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 * Let the scheduler adjust our priority etc. 125 */ 126 sched_userret(td); 127 KASSERT(td->td_locks == 0, 128 ("userret: Returning with %d locks held.", td->td_locks)); 129 #ifdef XEN 130 PT_UPDATES_FLUSH(); 131 #endif 132 } 133 134 /* 135 * Process an asynchronous software trap. 136 * This is relatively easy. 137 * This function will return with preemption disabled. 138 */ 139 void 140 ast(struct trapframe *framep) 141 { 142 struct thread *td; 143 struct proc *p; 144 int flags; 145 int sig; 146 147 td = curthread; 148 p = td->td_proc; 149 150 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid, 151 p->p_comm); 152 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode")); 153 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 154 mtx_assert(&Giant, MA_NOTOWNED); 155 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 156 td->td_frame = framep; 157 td->td_pticks = 0; 158 159 /* 160 * This updates the td_flag's for the checks below in one 161 * "atomic" operation with turning off the astpending flag. 162 * If another AST is triggered while we are handling the 163 * AST's saved in flags, the astpending flag will be set and 164 * ast() will be called again. 165 */ 166 thread_lock(td); 167 flags = td->td_flags; 168 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK | 169 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND); 170 thread_unlock(td); 171 PCPU_INC(cnt.v_trap); 172 173 if (td->td_ucred != p->p_ucred) 174 cred_update_thread(td); 175 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) { 176 addupc_task(td, td->td_profil_addr, td->td_profil_ticks); 177 td->td_profil_ticks = 0; 178 td->td_pflags &= ~TDP_OWEUPC; 179 } 180 if (flags & TDF_ALRMPEND) { 181 PROC_LOCK(p); 182 psignal(p, SIGVTALRM); 183 PROC_UNLOCK(p); 184 } 185 if (flags & TDF_PROFPEND) { 186 PROC_LOCK(p); 187 psignal(p, SIGPROF); 188 PROC_UNLOCK(p); 189 } 190 #ifdef MAC 191 if (flags & TDF_MACPEND) 192 mac_thread_userret(td); 193 #endif 194 if (flags & TDF_NEEDRESCHED) { 195 #ifdef KTRACE 196 if (KTRPOINT(td, KTR_CSW)) 197 ktrcsw(1, 1); 198 #endif 199 thread_lock(td); 200 sched_prio(td, td->td_user_pri); 201 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL); 202 thread_unlock(td); 203 #ifdef KTRACE 204 if (KTRPOINT(td, KTR_CSW)) 205 ktrcsw(0, 1); 206 #endif 207 } 208 209 /* 210 * Check for signals. Unlocked reads of p_pendingcnt or 211 * p_siglist might cause process-directed signal to be handled 212 * later. 213 */ 214 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 || 215 !SIGISEMPTY(p->p_siglist)) { 216 PROC_LOCK(p); 217 mtx_lock(&p->p_sigacts->ps_mtx); 218 while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0) 219 postsig(sig); 220 mtx_unlock(&p->p_sigacts->ps_mtx); 221 PROC_UNLOCK(p); 222 } 223 /* 224 * We need to check to see if we have to exit or wait due to a 225 * single threading requirement or some other STOP condition. 226 */ 227 if (flags & TDF_NEEDSUSPCHK) { 228 PROC_LOCK(p); 229 thread_suspend_check(0); 230 PROC_UNLOCK(p); 231 } 232 233 if (td->td_pflags & TDP_OLDMASK) { 234 td->td_pflags &= ~TDP_OLDMASK; 235 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0); 236 } 237 238 userret(td, framep); 239 mtx_assert(&Giant, MA_NOTOWNED); 240 } 241 242 #ifdef HAVE_SYSCALL_ARGS_DEF 243 const char * 244 syscallname(struct proc *p, u_int code) 245 { 246 static const char unknown[] = "unknown"; 247 struct sysentvec *sv; 248 249 sv = p->p_sysent; 250 if (sv->sv_syscallnames == NULL || code >= sv->sv_size) 251 return (unknown); 252 return (sv->sv_syscallnames[code]); 253 } 254 255 int 256 syscallenter(struct thread *td, struct syscall_args *sa) 257 { 258 struct proc *p; 259 int error, traced; 260 261 PCPU_INC(cnt.v_syscall); 262 p = td->td_proc; 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 error = syscall_thread_enter(td, sa->callp); 303 if (error != 0) 304 goto retval; 305 306 #ifdef KDTRACE_HOOKS 307 /* 308 * If the systrace module has registered it's probe 309 * callback and if there is a probe active for the 310 * syscall 'entry', process the probe. 311 */ 312 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 313 (*systrace_probe_func)(sa->callp->sy_entry, sa->code, 314 sa->callp, sa->args, 0); 315 #endif 316 317 AUDIT_SYSCALL_ENTER(sa->code, td); 318 error = (sa->callp->sy_call)(td, sa->args); 319 AUDIT_SYSCALL_EXIT(error, td); 320 321 /* Save the latest error return value. */ 322 td->td_errno = error; 323 324 #ifdef KDTRACE_HOOKS 325 /* 326 * If the systrace module has registered it's probe 327 * callback and if there is a probe active for the 328 * syscall 'return', process the probe. 329 */ 330 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 331 (*systrace_probe_func)(sa->callp->sy_return, sa->code, 332 sa->callp, NULL, (error) ? -1 : td->td_retval[0]); 333 #endif 334 syscall_thread_exit(td, sa->callp); 335 CTR4(KTR_SYSC, "syscall: p=%p error=%d return %#lx %#lx", 336 p, error, td->td_retval[0], td->td_retval[1]); 337 } 338 retval: 339 if (traced) { 340 PROC_LOCK(p); 341 td->td_dbgflags &= ~TDB_SCE; 342 PROC_UNLOCK(p); 343 } 344 (p->p_sysent->sv_set_syscall_retval)(td, error); 345 return (error); 346 } 347 348 void 349 syscallret(struct thread *td, int error, struct syscall_args *sa __unused) 350 { 351 struct proc *p; 352 int traced; 353 354 p = td->td_proc; 355 356 /* 357 * Check for misbehavior. 358 */ 359 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 360 syscallname(p, sa->code)); 361 KASSERT(td->td_critnest == 0, 362 ("System call %s returning in a critical section", 363 syscallname(p, sa->code))); 364 KASSERT(td->td_locks == 0, 365 ("System call %s returning with %d locks held", 366 syscallname(p, sa->code), td->td_locks)); 367 368 /* 369 * Handle reschedule and other end-of-syscall issues 370 */ 371 userret(td, td->td_frame); 372 373 CTR4(KTR_SYSC, "syscall %s exit thread %p pid %d proc %s", 374 syscallname(p, sa->code), td, td->td_proc->p_pid, td->td_name); 375 376 #ifdef KTRACE 377 if (KTRPOINT(td, KTR_SYSRET)) 378 ktrsysret(sa->code, error, td->td_retval[0]); 379 #endif 380 381 if (p->p_flag & P_TRACED) { 382 traced = 1; 383 PROC_LOCK(p); 384 td->td_dbgflags |= TDB_SCX; 385 PROC_UNLOCK(p); 386 } else 387 traced = 0; 388 /* 389 * This works because errno is findable through the 390 * register set. If we ever support an emulation where this 391 * is not the case, this code will need to be revisited. 392 */ 393 STOPEVENT(p, S_SCX, sa->code); 394 PTRACESTOP_SC(p, td, S_PT_SCX); 395 if (traced || (td->td_dbgflags & TDB_EXEC) != 0) { 396 PROC_LOCK(p); 397 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC); 398 PROC_UNLOCK(p); 399 } 400 } 401 #endif /* HAVE_SYSCALL_ARGS_DEF */ 402