subr_syscall.c revision 209461
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: head/sys/kern/subr_trap.c 209461 2010-06-23 11:12:58Z 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 */ 88void 89userret(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 /* 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 */ 139void 140ast(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 243const char * 244syscallname(struct proc *p, u_int code) 245{ 246 static const char unknown[] = "unknown"; 247 248 if (p->p_sysent->sv_syscallnames == NULL) 249 return (unknown); 250 return (p->p_sysent->sv_syscallnames[code]); 251} 252 253int 254syscallenter(struct thread *td, struct syscall_args *sa) 255{ 256 struct proc *p; 257 int error, traced; 258 259 PCPU_INC(cnt.v_syscall); 260 p = td->td_proc; 261 td->td_syscalls++; 262 263 td->td_pticks = 0; 264 if (td->td_ucred != p->p_ucred) 265 cred_update_thread(td); 266 if (p->p_flag & P_TRACED) { 267 traced = 1; 268 PROC_LOCK(p); 269 td->td_dbgflags &= ~TDB_USERWR; 270 td->td_dbgflags |= TDB_SCE; 271 PROC_UNLOCK(p); 272 } else 273 traced = 0; 274 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 275#ifdef KTRACE 276 if (KTRPOINT(td, KTR_SYSCALL)) 277 ktrsyscall(sa->code, sa->narg, sa->args); 278#endif 279 280 CTR6(KTR_SYSC, 281"syscall: td=%p pid %d %s (%#lx, %#lx, %#lx)", 282 td, td->td_proc->p_pid, syscallname(p, sa->code), 283 sa->args[0], sa->args[1], sa->args[2]); 284 285 if (error == 0) { 286 STOPEVENT(p, S_SCE, sa->narg); 287 PTRACESTOP_SC(p, td, S_PT_SCE); 288 if (td->td_dbgflags & TDB_USERWR) { 289 /* 290 * Reread syscall number and arguments if 291 * debugger modified registers or memory. 292 */ 293 error = (p->p_sysent->sv_fetch_syscall_args)(td, sa); 294#ifdef KTRACE 295 if (KTRPOINT(td, KTR_SYSCALL)) 296 ktrsyscall(sa->code, sa->narg, sa->args); 297#endif 298 if (error != 0) 299 goto retval; 300 } 301 302#ifdef KDTRACE_HOOKS 303 /* 304 * If the systrace module has registered it's probe 305 * callback and if there is a probe active for the 306 * syscall 'entry', process the probe. 307 */ 308 if (systrace_probe_func != NULL && sa->callp->sy_entry != 0) 309 (*systrace_probe_func)(sa->callp->sy_entry, sa->code, 310 sa->callp, sa->args); 311#endif 312 313 AUDIT_SYSCALL_ENTER(sa->code, td); 314 error = (sa->callp->sy_call)(td, sa->args); 315 AUDIT_SYSCALL_EXIT(error, td); 316 317 /* Save the latest error return value. */ 318 td->td_errno = error; 319 320#ifdef KDTRACE_HOOKS 321 /* 322 * If the systrace module has registered it's probe 323 * callback and if there is a probe active for the 324 * syscall 'return', process the probe. 325 */ 326 if (systrace_probe_func != NULL && sa->callp->sy_return != 0) 327 (*systrace_probe_func)(sa->callp->sy_return, sa->code, 328 sa->callp, sa->args); 329#endif 330 CTR4(KTR_SYSC, "syscall: p=%p error=%d return %#lx %#lx", 331 p, error, td->td_retval[0], td->td_retval[1]); 332 } 333 retval: 334 if (traced) { 335 PROC_LOCK(p); 336 td->td_dbgflags &= ~TDB_SCE; 337 PROC_UNLOCK(p); 338 } 339 (p->p_sysent->sv_set_syscall_retval)(td, error); 340 return (error); 341} 342 343void 344syscallret(struct thread *td, int error, struct syscall_args *sa __unused) 345{ 346 struct proc *p; 347 int traced; 348 349 p = td->td_proc; 350 351 /* 352 * Check for misbehavior. 353 */ 354 WITNESS_WARN(WARN_PANIC, NULL, "System call %s returning", 355 syscallname(p, sa->code)); 356 KASSERT(td->td_critnest == 0, 357 ("System call %s returning in a critical section", 358 syscallname(p, sa->code))); 359 KASSERT(td->td_locks == 0, 360 ("System call %s returning with %d locks held", 361 syscallname(p, sa->code), td->td_locks)); 362 363 /* 364 * Handle reschedule and other end-of-syscall issues 365 */ 366 userret(td, td->td_frame); 367 368 CTR4(KTR_SYSC, "syscall %s exit thread %p pid %d proc %s", 369 syscallname(p, sa->code), td, td->td_proc->p_pid, td->td_name); 370 371#ifdef KTRACE 372 if (KTRPOINT(td, KTR_SYSRET)) 373 ktrsysret(sa->code, error, td->td_retval[0]); 374#endif 375 376 if (p->p_flag & P_TRACED) { 377 traced = 1; 378 PROC_LOCK(p); 379 td->td_dbgflags |= TDB_SCX; 380 PROC_UNLOCK(p); 381 } else 382 traced = 0; 383 /* 384 * This works because errno is findable through the 385 * register set. If we ever support an emulation where this 386 * is not the case, this code will need to be revisited. 387 */ 388 STOPEVENT(p, S_SCX, sa->code); 389 PTRACESTOP_SC(p, td, S_PT_SCX); 390 if (traced || (td->td_dbgflags & TDB_EXEC) != 0) { 391 PROC_LOCK(p); 392 td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC); 393 PROC_UNLOCK(p); 394 } 395} 396#endif /* HAVE_SYSCALL_ARGS_DEF */ 397