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
7 * This code is derived from software contributed to Berkeley by
8 * the University of Utah, and William Jolitz.
10 * Portions of this software were developed by A. Joseph Koshy under
11 * sponsorship from the FreeBSD Foundation and Google, Inc.
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
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.
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
41 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91
44 #include <sys/cdefs.h>
45 __FBSDID("$FreeBSD$");
47 #include "opt_hwpmc_hooks.h"
48 #include "opt_ktrace.h"
49 #include "opt_sched.h"
51 #include <sys/param.h>
53 #include <sys/capsicum.h>
54 #include <sys/kernel.h>
56 #include <sys/mutex.h>
57 #include <sys/pmckern.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>
73 #include <sys/ktrace.h>
75 #include <security/audit/audit.h>
77 #include <machine/cpu.h>
84 #include <sys/pmckern.h>
87 #include <security/mac/mac_framework.h>
89 void (*softdep_ast_cleanup)(void);
92 * Define the code needed before returning to user mode, for trap and
96 userret(struct thread *td, struct trapframe *frame)
98 struct proc *p = td->td_proc;
100 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
102 KASSERT((p->p_flag & P_WEXIT) == 0,
103 ("Exiting process returns to usermode"));
106 * Check that we called signotify() enough. For
107 * multi-threaded processes, where signal distribution might
108 * change due to other threads changing sigmask, the check is
109 * racy and cannot be performed reliably.
110 * If current process is vfork child, indicated by P_PPWAIT, then
111 * issignal() ignores stops, so we block the check to avoid
112 * classifying pending signals.
114 if (p->p_numthreads == 1) {
117 if ((p->p_flag & P_PPWAIT) == 0) {
118 KASSERT(!SIGPENDING(td) || (td->td_flags &
119 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
120 (TDF_NEEDSIGCHK | TDF_ASTPENDING),
121 ("failed to set signal flags for ast p %p "
122 "td %p fl %x", p, td, td->td_flags));
131 if (softdep_ast_cleanup != NULL)
132 softdep_ast_cleanup();
135 * If this thread tickled GEOM, we need to wait for the giggling to
136 * stop before we return to userland
138 if (td->td_pflags & TDP_GEOM)
142 * Charge system time if profiling.
144 if (p->p_flag & P_PROFIL)
145 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
147 * Let the scheduler adjust our priority etc.
152 * Check for misbehavior.
154 * In case there is a callchain tracing ongoing because of
155 * hwpmc(4), skip the scheduler pinning check.
156 * hwpmc(4) subsystem, infact, will collect callchain informations
157 * at ast() checkpoint, which is past userret().
159 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning");
160 KASSERT(td->td_critnest == 0,
161 ("userret: Returning in a critical section"));
162 KASSERT(td->td_locks == 0,
163 ("userret: Returning with %d locks held", td->td_locks));
164 KASSERT(td->td_rw_rlocks == 0,
165 ("userret: Returning with %d rwlocks held in read mode",
167 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
168 ("userret: Returning with pagefaults disabled"));
169 KASSERT(td->td_no_sleeping == 0,
170 ("userret: Returning with sleep disabled"));
171 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0,
172 ("userret: Returning with with pinned thread"));
173 KASSERT(td->td_vp_reserv == 0,
174 ("userret: Returning while holding vnode reservation"));
175 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0,
176 ("userret: Returning with stop signals deferred"));
177 KASSERT(td->td_su == NULL,
178 ("userret: Returning with SU cleanup request not handled"));
180 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
181 VNET_ASSERT(curvnet == NULL,
182 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
183 __func__, td, p->p_pid, td->td_name, curvnet,
184 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
187 if (racct_enable && p->p_throttled != 0) {
189 while (p->p_throttled != 0) {
190 msleep(p->p_racct, &p->p_mtx, 0, "racct",
191 p->p_throttled < 0 ? 0 : p->p_throttled);
192 if (p->p_throttled > 0)
201 * Process an asynchronous software trap.
202 * This is relatively easy.
203 * This function will return with preemption disabled.
206 ast(struct trapframe *framep)
216 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
218 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
219 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
220 mtx_assert(&Giant, MA_NOTOWNED);
221 THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
222 td->td_frame = framep;
226 * This updates the td_flag's for the checks below in one
227 * "atomic" operation with turning off the astpending flag.
228 * If another AST is triggered while we are handling the
229 * AST's saved in flags, the astpending flag will be set and
230 * ast() will be called again.
233 flags = td->td_flags;
234 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
235 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
237 PCPU_INC(cnt.v_trap);
239 if (td->td_cowgen != p->p_cowgen)
240 thread_cow_update(td);
241 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
242 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
243 td->td_profil_ticks = 0;
244 td->td_pflags &= ~TDP_OWEUPC;
247 /* Handle Software PMC callchain capture. */
248 if (PMC_IS_PENDING_CALLCHAIN(td))
249 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep);
251 if (flags & TDF_ALRMPEND) {
253 kern_psignal(p, SIGVTALRM);
256 if (flags & TDF_PROFPEND) {
258 kern_psignal(p, SIGPROF);
262 if (flags & TDF_MACPEND)
263 mac_thread_userret(td);
265 if (flags & TDF_NEEDRESCHED) {
267 if (KTRPOINT(td, KTR_CSW))
268 ktrcsw(1, 1, __func__);
271 sched_prio(td, td->td_user_pri);
272 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
275 if (KTRPOINT(td, KTR_CSW))
276 ktrcsw(0, 1, __func__);
281 if (p->p_numthreads == 1 && (flags & TDF_NEEDSIGCHK) == 0) {
285 * Note that TDF_NEEDSIGCHK should be re-read from
286 * td_flags, since signal might have been delivered
287 * after we cleared td_flags above. This is one of
288 * the reason for looping check for AST condition.
289 * See comment in userret() about P_PPWAIT.
291 if ((p->p_flag & P_PPWAIT) == 0) {
292 KASSERT(!SIGPENDING(td) || (td->td_flags &
293 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
294 (TDF_NEEDSIGCHK | TDF_ASTPENDING),
295 ("failed2 to set signal flags for ast p %p td %p "
296 "fl %x %x", p, td, flags, td->td_flags));
304 * Check for signals. Unlocked reads of p_pendingcnt or
305 * p_siglist might cause process-directed signal to be handled
308 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
309 !SIGISEMPTY(p->p_siglist)) {
311 mtx_lock(&p->p_sigacts->ps_mtx);
312 while ((sig = cursig(td)) != 0) {
313 KASSERT(sig >= 0, ("sig %d", sig));
316 mtx_unlock(&p->p_sigacts->ps_mtx);
320 * We need to check to see if we have to exit or wait due to a
321 * single threading requirement or some other STOP condition.
323 if (flags & TDF_NEEDSUSPCHK) {
325 thread_suspend_check(0);
329 if (td->td_pflags & TDP_OLDMASK) {
330 td->td_pflags &= ~TDP_OLDMASK;
331 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
338 syscallname(struct proc *p, u_int code)
340 static const char unknown[] = "unknown";
341 struct sysentvec *sv;
344 if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
346 return (sv->sv_syscallnames[code]);