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 #ifdef KTRACE 134 KTRUSERRET(td); 135 #endif 136 137 td_softdep_cleanup(td); 138 MPASS(td->td_su == NULL); 139 140 /* 141 * Charge system time if profiling. 142 */ 143 if (__predict_false(p->p_flag & P_PROFIL)) 144 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio); 145 146 #ifdef HWPMC_HOOKS 147 if (PMC_THREAD_HAS_SAMPLES(td)) 148 PMC_CALL_HOOK(td, PMC_FN_THR_USERRET, NULL); 149 #endif 150 /* 151 * Let the scheduler adjust our priority etc. 152 */ 153 sched_userret(td); 154 155 /* 156 * Check for misbehavior. 157 * 158 * In case there is a callchain tracing ongoing because of 159 * hwpmc(4), skip the scheduler pinning check. 160 * hwpmc(4) subsystem, infact, will collect callchain informations 161 * at ast() checkpoint, which is past userret(). 162 */ 163 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning"); 164 KASSERT(td->td_critnest == 0, 165 ("userret: Returning in a critical section")); 166 KASSERT(td->td_locks == 0, 167 ("userret: Returning with %d locks held", td->td_locks)); 168 KASSERT(td->td_rw_rlocks == 0, 169 ("userret: Returning with %d rwlocks held in read mode", 170 td->td_rw_rlocks)); 171 KASSERT(td->td_sx_slocks == 0, 172 ("userret: Returning with %d sx locks held in shared mode", 173 td->td_sx_slocks)); 174 KASSERT(td->td_lk_slocks == 0, 175 ("userret: Returning with %d lockmanager locks held in shared mode", 176 td->td_lk_slocks)); 177 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0, 178 ("userret: Returning with pagefaults disabled")); 179 if (__predict_false(!THREAD_CAN_SLEEP())) { 180 #ifdef EPOCH_TRACE 181 epoch_trace_list(curthread); 182 #endif 183 KASSERT(0, ("userret: Returning with sleep disabled")); 184 } 185 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0, 186 ("userret: Returning with with pinned thread")); 187 KASSERT(td->td_vp_reserved == NULL, 188 ("userret: Returning with preallocated vnode")); 189 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0, 190 ("userret: Returning with stop signals deferred")); 191 KASSERT(td->td_su == NULL, 192 ("userret: Returning with SU cleanup request not handled")); 193 KASSERT(td->td_vslock_sz == 0, 194 ("userret: Returning with vslock-wired space")); 195 #ifdef VIMAGE 196 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */ 197 VNET_ASSERT(curvnet == NULL, 198 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s", 199 __func__, td, p->p_pid, td->td_name, curvnet, 200 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A")); 201 #endif 202 } 203 204 /* 205 * Process an asynchronous software trap. 206 * This is relatively easy. 207 * This function will return with preemption disabled. 208 */ 209 void 210 ast(struct trapframe *framep) 211 { 212 struct thread *td; 213 struct proc *p; 214 int flags, sig; 215 216 td = curthread; 217 p = td->td_proc; 218 219 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid, 220 p->p_comm); 221 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode")); 222 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 223 mtx_assert(&Giant, MA_NOTOWNED); 224 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 225 td->td_frame = framep; 226 td->td_pticks = 0; 227 228 /* 229 * This updates the td_flag's for the checks below in one 230 * "atomic" operation with turning off the astpending flag. 231 * If another AST is triggered while we are handling the 232 * AST's saved in flags, the astpending flag will be set and 233 * ast() will be called again. 234 */ 235 thread_lock(td); 236 flags = td->td_flags; 237 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK | 238 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND); 239 thread_unlock(td); 240 VM_CNT_INC(v_trap); 241 242 if (td->td_cowgen != p->p_cowgen) 243 thread_cow_update(td); 244 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) { 245 addupc_task(td, td->td_profil_addr, td->td_profil_ticks); 246 td->td_profil_ticks = 0; 247 td->td_pflags &= ~TDP_OWEUPC; 248 } 249 #ifdef HWPMC_HOOKS 250 /* Handle Software PMC callchain capture. */ 251 if (PMC_IS_PENDING_CALLCHAIN(td)) 252 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep); 253 #endif 254 if (flags & TDF_ALRMPEND) { 255 PROC_LOCK(p); 256 kern_psignal(p, SIGVTALRM); 257 PROC_UNLOCK(p); 258 } 259 if (flags & TDF_PROFPEND) { 260 PROC_LOCK(p); 261 kern_psignal(p, SIGPROF); 262 PROC_UNLOCK(p); 263 } 264 #ifdef MAC 265 if (flags & TDF_MACPEND) 266 mac_thread_userret(td); 267 #endif 268 if (flags & TDF_NEEDRESCHED) { 269 #ifdef KTRACE 270 if (KTRPOINT(td, KTR_CSW)) 271 ktrcsw(1, 1, __func__); 272 #endif 273 thread_lock(td); 274 sched_prio(td, td->td_user_pri); 275 mi_switch(SW_INVOL | SWT_NEEDRESCHED); 276 #ifdef KTRACE 277 if (KTRPOINT(td, KTR_CSW)) 278 ktrcsw(0, 1, __func__); 279 #endif 280 } 281 282 /* 283 * If this thread tickled GEOM, we need to wait for the giggling to 284 * stop before we return to userland 285 */ 286 if (__predict_false(td->td_pflags & TDP_GEOM)) 287 g_waitidle(); 288 289 #ifdef DIAGNOSTIC 290 if (p->p_numthreads == 1 && (flags & TDF_NEEDSIGCHK) == 0) { 291 PROC_LOCK(p); 292 thread_lock(td); 293 /* 294 * Note that TDF_NEEDSIGCHK should be re-read from 295 * td_flags, since signal might have been delivered 296 * after we cleared td_flags above. This is one of 297 * the reason for looping check for AST condition. 298 * See comment in userret() about P_PPWAIT. 299 */ 300 if ((p->p_flag & P_PPWAIT) == 0 && 301 (td->td_pflags & TDP_SIGFASTBLOCK) == 0) { 302 if (SIGPENDING(td) && (td->td_flags & 303 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) != 304 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) { 305 thread_unlock(td); /* fix dumps */ 306 panic( 307 "failed2 to set signal flags for ast p %p td %p fl %x %x", 308 p, td, flags, td->td_flags); 309 } 310 } 311 thread_unlock(td); 312 PROC_UNLOCK(p); 313 } 314 #endif 315 316 /* 317 * Check for signals. Unlocked reads of p_pendingcnt or 318 * p_siglist might cause process-directed signal to be handled 319 * later. 320 */ 321 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 || 322 !SIGISEMPTY(p->p_siglist)) { 323 sigfastblock_fetch(td); 324 if ((td->td_pflags & TDP_SIGFASTBLOCK) != 0 && 325 td->td_sigblock_val != 0) { 326 sigfastblock_setpend(td, true); 327 } else { 328 PROC_LOCK(p); 329 mtx_lock(&p->p_sigacts->ps_mtx); 330 while ((sig = cursig(td)) != 0) { 331 KASSERT(sig >= 0, ("sig %d", sig)); 332 postsig(sig); 333 } 334 mtx_unlock(&p->p_sigacts->ps_mtx); 335 PROC_UNLOCK(p); 336 } 337 } 338 339 /* 340 * Handle deferred update of the fast sigblock value, after 341 * the postsig() loop was performed. 342 */ 343 if (td->td_pflags & TDP_SIGFASTPENDING) 344 sigfastblock_setpend(td, false); 345 346 /* 347 * We need to check to see if we have to exit or wait due to a 348 * single threading requirement or some other STOP condition. 349 */ 350 if (flags & TDF_NEEDSUSPCHK) { 351 PROC_LOCK(p); 352 thread_suspend_check(0); 353 PROC_UNLOCK(p); 354 } 355 356 if (td->td_pflags & TDP_OLDMASK) { 357 td->td_pflags &= ~TDP_OLDMASK; 358 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0); 359 } 360 361 #ifdef RACCT 362 if (__predict_false(racct_enable && p->p_throttled != 0)) 363 racct_proc_throttled(p); 364 #endif 365 366 userret(td, framep); 367 } 368 369 const char * 370 syscallname(struct proc *p, u_int code) 371 { 372 static const char unknown[] = "unknown"; 373 struct sysentvec *sv; 374 375 sv = p->p_sysent; 376 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 377 return (unknown); 378 return (sv->sv_syscallnames[code]); 379 } 380