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 <asm/ucontext.h> 29 #include <asm/uaccess.h> 30 #include <asm/lowcore.h> 31 #include "entry.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 __get_user(new_ka.sa.sa_flags, &act->sa_flags) || 86 __get_user(mask, &act->sa_mask)) 87 return -EFAULT; 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 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || 98 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) 99 return -EFAULT; 100 } 101 102 return ret; 103 } 104 105 asmlinkage long 106 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss) 107 { 108 struct pt_regs *regs = task_pt_regs(current); 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 _sigregs user_sregs; 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 user_sregs.regs.psw.mask = PSW_MASK_MERGE(psw_user_bits, regs->psw.mask); 124 user_sregs.regs.psw.addr = regs->psw.addr; 125 memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs)); 126 memcpy(&user_sregs.regs.acrs, current->thread.acrs, 127 sizeof(sregs->regs.acrs)); 128 /* 129 * We have to store the fp registers to current->thread.fp_regs 130 * to merge them with the emulated registers. 131 */ 132 save_fp_regs(¤t->thread.fp_regs); 133 memcpy(&user_sregs.fpregs, ¤t->thread.fp_regs, 134 sizeof(s390_fp_regs)); 135 return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs)); 136 } 137 138 /* Returns positive number on error */ 139 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 140 { 141 int err; 142 _sigregs user_sregs; 143 144 /* Alwys make any pending restarted system call return -EINTR */ 145 current_thread_info()->restart_block.fn = do_no_restart_syscall; 146 147 err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs)); 148 if (err) 149 return err; 150 regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask, 151 user_sregs.regs.psw.mask); 152 regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr; 153 memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs)); 154 memcpy(¤t->thread.acrs, &user_sregs.regs.acrs, 155 sizeof(sregs->regs.acrs)); 156 restore_access_regs(current->thread.acrs); 157 158 memcpy(¤t->thread.fp_regs, &user_sregs.fpregs, 159 sizeof(s390_fp_regs)); 160 current->thread.fp_regs.fpc &= FPC_VALID_MASK; 161 162 restore_fp_regs(¤t->thread.fp_regs); 163 regs->trap = -1; /* disable syscall checks */ 164 return 0; 165 } 166 167 asmlinkage long sys_sigreturn(void) 168 { 169 struct pt_regs *regs = task_pt_regs(current); 170 sigframe __user *frame = (sigframe __user *)regs->gprs[15]; 171 sigset_t set; 172 173 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 174 goto badframe; 175 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE)) 176 goto badframe; 177 178 sigdelsetmask(&set, ~_BLOCKABLE); 179 spin_lock_irq(¤t->sighand->siglock); 180 current->blocked = set; 181 recalc_sigpending(); 182 spin_unlock_irq(¤t->sighand->siglock); 183 184 if (restore_sigregs(regs, &frame->sregs)) 185 goto badframe; 186 187 return regs->gprs[2]; 188 189 badframe: 190 force_sig(SIGSEGV, current); 191 return 0; 192 } 193 194 asmlinkage long sys_rt_sigreturn(void) 195 { 196 struct pt_regs *regs = task_pt_regs(current); 197 rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15]; 198 sigset_t set; 199 200 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 201 goto badframe; 202 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set))) 203 goto badframe; 204 205 sigdelsetmask(&set, ~_BLOCKABLE); 206 spin_lock_irq(¤t->sighand->siglock); 207 current->blocked = set; 208 recalc_sigpending(); 209 spin_unlock_irq(¤t->sighand->siglock); 210 211 if (restore_sigregs(regs, &frame->uc.uc_mcontext)) 212 goto badframe; 213 214 if (do_sigaltstack(&frame->uc.uc_stack, NULL, 215 regs->gprs[15]) == -EFAULT) 216 goto badframe; 217 return regs->gprs[2]; 218 219 badframe: 220 force_sig(SIGSEGV, current); 221 return 0; 222 } 223 224 /* 225 * Set up a signal frame. 226 */ 227 228 229 /* 230 * Determine which stack to use.. 231 */ 232 static inline void __user * 233 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 234 { 235 unsigned long sp; 236 237 /* Default to using normal stack */ 238 sp = regs->gprs[15]; 239 240 /* Overflow on alternate signal stack gives SIGSEGV. */ 241 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL)) 242 return (void __user *) -1UL; 243 244 /* This is the X/Open sanctioned signal stack switching. */ 245 if (ka->sa.sa_flags & SA_ONSTACK) { 246 if (! sas_ss_flags(sp)) 247 sp = current->sas_ss_sp + current->sas_ss_size; 248 } 249 250 /* This is the legacy signal stack switching. */ 251 else if (!user_mode(regs) && 252 !(ka->sa.sa_flags & SA_RESTORER) && 253 ka->sa.sa_restorer) { 254 sp = (unsigned long) ka->sa.sa_restorer; 255 } 256 257 return (void __user *)((sp - frame_size) & -8ul); 258 } 259 260 static inline int map_signal(int sig) 261 { 262 if (current_thread_info()->exec_domain 263 && current_thread_info()->exec_domain->signal_invmap 264 && sig < 32) 265 return current_thread_info()->exec_domain->signal_invmap[sig]; 266 else 267 return sig; 268 } 269 270 static int setup_frame(int sig, struct k_sigaction *ka, 271 sigset_t *set, struct pt_regs * regs) 272 { 273 sigframe __user *frame; 274 275 frame = get_sigframe(ka, regs, sizeof(sigframe)); 276 if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe))) 277 goto give_sigsegv; 278 279 if (frame == (void __user *) -1UL) 280 goto give_sigsegv; 281 282 if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE)) 283 goto give_sigsegv; 284 285 if (save_sigregs(regs, &frame->sregs)) 286 goto give_sigsegv; 287 if (__put_user(&frame->sregs, &frame->sc.sregs)) 288 goto give_sigsegv; 289 290 /* Set up to return from userspace. If provided, use a stub 291 already in userspace. */ 292 if (ka->sa.sa_flags & SA_RESTORER) { 293 regs->gprs[14] = (unsigned long) 294 ka->sa.sa_restorer | PSW_ADDR_AMODE; 295 } else { 296 regs->gprs[14] = (unsigned long) 297 frame->retcode | PSW_ADDR_AMODE; 298 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, 299 (u16 __user *)(frame->retcode))) 300 goto give_sigsegv; 301 } 302 303 /* Set up backchain. */ 304 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 305 goto give_sigsegv; 306 307 /* Set up registers for signal handler */ 308 regs->gprs[15] = (unsigned long) frame; 309 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 310 311 regs->gprs[2] = map_signal(sig); 312 regs->gprs[3] = (unsigned long) &frame->sc; 313 314 /* We forgot to include these in the sigcontext. 315 To avoid breaking binary compatibility, they are passed as args. */ 316 regs->gprs[4] = current->thread.trap_no; 317 regs->gprs[5] = current->thread.prot_addr; 318 319 /* Place signal number on stack to allow backtrace from handler. */ 320 if (__put_user(regs->gprs[2], (int __user *) &frame->signo)) 321 goto give_sigsegv; 322 return 0; 323 324 give_sigsegv: 325 force_sigsegv(sig, current); 326 return -EFAULT; 327 } 328 329 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 330 sigset_t *set, struct pt_regs * regs) 331 { 332 int err = 0; 333 rt_sigframe __user *frame; 334 335 frame = get_sigframe(ka, regs, sizeof(rt_sigframe)); 336 if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe))) 337 goto give_sigsegv; 338 339 if (frame == (void __user *) -1UL) 340 goto give_sigsegv; 341 342 if (copy_siginfo_to_user(&frame->info, info)) 343 goto give_sigsegv; 344 345 /* Create the ucontext. */ 346 err |= __put_user(0, &frame->uc.uc_flags); 347 err |= __put_user(NULL, &frame->uc.uc_link); 348 err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 349 err |= __put_user(sas_ss_flags(regs->gprs[15]), 350 &frame->uc.uc_stack.ss_flags); 351 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 352 err |= save_sigregs(regs, &frame->uc.uc_mcontext); 353 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 354 if (err) 355 goto give_sigsegv; 356 357 /* Set up to return from userspace. If provided, use a stub 358 already in userspace. */ 359 if (ka->sa.sa_flags & SA_RESTORER) { 360 regs->gprs[14] = (unsigned long) 361 ka->sa.sa_restorer | PSW_ADDR_AMODE; 362 } else { 363 regs->gprs[14] = (unsigned long) 364 frame->retcode | PSW_ADDR_AMODE; 365 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, 366 (u16 __user *)(frame->retcode))) 367 goto give_sigsegv; 368 } 369 370 /* Set up backchain. */ 371 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 372 goto give_sigsegv; 373 374 /* Set up registers for signal handler */ 375 regs->gprs[15] = (unsigned long) frame; 376 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 377 378 regs->gprs[2] = map_signal(sig); 379 regs->gprs[3] = (unsigned long) &frame->info; 380 regs->gprs[4] = (unsigned long) &frame->uc; 381 return 0; 382 383 give_sigsegv: 384 force_sigsegv(sig, current); 385 return -EFAULT; 386 } 387 388 /* 389 * OK, we're invoking a handler 390 */ 391 392 static int 393 handle_signal(unsigned long sig, struct k_sigaction *ka, 394 siginfo_t *info, sigset_t *oldset, struct pt_regs * regs) 395 { 396 int ret; 397 398 /* Set up the stack frame */ 399 if (ka->sa.sa_flags & SA_SIGINFO) 400 ret = setup_rt_frame(sig, ka, info, oldset, regs); 401 else 402 ret = setup_frame(sig, ka, oldset, regs); 403 404 if (ret == 0) { 405 spin_lock_irq(¤t->sighand->siglock); 406 sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); 407 if (!(ka->sa.sa_flags & SA_NODEFER)) 408 sigaddset(¤t->blocked,sig); 409 recalc_sigpending(); 410 spin_unlock_irq(¤t->sighand->siglock); 411 } 412 413 return ret; 414 } 415 416 /* 417 * Note that 'init' is a special process: it doesn't get signals it doesn't 418 * want to handle. Thus you cannot kill init even with a SIGKILL even by 419 * mistake. 420 * 421 * Note that we go through the signals twice: once to check the signals that 422 * the kernel can handle, and then we build all the user-level signal handling 423 * stack-frames in one go after that. 424 */ 425 void do_signal(struct pt_regs *regs) 426 { 427 unsigned long retval = 0, continue_addr = 0, restart_addr = 0; 428 siginfo_t info; 429 int signr; 430 struct k_sigaction ka; 431 sigset_t *oldset; 432 433 /* 434 * We want the common case to go fast, which 435 * is why we may in certain cases get here from 436 * kernel mode. Just return without doing anything 437 * if so. 438 */ 439 if (!user_mode(regs)) 440 return; 441 442 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 443 oldset = ¤t->saved_sigmask; 444 else 445 oldset = ¤t->blocked; 446 447 /* Are we from a system call? */ 448 if (regs->trap == __LC_SVC_OLD_PSW) { 449 continue_addr = regs->psw.addr; 450 restart_addr = continue_addr - regs->ilc; 451 retval = regs->gprs[2]; 452 453 /* Prepare for system call restart. We do this here so that a 454 debugger will see the already changed PSW. */ 455 switch (retval) { 456 case -ERESTARTNOHAND: 457 case -ERESTARTSYS: 458 case -ERESTARTNOINTR: 459 regs->gprs[2] = regs->orig_gpr2; 460 regs->psw.addr = restart_addr; 461 break; 462 case -ERESTART_RESTARTBLOCK: 463 regs->gprs[2] = -EINTR; 464 } 465 regs->trap = -1; /* Don't deal with this again. */ 466 } 467 468 /* Get signal to deliver. When running under ptrace, at this point 469 the debugger may change all our registers ... */ 470 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 471 472 /* Depending on the signal settings we may need to revert the 473 decision to restart the system call. */ 474 if (signr > 0 && regs->psw.addr == restart_addr) { 475 if (retval == -ERESTARTNOHAND 476 || (retval == -ERESTARTSYS 477 && !(current->sighand->action[signr-1].sa.sa_flags 478 & SA_RESTART))) { 479 regs->gprs[2] = -EINTR; 480 regs->psw.addr = continue_addr; 481 } 482 } 483 484 if (signr > 0) { 485 /* Whee! Actually deliver the signal. */ 486 int ret; 487 #ifdef CONFIG_COMPAT 488 if (test_thread_flag(TIF_31BIT)) { 489 ret = handle_signal32(signr, &ka, &info, oldset, regs); 490 } 491 else 492 #endif 493 ret = handle_signal(signr, &ka, &info, oldset, regs); 494 if (!ret) { 495 /* 496 * A signal was successfully delivered; the saved 497 * sigmask will have been stored in the signal frame, 498 * and will be restored by sigreturn, so we can simply 499 * clear the TIF_RESTORE_SIGMASK flag. 500 */ 501 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 502 clear_thread_flag(TIF_RESTORE_SIGMASK); 503 504 /* 505 * If we would have taken a single-step trap 506 * for a normal instruction, act like we took 507 * one for the handler setup. 508 */ 509 if (current->thread.per_info.single_step) 510 set_thread_flag(TIF_SINGLE_STEP); 511 512 /* 513 * Let tracing know that we've done the handler setup. 514 */ 515 tracehook_signal_handler(signr, &info, &ka, regs, 516 test_thread_flag(TIF_SINGLE_STEP)); 517 } 518 return; 519 } 520 521 /* 522 * If there's no signal to deliver, we just put the saved sigmask back. 523 */ 524 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 525 clear_thread_flag(TIF_RESTORE_SIGMASK); 526 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 527 } 528 529 /* Restart a different system call. */ 530 if (retval == -ERESTART_RESTARTBLOCK 531 && regs->psw.addr == continue_addr) { 532 regs->gprs[2] = __NR_restart_syscall; 533 set_thread_flag(TIF_RESTART_SVC); 534 } 535 } 536 537 void do_notify_resume(struct pt_regs *regs) 538 { 539 clear_thread_flag(TIF_NOTIFY_RESUME); 540 tracehook_notify_resume(regs); 541 } 542