Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_trap.c
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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: releng/8.2/sys/kern/subr_trap.c 215513 2010-11-19 09:49:14Z kib $"); 46 47 #include "opt_ktrace.h" 48 #include "opt_kdtrace.h" 49 #include "opt_sched.h" 50 51 #include <sys/param.h> 52 #include <sys/bus.h> 53 #include <sys/kernel.h> 54 #include <sys/lock.h> 55 #include <sys/mutex.h> 56 #include <sys/pmckern.h> 57 #include <sys/proc.h> 58 #include <sys/ktr.h> 59 #include <sys/pioctl.h> 60 #include <sys/ptrace.h> 61 #include <sys/resourcevar.h> 62 #include <sys/sched.h> 63 #include <sys/signalvar.h> 64 #include <sys/syscall.h> 65 #include <sys/sysent.h> 66 #include <sys/systm.h> 67 #include <sys/vmmeter.h> 68 #ifdef KTRACE 69 #include <sys/uio.h> 70 #include <sys/ktrace.h> 71 #endif 72 #include <security/audit/audit.h> 73 74 #include <machine/cpu.h> 75 76 #ifdef XEN 77 #include <vm/vm.h> 78 #include <vm/vm_param.h> 79 #include <vm/pmap.h> 80 #endif 81 82 #include <security/mac/mac_framework.h> 83 84 /* 85 * Define the code needed before returning to user mode, for trap and 86 * syscall. 87 */ 88 void 89 userret(struct thread *td, struct trapframe *frame) 90 { 91 struct proc *p = td->td_proc; 92 93 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid, 94 td->td_name); 95 #if 0 96 #ifdef DIAGNOSTIC 97 /* Check that we called signotify() enough. */ 98 PROC_LOCK(p); 99 thread_lock(td); 100 if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 || 101 (td->td_flags & TDF_ASTPENDING) == 0)) 102 printf("failed to set signal flags properly for ast()\n"); 103 thread_unlock(td); 104 PROC_UNLOCK(p); 105 #endif 106 #endif 107 #ifdef KTRACE 108 KTRUSERRET(td); 109 #endif 110 /* 111 * If this thread tickled GEOM, we need to wait for the giggling to 112 * stop before we return to userland 113 */ 114 if (td->td_pflags & TDP_GEOM) 115 g_waitidle(); 116 117 /* 118 * Charge system time if profiling. 119 */ 120 if (p->p_flag & P_PROFIL) 121 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio); 122 /* 123 * Let the scheduler adjust our priority etc. 124 */ 125 sched_userret(td); 126 KASSERT(td->td_locks == 0, 127 ("userret: Returning with %d locks held.", td->td_locks)); 128 #ifdef XEN 129 PT_UPDATES_FLUSH(); 130 #endif 131 } 132 133 /* 134 * Process an asynchronous software trap. 135 * This is relatively easy. 136 * This function will return with preemption disabled. 137 */ 138 void 139 ast(struct trapframe *framep) 140 { 141 struct thread *td; 142 struct proc *p; 143 int flags; 144 int sig; 145 146 td = curthread; 147 p = td->td_proc; 148 149 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid, 150 p->p_comm); 151 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode")); 152 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 153 mtx_assert(&Giant, MA_NOTOWNED); 154 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 155 td->td_frame = framep; 156 td->td_pticks = 0; 157 158 /* 159 * This updates the td_flag's for the checks below in one 160 * "atomic" operation with turning off the astpending flag. 161 * If another AST is triggered while we are handling the 162 * AST's saved in flags, the astpending flag will be set and 163 * ast() will be called again. 164 */ 165 thread_lock(td); 166 flags = td->td_flags; 167 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK | 168 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND); 169 thread_unlock(td); 170 PCPU_INC(cnt.v_trap); 171 172 if (td->td_ucred != p->p_ucred) 173 cred_update_thread(td); 174 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) { 175 addupc_task(td, td->td_profil_addr, td->td_profil_ticks); 176 td->td_profil_ticks = 0; 177 td->td_pflags &= ~TDP_OWEUPC; 178 } 179 if (flags & TDF_ALRMPEND) { 180 PROC_LOCK(p); 181 psignal(p, SIGVTALRM); 182 PROC_UNLOCK(p); 183 } 184 if (flags & TDF_PROFPEND) { 185 PROC_LOCK(p); 186 psignal(p, SIGPROF); 187 PROC_UNLOCK(p); 188 } 189 #ifdef MAC 190 if (flags & TDF_MACPEND) 191 mac_thread_userret(td); 192 #endif 193 if (flags & TDF_NEEDRESCHED) { 194 #ifdef KTRACE 195 if (KTRPOINT(td, KTR_CSW)) 196 ktrcsw(1, 1); 197 #endif 198 thread_lock(td); 199 sched_prio(td, td->td_user_pri); 200 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL); 201 thread_unlock(td); 202 #ifdef KTRACE 203 if (KTRPOINT(td, KTR_CSW)) 204 ktrcsw(0, 1); 205 #endif 206 } 207 208 /* 209 * Check for signals. Unlocked reads of p_pendingcnt or 210 * p_siglist might cause process-directed signal to be handled 211 * later. 212 */ 213 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 || 214 !SIGISEMPTY(p->p_siglist)) { 215 PROC_LOCK(p); 216 mtx_lock(&p->p_sigacts->ps_mtx); 217 while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0) 218 postsig(sig); 219 mtx_unlock(&p->p_sigacts->ps_mtx); 220 PROC_UNLOCK(p); 221 } 222 /* 223 * We need to check to see if we have to exit or wait due to a 224 * single threading requirement or some other STOP condition. 225 */ 226 if (flags & TDF_NEEDSUSPCHK) { 227 PROC_LOCK(p); 228 thread_suspend_check(0); 229 PROC_UNLOCK(p); 230 } 231 232 if (td->td_pflags & TDP_OLDMASK) { 233 td->td_pflags &= ~TDP_OLDMASK; 234 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0); 235 } 236 237 userret(td, framep); 238 mtx_assert(&Giant, MA_NOTOWNED); 239 } 240 241 #ifdef HAVE_SYSCALL_ARGS_DEF 242 const char * 243 syscallname(struct proc *p, u_int code) 244 { 245 static const char unknown[] = "unknown"; 246 struct sysentvec *sv; 247 248 sv = p->p_sysent; 249 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 250 return (unknown); 251 return (sv->sv_syscallnames[code]); 252 } 253 254 int 255 syscallenter(struct thread *td, struct syscall_args *sa) 256 { 257 struct proc *p; 258 int error, traced; 259 260 PCPU_INC(cnt.v_syscall); 261 p = td->td_proc; 262 td->td_syscalls++; 263 264 td->td_pticks = 0; 265 if (td->td_ucred != p->p_ucred) 266 cred_update_thread(td); 267 if (p->p_flag & P_TRACED) { 268 traced = 1; 269 PROC_LOCK(p); 270 td->td_dbgflags &= ~TDB_USERWR; 271 td->td_dbgflags |= TDB_SCE; 272 PROC_UNLOCK(p); 273 } else 274 traced = 0; 275 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 276 #ifdef KTRACE 277 if (KTRPOINT(td, KTR_SYSCALL)) 278 ktrsyscall(sa->code, sa->narg, sa->args); 279 #endif 280 281 CTR6(KTR_SYSC, 282 "syscall: td=%p pid %d %s (%#lx, %#lx, %#lx)", 283 td, td->td_proc->p_pid, syscallname(p, sa->code), 284 sa->args[0], sa->args[1], sa->args[2]); 285 286 if (error == 0) { 287 STOPEVENT(p, S_SCE, sa->narg); 288 PTRACESTOP_SC(p, td, S_PT_SCE); 289 if (td->td_dbgflags & TDB_USERWR) { 290 /* 291 * Reread syscall number and arguments if 292 * debugger modified registers or memory. 293 */ 294 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 295 #ifdef KTRACE 296 if (KTRPOINT(td, KTR_SYSCALL)) 297 ktrsyscall(sa->code, sa->narg, sa->args); 298 #endif 299 if (error != 0) 300 goto retval; 301 } 302 303 #ifdef KDTRACE_HOOKS 304 /* 305 * If the systrace module has registered it's probe 306 * callback and if there is a probe active for the 307 * syscall 'entry', process the probe. 308 */ 309 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 310 (*systrace_probe_func)(sa->callp->sy_entry, sa->code, 311 sa->callp, sa->args); 312 #endif 313 314 AUDIT_SYSCALL_ENTER(sa->code, td); 315 error = (sa->callp->sy_call)(td, sa->args); 316 AUDIT_SYSCALL_EXIT(error, td); 317 318 /* Save the latest error return value. */ 319 td->td_errno = error; 320 321 #ifdef KDTRACE_HOOKS 322 /* 323 * If the systrace module has registered it's probe 324 * callback and if there is a probe active for the 325 * syscall 'return', process the probe. 326 */ 327 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 328 (*systrace_probe_func)(sa->callp->sy_return, sa->code, 329 sa->callp, sa->args); 330 #endif 331 CTR4(KTR_SYSC, "syscall: p=%p error=%d return %#lx %#lx", 332 p, error, td->td_retval[0], td->td_retval[1]); 333 } 334 retval: 335 if (traced) { 336 PROC_LOCK(p); 337 td->td_dbgflags &= ~TDB_SCE; 338 PROC_UNLOCK(p); 339 } 340 (p->p_sysent->sv_set_syscall_retval)(td, error); 341 return (error); 342 } 343 344 void 345 syscallret(struct thread *td, int error, struct syscall_args *sa __unused) 346 { 347 struct proc *p; 348 int traced; 349 350 p = td->td_proc; 351 352 /* 353 * Check for misbehavior. 354 */ 355 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 356 syscallname(p, sa->code)); 357 KASSERT(td->td_critnest == 0, 358 ("System call %s returning in a critical section", 359 syscallname(p, sa->code))); 360 KASSERT(td->td_locks == 0, 361 ("System call %s returning with %d locks held", 362 syscallname(p, sa->code), td->td_locks)); 363 364 /* 365 * Handle reschedule and other end-of-syscall issues 366 */ 367 userret(td, td->td_frame); 368 369 CTR4(KTR_SYSC, "syscall %s exit thread %p pid %d proc %s", 370 syscallname(p, sa->code), td, td->td_proc->p_pid, td->td_name); 371 372 #ifdef KTRACE 373 if (KTRPOINT(td, KTR_SYSRET)) 374 ktrsysret(sa->code, error, td->td_retval[0]); 375 #endif 376 377 if (p->p_flag & P_TRACED) { 378 traced = 1; 379 PROC_LOCK(p); 380 td->td_dbgflags |= TDB_SCX; 381 PROC_UNLOCK(p); 382 } else 383 traced = 0; 384 /* 385 * This works because errno is findable through the 386 * register set. If we ever support an emulation where this 387 * is not the case, this code will need to be revisited. 388 */ 389 STOPEVENT(p, S_SCX, sa->code); 390 PTRACESTOP_SC(p, td, S_PT_SCX); 391 if (traced || (td->td_dbgflags & TDB_EXEC) != 0) { 392 PROC_LOCK(p); 393 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC); 394 PROC_UNLOCK(p); 395 } 396 } 397 #endif /* HAVE_SYSCALL_ARGS_DEF */
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