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 <asm/ucontext.h> 28 #include <asm/uaccess.h> 29 #include <asm/lowcore.h> 30 #include "entry.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 __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 asmlinkage long 105 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss) 106 { 107 struct pt_regs *regs = task_pt_regs(current); 108 return do_sigaltstack(uss, uoss, regs->gprs[15]); 109 } 110 111 112 113 /* Returns non-zero on fault. */ 114 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 115 { 116 _sigregs user_sregs; 117 118 save_access_regs(current->thread.acrs); 119 120 /* Copy a 'clean' PSW mask to the user to avoid leaking 121 information about whether PER is currently on. */ 122 user_sregs.regs.psw.mask = PSW_MASK_MERGE(psw_user_bits, regs->psw.mask); 123 user_sregs.regs.psw.addr = regs->psw.addr; 124 memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs)); 125 memcpy(&user_sregs.regs.acrs, current->thread.acrs, 126 sizeof(sregs->regs.acrs)); 127 /* 128 * We have to store the fp registers to current->thread.fp_regs 129 * to merge them with the emulated registers. 130 */ 131 save_fp_regs(¤t->thread.fp_regs); 132 memcpy(&user_sregs.fpregs, ¤t->thread.fp_regs, 133 sizeof(s390_fp_regs)); 134 return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs)); 135 } 136 137 /* Returns positive number on error */ 138 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 139 { 140 int err; 141 _sigregs user_sregs; 142 143 /* Alwys make any pending restarted system call return -EINTR */ 144 current_thread_info()->restart_block.fn = do_no_restart_syscall; 145 146 err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs)); 147 if (err) 148 return err; 149 regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask, 150 user_sregs.regs.psw.mask); 151 regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr; 152 memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs)); 153 memcpy(¤t->thread.acrs, &user_sregs.regs.acrs, 154 sizeof(sregs->regs.acrs)); 155 restore_access_regs(current->thread.acrs); 156 157 memcpy(¤t->thread.fp_regs, &user_sregs.fpregs, 158 sizeof(s390_fp_regs)); 159 current->thread.fp_regs.fpc &= FPC_VALID_MASK; 160 161 restore_fp_regs(¤t->thread.fp_regs); 162 regs->trap = -1; /* disable syscall checks */ 163 return 0; 164 } 165 166 asmlinkage long sys_sigreturn(void) 167 { 168 struct pt_regs *regs = task_pt_regs(current); 169 sigframe __user *frame = (sigframe __user *)regs->gprs[15]; 170 sigset_t set; 171 172 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 173 goto badframe; 174 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE)) 175 goto badframe; 176 177 sigdelsetmask(&set, ~_BLOCKABLE); 178 spin_lock_irq(¤t->sighand->siglock); 179 current->blocked = set; 180 recalc_sigpending(); 181 spin_unlock_irq(¤t->sighand->siglock); 182 183 if (restore_sigregs(regs, &frame->sregs)) 184 goto badframe; 185 186 return regs->gprs[2]; 187 188 badframe: 189 force_sig(SIGSEGV, current); 190 return 0; 191 } 192 193 asmlinkage long sys_rt_sigreturn(void) 194 { 195 struct pt_regs *regs = task_pt_regs(current); 196 rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15]; 197 sigset_t set; 198 199 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 200 goto badframe; 201 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set))) 202 goto badframe; 203 204 sigdelsetmask(&set, ~_BLOCKABLE); 205 spin_lock_irq(¤t->sighand->siglock); 206 current->blocked = set; 207 recalc_sigpending(); 208 spin_unlock_irq(¤t->sighand->siglock); 209 210 if (restore_sigregs(regs, &frame->uc.uc_mcontext)) 211 goto badframe; 212 213 if (do_sigaltstack(&frame->uc.uc_stack, NULL, 214 regs->gprs[15]) == -EFAULT) 215 goto badframe; 216 return regs->gprs[2]; 217 218 badframe: 219 force_sig(SIGSEGV, current); 220 return 0; 221 } 222 223 /* 224 * Set up a signal frame. 225 */ 226 227 228 /* 229 * Determine which stack to use.. 230 */ 231 static inline void __user * 232 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 233 { 234 unsigned long sp; 235 236 /* Default to using normal stack */ 237 sp = regs->gprs[15]; 238 239 /* Overflow on alternate signal stack gives SIGSEGV. */ 240 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL)) 241 return (void __user *) -1UL; 242 243 /* This is the X/Open sanctioned signal stack switching. */ 244 if (ka->sa.sa_flags & SA_ONSTACK) { 245 if (! sas_ss_flags(sp)) 246 sp = current->sas_ss_sp + current->sas_ss_size; 247 } 248 249 /* This is the legacy signal stack switching. */ 250 else if (!user_mode(regs) && 251 !(ka->sa.sa_flags & SA_RESTORER) && 252 ka->sa.sa_restorer) { 253 sp = (unsigned long) ka->sa.sa_restorer; 254 } 255 256 return (void __user *)((sp - frame_size) & -8ul); 257 } 258 259 static inline int map_signal(int sig) 260 { 261 if (current_thread_info()->exec_domain 262 && current_thread_info()->exec_domain->signal_invmap 263 && sig < 32) 264 return current_thread_info()->exec_domain->signal_invmap[sig]; 265 else 266 return sig; 267 } 268 269 static int setup_frame(int sig, struct k_sigaction *ka, 270 sigset_t *set, struct pt_regs * regs) 271 { 272 sigframe __user *frame; 273 274 frame = get_sigframe(ka, regs, sizeof(sigframe)); 275 if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe))) 276 goto give_sigsegv; 277 278 if (frame == (void __user *) -1UL) 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 (frame == (void __user *) -1UL) 339 goto give_sigsegv; 340 341 if (copy_siginfo_to_user(&frame->info, info)) 342 goto give_sigsegv; 343 344 /* Create the ucontext. */ 345 err |= __put_user(0, &frame->uc.uc_flags); 346 err |= __put_user(NULL, &frame->uc.uc_link); 347 err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 348 err |= __put_user(sas_ss_flags(regs->gprs[15]), 349 &frame->uc.uc_stack.ss_flags); 350 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 351 err |= save_sigregs(regs, &frame->uc.uc_mcontext); 352 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 353 if (err) 354 goto give_sigsegv; 355 356 /* Set up to return from userspace. If provided, use a stub 357 already in userspace. */ 358 if (ka->sa.sa_flags & SA_RESTORER) { 359 regs->gprs[14] = (unsigned long) 360 ka->sa.sa_restorer | PSW_ADDR_AMODE; 361 } else { 362 regs->gprs[14] = (unsigned long) 363 frame->retcode | PSW_ADDR_AMODE; 364 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, 365 (u16 __user *)(frame->retcode))) 366 goto give_sigsegv; 367 } 368 369 /* Set up backchain. */ 370 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 371 goto give_sigsegv; 372 373 /* Set up registers for signal handler */ 374 regs->gprs[15] = (unsigned long) frame; 375 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 376 377 regs->gprs[2] = map_signal(sig); 378 regs->gprs[3] = (unsigned long) &frame->info; 379 regs->gprs[4] = (unsigned long) &frame->uc; 380 return 0; 381 382 give_sigsegv: 383 force_sigsegv(sig, current); 384 return -EFAULT; 385 } 386 387 /* 388 * OK, we're invoking a handler 389 */ 390 391 static int 392 handle_signal(unsigned long sig, struct k_sigaction *ka, 393 siginfo_t *info, sigset_t *oldset, struct pt_regs * regs) 394 { 395 int ret; 396 397 /* Set up the stack frame */ 398 if (ka->sa.sa_flags & SA_SIGINFO) 399 ret = setup_rt_frame(sig, ka, info, oldset, regs); 400 else 401 ret = setup_frame(sig, ka, oldset, regs); 402 403 if (ret == 0) { 404 spin_lock_irq(¤t->sighand->siglock); 405 sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); 406 if (!(ka->sa.sa_flags & SA_NODEFER)) 407 sigaddset(¤t->blocked,sig); 408 recalc_sigpending(); 409 spin_unlock_irq(¤t->sighand->siglock); 410 } 411 412 return ret; 413 } 414 415 /* 416 * Note that 'init' is a special process: it doesn't get signals it doesn't 417 * want to handle. Thus you cannot kill init even with a SIGKILL even by 418 * mistake. 419 * 420 * Note that we go through the signals twice: once to check the signals that 421 * the kernel can handle, and then we build all the user-level signal handling 422 * stack-frames in one go after that. 423 */ 424 void do_signal(struct pt_regs *regs) 425 { 426 unsigned long retval = 0, continue_addr = 0, restart_addr = 0; 427 siginfo_t info; 428 int signr; 429 struct k_sigaction ka; 430 sigset_t *oldset; 431 432 /* 433 * We want the common case to go fast, which 434 * is why we may in certain cases get here from 435 * kernel mode. Just return without doing anything 436 * if so. 437 */ 438 if (!user_mode(regs)) 439 return; 440 441 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 442 oldset = ¤t->saved_sigmask; 443 else 444 oldset = ¤t->blocked; 445 446 /* Are we from a system call? */ 447 if (regs->trap == __LC_SVC_OLD_PSW) { 448 continue_addr = regs->psw.addr; 449 restart_addr = continue_addr - regs->ilc; 450 retval = regs->gprs[2]; 451 452 /* Prepare for system call restart. We do this here so that a 453 debugger will see the already changed PSW. */ 454 switch (retval) { 455 case -ERESTARTNOHAND: 456 case -ERESTARTSYS: 457 case -ERESTARTNOINTR: 458 regs->gprs[2] = regs->orig_gpr2; 459 regs->psw.addr = restart_addr; 460 break; 461 case -ERESTART_RESTARTBLOCK: 462 regs->gprs[2] = -EINTR; 463 } 464 regs->trap = -1; /* Don't deal with this again. */ 465 } 466 467 /* Get signal to deliver. When running under ptrace, at this point 468 the debugger may change all our registers ... */ 469 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 470 471 /* Depending on the signal settings we may need to revert the 472 decision to restart the system call. */ 473 if (signr > 0 && regs->psw.addr == restart_addr) { 474 if (retval == -ERESTARTNOHAND 475 || (retval == -ERESTARTSYS 476 && !(current->sighand->action[signr-1].sa.sa_flags 477 & SA_RESTART))) { 478 regs->gprs[2] = -EINTR; 479 regs->psw.addr = continue_addr; 480 } 481 } 482 483 if (signr > 0) { 484 /* Whee! Actually deliver the signal. */ 485 int ret; 486 #ifdef CONFIG_COMPAT 487 if (test_thread_flag(TIF_31BIT)) { 488 ret = handle_signal32(signr, &ka, &info, oldset, regs); 489 } 490 else 491 #endif 492 ret = handle_signal(signr, &ka, &info, oldset, regs); 493 if (!ret) { 494 /* 495 * A signal was successfully delivered; the saved 496 * sigmask will have been stored in the signal frame, 497 * and will be restored by sigreturn, so we can simply 498 * clear the TIF_RESTORE_SIGMASK flag. 499 */ 500 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 501 clear_thread_flag(TIF_RESTORE_SIGMASK); 502 503 /* 504 * If we would have taken a single-step trap 505 * for a normal instruction, act like we took 506 * one for the handler setup. 507 */ 508 if (current->thread.per_info.single_step) 509 set_thread_flag(TIF_SINGLE_STEP); 510 } 511 return; 512 } 513 514 /* 515 * If there's no signal to deliver, we just put the saved sigmask back. 516 */ 517 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 518 clear_thread_flag(TIF_RESTORE_SIGMASK); 519 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 520 } 521 522 /* Restart a different system call. */ 523 if (retval == -ERESTART_RESTARTBLOCK 524 && regs->psw.addr == continue_addr) { 525 regs->gprs[2] = __NR_restart_syscall; 526 set_thread_flag(TIF_RESTART_SVC); 527 } 528 } 529