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 #ifdef __i386__ 49 #include "opt_npx.h" 50 #endif 51 #include "opt_sched.h" 52 53 #include <sys/param.h> 54 #include <sys/bus.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/sysent.h> 68 #include <sys/systm.h> 69 #include <sys/vmmeter.h> 70 #ifdef KTRACE 71 #include <sys/uio.h> 72 #include <sys/ktrace.h> 73 #endif 74 #include <security/audit/audit.h> 75 76 #include <machine/cpu.h> 77 #include <machine/pcb.h> 78 79 #ifdef XEN 80 #include <vm/vm.h> 81 #include <vm/vm_param.h> 82 #include <vm/pmap.h> 83 #endif 84 85 #include <security/mac/mac_framework.h> 86 87 /* 88 * Define the code needed before returning to user mode, for trap and 89 * syscall. 90 */ 91 void 92 userret(struct thread *td, struct trapframe *frame) 93 { 94 struct proc *p = td->td_proc; 95 96 CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid, 97 td->td_name); 98 #if 0 99 #ifdef DIAGNOSTIC 100 /* Check that we called signotify() enough. */ 101 PROC_LOCK(p); 102 thread_lock(td); 103 if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 || 104 (td->td_flags & TDF_ASTPENDING) == 0)) 105 printf("failed to set signal flags properly for ast()\n"); 106 thread_unlock(td); 107 PROC_UNLOCK(p); 108 #endif 109 #endif 110 #ifdef KTRACE 111 KTRUSERRET(td); 112 #endif 113 /* 114 * If this thread tickled GEOM, we need to wait for the giggling to 115 * stop before we return to userland 116 */ 117 if (td->td_pflags & TDP_GEOM) 118 g_waitidle(); 119 120 /* 121 * Charge system time if profiling. 122 */ 123 if (p->p_flag & P_PROFIL) { 124 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio); 125 } 126 /* 127 * Let the scheduler adjust our priority etc. 128 */ 129 sched_userret(td); 130 KASSERT(td->td_locks == 0, 131 ("userret: Returning with %d locks held.", td->td_locks)); 132 #ifdef XEN 133 PT_UPDATES_FLUSH(); 134 #endif 135 } 136 137 /* 138 * Process an asynchronous software trap. 139 * This is relatively easy. 140 * This function will return with preemption disabled. 141 */ 142 void 143 ast(struct trapframe *framep) 144 { 145 struct thread *td; 146 struct proc *p; 147 int flags; 148 int sig; 149 #if defined(DEV_NPX) && !defined(SMP) 150 int ucode; 151 ksiginfo_t ksi; 152 #endif 153 154 td = curthread; 155 p = td->td_proc; 156 157 CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid, 158 p->p_comm); 159 KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode")); 160 WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode"); 161 mtx_assert(&Giant, MA_NOTOWNED); 162 THREAD_LOCK_ASSERT(td, MA_NOTOWNED); 163 td->td_frame = framep; 164 td->td_pticks = 0; 165 166 /* 167 * This updates the td_flag's for the checks below in one 168 * "atomic" operation with turning off the astpending flag. 169 * If another AST is triggered while we are handling the 170 * AST's saved in flags, the astpending flag will be set and 171 * ast() will be called again. 172 */ 173 thread_lock(td); 174 flags = td->td_flags; 175 td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK | 176 TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND); 177 thread_unlock(td); 178 PCPU_INC(cnt.v_trap); 179 180 if (td->td_ucred != p->p_ucred) 181 cred_update_thread(td); 182 if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) { 183 addupc_task(td, td->td_profil_addr, td->td_profil_ticks); 184 td->td_profil_ticks = 0; 185 td->td_pflags &= ~TDP_OWEUPC; 186 } 187 if (flags & TDF_ALRMPEND) { 188 PROC_LOCK(p); 189 psignal(p, SIGVTALRM); 190 PROC_UNLOCK(p); 191 } 192 #if defined(DEV_NPX) && !defined(SMP) 193 if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) { 194 atomic_clear_int(&PCPU_GET(curpcb)->pcb_flags, 195 PCB_NPXTRAP); 196 ucode = npxtrap(); 197 if (ucode != -1) { 198 ksiginfo_init_trap(&ksi); 199 ksi.ksi_signo = SIGFPE; 200 ksi.ksi_code = ucode; 201 trapsignal(td, &ksi); 202 } 203 } 204 #endif 205 if (flags & TDF_PROFPEND) { 206 PROC_LOCK(p); 207 psignal(p, SIGPROF); 208 PROC_UNLOCK(p); 209 } 210 #ifdef MAC 211 if (flags & TDF_MACPEND) 212 mac_thread_userret(td); 213 #endif 214 if (flags & TDF_NEEDRESCHED) { 215 #ifdef KTRACE 216 if (KTRPOINT(td, KTR_CSW)) 217 ktrcsw(1, 1); 218 #endif 219 thread_lock(td); 220 sched_prio(td, td->td_user_pri); 221 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL); 222 thread_unlock(td); 223 #ifdef KTRACE 224 if (KTRPOINT(td, KTR_CSW)) 225 ktrcsw(0, 1); 226 #endif 227 } 228 229 /* 230 * Check for signals. Unlocked reads of p_pendingcnt or 231 * p_siglist might cause process-directed signal to be handled 232 * later. 233 */ 234 if (flags & TDF_NEEDSIGCHK || p->p_pendingcnt > 0 || 235 !SIGISEMPTY(p->p_siglist)) { 236 PROC_LOCK(p); 237 mtx_lock(&p->p_sigacts->ps_mtx); 238 while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0) 239 postsig(sig); 240 mtx_unlock(&p->p_sigacts->ps_mtx); 241 PROC_UNLOCK(p); 242 } 243 /* 244 * We need to check to see if we have to exit or wait due to a 245 * single threading requirement or some other STOP condition. 246 */ 247 if (flags & TDF_NEEDSUSPCHK) { 248 PROC_LOCK(p); 249 thread_suspend_check(0); 250 PROC_UNLOCK(p); 251 } 252 253 if (td->td_pflags & TDP_OLDMASK) { 254 td->td_pflags &= ~TDP_OLDMASK; 255 kern_sigprocmask(td, SIG_SETMASK, &td->td_oldsigmask, NULL, 0); 256 } 257 258 userret(td, framep); 259 mtx_assert(&Giant, MA_NOTOWNED); 260 } 261 262 #ifdef HAVE_SYSCALL_ARGS_DEF 263 const char * 264 syscallname(struct proc *p, u_int code) 265 { 266 static const char unknown[] = "unknown"; 267 268 if (p->p_sysent->sv_syscallnames == NULL) 269 return (unknown); 270 return (p->p_sysent->sv_syscallnames[code]); 271 } 272 273 int 274 syscallenter(struct thread *td, struct syscall_args *sa) 275 { 276 struct proc *p; 277 int error, traced; 278 279 PCPU_INC(cnt.v_syscall); 280 p = td->td_proc; 281 td->td_syscalls++; 282 283 td->td_pticks = 0; 284 if (td->td_ucred != p->p_ucred) 285 cred_update_thread(td); 286 if (p->p_flag & P_TRACED) { 287 traced = 1; 288 PROC_LOCK(p); 289 td->td_dbgflags &= ~TDB_USERWR; 290 td->td_dbgflags |= TDB_SCE; 291 PROC_UNLOCK(p); 292 } else 293 traced = 0; 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 299 300 CTR6(KTR_SYSC, 301 "syscall: td=%p pid %d %s (%#lx, %#lx, %#lx)", 302 td, td->td_proc->p_pid, syscallname(p, sa->code), 303 sa->args[0], sa->args[1], sa->args[2]); 304 305 if (error == 0) { 306 STOPEVENT(p, S_SCE, sa->narg); 307 PTRACESTOP_SC(p, td, S_PT_SCE); 308 if (td->td_dbgflags & TDB_USERWR) { 309 /* 310 * Reread syscall number and arguments if 311 * debugger modified registers or memory. 312 */ 313 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 314 #ifdef KTRACE 315 if (KTRPOINT(td, KTR_SYSCALL)) 316 ktrsyscall(sa->code, sa->narg, sa->args); 317 #endif 318 if (error != 0) 319 goto retval; 320 } 321 322 #ifdef KDTRACE_HOOKS 323 /* 324 * If the systrace module has registered it's probe 325 * callback and if there is a probe active for the 326 * syscall 'entry', process the probe. 327 */ 328 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 329 (*systrace_probe_func)(sa->callp->sy_entry, sa->code, 330 sa->callp, sa->args); 331 #endif 332 333 AUDIT_SYSCALL_ENTER(sa->code, td); 334 error = (sa->callp->sy_call)(td, sa->args); 335 AUDIT_SYSCALL_EXIT(error, td); 336 337 /* Save the latest error return value. */ 338 td->td_errno = error; 339 340 #ifdef KDTRACE_HOOKS 341 /* 342 * If the systrace module has registered it's probe 343 * callback and if there is a probe active for the 344 * syscall 'return', process the probe. 345 */ 346 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 347 (*systrace_probe_func)(sa->callp->sy_return, sa->code, 348 sa->callp, sa->args); 349 #endif 350 CTR4(KTR_SYSC, "syscall: p=%p error=%d return %#lx %#lx", 351 p, error, td->td_retval[0], td->td_retval[1]); 352 } 353 retval: 354 if (traced) { 355 PROC_LOCK(p); 356 td->td_dbgflags &= ~TDB_SCE; 357 PROC_UNLOCK(p); 358 } 359 (p->p_sysent->sv_set_syscall_retval)(td, error); 360 return (error); 361 } 362 363 void 364 syscallret(struct thread *td, int error, struct syscall_args *sa __unused) 365 { 366 struct proc *p; 367 int traced; 368 369 p = td->td_proc; 370 371 /* 372 * Check for misbehavior. 373 */ 374 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 375 syscallname(p, sa->code)); 376 KASSERT(td->td_critnest == 0, 377 ("System call %s returning in a critical section", 378 syscallname(p, sa->code))); 379 KASSERT(td->td_locks == 0, 380 ("System call %s returning with %d locks held", 381 syscallname(p, sa->code), td->td_locks)); 382 383 /* 384 * Handle reschedule and other end-of-syscall issues 385 */ 386 userret(td, td->td_frame); 387 388 CTR4(KTR_SYSC, "syscall %s exit thread %p pid %d proc %s", 389 syscallname(p, sa->code), td, td->td_proc->p_pid, td->td_name); 390 391 #ifdef KTRACE 392 if (KTRPOINT(td, KTR_SYSRET)) 393 ktrsysret(sa->code, error, td->td_retval[0]); 394 #endif 395 396 if (p->p_flag & P_TRACED) { 397 traced = 1; 398 PROC_LOCK(p); 399 td->td_dbgflags |= TDB_SCX; 400 PROC_UNLOCK(p); 401 } else 402 traced = 0; 403 /* 404 * This works because errno is findable through the 405 * register set. If we ever support an emulation where this 406 * is not the case, this code will need to be revisited. 407 */ 408 STOPEVENT(p, S_SCX, sa->code); 409 PTRACESTOP_SC(p, td, S_PT_SCX); 410 if (traced || (td->td_dbgflags & TDB_EXEC) != 0) { 411 PROC_LOCK(p); 412 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC); 413 PROC_UNLOCK(p); 414 } 415 } 416 #endif /* HAVE_SYSCALL_ARGS_DEF */ 417