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/9.1/sys/kern/subr_trap.c 237719 2012-06-28 18:38:24Z 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 #ifdef VIMAGE
143 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
144 VNET_ASSERT(curvnet == NULL,
145 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
146 __func__, td, p->p_pid, td->td_name, curvnet,
147 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
148 #endif
149 #ifdef XEN
150 PT_UPDATES_FLUSH();
151 #endif
152 }
153
154 /*
155 * Process an asynchronous software trap.
156 * This is relatively easy.
157 * This function will return with preemption disabled.
158 */
159 void
160 ast(struct trapframe *framep)
161 {
162 struct thread *td;
163 struct proc *p;
164 int flags;
165 int sig;
166
167 td = curthread;
168 p = td->td_proc;
169
170 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
171 p->p_comm);
172 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
173 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
174 mtx_assert(&Giant, MA_NOTOWNED);
175 THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
176 td->td_frame = framep;
177 td->td_pticks = 0;
178
179 /*
180 * This updates the td_flag's for the checks below in one
181 * "atomic" operation with turning off the astpending flag.
182 * If another AST is triggered while we are handling the
183 * AST's saved in flags, the astpending flag will be set and
184 * ast() will be called again.
185 */
186 thread_lock(td);
187 flags = td->td_flags;
188 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
189 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
190 thread_unlock(td);
191 PCPU_INC(cnt.v_trap);
192
193 if (td->td_ucred != p->p_ucred)
194 cred_update_thread(td);
195 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
196 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
197 td->td_profil_ticks = 0;
198 td->td_pflags &= ~TDP_OWEUPC;
199 }
200 #ifdef HWPMC_HOOKS
201 /* Handle Software PMC callchain capture. */
202 if (PMC_IS_PENDING_CALLCHAIN(td))
203 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep);
204 #endif
205 if (flags & TDF_ALRMPEND) {
206 PROC_LOCK(p);
207 kern_psignal(p, SIGVTALRM);
208 PROC_UNLOCK(p);
209 }
210 if (flags & TDF_PROFPEND) {
211 PROC_LOCK(p);
212 kern_psignal(p, SIGPROF);
213 PROC_UNLOCK(p);
214 }
215 #ifdef MAC
216 if (flags & TDF_MACPEND)
217 mac_thread_userret(td);
218 #endif
219 if (flags & TDF_NEEDRESCHED) {
220 #ifdef KTRACE
221 if (KTRPOINT(td, KTR_CSW))
222 ktrcsw(1, 1, __func__);
223 #endif
224 thread_lock(td);
225 sched_prio(td, td->td_user_pri);
226 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
227 thread_unlock(td);
228 #ifdef KTRACE
229 if (KTRPOINT(td, KTR_CSW))
230 ktrcsw(0, 1, __func__);
231 #endif
232 }
233
234 /*
235 * Check for signals. Unlocked reads of p_pendingcnt or
236 * p_siglist might cause process-directed signal to be handled
237 * later.
238 */
239 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
240 !SIGISEMPTY(p->p_siglist)) {
241 PROC_LOCK(p);
242 mtx_lock(&p->p_sigacts->ps_mtx);
243 while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0)
244 postsig(sig);
245 mtx_unlock(&p->p_sigacts->ps_mtx);
246 PROC_UNLOCK(p);
247 }
248 /*
249 * We need to check to see if we have to exit or wait due to a
250 * single threading requirement or some other STOP condition.
251 */
252 if (flags & TDF_NEEDSUSPCHK) {
253 PROC_LOCK(p);
254 thread_suspend_check(0);
255 PROC_UNLOCK(p);
256 }
257
258 if (td->td_pflags & TDP_OLDMASK) {
259 td->td_pflags &= ~TDP_OLDMASK;
260 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
261 }
262
263 userret(td, framep);
264 mtx_assert(&Giant, MA_NOTOWNED);
265 }
266
267 const char *
268 syscallname(struct proc *p, u_int code)
269 {
270 static const char unknown[] = "unknown";
271 struct sysentvec *sv;
272
273 sv = p->p_sysent;
274 if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
275 return (unknown);
276 return (sv->sv_syscallnames[code]);
277 }
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