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_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/syscallsubr.h> 66 #include <sys/sysent.h> 67 #include <sys/systm.h> 68 #include <sys/vmmeter.h> 69 #ifdef KTRACE 70 #include <sys/uio.h> 71 #include <sys/ktrace.h> 72 #endif 73 #include <security/audit/audit.h> 74 75 #include <machine/cpu.h> 76 77 #ifdef XEN 78 #include <vm/vm.h> 79 #include <vm/vm_param.h> 80 #include <vm/pmap.h> 81 #endif 82 83 #include <security/mac/mac_framework.h> 84 85 /* 86 * Define the code needed before returning to user mode, for trap and 87 * syscall. 88 */ 89 void 90 userret(struct thread *td, struct trapframe *frame) 91 { 92 struct proc *p = td->td_proc; 93 94 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid, 95 td->td_name); 96 #if 0 97 #ifdef DIAGNOSTIC 98 /* Check that we called signotify() enough. */ 99 PROC_LOCK(p); 100 thread_lock(td); 101 if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 || 102 (td->td_flags & TDF_ASTPENDING) == 0)) 103 printf("failed to set signal flags properly for ast()\n"); 104 thread_unlock(td); 105 PROC_UNLOCK(p); 106 #endif 107 #endif 108 #ifdef KTRACE 109 KTRUSERRET(td); 110 #endif 111 /* 112 * If this thread tickled GEOM, we need to wait for the giggling to 113 * stop before we return to userland 114 */ 115 if (td->td_pflags & TDP_GEOM) 116 g_waitidle(); 117 118 /* 119 * Charge system time if profiling. 120 */ 121 if (p->p_flag & P_PROFIL) { 122 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio); 123 } 124 /* 125 * Let the scheduler adjust our priority etc. 126 */ 127 sched_userret(td); 128 KASSERT(td->td_locks == 0, 129 ("userret: Returning with %d locks held.", td->td_locks)); 130 #ifdef XEN 131 PT_UPDATES_FLUSH(); 132 #endif 133 } 134 135 /* 136 * Process an asynchronous software trap. 137 * This is relatively easy. 138 * This function will return with preemption disabled. 139 */ 140 void 141 ast(struct trapframe *framep) 142 { 143 struct thread *td; 144 struct proc *p; 145 int flags; 146 int sig; 147 148 td = curthread; 149 p = td->td_proc; 150 151 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid, 152 p->p_comm); 153 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode")); 154 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 155 mtx_assert(&Giant, MA_NOTOWNED); 156 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 157 td->td_frame = framep; 158 td->td_pticks = 0; 159 160 /* 161 * This updates the td_flag's for the checks below in one 162 * "atomic" operation with turning off the astpending flag. 163 * If another AST is triggered while we are handling the 164 * AST's saved in flags, the astpending flag will be set and 165 * ast() will be called again. 166 */ 167 thread_lock(td); 168 flags = td->td_flags; 169 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK | 170 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND); 171 thread_unlock(td); 172 PCPU_INC(cnt.v_trap); 173 174 if (td->td_ucred != p->p_ucred) 175 cred_update_thread(td); 176 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) { 177 addupc_task(td, td->td_profil_addr, td->td_profil_ticks); 178 td->td_profil_ticks = 0; 179 td->td_pflags &= ~TDP_OWEUPC; 180 } 181 if (flags & TDF_ALRMPEND) { 182 PROC_LOCK(p); 183 psignal(p, SIGVTALRM); 184 PROC_UNLOCK(p); 185 } 186 if (flags & TDF_PROFPEND) { 187 PROC_LOCK(p); 188 psignal(p, SIGPROF); 189 PROC_UNLOCK(p); 190 } 191 #ifdef MAC 192 if (flags & TDF_MACPEND) 193 mac_thread_userret(td); 194 #endif 195 if (flags & TDF_NEEDRESCHED) { 196 #ifdef KTRACE 197 if (KTRPOINT(td, KTR_CSW)) 198 ktrcsw(1, 1); 199 #endif 200 thread_lock(td); 201 sched_prio(td, td->td_user_pri); 202 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL); 203 thread_unlock(td); 204 #ifdef KTRACE 205 if (KTRPOINT(td, KTR_CSW)) 206 ktrcsw(0, 1); 207 #endif 208 } 209 210 /* 211 * Check for signals. Unlocked reads of p_pendingcnt or 212 * p_siglist might cause process-directed signal to be handled 213 * later. 214 */ 215 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 || 216 !SIGISEMPTY(p->p_siglist)) { 217 PROC_LOCK(p); 218 mtx_lock(&p->p_sigacts->ps_mtx); 219 while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0) 220 postsig(sig); 221 mtx_unlock(&p->p_sigacts->ps_mtx); 222 PROC_UNLOCK(p); 223 } 224 /* 225 * We need to check to see if we have to exit or wait due to a 226 * single threading requirement or some other STOP condition. 227 */ 228 if (flags & TDF_NEEDSUSPCHK) { 229 PROC_LOCK(p); 230 thread_suspend_check(0); 231 PROC_UNLOCK(p); 232 } 233 234 if (td->td_pflags & TDP_OLDMASK) { 235 td->td_pflags &= ~TDP_OLDMASK; 236 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0); 237 } 238 239 userret(td, framep); 240 mtx_assert(&Giant, MA_NOTOWNED); 241 } 242 243 #ifdef HAVE_SYSCALL_ARGS_DEF 244 const char * 245 syscallname(struct proc *p, u_int code) 246 { 247 static const char unknown[] = "unknown"; 248 struct sysentvec *sv; 249 250 sv = p->p_sysent; 251 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 252 return (unknown); 253 return (sv->sv_syscallnames[code]); 254 } 255 256 int 257 syscallenter(struct thread *td, struct syscall_args *sa) 258 { 259 struct proc *p; 260 int error, traced; 261 262 PCPU_INC(cnt.v_syscall); 263 p = td->td_proc; 264 265 td->td_pticks = 0; 266 if (td->td_ucred != p->p_ucred) 267 cred_update_thread(td); 268 if (p->p_flag & P_TRACED) { 269 traced = 1; 270 PROC_LOCK(p); 271 td->td_dbgflags &= ~TDB_USERWR; 272 td->td_dbgflags |= TDB_SCE; 273 PROC_UNLOCK(p); 274 } else 275 traced = 0; 276 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 277 #ifdef KTRACE 278 if (KTRPOINT(td, KTR_SYSCALL)) 279 ktrsyscall(sa->code, sa->narg, sa->args); 280 #endif 281 282 CTR6(KTR_SYSC, 283 "syscall: td=%p pid %d %s (%#lx, %#lx, %#lx)", 284 td, td->td_proc->p_pid, syscallname(p, sa->code), 285 sa->args[0], sa->args[1], sa->args[2]); 286 287 if (error == 0) { 288 STOPEVENT(p, S_SCE, sa->narg); 289 PTRACESTOP_SC(p, td, S_PT_SCE); 290 if (td->td_dbgflags & TDB_USERWR) { 291 /* 292 * Reread syscall number and arguments if 293 * debugger modified registers or memory. 294 */ 295 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 296 #ifdef KTRACE 297 if (KTRPOINT(td, KTR_SYSCALL)) 298 ktrsyscall(sa->code, sa->narg, sa->args); 299 #endif 300 if (error != 0) 301 goto retval; 302 } 303 error = syscall_thread_enter(td, sa->callp); 304 if (error != 0) 305 goto retval; 306 307 #ifdef KDTRACE_HOOKS 308 /* 309 * If the systrace module has registered it's probe 310 * callback and if there is a probe active for the 311 * syscall 'entry', process the probe. 312 */ 313 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 314 (*systrace_probe_func)(sa->callp->sy_entry, sa->code, 315 sa->callp, sa->args); 316 #endif 317 318 AUDIT_SYSCALL_ENTER(sa->code, td); 319 error = (sa->callp->sy_call)(td, sa->args); 320 AUDIT_SYSCALL_EXIT(error, td); 321 322 /* Save the latest error return value. */ 323 td->td_errno = error; 324 325 #ifdef KDTRACE_HOOKS 326 /* 327 * If the systrace module has registered it's probe 328 * callback and if there is a probe active for the 329 * syscall 'return', process the probe. 330 */ 331 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 332 (*systrace_probe_func)(sa->callp->sy_return, sa->code, 333 sa->callp, sa->args); 334 #endif 335 syscall_thread_exit(td, sa->callp); 336 CTR4(KTR_SYSC, "syscall: p=%p error=%d return %#lx %#lx", 337 p, error, td->td_retval[0], td->td_retval[1]); 338 } 339 retval: 340 if (traced) { 341 PROC_LOCK(p); 342 td->td_dbgflags &= ~TDB_SCE; 343 PROC_UNLOCK(p); 344 } 345 (p->p_sysent->sv_set_syscall_retval)(td, error); 346 return (error); 347 } 348 349 void 350 syscallret(struct thread *td, int error, struct syscall_args *sa __unused) 351 { 352 struct proc *p; 353 int traced; 354 355 p = td->td_proc; 356 357 /* 358 * Check for misbehavior. 359 */ 360 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 361 syscallname(p, sa->code)); 362 KASSERT(td->td_critnest == 0, 363 ("System call %s returning in a critical section", 364 syscallname(p, sa->code))); 365 KASSERT(td->td_locks == 0, 366 ("System call %s returning with %d locks held", 367 syscallname(p, sa->code), td->td_locks)); 368 369 /* 370 * Handle reschedule and other end-of-syscall issues 371 */ 372 userret(td, td->td_frame); 373 374 CTR4(KTR_SYSC, "syscall %s exit thread %p pid %d proc %s", 375 syscallname(p, sa->code), td, td->td_proc->p_pid, td->td_name); 376 377 #ifdef KTRACE 378 if (KTRPOINT(td, KTR_SYSRET)) 379 ktrsysret(sa->code, error, td->td_retval[0]); 380 #endif 381 382 if (p->p_flag & P_TRACED) { 383 traced = 1; 384 PROC_LOCK(p); 385 td->td_dbgflags |= TDB_SCX; 386 PROC_UNLOCK(p); 387 } else 388 traced = 0; 389 /* 390 * This works because errno is findable through the 391 * register set. If we ever support an emulation where this 392 * is not the case, this code will need to be revisited. 393 */ 394 STOPEVENT(p, S_SCX, sa->code); 395 PTRACESTOP_SC(p, td, S_PT_SCX); 396 if (traced || (td->td_dbgflags & TDB_EXEC) != 0) { 397 PROC_LOCK(p); 398 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC); 399 PROC_UNLOCK(p); 400 } 401 } 402 #endif /* HAVE_SYSCALL_ARGS_DEF */ 403