1 /*- 2 * Copyright (C) 1994, David Greenman 3 * Copyright (c) 1990, 1993 4 * The Regents of the University of California. All rights reserved. 5 * Copyright (c) 2007 The FreeBSD Foundation 6 * 7 * This code is derived from software contributed to Berkeley by 8 * the University of Utah, and William Jolitz. 9 * 10 * Portions of this software were developed by A. Joseph Koshy under 11 * sponsorship from the FreeBSD Foundation and Google, Inc. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91 42 */ 43 44 #include <sys/cdefs.h> 45 __FBSDID("$FreeBSD$"); 46 47 #include "opt_hwpmc_hooks.h" 48 #include "opt_ktrace.h" 49 #include "opt_sched.h" 50 51 #include <sys/param.h> 52 #include <sys/bus.h> 53 #include <sys/capsicum.h> 54 #include <sys/kernel.h> 55 #include <sys/lock.h> 56 #include <sys/mutex.h> 57 #include <sys/pmckern.h> 58 #include <sys/proc.h> 59 #include <sys/ktr.h> 60 #include <sys/pioctl.h> 61 #include <sys/ptrace.h> 62 #include <sys/racct.h> 63 #include <sys/resourcevar.h> 64 #include <sys/sched.h> 65 #include <sys/signalvar.h> 66 #include <sys/syscall.h> 67 #include <sys/syscallsubr.h> 68 #include <sys/sysent.h> 69 #include <sys/systm.h> 70 #include <sys/vmmeter.h> 71 #ifdef KTRACE 72 #include <sys/uio.h> 73 #include <sys/ktrace.h> 74 #endif 75 #include <security/audit/audit.h> 76 77 #include <machine/cpu.h> 78 79 #ifdef VIMAGE 80 #include <net/vnet.h> 81 #endif 82 83 #ifdef HWPMC_HOOKS 84 #include <sys/pmckern.h> 85 #endif 86 87 #include <security/mac/mac_framework.h> 88 89 void (*softdep_ast_cleanup)(struct thread *); 90 91 /* 92 * Define the code needed before returning to user mode, for trap and 93 * syscall. 94 */ 95 void 96 userret(struct thread *td, struct trapframe *frame) 97 { 98 struct proc *p = td->td_proc; 99 100 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid, 101 td->td_name); 102 KASSERT((p->p_flag & P_WEXIT) == 0, 103 ("Exiting process returns to usermode")); 104 #ifdef DIAGNOSTIC 105 /* 106 * Check that we called signotify() enough. For 107 * multi-threaded processes, where signal distribution might 108 * change due to other threads changing sigmask, the check is 109 * racy and cannot be performed reliably. 110 * If current process is vfork child, indicated by P_PPWAIT, then 111 * issignal() ignores stops, so we block the check to avoid 112 * classifying pending signals. 113 */ 114 if (p->p_numthreads == 1) { 115 PROC_LOCK(p); 116 thread_lock(td); 117 if ((p->p_flag & P_PPWAIT) == 0) { 118 KASSERT(!SIGPENDING(td) || (td->td_flags & 119 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) == 120 (TDF_NEEDSIGCHK | TDF_ASTPENDING), 121 ("failed to set signal flags for ast p %p " 122 "td %p fl %x", p, td, td->td_flags)); 123 } 124 thread_unlock(td); 125 PROC_UNLOCK(p); 126 } 127 #endif 128 #ifdef KTRACE 129 KTRUSERRET(td); 130 #endif 131 td_softdep_cleanup(td); 132 MPASS(td->td_su == NULL); 133 134 /* 135 * If this thread tickled GEOM, we need to wait for the giggling to 136 * stop before we return to userland 137 */ 138 if (td->td_pflags & TDP_GEOM) 139 g_waitidle(); 140 141 /* 142 * Charge system time if profiling. 143 */ 144 if (p->p_flag & P_PROFIL) 145 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio); 146 /* 147 * Let the scheduler adjust our priority etc. 148 */ 149 sched_userret(td); 150 151 /* 152 * Check for misbehavior. 153 * 154 * In case there is a callchain tracing ongoing because of 155 * hwpmc(4), skip the scheduler pinning check. 156 * hwpmc(4) subsystem, infact, will collect callchain informations 157 * at ast() checkpoint, which is past userret(). 158 */ 159 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning"); 160 KASSERT(td->td_critnest == 0, 161 ("userret: Returning in a critical section")); 162 KASSERT(td->td_locks == 0, 163 ("userret: Returning with %d locks held", td->td_locks)); 164 KASSERT(td->td_rw_rlocks == 0, 165 ("userret: Returning with %d rwlocks held in read mode", 166 td->td_rw_rlocks)); 167 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0, 168 ("userret: Returning with pagefaults disabled")); 169 KASSERT(td->td_no_sleeping == 0, 170 ("userret: Returning with sleep disabled")); 171 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0, 172 ("userret: Returning with with pinned thread")); 173 KASSERT(td->td_vp_reserv == 0, 174 ("userret: Returning while holding vnode reservation")); 175 KASSERT((td->td_flags & (TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0, 176 ("userret: Returning with stop signals deferred")); 177 KASSERT(td->td_su == NULL, 178 ("userret: Returning with SU cleanup request not handled")); 179 #ifdef VIMAGE 180 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */ 181 VNET_ASSERT(curvnet == NULL, 182 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s", 183 __func__, td, p->p_pid, td->td_name, curvnet, 184 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A")); 185 #endif 186 #ifdef RACCT 187 if (racct_enable && p->p_throttled != 0) { 188 PROC_LOCK(p); 189 while (p->p_throttled != 0) { 190 msleep(p->p_racct, &p->p_mtx, 0, "racct", 191 p->p_throttled < 0 ? 0 : p->p_throttled); 192 if (p->p_throttled > 0) 193 p->p_throttled = 0; 194 } 195 PROC_UNLOCK(p); 196 } 197 #endif 198 } 199 200 /* 201 * Process an asynchronous software trap. 202 * This is relatively easy. 203 * This function will return with preemption disabled. 204 */ 205 void 206 ast(struct trapframe *framep) 207 { 208 struct thread *td; 209 struct proc *p; 210 int flags; 211 int sig; 212 213 td = curthread; 214 p = td->td_proc; 215 216 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid, 217 p->p_comm); 218 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode")); 219 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 220 mtx_assert(&Giant, MA_NOTOWNED); 221 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 222 td->td_frame = framep; 223 td->td_pticks = 0; 224 225 /* 226 * This updates the td_flag's for the checks below in one 227 * "atomic" operation with turning off the astpending flag. 228 * If another AST is triggered while we are handling the 229 * AST's saved in flags, the astpending flag will be set and 230 * ast() will be called again. 231 */ 232 thread_lock(td); 233 flags = td->td_flags; 234 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK | 235 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND); 236 thread_unlock(td); 237 VM_CNT_INC(v_trap); 238 239 if (td->td_cowgen != p->p_cowgen) 240 thread_cow_update(td); 241 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) { 242 addupc_task(td, td->td_profil_addr, td->td_profil_ticks); 243 td->td_profil_ticks = 0; 244 td->td_pflags &= ~TDP_OWEUPC; 245 } 246 #ifdef HWPMC_HOOKS 247 /* Handle Software PMC callchain capture. */ 248 if (PMC_IS_PENDING_CALLCHAIN(td)) 249 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep); 250 #endif 251 if (flags & TDF_ALRMPEND) { 252 PROC_LOCK(p); 253 kern_psignal(p, SIGVTALRM); 254 PROC_UNLOCK(p); 255 } 256 if (flags & TDF_PROFPEND) { 257 PROC_LOCK(p); 258 kern_psignal(p, SIGPROF); 259 PROC_UNLOCK(p); 260 } 261 #ifdef MAC 262 if (flags & TDF_MACPEND) 263 mac_thread_userret(td); 264 #endif 265 if (flags & TDF_NEEDRESCHED) { 266 #ifdef KTRACE 267 if (KTRPOINT(td, KTR_CSW)) 268 ktrcsw(1, 1, __func__); 269 #endif 270 thread_lock(td); 271 sched_prio(td, td->td_user_pri); 272 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL); 273 thread_unlock(td); 274 #ifdef KTRACE 275 if (KTRPOINT(td, KTR_CSW)) 276 ktrcsw(0, 1, __func__); 277 #endif 278 } 279 280 #ifdef DIAGNOSTIC 281 if (p->p_numthreads == 1 && (flags & TDF_NEEDSIGCHK) == 0) { 282 PROC_LOCK(p); 283 thread_lock(td); 284 /* 285 * Note that TDF_NEEDSIGCHK should be re-read from 286 * td_flags, since signal might have been delivered 287 * after we cleared td_flags above. This is one of 288 * the reason for looping check for AST condition. 289 * See comment in userret() about P_PPWAIT. 290 */ 291 if ((p->p_flag & P_PPWAIT) == 0) { 292 KASSERT(!SIGPENDING(td) || (td->td_flags & 293 (TDF_NEEDSIGCHK | TDF_ASTPENDING)) == 294 (TDF_NEEDSIGCHK | TDF_ASTPENDING), 295 ("failed2 to set signal flags for ast p %p td %p " 296 "fl %x %x", p, td, flags, td->td_flags)); 297 } 298 thread_unlock(td); 299 PROC_UNLOCK(p); 300 } 301 #endif 302 303 /* 304 * Check for signals. Unlocked reads of p_pendingcnt or 305 * p_siglist might cause process-directed signal to be handled 306 * later. 307 */ 308 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 || 309 !SIGISEMPTY(p->p_siglist)) { 310 PROC_LOCK(p); 311 mtx_lock(&p->p_sigacts->ps_mtx); 312 while ((sig = cursig(td)) != 0) { 313 KASSERT(sig >= 0, ("sig %d", sig)); 314 postsig(sig); 315 } 316 mtx_unlock(&p->p_sigacts->ps_mtx); 317 PROC_UNLOCK(p); 318 } 319 /* 320 * We need to check to see if we have to exit or wait due to a 321 * single threading requirement or some other STOP condition. 322 */ 323 if (flags & TDF_NEEDSUSPCHK) { 324 PROC_LOCK(p); 325 thread_suspend_check(0); 326 PROC_UNLOCK(p); 327 } 328 329 if (td->td_pflags & TDP_OLDMASK) { 330 td->td_pflags &= ~TDP_OLDMASK; 331 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0); 332 } 333 334 userret(td, framep); 335 } 336 337 const char * 338 syscallname(struct proc *p, u_int code) 339 { 340 static const char unknown[] = "unknown"; 341 struct sysentvec *sv; 342 343 sv = p->p_sysent; 344 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 345 return (unknown); 346 return (sv->sv_syscallnames[code]); 347 } 348