOCK(p);
246 }
247 if (flags & TDF_PROFPEND) {
248 PROC_LOCK(p);
249 kern_psignal(p, SIGPROF);
250 PROC_UNLOCK(p);
251 }
252 #ifdef MAC
253 if (flags & TDF_MACPEND)
254 mac_thread_userret(td);
255 #endif
256 if (flags & TDF_NEEDRESCHED) {
257 #ifdef KTRACE
258 if (KTRPOINT(td, KTR_CSW))
259 ktrcsw(1, 1, __func__);
260 #endif
261 thread_lock(td);
262 sched_prio(td, td->td_user_pri);
263 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
264 thread_unlock(td);
265 #ifdef KTRACE
266 if (KTRPOINT(td, KTR_CSW))
267 ktrcsw(0, 1, __func__);
268 #endif
269 }
270
271 /*
272 * Check for signals. Unlocked reads of p_pendingcnt or
273 * p_siglist might cause process-directed signal to be handled
274 * later.
275 */
276 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
277 !SIGISEMPTY(p->p_siglist)) {
278 PROC_LOCK(p);
279 mtx_lock(&p->p_sigacts->ps_mtx);
280 while ((sig = cursig(td)) != 0)
281 postsig(sig);
282 mtx_unlock(&p->p_sigacts->ps_mtx);
283 PROC_UNLOCK(p);
284 }
285 /*
286 * We need to check to see if we have to exit or wait due to a
287 * single threading requirement or some other STOP condition.
288 */
289 if (flags & TDF_NEEDSUSPCHK) {
290 PROC_LOCK(p);
291 thread_suspend_check(0);
292 PROC_UNLOCK(p);
293 }
294
295 if (td->td_pflags & TDP_OLDMASK) {
296 td->td_pflags &= ~TDP_OLDMASK;
297 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
298 }
299
300 userret(td, framep);
301 }
302
303 const char *
304 syscallname(struct proc *p, u_int code)
305 {
306 static const char unknown[] = "unknown";
307 struct sysentvec *sv;
308
309 sv = p->p_sysent;
310 if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
311 return (unknown);
312 return (sv->sv_syscallnames[code]);
313 }
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