1 /* 2 * arch/s390/kernel/signal.c 3 * 4 * Copyright (C) IBM Corp. 1999,2006 5 * Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com) 6 * 7 * Based on Intel version 8 * 9 * Copyright (C) 1991, 1992 Linus Torvalds 10 * 11 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson 12 */ 13 14 #include <linux/sched.h> 15 #include <linux/mm.h> 16 #include <linux/smp.h> 17 #include <linux/kernel.h> 18 #include <linux/signal.h> 19 #include <linux/errno.h> 20 #include <linux/wait.h> 21 #include <linux/ptrace.h> 22 #include <linux/unistd.h> 23 #include <linux/stddef.h> 24 #include <linux/tty.h> 25 #include <linux/personality.h> 26 #include <linux/binfmts.h> 27 #include <linux/tracehook.h> 28 #include <linux/syscalls.h> 29 #include <asm/ucontext.h> 30 #include <asm/uaccess.h> 31 #include <asm/lowcore.h> 32 #include "entry.h" 33 34 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 35 36 37 typedef struct 38 { 39 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 40 struct sigcontext sc; 41 _sigregs sregs; 42 int signo; 43 __u8 retcode[S390_SYSCALL_SIZE]; 44 } sigframe; 45 46 typedef struct 47 { 48 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 49 __u8 retcode[S390_SYSCALL_SIZE]; 50 struct siginfo info; 51 struct ucontext uc; 52 } rt_sigframe; 53 54 /* 55 * Atomically swap in the new signal mask, and wait for a signal. 56 */ 57 SYSCALL_DEFINE3(sigsuspend, int, history0, int, history1, old_sigset_t, mask) 58 { 59 mask &= _BLOCKABLE; 60 spin_lock_irq(¤t->sighand->siglock); 61 current->saved_sigmask = current->blocked; 62 siginitset(¤t->blocked, mask); 63 recalc_sigpending(); 64 spin_unlock_irq(¤t->sighand->siglock); 65 66 current->state = TASK_INTERRUPTIBLE; 67 schedule(); 68 set_thread_flag(TIF_RESTORE_SIGMASK); 69 70 return -ERESTARTNOHAND; 71 } 72 73 SYSCALL_DEFINE3(sigaction, int, sig, const struct old_sigaction __user *, act, 74 struct old_sigaction __user *, oact) 75 { 76 struct k_sigaction new_ka, old_ka; 77 int ret; 78 79 if (act) { 80 old_sigset_t mask; 81 if (!access_ok(VERIFY_READ, act, sizeof(*act)) || 82 __get_user(new_ka.sa.sa_handler, &act->sa_handler) || 83 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) || 84 __get_user(new_ka.sa.sa_flags, &act->sa_flags) || 85 __get_user(mask, &act->sa_mask)) 86 return -EFAULT; 87 siginitset(&new_ka.sa.sa_mask, mask); 88 } 89 90 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 91 92 if (!ret && oact) { 93 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || 94 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || 95 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) || 96 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || 97 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) 98 return -EFAULT; 99 } 100 101 return ret; 102 } 103 104 SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss, 105 stack_t __user *, uoss) 106 { 107 struct pt_regs *regs = task_pt_regs(current); 108 return do_sigaltstack(uss, uoss, regs->gprs[15]); 109 } 110 111 /* Returns non-zero on fault. */ 112 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 113 { 114 _sigregs user_sregs; 115 116 save_access_regs(current->thread.acrs); 117 118 /* Copy a 'clean' PSW mask to the user to avoid leaking 119 information about whether PER is currently on. */ 120 user_sregs.regs.psw.mask = PSW_MASK_MERGE(psw_user_bits, regs->psw.mask); 121 user_sregs.regs.psw.addr = regs->psw.addr; 122 memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs)); 123 memcpy(&user_sregs.regs.acrs, current->thread.acrs, 124 sizeof(sregs->regs.acrs)); 125 /* 126 * We have to store the fp registers to current->thread.fp_regs 127 * to merge them with the emulated registers. 128 */ 129 save_fp_regs(¤t->thread.fp_regs); 130 memcpy(&user_sregs.fpregs, ¤t->thread.fp_regs, 131 sizeof(s390_fp_regs)); 132 return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs)); 133 } 134 135 /* Returns positive number on error */ 136 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 137 { 138 int err; 139 _sigregs user_sregs; 140 141 /* Alwys make any pending restarted system call return -EINTR */ 142 current_thread_info()->restart_block.fn = do_no_restart_syscall; 143 144 err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs)); 145 if (err) 146 return err; 147 regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask, 148 user_sregs.regs.psw.mask); 149 regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr; 150 memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs)); 151 memcpy(¤t->thread.acrs, &user_sregs.regs.acrs, 152 sizeof(sregs->regs.acrs)); 153 restore_access_regs(current->thread.acrs); 154 155 memcpy(¤t->thread.fp_regs, &user_sregs.fpregs, 156 sizeof(s390_fp_regs)); 157 current->thread.fp_regs.fpc &= FPC_VALID_MASK; 158 159 restore_fp_regs(¤t->thread.fp_regs); 160 regs->svcnr = 0; /* disable syscall checks */ 161 return 0; 162 } 163 164 SYSCALL_DEFINE0(sigreturn) 165 { 166 struct pt_regs *regs = task_pt_regs(current); 167 sigframe __user *frame = (sigframe __user *)regs->gprs[15]; 168 sigset_t set; 169 170 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 171 goto badframe; 172 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE)) 173 goto badframe; 174 175 sigdelsetmask(&set, ~_BLOCKABLE); 176 spin_lock_irq(¤t->sighand->siglock); 177 current->blocked = set; 178 recalc_sigpending(); 179 spin_unlock_irq(¤t->sighand->siglock); 180 181 if (restore_sigregs(regs, &frame->sregs)) 182 goto badframe; 183 184 return regs->gprs[2]; 185 186 badframe: 187 force_sig(SIGSEGV, current); 188 return 0; 189 } 190 191 SYSCALL_DEFINE0(rt_sigreturn) 192 { 193 struct pt_regs *regs = task_pt_regs(current); 194 rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15]; 195 sigset_t set; 196 197 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 198 goto badframe; 199 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set))) 200 goto badframe; 201 202 sigdelsetmask(&set, ~_BLOCKABLE); 203 spin_lock_irq(¤t->sighand->siglock); 204 current->blocked = set; 205 recalc_sigpending(); 206 spin_unlock_irq(¤t->sighand->siglock); 207 208 if (restore_sigregs(regs, &frame->uc.uc_mcontext)) 209 goto badframe; 210 211 if (do_sigaltstack(&frame->uc.uc_stack, NULL, 212 regs->gprs[15]) == -EFAULT) 213 goto badframe; 214 return regs->gprs[2]; 215 216 badframe: 217 force_sig(SIGSEGV, current); 218 return 0; 219 } 220 221 /* 222 * Set up a signal frame. 223 */ 224 225 226 /* 227 * Determine which stack to use.. 228 */ 229 static inline void __user * 230 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 231 { 232 unsigned long sp; 233 234 /* Default to using normal stack */ 235 sp = regs->gprs[15]; 236 237 /* Overflow on alternate signal stack gives SIGSEGV. */ 238 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL)) 239 return (void __user *) -1UL; 240 241 /* This is the X/Open sanctioned signal stack switching. */ 242 if (ka->sa.sa_flags & SA_ONSTACK) { 243 if (! sas_ss_flags(sp)) 244 sp = current->sas_ss_sp + current->sas_ss_size; 245 } 246 247 /* This is the legacy signal stack switching. */ 248 else if (!user_mode(regs) && 249 !(ka->sa.sa_flags & SA_RESTORER) && 250 ka->sa.sa_restorer) { 251 sp = (unsigned long) ka->sa.sa_restorer; 252 } 253 254 return (void __user *)((sp - frame_size) & -8ul); 255 } 256 257 static inline int map_signal(int sig) 258 { 259 if (current_thread_info()->exec_domain 260 && current_thread_info()->exec_domain->signal_invmap 261 && sig < 32) 262 return current_thread_info()->exec_domain->signal_invmap[sig]; 263 else 264 return sig; 265 } 266 267 static int setup_frame(int sig, struct k_sigaction *ka, 268 sigset_t *set, struct pt_regs * regs) 269 { 270 sigframe __user *frame; 271 272 frame = get_sigframe(ka, regs, sizeof(sigframe)); 273 if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe))) 274 goto give_sigsegv; 275 276 if (frame == (void __user *) -1UL) 277 goto give_sigsegv; 278 279 if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE)) 280 goto give_sigsegv; 281 282 if (save_sigregs(regs, &frame->sregs)) 283 goto give_sigsegv; 284 if (__put_user(&frame->sregs, &frame->sc.sregs)) 285 goto give_sigsegv; 286 287 /* Set up to return from userspace. If provided, use a stub 288 already in userspace. */ 289 if (ka->sa.sa_flags & SA_RESTORER) { 290 regs->gprs[14] = (unsigned long) 291 ka->sa.sa_restorer | PSW_ADDR_AMODE; 292 } else { 293 regs->gprs[14] = (unsigned long) 294 frame->retcode | PSW_ADDR_AMODE; 295 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, 296 (u16 __user *)(frame->retcode))) 297 goto give_sigsegv; 298 } 299 300 /* Set up backchain. */ 301 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 302 goto give_sigsegv; 303 304 /* Set up registers for signal handler */ 305 regs->gprs[15] = (unsigned long) frame; 306 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 307 308 regs->gprs[2] = map_signal(sig); 309 regs->gprs[3] = (unsigned long) &frame->sc; 310 311 /* We forgot to include these in the sigcontext. 312 To avoid breaking binary compatibility, they are passed as args. */ 313 regs->gprs[4] = current->thread.trap_no; 314 regs->gprs[5] = current->thread.prot_addr; 315 316 /* Place signal number on stack to allow backtrace from handler. */ 317 if (__put_user(regs->gprs[2], (int __user *) &frame->signo)) 318 goto give_sigsegv; 319 return 0; 320 321 give_sigsegv: 322 force_sigsegv(sig, current); 323 return -EFAULT; 324 } 325 326 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 327 sigset_t *set, struct pt_regs * regs) 328 { 329 int err = 0; 330 rt_sigframe __user *frame; 331 332 frame = get_sigframe(ka, regs, sizeof(rt_sigframe)); 333 if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe))) 334 goto give_sigsegv; 335 336 if (frame == (void __user *) -1UL) 337 goto give_sigsegv; 338 339 if (copy_siginfo_to_user(&frame->info, info)) 340 goto give_sigsegv; 341 342 /* Create the ucontext. */ 343 err |= __put_user(0, &frame->uc.uc_flags); 344 err |= __put_user(NULL, &frame->uc.uc_link); 345 err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 346 err |= __put_user(sas_ss_flags(regs->gprs[15]), 347 &frame->uc.uc_stack.ss_flags); 348 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 349 err |= save_sigregs(regs, &frame->uc.uc_mcontext); 350 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 351 if (err) 352 goto give_sigsegv; 353 354 /* Set up to return from userspace. If provided, use a stub 355 already in userspace. */ 356 if (ka->sa.sa_flags & SA_RESTORER) { 357 regs->gprs[14] = (unsigned long) 358 ka->sa.sa_restorer | PSW_ADDR_AMODE; 359 } else { 360 regs->gprs[14] = (unsigned long) 361 frame->retcode | PSW_ADDR_AMODE; 362 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, 363 (u16 __user *)(frame->retcode))) 364 goto give_sigsegv; 365 } 366 367 /* Set up backchain. */ 368 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 369 goto give_sigsegv; 370 371 /* Set up registers for signal handler */ 372 regs->gprs[15] = (unsigned long) frame; 373 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 374 375 regs->gprs[2] = map_signal(sig); 376 regs->gprs[3] = (unsigned long) &frame->info; 377 regs->gprs[4] = (unsigned long) &frame->uc; 378 return 0; 379 380 give_sigsegv: 381 force_sigsegv(sig, current); 382 return -EFAULT; 383 } 384 385 /* 386 * OK, we're invoking a handler 387 */ 388 389 static int 390 handle_signal(unsigned long sig, struct k_sigaction *ka, 391 siginfo_t *info, sigset_t *oldset, struct pt_regs * regs) 392 { 393 int ret; 394 395 /* Set up the stack frame */ 396 if (ka->sa.sa_flags & SA_SIGINFO) 397 ret = setup_rt_frame(sig, ka, info, oldset, regs); 398 else 399 ret = setup_frame(sig, ka, oldset, regs); 400 401 if (ret == 0) { 402 spin_lock_irq(¤t->sighand->siglock); 403 sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); 404 if (!(ka->sa.sa_flags & SA_NODEFER)) 405 sigaddset(¤t->blocked,sig); 406 recalc_sigpending(); 407 spin_unlock_irq(¤t->sighand->siglock); 408 } 409 410 return ret; 411 } 412 413 /* 414 * Note that 'init' is a special process: it doesn't get signals it doesn't 415 * want to handle. Thus you cannot kill init even with a SIGKILL even by 416 * mistake. 417 * 418 * Note that we go through the signals twice: once to check the signals that 419 * the kernel can handle, and then we build all the user-level signal handling 420 * stack-frames in one go after that. 421 */ 422 void do_signal(struct pt_regs *regs) 423 { 424 unsigned long retval = 0, continue_addr = 0, restart_addr = 0; 425 siginfo_t info; 426 int signr; 427 struct k_sigaction ka; 428 sigset_t *oldset; 429 430 /* 431 * We want the common case to go fast, which 432 * is why we may in certain cases get here from 433 * kernel mode. Just return without doing anything 434 * if so. 435 */ 436 if (!user_mode(regs)) 437 return; 438 439 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 440 oldset = ¤t->saved_sigmask; 441 else 442 oldset = ¤t->blocked; 443 444 /* Are we from a system call? */ 445 if (regs->svcnr) { 446 continue_addr = regs->psw.addr; 447 restart_addr = continue_addr - regs->ilc; 448 retval = regs->gprs[2]; 449 450 /* Prepare for system call restart. We do this here so that a 451 debugger will see the already changed PSW. */ 452 switch (retval) { 453 case -ERESTARTNOHAND: 454 case -ERESTARTSYS: 455 case -ERESTARTNOINTR: 456 regs->gprs[2] = regs->orig_gpr2; 457 regs->psw.addr = restart_addr; 458 break; 459 case -ERESTART_RESTARTBLOCK: 460 regs->gprs[2] = -EINTR; 461 } 462 regs->svcnr = 0; /* Don't deal with this again. */ 463 } 464 465 /* Get signal to deliver. When running under ptrace, at this point 466 the debugger may change all our registers ... */ 467 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 468 469 /* Depending on the signal settings we may need to revert the 470 decision to restart the system call. */ 471 if (signr > 0 && regs->psw.addr == restart_addr) { 472 if (retval == -ERESTARTNOHAND 473 || (retval == -ERESTARTSYS 474 && !(current->sighand->action[signr-1].sa.sa_flags 475 & SA_RESTART))) { 476 regs->gprs[2] = -EINTR; 477 regs->psw.addr = continue_addr; 478 } 479 } 480 481 if (signr > 0) { 482 /* Whee! Actually deliver the signal. */ 483 int ret; 484 #ifdef CONFIG_COMPAT 485 if (test_thread_flag(TIF_31BIT)) { 486 ret = handle_signal32(signr, &ka, &info, oldset, regs); 487 } 488 else 489 #endif 490 ret = handle_signal(signr, &ka, &info, oldset, regs); 491 if (!ret) { 492 /* 493 * A signal was successfully delivered; the saved 494 * sigmask will have been stored in the signal frame, 495 * and will be restored by sigreturn, so we can simply 496 * clear the TIF_RESTORE_SIGMASK flag. 497 */ 498 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 499 clear_thread_flag(TIF_RESTORE_SIGMASK); 500 501 /* 502 * If we would have taken a single-step trap 503 * for a normal instruction, act like we took 504 * one for the handler setup. 505 */ 506 if (current->thread.per_info.single_step) 507 set_thread_flag(TIF_SINGLE_STEP); 508 509 /* 510 * Let tracing know that we've done the handler setup. 511 */ 512 tracehook_signal_handler(signr, &info, &ka, regs, 513 test_thread_flag(TIF_SINGLE_STEP)); 514 } 515 return; 516 } 517 518 /* 519 * If there's no signal to deliver, we just put the saved sigmask back. 520 */ 521 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 522 clear_thread_flag(TIF_RESTORE_SIGMASK); 523 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 524 } 525 526 /* Restart a different system call. */ 527 if (retval == -ERESTART_RESTARTBLOCK 528 && regs->psw.addr == continue_addr) { 529 regs->gprs[2] = __NR_restart_syscall; 530 set_thread_flag(TIF_RESTART_SVC); 531 } 532 } 533 534 void do_notify_resume(struct pt_regs *regs) 535 { 536 clear_thread_flag(TIF_NOTIFY_RESUME); 537 tracehook_notify_resume(regs); 538 } 539