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/smp_lock.h> 18 #include <linux/kernel.h> 19 #include <linux/signal.h> 20 #include <linux/errno.h> 21 #include <linux/wait.h> 22 #include <linux/ptrace.h> 23 #include <linux/unistd.h> 24 #include <linux/stddef.h> 25 #include <linux/tty.h> 26 #include <linux/personality.h> 27 #include <linux/binfmts.h> 28 #include <asm/ucontext.h> 29 #include <asm/uaccess.h> 30 #include <asm/lowcore.h> 31 32 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 33 34 35 typedef struct 36 { 37 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 38 struct sigcontext sc; 39 _sigregs sregs; 40 int signo; 41 __u8 retcode[S390_SYSCALL_SIZE]; 42 } sigframe; 43 44 typedef struct 45 { 46 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 47 __u8 retcode[S390_SYSCALL_SIZE]; 48 struct siginfo info; 49 struct ucontext uc; 50 } rt_sigframe; 51 52 /* 53 * Atomically swap in the new signal mask, and wait for a signal. 54 */ 55 asmlinkage int 56 sys_sigsuspend(int history0, int history1, old_sigset_t mask) 57 { 58 mask &= _BLOCKABLE; 59 spin_lock_irq(¤t->sighand->siglock); 60 current->saved_sigmask = current->blocked; 61 siginitset(¤t->blocked, mask); 62 recalc_sigpending(); 63 spin_unlock_irq(¤t->sighand->siglock); 64 65 current->state = TASK_INTERRUPTIBLE; 66 schedule(); 67 set_thread_flag(TIF_RESTORE_SIGMASK); 68 69 return -ERESTARTNOHAND; 70 } 71 72 asmlinkage long 73 sys_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 return -EFAULT; 85 __get_user(new_ka.sa.sa_flags, &act->sa_flags); 86 __get_user(mask, &act->sa_mask); 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 return -EFAULT; 97 __put_user(old_ka.sa.sa_flags, &oact->sa_flags); 98 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask); 99 } 100 101 return ret; 102 } 103 104 asmlinkage long 105 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, 106 struct pt_regs *regs) 107 { 108 return do_sigaltstack(uss, uoss, regs->gprs[15]); 109 } 110 111 112 113 /* Returns non-zero on fault. */ 114 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 115 { 116 unsigned long old_mask = regs->psw.mask; 117 int err; 118 119 save_access_regs(current->thread.acrs); 120 121 /* Copy a 'clean' PSW mask to the user to avoid leaking 122 information about whether PER is currently on. */ 123 regs->psw.mask = PSW_MASK_MERGE(PSW_USER_BITS, regs->psw.mask); 124 err = __copy_to_user(&sregs->regs.psw, ®s->psw, 125 sizeof(sregs->regs.psw)+sizeof(sregs->regs.gprs)); 126 regs->psw.mask = old_mask; 127 if (err != 0) 128 return err; 129 err = __copy_to_user(&sregs->regs.acrs, current->thread.acrs, 130 sizeof(sregs->regs.acrs)); 131 if (err != 0) 132 return err; 133 /* 134 * We have to store the fp registers to current->thread.fp_regs 135 * to merge them with the emulated registers. 136 */ 137 save_fp_regs(¤t->thread.fp_regs); 138 return __copy_to_user(&sregs->fpregs, ¤t->thread.fp_regs, 139 sizeof(s390_fp_regs)); 140 } 141 142 /* Returns positive number on error */ 143 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 144 { 145 unsigned long old_mask = regs->psw.mask; 146 int err; 147 148 /* Alwys make any pending restarted system call return -EINTR */ 149 current_thread_info()->restart_block.fn = do_no_restart_syscall; 150 151 err = __copy_from_user(®s->psw, &sregs->regs.psw, 152 sizeof(sregs->regs.psw)+sizeof(sregs->regs.gprs)); 153 regs->psw.mask = PSW_MASK_MERGE(old_mask, regs->psw.mask); 154 regs->psw.addr |= PSW_ADDR_AMODE; 155 if (err) 156 return err; 157 err = __copy_from_user(¤t->thread.acrs, &sregs->regs.acrs, 158 sizeof(sregs->regs.acrs)); 159 if (err) 160 return err; 161 restore_access_regs(current->thread.acrs); 162 163 err = __copy_from_user(¤t->thread.fp_regs, &sregs->fpregs, 164 sizeof(s390_fp_regs)); 165 current->thread.fp_regs.fpc &= FPC_VALID_MASK; 166 if (err) 167 return err; 168 169 restore_fp_regs(¤t->thread.fp_regs); 170 regs->trap = -1; /* disable syscall checks */ 171 return 0; 172 } 173 174 asmlinkage long sys_sigreturn(struct pt_regs *regs) 175 { 176 sigframe __user *frame = (sigframe __user *)regs->gprs[15]; 177 sigset_t set; 178 179 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 180 goto badframe; 181 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE)) 182 goto badframe; 183 184 sigdelsetmask(&set, ~_BLOCKABLE); 185 spin_lock_irq(¤t->sighand->siglock); 186 current->blocked = set; 187 recalc_sigpending(); 188 spin_unlock_irq(¤t->sighand->siglock); 189 190 if (restore_sigregs(regs, &frame->sregs)) 191 goto badframe; 192 193 return regs->gprs[2]; 194 195 badframe: 196 force_sig(SIGSEGV, current); 197 return 0; 198 } 199 200 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) 201 { 202 rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15]; 203 sigset_t set; 204 205 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 206 goto badframe; 207 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set))) 208 goto badframe; 209 210 sigdelsetmask(&set, ~_BLOCKABLE); 211 spin_lock_irq(¤t->sighand->siglock); 212 current->blocked = set; 213 recalc_sigpending(); 214 spin_unlock_irq(¤t->sighand->siglock); 215 216 if (restore_sigregs(regs, &frame->uc.uc_mcontext)) 217 goto badframe; 218 219 if (do_sigaltstack(&frame->uc.uc_stack, NULL, 220 regs->gprs[15]) == -EFAULT) 221 goto badframe; 222 return regs->gprs[2]; 223 224 badframe: 225 force_sig(SIGSEGV, current); 226 return 0; 227 } 228 229 /* 230 * Set up a signal frame. 231 */ 232 233 234 /* 235 * Determine which stack to use.. 236 */ 237 static inline void __user * 238 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 239 { 240 unsigned long sp; 241 242 /* Default to using normal stack */ 243 sp = regs->gprs[15]; 244 245 /* This is the X/Open sanctioned signal stack switching. */ 246 if (ka->sa.sa_flags & SA_ONSTACK) { 247 if (! sas_ss_flags(sp)) 248 sp = current->sas_ss_sp + current->sas_ss_size; 249 } 250 251 /* This is the legacy signal stack switching. */ 252 else if (!user_mode(regs) && 253 !(ka->sa.sa_flags & SA_RESTORER) && 254 ka->sa.sa_restorer) { 255 sp = (unsigned long) ka->sa.sa_restorer; 256 } 257 258 return (void __user *)((sp - frame_size) & -8ul); 259 } 260 261 static inline int map_signal(int sig) 262 { 263 if (current_thread_info()->exec_domain 264 && current_thread_info()->exec_domain->signal_invmap 265 && sig < 32) 266 return current_thread_info()->exec_domain->signal_invmap[sig]; 267 else 268 return sig; 269 } 270 271 static int setup_frame(int sig, struct k_sigaction *ka, 272 sigset_t *set, struct pt_regs * regs) 273 { 274 sigframe __user *frame; 275 276 frame = get_sigframe(ka, regs, sizeof(sigframe)); 277 if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe))) 278 goto give_sigsegv; 279 280 if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE)) 281 goto give_sigsegv; 282 283 if (save_sigregs(regs, &frame->sregs)) 284 goto give_sigsegv; 285 if (__put_user(&frame->sregs, &frame->sc.sregs)) 286 goto give_sigsegv; 287 288 /* Set up to return from userspace. If provided, use a stub 289 already in userspace. */ 290 if (ka->sa.sa_flags & SA_RESTORER) { 291 regs->gprs[14] = (unsigned long) 292 ka->sa.sa_restorer | PSW_ADDR_AMODE; 293 } else { 294 regs->gprs[14] = (unsigned long) 295 frame->retcode | PSW_ADDR_AMODE; 296 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, 297 (u16 __user *)(frame->retcode))) 298 goto give_sigsegv; 299 } 300 301 /* Set up backchain. */ 302 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 303 goto give_sigsegv; 304 305 /* Set up registers for signal handler */ 306 regs->gprs[15] = (unsigned long) frame; 307 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 308 309 regs->gprs[2] = map_signal(sig); 310 regs->gprs[3] = (unsigned long) &frame->sc; 311 312 /* We forgot to include these in the sigcontext. 313 To avoid breaking binary compatibility, they are passed as args. */ 314 regs->gprs[4] = current->thread.trap_no; 315 regs->gprs[5] = current->thread.prot_addr; 316 317 /* Place signal number on stack to allow backtrace from handler. */ 318 if (__put_user(regs->gprs[2], (int __user *) &frame->signo)) 319 goto give_sigsegv; 320 return 0; 321 322 give_sigsegv: 323 force_sigsegv(sig, current); 324 return -EFAULT; 325 } 326 327 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 328 sigset_t *set, struct pt_regs * regs) 329 { 330 int err = 0; 331 rt_sigframe __user *frame; 332 333 frame = get_sigframe(ka, regs, sizeof(rt_sigframe)); 334 if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe))) 335 goto give_sigsegv; 336 337 if (copy_siginfo_to_user(&frame->info, info)) 338 goto give_sigsegv; 339 340 /* Create the ucontext. */ 341 err |= __put_user(0, &frame->uc.uc_flags); 342 err |= __put_user(NULL, &frame->uc.uc_link); 343 err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 344 err |= __put_user(sas_ss_flags(regs->gprs[15]), 345 &frame->uc.uc_stack.ss_flags); 346 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 347 err |= save_sigregs(regs, &frame->uc.uc_mcontext); 348 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 349 if (err) 350 goto give_sigsegv; 351 352 /* Set up to return from userspace. If provided, use a stub 353 already in userspace. */ 354 if (ka->sa.sa_flags & SA_RESTORER) { 355 regs->gprs[14] = (unsigned long) 356 ka->sa.sa_restorer | PSW_ADDR_AMODE; 357 } else { 358 regs->gprs[14] = (unsigned long) 359 frame->retcode | PSW_ADDR_AMODE; 360 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, 361 (u16 __user *)(frame->retcode))) 362 goto give_sigsegv; 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