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