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/9.2/sys/kern/subr_trap.c 251147 2013-05-30 19:14:34Z jhb $");
46
47 #include "opt_capsicum.h"
48 #include "opt_hwpmc_hooks.h"
49 #include "opt_ktrace.h"
50 #include "opt_kdtrace.h"
51 #include "opt_sched.h"
52
53 #include <sys/param.h>
54 #include <sys/bus.h>
55 #include <sys/capability.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/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 /*
97 * Define the code needed before returning to user mode, for trap and
98 * syscall.
99 */
100 void
101 userret(struct thread *td, struct trapframe *frame)
102 {
103 struct proc *p = td->td_proc;
104
105 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
106 td->td_name);
107 KASSERT((p->p_flag & P_WEXIT) == 0,
108 ("Exiting process returns to usermode"));
109 #if 0
110 #ifdef DIAGNOSTIC
111 /* Check that we called signotify() enough. */
112 PROC_LOCK(p);
113 thread_lock(td);
114 if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
115 (td->td_flags & TDF_ASTPENDING) == 0))
116 printf("failed to set signal flags properly for ast()\n");
117 thread_unlock(td);
118 PROC_UNLOCK(p);
119 #endif
120 #endif
121 #ifdef KTRACE
122 KTRUSERRET(td);
123 #endif
124 /*
125 * If this thread tickled GEOM, we need to wait for the giggling to
126 * stop before we return to userland
127 */
128 if (td->td_pflags & TDP_GEOM)
129 g_waitidle();
130
131 /*
132 * Charge system time if profiling.
133 */
134 if (p->p_flag & P_PROFIL)
135 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
136 /*
137 * Let the scheduler adjust our priority etc.
138 */
139 sched_userret(td);
140 KASSERT(td->td_locks == 0,
141 ("userret: Returning with %d locks held.", td->td_locks));
142 KASSERT(td->td_vp_reserv == 0,
143 ("userret: Returning while holding vnode reservation"));
144 KASSERT((td->td_flags & TDF_SBDRY) == 0,
145 ("userret: Returning with stop signals deferred"));
146 #ifdef VIMAGE
147 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
148 VNET_ASSERT(curvnet == NULL,
149 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
150 __func__, td, p->p_pid, td->td_name, curvnet,
151 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
152 #endif
153 #ifdef XEN
154 PT_UPDATES_FLUSH();
155 #endif
156 #ifdef RACCT
157 PROC_LOCK(p);
158 while (p->p_throttled == 1)
159 msleep(p->p_racct, &p->p_mtx, 0, "racct", 0);
160 PROC_UNLOCK(p);
161 #endif
162 }
163
164 /*
165 * Process an asynchronous software trap.
166 * This is relatively easy.
167 * This function will return with preemption disabled.
168 */
169 void
170 ast(struct trapframe *framep)
171 {
172 struct thread *td;
173 struct proc *p;
174 int flags;
175 int sig;
176
177 td = curthread;
178 p = td->td_proc;
179
180 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
181 p->p_comm);
182 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
183 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
184 mtx_assert(&Giant, MA_NOTOWNED);
185 THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
186 td->td_frame = framep;
187 td->td_pticks = 0;
188
189 /*
190 * This updates the td_flag's for the checks below in one
191 * "atomic" operation with turning off the astpending flag.
192 * If another AST is triggered while we are handling the
193 * AST's saved in flags, the astpending flag will be set and
194 * ast() will be called again.
195 */
196 thread_lock(td);
197 flags = td->td_flags;
198 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
199 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
200 thread_unlock(td);
201 PCPU_INC(cnt.v_trap);
202
203 if (td->td_ucred != p->p_ucred)
204 cred_update_thread(td);
205 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
206 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
207 td->td_profil_ticks = 0;
208 td->td_pflags &= ~TDP_OWEUPC;
209 }
210 #ifdef HWPMC_HOOKS
211 /* Handle Software PMC callchain capture. */
212 if (PMC_IS_PENDING_CALLCHAIN(td))
213 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep);
214 #endif
215 if (flags & TDF_ALRMPEND) {
216 PROC_LOCK(p);
217 kern_psignal(p, SIGVTALRM);
218 PROC_UNLOCK(p);
219 }
220 if (flags & TDF_PROFPEND) {
221 PROC_LOCK(p);
222 kern_psignal(p, SIGPROF);
223 PROC_UNLOCK(p);
224 }
225 #ifdef MAC
226 if (flags & TDF_MACPEND)
227 mac_thread_userret(td);
228 #endif
229 if (flags & TDF_NEEDRESCHED) {
230 #ifdef KTRACE
231 if (KTRPOINT(td, KTR_CSW))
232 ktrcsw(1, 1, __func__);
233 #endif
234 thread_lock(td);
235 sched_prio(td, td->td_user_pri);
236 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
237 thread_unlock(td);
238 #ifdef KTRACE
239 if (KTRPOINT(td, KTR_CSW))
240 ktrcsw(0, 1, __func__);
241 #endif
242 }
243
244 /*
245 * Check for signals. Unlocked reads of p_pendingcnt or
246 * p_siglist might cause process-directed signal to be handled
247 * later.
248 */
249 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
250 !SIGISEMPTY(p->p_siglist)) {
251 PROC_LOCK(p);
252 mtx_lock(&p->p_sigacts->ps_mtx);
253 while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0)
254 postsig(sig);
255 mtx_unlock(&p->p_sigacts->ps_mtx);
256 PROC_UNLOCK(p);
257 }
258 /*
259 * We need to check to see if we have to exit or wait due to a
260 * single threading requirement or some other STOP condition.
261 */
262 if (flags & TDF_NEEDSUSPCHK) {
263 PROC_LOCK(p);
264 thread_suspend_check(0);
265 PROC_UNLOCK(p);
266 }
267
268 if (td->td_pflags & TDP_OLDMASK) {
269 td->td_pflags &= ~TDP_OLDMASK;
270 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
271 }
272
273 userret(td, framep);
274 mtx_assert(&Giant, MA_NOTOWNED);
275 }
276
277 const char *
278 syscallname(struct proc *p, u_int code)
279 {
280 static const char unknown[] = "unknown";
281 struct sysentvec *sv;
282
283 sv = p->p_sysent;
284 if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
285 return (unknown);
286 return (sv->sv_syscallnames[code]);
287 }
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