subr_trap.c revision 284199
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: stable/10/sys/kern/subr_trap.c 284199 2015-06-10 02:04:02Z kib $"); 46 47#include "opt_hwpmc_hooks.h" 48#include "opt_ktrace.h" 49#include "opt_kdtrace.h" 50#include "opt_sched.h" 51 52#include <sys/param.h> 53#include <sys/bus.h> 54#include <sys/capsicum.h> 55#include <sys/kernel.h> 56#include <sys/lock.h> 57#include <sys/mutex.h> 58#include <sys/pmckern.h> 59#include <sys/proc.h> 60#include <sys/ktr.h> 61#include <sys/pioctl.h> 62#include <sys/ptrace.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 XEN 84#include <vm/vm.h> 85#include <vm/vm_param.h> 86#include <vm/pmap.h> 87#endif 88 89#ifdef HWPMC_HOOKS 90#include <sys/pmckern.h> 91#endif 92 93#include <security/mac/mac_framework.h> 94 95void (*softdep_ast_cleanup)(void); 96 97/* 98 * Define the code needed before returning to user mode, for trap and 99 * syscall. 100 */ 101void 102userret(struct thread *td, struct trapframe *frame) 103{ 104 struct proc *p = td->td_proc; 105 106 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid, 107 td->td_name); 108 KASSERT((p->p_flag & P_WEXIT) == 0, 109 ("Exiting process returns to usermode")); 110#if 0 111#ifdef DIAGNOSTIC 112 /* Check that we called signotify() enough. */ 113 PROC_LOCK(p); 114 thread_lock(td); 115 if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 || 116 (td->td_flags & TDF_ASTPENDING) == 0)) 117 printf("failed to set signal flags properly for ast()\n"); 118 thread_unlock(td); 119 PROC_UNLOCK(p); 120#endif 121#endif 122#ifdef KTRACE 123 KTRUSERRET(td); 124#endif 125 if (softdep_ast_cleanup != NULL) 126 softdep_ast_cleanup(); 127 128 /* 129 * If this thread tickled GEOM, we need to wait for the giggling to 130 * stop before we return to userland 131 */ 132 if (td->td_pflags & TDP_GEOM) 133 g_waitidle(); 134 135 /* 136 * Charge system time if profiling. 137 */ 138 if (p->p_flag & P_PROFIL) 139 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio); 140 /* 141 * Let the scheduler adjust our priority etc. 142 */ 143 sched_userret(td); 144#ifdef XEN 145 PT_UPDATES_FLUSH(); 146#endif 147 148 /* 149 * Check for misbehavior. 150 * 151 * In case there is a callchain tracing ongoing because of 152 * hwpmc(4), skip the scheduler pinning check. 153 * hwpmc(4) subsystem, infact, will collect callchain informations 154 * at ast() checkpoint, which is past userret(). 155 */ 156 WITNESS_WARN(WARN_PANIC, NULL, "userret: returning"); 157 KASSERT(td->td_critnest == 0, 158 ("userret: Returning in a critical section")); 159 KASSERT(td->td_locks == 0, 160 ("userret: Returning with %d locks held", td->td_locks)); 161 KASSERT((td->td_pflags & TDP_NOFAULTING) == 0, 162 ("userret: Returning with pagefaults disabled")); 163 KASSERT(td->td_no_sleeping == 0, 164 ("userret: Returning with sleep disabled")); 165 KASSERT(td->td_pinned == 0 || (td->td_pflags & TDP_CALLCHAIN) != 0, 166 ("userret: Returning with with pinned thread")); 167 KASSERT(td->td_vp_reserv == 0, 168 ("userret: Returning while holding vnode reservation")); 169 KASSERT((td->td_flags & TDF_SBDRY) == 0, 170 ("userret: Returning with stop signals deferred")); 171 KASSERT(td->td_su == NULL, 172 ("userret: Returning with SU cleanup request not handled")); 173#ifdef VIMAGE 174 /* Unfortunately td_vnet_lpush needs VNET_DEBUG. */ 175 VNET_ASSERT(curvnet == NULL, 176 ("%s: Returning on td %p (pid %d, %s) with vnet %p set in %s", 177 __func__, td, p->p_pid, td->td_name, curvnet, 178 (td->td_vnet_lpush != NULL) ? td->td_vnet_lpush : "N/A")); 179#endif 180#ifdef RACCT 181 PROC_LOCK(p); 182 while (p->p_throttled == 1) 183 msleep(p->p_racct, &p->p_mtx, 0, "racct", 0); 184 PROC_UNLOCK(p); 185#endif 186} 187 188/* 189 * Process an asynchronous software trap. 190 * This is relatively easy. 191 * This function will return with preemption disabled. 192 */ 193void 194ast(struct trapframe *framep) 195{ 196 struct thread *td; 197 struct proc *p; 198 int flags; 199 int sig; 200 201 td = curthread; 202 p = td->td_proc; 203 204 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid, 205 p->p_comm); 206 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode")); 207 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 208 mtx_assert(&Giant, MA_NOTOWNED); 209 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 210 td->td_frame = framep; 211 td->td_pticks = 0; 212 213 /* 214 * This updates the td_flag's for the checks below in one 215 * "atomic" operation with turning off the astpending flag. 216 * If another AST is triggered while we are handling the 217 * AST's saved in flags, the astpending flag will be set and 218 * ast() will be called again. 219 */ 220 thread_lock(td); 221 flags = td->td_flags; 222 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK | 223 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND); 224 thread_unlock(td); 225 PCPU_INC(cnt.v_trap); 226 227 if (td->td_ucred != p->p_ucred) 228 cred_update_thread(td); 229 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) { 230 addupc_task(td, td->td_profil_addr, td->td_profil_ticks); 231 td->td_profil_ticks = 0; 232 td->td_pflags &= ~TDP_OWEUPC; 233 } 234#ifdef HWPMC_HOOKS 235 /* Handle Software PMC callchain capture. */ 236 if (PMC_IS_PENDING_CALLCHAIN(td)) 237 PMC_CALL_HOOK_UNLOCKED(td, PMC_FN_USER_CALLCHAIN_SOFT, (void *) framep); 238#endif 239 if (flags & TDF_ALRMPEND) { 240 PROC_LOCK(p); 241 kern_psignal(p, SIGVTALRM); 242 PROC_UNLOCK(p); 243 } 244 if (flags & TDF_PROFPEND) { 245 PROC_LOCK(p); 246 kern_psignal(p, SIGPROF); 247 PROC_UNLOCK(p); 248 } 249#ifdef MAC 250 if (flags & TDF_MACPEND) 251 mac_thread_userret(td); 252#endif 253 if (flags & TDF_NEEDRESCHED) { 254#ifdef KTRACE 255 if (KTRPOINT(td, KTR_CSW)) 256 ktrcsw(1, 1, __func__); 257#endif 258 thread_lock(td); 259 sched_prio(td, td->td_user_pri); 260 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL); 261 thread_unlock(td); 262#ifdef KTRACE 263 if (KTRPOINT(td, KTR_CSW)) 264 ktrcsw(0, 1, __func__); 265#endif 266 } 267 268 /* 269 * Check for signals. Unlocked reads of p_pendingcnt or 270 * p_siglist might cause process-directed signal to be handled 271 * later. 272 */ 273 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 || 274 !SIGISEMPTY(p->p_siglist)) { 275 PROC_LOCK(p); 276 mtx_lock(&p->p_sigacts->ps_mtx); 277 while ((sig = cursig(td)) != 0) 278 postsig(sig); 279 mtx_unlock(&p->p_sigacts->ps_mtx); 280 PROC_UNLOCK(p); 281 } 282 /* 283 * We need to check to see if we have to exit or wait due to a 284 * single threading requirement or some other STOP condition. 285 */ 286 if (flags & TDF_NEEDSUSPCHK) { 287 PROC_LOCK(p); 288 thread_suspend_check(0); 289 PROC_UNLOCK(p); 290 } 291 292 if (td->td_pflags & TDP_OLDMASK) { 293 td->td_pflags &= ~TDP_OLDMASK; 294 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0); 295 } 296 297 userret(td, framep); 298} 299 300const char * 301syscallname(struct proc *p, u_int code) 302{ 303 static const char unknown[] = "unknown"; 304 struct sysentvec *sv; 305 306 sv = p->p_sysent; 307 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 308 return (unknown); 309 return (sv->sv_syscallnames[code]); 310} 311