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 KASSERT(!SIGPENDING(td) || (td->td_flags & 121 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) == 122 (TDF_NEEDSIGCHK | TDF_ASTPENDING), 123 ("failed to set signal flags for ast p %p " 124 "td %p fl %x", p, td, td->td_flags)); 125 } 126 thread_unlock(td); 127 PROC_UNLOCK(p); 128 } 129 #endif 130 #ifdef KTRACE 131 KTRUSERRET(td); 132 #endif 133 td_softdep_cleanup(td); 134 MPASS(td->td_su == NULL); 135 136 /* 137 * If this thread tickled GEOM, we need to wait for the giggling to 138 * stop before we return to userland 139 */ 140 if (td->td_pflags & TDP_GEOM) 141 g_waitidle(); 142 143 /* 144 * Charge system time if profiling. 145 */ 146 if (p->p_flag & P_PROFIL) 147 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio); 148 /* 149 * Let the scheduler adjust our priority etc. 150 */ 151 sched_userret(td); 152 153 /* 154 * Check for misbehavior. 155 * 156 * In case there is a callchain tracing ongoing because of 157 * hwpmc(4), skip the scheduler pinning check. 158 * hwpmc(4) subsystem, infact, will collect callchain informations 159 * at ast() checkpoint, which is past userret(). 160 */ 161 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning"); 162 KASSERT(td->td_critnest == 0, 163 ("userret: Returning in a critical section")); 164 KASSERT(td->td_locks == 0, 165 ("userret: Returning with %d locks held", td->td_locks)); 166 KASSERT(td->td_rw_rlocks == 0, 167 ("userret: Returning with %d rwlocks held in read mode", 168 td->td_rw_rlocks)); 169 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0, 170 ("userret: Returning with pagefaults disabled")); 171 KASSERT(td->td_no_sleeping == 0, 172 ("userret: Returning with sleep disabled")); 173 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0, 174 ("userret: Returning with with pinned thread")); 175 KASSERT(td->td_vp_reserv == 0, 176 ("userret: Returning while holding vnode reservation")); 177 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0, 178 ("userret: Returning with stop signals deferred")); 179 KASSERT(td->td_su == NULL, 180 ("userret: Returning with SU cleanup request not handled")); 181 KASSERT(td->td_vslock_sz == 0, 182 ("userret: Returning with vslock-wired space")); 183 #ifdef VIMAGE 184 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */ 185 VNET_ASSERT(curvnet == NULL, 186 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s", 187 __func__, td, p->p_pid, td->td_name, curvnet, 188 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A")); 189 #endif 190 #ifdef RACCT 191 if (racct_enable && p->p_throttled != 0) { 192 PROC_LOCK(p); 193 while (p->p_throttled != 0) { 194 msleep(p->p_racct, &p->p_mtx, 0, "racct", 195 p->p_throttled < 0 ? 0 : p->p_throttled); 196 if (p->p_throttled > 0) 197 p->p_throttled = 0; 198 } 199 PROC_UNLOCK(p); 200 } 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; 215 int sig; 216 217 td = curthread; 218 p = td->td_proc; 219 220 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid, 221 p->p_comm); 222 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode")); 223 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 224 mtx_assert(&Giant, MA_NOTOWNED); 225 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 226 td->td_frame = framep; 227 td->td_pticks = 0; 228 229 /* 230 * This updates the td_flag's for the checks below in one 231 * "atomic" operation with turning off the astpending flag. 232 * If another AST is triggered while we are handling the 233 * AST's saved in flags, the astpending flag will be set and 234 * ast() will be called again. 235 */ 236 thread_lock(td); 237 flags = td->td_flags; 238 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK | 239 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND); 240 thread_unlock(td); 241 VM_CNT_INC(v_trap); 242 243 if (td->td_cowgen != p->p_cowgen) 244 thread_cow_update(td); 245 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) { 246 addupc_task(td, td->td_profil_addr, td->td_profil_ticks); 247 td->td_profil_ticks = 0; 248 td->td_pflags &= ~TDP_OWEUPC; 249 } 250 #ifdef HWPMC_HOOKS 251 /* Handle Software PMC callchain capture. */ 252 if (PMC_IS_PENDING_CALLCHAIN(td)) 253 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep); 254 #endif 255 if (flags & TDF_ALRMPEND) { 256 PROC_LOCK(p); 257 kern_psignal(p, SIGVTALRM); 258 PROC_UNLOCK(p); 259 } 260 if (flags & TDF_PROFPEND) { 261 PROC_LOCK(p); 262 kern_psignal(p, SIGPROF); 263 PROC_UNLOCK(p); 264 } 265 #ifdef MAC 266 if (flags & TDF_MACPEND) 267 mac_thread_userret(td); 268 #endif 269 if (flags & TDF_NEEDRESCHED) { 270 #ifdef KTRACE 271 if (KTRPOINT(td, KTR_CSW)) 272 ktrcsw(1, 1, __func__); 273 #endif 274 thread_lock(td); 275 sched_prio(td, td->td_user_pri); 276 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL); 277 thread_unlock(td); 278 #ifdef KTRACE 279 if (KTRPOINT(td, KTR_CSW)) 280 ktrcsw(0, 1, __func__); 281 #endif 282 } 283 284 #ifdef DIAGNOSTIC 285 if (p->p_numthreads == 1 && (flags & TDF_NEEDSIGCHK) == 0) { 286 PROC_LOCK(p); 287 thread_lock(td); 288 /* 289 * Note that TDF_NEEDSIGCHK should be re-read from 290 * td_flags, since signal might have been delivered 291 * after we cleared td_flags above. This is one of 292 * the reason for looping check for AST condition. 293 * See comment in userret() about P_PPWAIT. 294 */ 295 if ((p->p_flag & P_PPWAIT) == 0) { 296 KASSERT(!SIGPENDING(td) || (td->td_flags & 297 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) == 298 (TDF_NEEDSIGCHK | TDF_ASTPENDING), 299 ("failed2 to set signal flags for ast p %p td %p " 300 "fl %x %x", p, td, flags, td->td_flags)); 301 } 302 thread_unlock(td); 303 PROC_UNLOCK(p); 304 } 305 #endif 306 307 /* 308 * Check for signals. Unlocked reads of p_pendingcnt or 309 * p_siglist might cause process-directed signal to be handled 310 * later. 311 */ 312 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 || 313 !SIGISEMPTY(p->p_siglist)) { 314 PROC_LOCK(p); 315 mtx_lock(&p->p_sigacts->ps_mtx); 316 while ((sig = cursig(td)) != 0) { 317 KASSERT(sig >= 0, ("sig %d", sig)); 318 postsig(sig); 319 } 320 mtx_unlock(&p->p_sigacts->ps_mtx); 321 PROC_UNLOCK(p); 322 } 323 /* 324 * We need to check to see if we have to exit or wait due to a 325 * single threading requirement or some other STOP condition. 326 */ 327 if (flags & TDF_NEEDSUSPCHK) { 328 PROC_LOCK(p); 329 thread_suspend_check(0); 330 PROC_UNLOCK(p); 331 } 332 333 if (td->td_pflags & TDP_OLDMASK) { 334 td->td_pflags &= ~TDP_OLDMASK; 335 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0); 336 } 337 338 userret(td, framep); 339 } 340 341 const char * 342 syscallname(struct proc *p, u_int code) 343 { 344 static const char unknown[] = "unknown"; 345 struct sysentvec *sv; 346 347 sv = p->p_sysent; 348 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 349 return (unknown); 350 return (sv->sv_syscallnames[code]); 351 } 352