2 * SPDX-License-Identifier: BSD-4-Clause
4 * Copyright (C) 1994, David Greenman
5 * Copyright (c) 1990, 1993
6 * The Regents of the University of California. All rights reserved.
7 * Copyright (c) 2007 The FreeBSD Foundation
9 * This code is derived from software contributed to Berkeley by
10 * the University of Utah, and William Jolitz.
12 * Portions of this software were developed by A. Joseph Koshy under
13 * sponsorship from the FreeBSD Foundation and Google, Inc.
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
18 * 1. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 * 3. All advertising materials mentioning features or use of this software
24 * must display the following acknowledgement:
25 * This product includes software developed by the University of
26 * California, Berkeley and its contributors.
27 * 4. Neither the name of the University nor the names of its contributors
28 * may be used to endorse or promote products derived from this software
29 * without specific prior written permission.
31 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
32 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
33 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
34 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
35 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
39 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
40 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
43 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91
46 #include <sys/cdefs.h>
47 __FBSDID("$FreeBSD$");
49 #include "opt_hwpmc_hooks.h"
50 #include "opt_ktrace.h"
51 #include "opt_sched.h"
53 #include <sys/param.h>
55 #include <sys/capsicum.h>
56 #include <sys/kernel.h>
58 #include <sys/mutex.h>
59 #include <sys/pmckern.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>
74 #include <sys/ktrace.h>
76 #include <security/audit/audit.h>
78 #include <machine/cpu.h>
85 #include <sys/pmckern.h>
88 #include <security/mac/mac_framework.h>
90 void (*softdep_ast_cleanup)(struct thread *);
93 * Define the code needed before returning to user mode, for trap and
97 userret(struct thread *td, struct trapframe *frame)
99 struct proc *p = td->td_proc;
101 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
103 KASSERT((p->p_flag & P_WEXIT) == 0,
104 ("Exiting process returns to usermode"));
107 * Check that we called signotify() enough. For
108 * multi-threaded processes, where signal distribution might
109 * change due to other threads changing sigmask, the check is
110 * racy and cannot be performed reliably.
111 * If current process is vfork child, indicated by P_PPWAIT, then
112 * issignal() ignores stops, so we block the check to avoid
113 * classifying pending signals.
115 if (p->p_numthreads == 1) {
118 if ((p->p_flag & P_PPWAIT) == 0 &&
119 (td->td_pflags & TDP_SIGFASTBLOCK) == 0) {
120 if (SIGPENDING(td) && (td->td_flags &
121 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) !=
122 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) {
125 "failed to set signal flags for ast p %p td %p fl %x",
126 p, td, td->td_flags);
135 * Charge system time if profiling.
137 if (__predict_false(p->p_flag & P_PROFIL))
138 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
141 if (PMC_THREAD_HAS_SAMPLES(td))
142 PMC_CALL_HOOK(td, PMC_FN_THR_USERRET, NULL);
145 * Let the scheduler adjust our priority etc.
150 * Check for misbehavior.
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().
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_rw_rlocks == 0,
163 ("userret: Returning with %d rwlocks held in read mode",
165 KASSERT(td->td_sx_slocks == 0,
166 ("userret: Returning with %d sx locks held in shared mode",
168 KASSERT(td->td_lk_slocks == 0,
169 ("userret: Returning with %d lockmanager locks held in shared mode",
171 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0,
172 ("userret: Returning with pagefaults disabled"));
173 if (__predict_false(!THREAD_CAN_SLEEP())) {
175 epoch_trace_list(curthread);
177 KASSERT(0, ("userret: Returning with sleep disabled"));
179 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0,
180 ("userret: Returning with with pinned thread"));
181 KASSERT(td->td_vp_reserved == NULL,
182 ("userret: Returning with preallocated vnode"));
183 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0,
184 ("userret: Returning with stop signals deferred"));
185 KASSERT(td->td_vslock_sz == 0,
186 ("userret: Returning with vslock-wired space"));
188 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */
189 VNET_ASSERT(curvnet == NULL,
190 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s",
191 __func__, td, p->p_pid, td->td_name, curvnet,
192 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A"));
197 * Process an asynchronous software trap.
198 * This is relatively easy.
199 * This function will return with preemption disabled.
202 ast(struct trapframe *framep)
212 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
214 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
215 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
216 mtx_assert(&Giant, MA_NOTOWNED);
217 THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
218 td->td_frame = framep;
222 * This updates the td_flag's for the checks below in one
223 * "atomic" operation with turning off the astpending flag.
224 * If another AST is triggered while we are handling the
225 * AST's saved in flags, the astpending flag will be set and
226 * ast() will be called again.
229 flags = td->td_flags;
230 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
231 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
235 if (td->td_cowgen != p->p_cowgen)
236 thread_cow_update(td);
237 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
238 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
239 td->td_profil_ticks = 0;
240 td->td_pflags &= ~TDP_OWEUPC;
243 /* Handle Software PMC callchain capture. */
244 if (PMC_IS_PENDING_CALLCHAIN(td))
245 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep);
247 if (flags & TDF_ALRMPEND) {
249 kern_psignal(p, SIGVTALRM);
252 if (flags & TDF_PROFPEND) {
254 kern_psignal(p, SIGPROF);
258 if (flags & TDF_MACPEND)
259 mac_thread_userret(td);
261 if (flags & TDF_NEEDRESCHED) {
263 if (KTRPOINT(td, KTR_CSW))
264 ktrcsw(1, 1, __func__);
267 sched_prio(td, td->td_user_pri);
268 mi_switch(SW_INVOL | SWT_NEEDRESCHED);
270 if (KTRPOINT(td, KTR_CSW))
271 ktrcsw(0, 1, __func__);
275 td_softdep_cleanup(td);
276 MPASS(td->td_su == NULL);
279 * If this thread tickled GEOM, we need to wait for the giggling to
280 * stop before we return to userland
282 if (__predict_false(td->td_pflags & TDP_GEOM))
286 if (p->p_numthreads == 1 && (flags & TDF_NEEDSIGCHK) == 0) {
290 * Note that TDF_NEEDSIGCHK should be re-read from
291 * td_flags, since signal might have been delivered
292 * after we cleared td_flags above. This is one of
293 * the reason for looping check for AST condition.
294 * See comment in userret() about P_PPWAIT.
296 if ((p->p_flag & P_PPWAIT) == 0 &&
297 (td->td_pflags & TDP_SIGFASTBLOCK) == 0) {
298 if (SIGPENDING(td) && (td->td_flags &
299 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) !=
300 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) {
301 thread_unlock(td); /* fix dumps */
303 "failed2 to set signal flags for ast p %p td %p fl %x %x",
304 p, td, flags, td->td_flags);
313 * Check for signals. Unlocked reads of p_pendingcnt or
314 * p_siglist might cause process-directed signal to be handled
317 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 ||
318 !SIGISEMPTY(p->p_siglist)) {
319 sigfastblock_fetch(td);
321 mtx_lock(&p->p_sigacts->ps_mtx);
322 while ((sig = cursig(td)) != 0) {
323 KASSERT(sig >= 0, ("sig %d", sig));
326 mtx_unlock(&p->p_sigacts->ps_mtx);
330 resched_sigs = false;
334 * Handle deferred update of the fast sigblock value, after
335 * the postsig() loop was performed.
337 sigfastblock_setpend(td, resched_sigs);
344 * We need to check to see if we have to exit or wait due to a
345 * single threading requirement or some other STOP condition.
347 if (flags & TDF_NEEDSUSPCHK) {
349 thread_suspend_check(0);
353 if (td->td_pflags & TDP_OLDMASK) {
354 td->td_pflags &= ~TDP_OLDMASK;
355 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0);
359 if (__predict_false(racct_enable && p->p_throttled != 0))
360 racct_proc_throttled(p);
367 syscallname(struct proc *p, u_int code)
369 static const char unknown[] = "unknown";
370 struct sysentvec *sv;
373 if (sv->sv_syscallnames == NULL || code >= sv->sv_size)
375 return (sv->sv_syscallnames[code]);