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