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/pioctl.h> 63 #include <sys/ptrace.h> 64 #include <sys/racct.h> 65 #include <sys/resourcevar.h> 66 #include <sys/sched.h> 67 #include <sys/signalvar.h> 68 #include <sys/syscall.h> 69 #include <sys/syscallsubr.h> 70 #include <sys/sysent.h> 71 #include <sys/systm.h> 72 #include <sys/vmmeter.h> 73 #ifdef KTRACE 74 #include <sys/uio.h> 75 #include <sys/ktrace.h> 76 #endif 77 #include <security/audit/audit.h> 78 79 #include <machine/cpu.h> 80 81 #ifdef VIMAGE 82 #include <net/vnet.h> 83 #endif 84 85 #ifdef HWPMC_HOOKS 86 #include <sys/pmckern.h> 87 #endif 88 89 #include <security/mac/mac_framework.h> 90 91 void (*softdep_ast_cleanup)(struct thread *); 92 93 /* 94 * Define the code needed before returning to user mode, for trap and 95 * syscall. 96 */ 97 void 98 userret(struct thread *td, struct trapframe *frame) 99 { 100 struct proc *p = td->td_proc; 101 102 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid, 103 td->td_name); 104 KASSERT((p->p_flag & P_WEXIT) == 0, 105 ("Exiting process returns to usermode")); 106 #ifdef DIAGNOSTIC 107 /* 108 * Check that we called signotify() enough. For 109 * multi-threaded processes, where signal distribution might 110 * change due to other threads changing sigmask, the check is 111 * racy and cannot be performed reliably. 112 * If current process is vfork child, indicated by P_PPWAIT, then 113 * issignal() ignores stops, so we block the check to avoid 114 * classifying pending signals. 115 */ 116 if (p->p_numthreads == 1) { 117 PROC_LOCK(p); 118 thread_lock(td); 119 if ((p->p_flag & P_PPWAIT) == 0 && 120 (td->td_pflags & TDP_SIGFASTBLOCK) == 0) { 121 if (SIGPENDING(td) && (td->td_flags & 122 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) != 123 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) { 124 thread_unlock(td); 125 panic( 126 "failed to set signal flags for ast p %p td %p fl %x", 127 p, td, td->td_flags); 128 } 129 } 130 thread_unlock(td); 131 PROC_UNLOCK(p); 132 } 133 #endif 134 #ifdef KTRACE 135 KTRUSERRET(td); 136 #endif 137 td_softdep_cleanup(td); 138 MPASS(td->td_su == NULL); 139 140 /* 141 * If this thread tickled GEOM, we need to wait for the giggling to 142 * stop before we return to userland 143 */ 144 if (__predict_false(td->td_pflags & TDP_GEOM)) 145 g_waitidle(); 146 147 /* 148 * Charge system time if profiling. 149 */ 150 if (__predict_false(p->p_flag & P_PROFIL)) 151 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio); 152 153 #ifdef HWPMC_HOOKS 154 if (PMC_THREAD_HAS_SAMPLES(td)) 155 PMC_CALL_HOOK(td, PMC_FN_THR_USERRET, NULL); 156 #endif 157 /* 158 * Let the scheduler adjust our priority etc. 159 */ 160 sched_userret(td); 161 162 /* 163 * Check for misbehavior. 164 * 165 * In case there is a callchain tracing ongoing because of 166 * hwpmc(4), skip the scheduler pinning check. 167 * hwpmc(4) subsystem, infact, will collect callchain informations 168 * at ast() checkpoint, which is past userret(). 169 */ 170 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning"); 171 KASSERT(td->td_critnest == 0, 172 ("userret: Returning in a critical section")); 173 KASSERT(td->td_locks == 0, 174 ("userret: Returning with %d locks held", td->td_locks)); 175 KASSERT(td->td_rw_rlocks == 0, 176 ("userret: Returning with %d rwlocks held in read mode", 177 td->td_rw_rlocks)); 178 KASSERT(td->td_sx_slocks == 0, 179 ("userret: Returning with %d sx locks held in shared mode", 180 td->td_sx_slocks)); 181 KASSERT(td->td_lk_slocks == 0, 182 ("userret: Returning with %d lockmanager locks held in shared mode", 183 td->td_lk_slocks)); 184 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0, 185 ("userret: Returning with pagefaults disabled")); 186 if (__predict_false(!THREAD_CAN_SLEEP())) { 187 #ifdef EPOCH_TRACE 188 epoch_trace_list(curthread); 189 #endif 190 KASSERT(1, ("userret: Returning with sleep disabled")); 191 } 192 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0, 193 ("userret: Returning with with pinned thread")); 194 KASSERT(td->td_vp_reserved == NULL, 195 ("userret: Returning with preallocated vnode")); 196 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0, 197 ("userret: Returning with stop signals deferred")); 198 KASSERT(td->td_su == NULL, 199 ("userret: Returning with SU cleanup request not handled")); 200 KASSERT(td->td_vslock_sz == 0, 201 ("userret: Returning with vslock-wired space")); 202 #ifdef VIMAGE 203 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */ 204 VNET_ASSERT(curvnet == NULL, 205 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s", 206 __func__, td, p->p_pid, td->td_name, curvnet, 207 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A")); 208 #endif 209 #ifdef RACCT 210 if (__predict_false(racct_enable && p->p_throttled != 0)) 211 racct_proc_throttled(p); 212 #endif 213 } 214 215 /* 216 * Process an asynchronous software trap. 217 * This is relatively easy. 218 * This function will return with preemption disabled. 219 */ 220 void 221 ast(struct trapframe *framep) 222 { 223 struct thread *td; 224 struct proc *p; 225 uint32_t oldval; 226 int flags, sig, res; 227 228 td = curthread; 229 p = td->td_proc; 230 231 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid, 232 p->p_comm); 233 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode")); 234 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 235 mtx_assert(&Giant, MA_NOTOWNED); 236 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 237 td->td_frame = framep; 238 td->td_pticks = 0; 239 240 /* 241 * This updates the td_flag's for the checks below in one 242 * "atomic" operation with turning off the astpending flag. 243 * If another AST is triggered while we are handling the 244 * AST's saved in flags, the astpending flag will be set and 245 * ast() will be called again. 246 */ 247 thread_lock(td); 248 flags = td->td_flags; 249 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK | 250 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND); 251 thread_unlock(td); 252 VM_CNT_INC(v_trap); 253 254 if (td->td_cowgen != p->p_cowgen) 255 thread_cow_update(td); 256 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) { 257 addupc_task(td, td->td_profil_addr, td->td_profil_ticks); 258 td->td_profil_ticks = 0; 259 td->td_pflags &= ~TDP_OWEUPC; 260 } 261 #ifdef HWPMC_HOOKS 262 /* Handle Software PMC callchain capture. */ 263 if (PMC_IS_PENDING_CALLCHAIN(td)) 264 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep); 265 #endif 266 if (flags & TDF_ALRMPEND) { 267 PROC_LOCK(p); 268 kern_psignal(p, SIGVTALRM); 269 PROC_UNLOCK(p); 270 } 271 if (flags & TDF_PROFPEND) { 272 PROC_LOCK(p); 273 kern_psignal(p, SIGPROF); 274 PROC_UNLOCK(p); 275 } 276 #ifdef MAC 277 if (flags & TDF_MACPEND) 278 mac_thread_userret(td); 279 #endif 280 if (flags & TDF_NEEDRESCHED) { 281 #ifdef KTRACE 282 if (KTRPOINT(td, KTR_CSW)) 283 ktrcsw(1, 1, __func__); 284 #endif 285 thread_lock(td); 286 sched_prio(td, td->td_user_pri); 287 mi_switch(SW_INVOL | SWT_NEEDRESCHED); 288 #ifdef KTRACE 289 if (KTRPOINT(td, KTR_CSW)) 290 ktrcsw(0, 1, __func__); 291 #endif 292 } 293 294 #ifdef DIAGNOSTIC 295 if (p->p_numthreads == 1 && (flags & TDF_NEEDSIGCHK) == 0) { 296 PROC_LOCK(p); 297 thread_lock(td); 298 /* 299 * Note that TDF_NEEDSIGCHK should be re-read from 300 * td_flags, since signal might have been delivered 301 * after we cleared td_flags above. This is one of 302 * the reason for looping check for AST condition. 303 * See comment in userret() about P_PPWAIT. 304 */ 305 if ((p->p_flag & P_PPWAIT) == 0 && 306 (td->td_pflags & TDP_SIGFASTBLOCK) == 0) { 307 if (SIGPENDING(td) && (td->td_flags & 308 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) != 309 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) { 310 thread_unlock(td); /* fix dumps */ 311 panic( 312 "failed2 to set signal flags for ast p %p td %p fl %x %x", 313 p, td, flags, td->td_flags); 314 } 315 } 316 thread_unlock(td); 317 PROC_UNLOCK(p); 318 } 319 #endif 320 321 /* 322 * Check for signals. Unlocked reads of p_pendingcnt or 323 * p_siglist might cause process-directed signal to be handled 324 * later. 325 */ 326 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 || 327 !SIGISEMPTY(p->p_siglist)) { 328 fetch_sigfastblock(td); 329 PROC_LOCK(p); 330 mtx_lock(&p->p_sigacts->ps_mtx); 331 if ((td->td_pflags & TDP_SIGFASTBLOCK) != 0 && 332 td->td_sigblock_val != 0) { 333 reschedule_signals(p, fastblock_mask, 334 SIGPROCMASK_PS_LOCKED | SIGPROCMASK_FASTBLK); 335 } else { 336 while ((sig = cursig(td)) != 0) { 337 KASSERT(sig >= 0, ("sig %d", sig)); 338 postsig(sig); 339 } 340 } 341 mtx_unlock(&p->p_sigacts->ps_mtx); 342 PROC_UNLOCK(p); 343 } 344 345 /* 346 * Handle deferred update of the fast sigblock value, after 347 * the postsig() loop was performed. 348 */ 349 if (td->td_pflags & TDP_SIGFASTPENDING) { 350 td->td_pflags &= ~TDP_SIGFASTPENDING; 351 res = fueword32(td->td_sigblock_ptr, &oldval); 352 if (res == -1) { 353 fetch_sigfastblock_failed(td, false); 354 } else { 355 for (;;) { 356 oldval |= SIGFASTBLOCK_PEND; 357 res = casueword32(td->td_sigblock_ptr, oldval, 358 &oldval, oldval | SIGFASTBLOCK_PEND); 359 if (res == -1) { 360 fetch_sigfastblock_failed(td, true); 361 break; 362 } 363 if (res == 0) { 364 td->td_sigblock_val = oldval & 365 ~SIGFASTBLOCK_FLAGS; 366 break; 367 } 368 MPASS(res == 1); 369 res = thread_check_susp(td, false); 370 if (res != 0) 371 break; 372 } 373 } 374 } 375 376 /* 377 * We need to check to see if we have to exit or wait due to a 378 * single threading requirement or some other STOP condition. 379 */ 380 if (flags & TDF_NEEDSUSPCHK) { 381 PROC_LOCK(p); 382 thread_suspend_check(0); 383 PROC_UNLOCK(p); 384 } 385 386 if (td->td_pflags & TDP_OLDMASK) { 387 td->td_pflags &= ~TDP_OLDMASK; 388 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0); 389 } 390 391 userret(td, framep); 392 } 393 394 const char * 395 syscallname(struct proc *p, u_int code) 396 { 397 static const char unknown[] = "unknown"; 398 struct sysentvec *sv; 399 400 sv = p->p_sysent; 401 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 402 return (unknown); 403 return (sv->sv_syscallnames[code]); 404 } 405