1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 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 8 * 9 * This code is derived from software contributed to Berkeley by 10 * the University of Utah, and William Jolitz. 11 * 12 * Portions of this software were developed by A. Joseph Koshy under 13 * sponsorship from the FreeBSD Foundation and Google, Inc. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 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. 30 * 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 41 * SUCH DAMAGE. 42 * 43 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91 44 */ 45 46 #include <sys/cdefs.h> 47 __FBSDID("$FreeBSD$"); 48 49 #include "opt_hwpmc_hooks.h" 50 #include "opt_ktrace.h" 51 #include "opt_sched.h" 52 53 #include <sys/param.h> 54 #include <sys/bus.h> 55 #include <sys/capsicum.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/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> 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 HWPMC_HOOKS 85 #include <sys/pmckern.h> 86 #endif 87 88 #include <security/mac/mac_framework.h> 89 90 void (*softdep_ast_cleanup)(struct thread *); 91 92 /* 93 * Define the code needed before returning to user mode, for trap and 94 * syscall. 95 */ 96 void 97 userret(struct thread *td, struct trapframe *frame) 98 { 99 struct proc *p = td->td_proc; 100 101 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid, 102 td->td_name); 103 KASSERT((p->p_flag & P_WEXIT) == 0, 104 ("Exiting process returns to usermode")); 105 #ifdef DIAGNOSTIC 106 /* 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. 114 */ 115 if (p->p_numthreads == 1) { 116 PROC_LOCK(p); 117 thread_lock(td); 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)) { 123 thread_unlock(td); 124 panic( 125 "failed to set signal flags for ast p %p td %p fl %x", 126 p, td, td->td_flags); 127 } 128 } 129 thread_unlock(td); 130 PROC_UNLOCK(p); 131 } 132 #endif 133 134 /* 135 * Charge system time if profiling. 136 */ 137 if (__predict_false(p->p_flag & P_PROFIL)) 138 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio); 139 140 #ifdef HWPMC_HOOKS 141 if (PMC_THREAD_HAS_SAMPLES(td)) 142 PMC_CALL_HOOK(td, PMC_FN_THR_USERRET, NULL); 143 #endif 144 #ifdef TCPHPTS 145 /* 146 * @gallatin is adament that this needs to go here, I 147 * am not so sure. Running hpts is a lot like 148 * a lro_flush() that happens while a user process 149 * is running. But he may know best so I will go 150 * with his view of accounting. :-) 151 */ 152 tcp_run_hpts(); 153 #endif 154 /* 155 * Let the scheduler adjust our priority etc. 156 */ 157 sched_userret(td); 158 159 /* 160 * Check for misbehavior. 161 * 162 * In case there is a callchain tracing ongoing because of 163 * hwpmc(4), skip the scheduler pinning check. 164 * hwpmc(4) subsystem, infact, will collect callchain informations 165 * at ast() checkpoint, which is past userret(). 166 */ 167 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning"); 168 KASSERT(td->td_critnest == 0, 169 ("userret: Returning in a critical section")); 170 KASSERT(td->td_locks == 0, 171 ("userret: Returning with %d locks held", td->td_locks)); 172 KASSERT(td->td_rw_rlocks == 0, 173 ("userret: Returning with %d rwlocks held in read mode", 174 td->td_rw_rlocks)); 175 KASSERT(td->td_sx_slocks == 0, 176 ("userret: Returning with %d sx locks held in shared mode", 177 td->td_sx_slocks)); 178 KASSERT(td->td_lk_slocks == 0, 179 ("userret: Returning with %d lockmanager locks held in shared mode", 180 td->td_lk_slocks)); 181 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0, 182 ("userret: Returning with pagefaults disabled")); 183 if (__predict_false(!THREAD_CAN_SLEEP())) { 184 #ifdef EPOCH_TRACE 185 epoch_trace_list(curthread); 186 #endif 187 KASSERT(0, ("userret: Returning with sleep disabled")); 188 } 189 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0, 190 ("userret: Returning with with pinned thread")); 191 KASSERT(td->td_vp_reserved == NULL, 192 ("userret: Returning with preallocated vnode")); 193 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0, 194 ("userret: Returning with stop signals deferred")); 195 KASSERT(td->td_vslock_sz == 0, 196 ("userret: Returning with vslock-wired space")); 197 #ifdef VIMAGE 198 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */ 199 VNET_ASSERT(curvnet == NULL, 200 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s", 201 __func__, td, p->p_pid, td->td_name, curvnet, 202 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A")); 203 #endif 204 } 205 206 /* 207 * Process an asynchronous software trap. 208 * This is relatively easy. 209 * This function will return with preemption disabled. 210 */ 211 void 212 ast(struct trapframe *framep) 213 { 214 struct thread *td; 215 struct proc *p; 216 int flags, sig; 217 bool resched_sigs; 218 219 td = curthread; 220 p = td->td_proc; 221 222 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid, 223 p->p_comm); 224 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode")); 225 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 226 mtx_assert(&Giant, MA_NOTOWNED); 227 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 228 td->td_frame = framep; 229 td->td_pticks = 0; 230 231 /* 232 * This updates the td_flag's for the checks below in one 233 * "atomic" operation with turning off the astpending flag. 234 * If another AST is triggered while we are handling the 235 * AST's saved in flags, the astpending flag will be set and 236 * ast() will be called again. 237 */ 238 thread_lock(td); 239 flags = td->td_flags; 240 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK | 241 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND); 242 thread_unlock(td); 243 VM_CNT_INC(v_trap); 244 245 if (td->td_cowgen != p->p_cowgen) 246 thread_cow_update(td); 247 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) { 248 addupc_task(td, td->td_profil_addr, td->td_profil_ticks); 249 td->td_profil_ticks = 0; 250 td->td_pflags &= ~TDP_OWEUPC; 251 } 252 #ifdef HWPMC_HOOKS 253 /* Handle Software PMC callchain capture. */ 254 if (PMC_IS_PENDING_CALLCHAIN(td)) 255 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep); 256 #endif 257 if (flags & TDF_ALRMPEND) { 258 PROC_LOCK(p); 259 kern_psignal(p, SIGVTALRM); 260 PROC_UNLOCK(p); 261 } 262 if (flags & TDF_PROFPEND) { 263 PROC_LOCK(p); 264 kern_psignal(p, SIGPROF); 265 PROC_UNLOCK(p); 266 } 267 #ifdef MAC 268 if (flags & TDF_MACPEND) 269 mac_thread_userret(td); 270 #endif 271 if (flags & TDF_NEEDRESCHED) { 272 #ifdef KTRACE 273 if (KTRPOINT(td, KTR_CSW)) 274 ktrcsw(1, 1, __func__); 275 #endif 276 thread_lock(td); 277 sched_prio(td, td->td_user_pri); 278 mi_switch(SW_INVOL | SWT_NEEDRESCHED); 279 #ifdef KTRACE 280 if (KTRPOINT(td, KTR_CSW)) 281 ktrcsw(0, 1, __func__); 282 #endif 283 } 284 285 td_softdep_cleanup(td); 286 MPASS(td->td_su == NULL); 287 288 /* 289 * If this thread tickled GEOM, we need to wait for the giggling to 290 * stop before we return to userland 291 */ 292 if (__predict_false(td->td_pflags & TDP_GEOM)) 293 g_waitidle(); 294 295 #ifdef DIAGNOSTIC 296 if (p->p_numthreads == 1 && (flags & TDF_NEEDSIGCHK) == 0) { 297 PROC_LOCK(p); 298 thread_lock(td); 299 /* 300 * Note that TDF_NEEDSIGCHK should be re-read from 301 * td_flags, since signal might have been delivered 302 * after we cleared td_flags above. This is one of 303 * the reason for looping check for AST condition. 304 * See comment in userret() about P_PPWAIT. 305 */ 306 if ((p->p_flag & P_PPWAIT) == 0 && 307 (td->td_pflags & TDP_SIGFASTBLOCK) == 0) { 308 if (SIGPENDING(td) && (td->td_flags & 309 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) != 310 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) { 311 thread_unlock(td); /* fix dumps */ 312 panic( 313 "failed2 to set signal flags for ast p %p td %p fl %x %x", 314 p, td, flags, td->td_flags); 315 } 316 } 317 thread_unlock(td); 318 PROC_UNLOCK(p); 319 } 320 #endif 321 322 /* 323 * Check for signals. Unlocked reads of p_pendingcnt or 324 * p_siglist might cause process-directed signal to be handled 325 * later. 326 */ 327 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 || 328 !SIGISEMPTY(p->p_siglist)) { 329 sigfastblock_fetch(td); 330 PROC_LOCK(p); 331 mtx_lock(&p->p_sigacts->ps_mtx); 332 while ((sig = cursig(td)) != 0) { 333 KASSERT(sig >= 0, ("sig %d", sig)); 334 postsig(sig); 335 } 336 mtx_unlock(&p->p_sigacts->ps_mtx); 337 PROC_UNLOCK(p); 338 resched_sigs = true; 339 } else { 340 resched_sigs = false; 341 } 342 343 /* 344 * Handle deferred update of the fast sigblock value, after 345 * the postsig() loop was performed. 346 */ 347 sigfastblock_setpend(td, resched_sigs); 348 349 #ifdef KTRACE 350 KTRUSERRET(td); 351 #endif 352 353 /* 354 * We need to check to see if we have to exit or wait due to a 355 * single threading requirement or some other STOP condition. 356 */ 357 if (flags & TDF_NEEDSUSPCHK) { 358 PROC_LOCK(p); 359 thread_suspend_check(0); 360 PROC_UNLOCK(p); 361 } 362 363 if (td->td_pflags & TDP_OLDMASK) { 364 td->td_pflags &= ~TDP_OLDMASK; 365 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0); 366 } 367 368 #ifdef RACCT 369 if (__predict_false(racct_enable && p->p_throttled != 0)) 370 racct_proc_throttled(p); 371 #endif 372 373 userret(td, framep); 374 } 375 376 const char * 377 syscallname(struct proc *p, u_int code) 378 { 379 static const char unknown[] = "unknown"; 380 struct sysentvec *sv; 381 382 sv = p->p_sysent; 383 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 384 return (unknown); 385 return (sv->sv_syscallnames[code]); 386 } 387