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 __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 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 _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(struct pt_regs *regs) 167 { 168 sigframe __user *frame = (sigframe __user *)regs->gprs[15]; 169 sigset_t set; 170 171 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 172 goto badframe; 173 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE)) 174 goto badframe; 175 176 sigdelsetmask(&set, ~_BLOCKABLE); 177 spin_lock_irq(¤t->sighand->siglock); 178 current->blocked = set; 179 recalc_sigpending(); 180 spin_unlock_irq(¤t->sighand->siglock); 181 182 if (restore_sigregs(regs, &frame->sregs)) 183 goto badframe; 184 185 return regs->gprs[2]; 186 187 badframe: 188 force_sig(SIGSEGV, current); 189 return 0; 190 } 191 192 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) 193 { 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 /* This is the X/Open sanctioned signal stack switching. */ 238 if (ka->sa.sa_flags & SA_ONSTACK) { 239 if (! sas_ss_flags(sp)) 240 sp = current->sas_ss_sp + current->sas_ss_size; 241 } 242 243 /* This is the legacy signal stack switching. */ 244 else if (!user_mode(regs) && 245 !(ka->sa.sa_flags & SA_RESTORER) && 246 ka->sa.sa_restorer) { 247 sp = (unsigned long) ka->sa.sa_restorer; 248 } 249 250 return (void __user *)((sp - frame_size) & -8ul); 251 } 252 253 static inline int map_signal(int sig) 254 { 255 if (current_thread_info()->exec_domain 256 && current_thread_info()->exec_domain->signal_invmap 257 && sig < 32) 258 return current_thread_info()->exec_domain->signal_invmap[sig]; 259 else 260 return sig; 261 } 262 263 static int setup_frame(int sig, struct k_sigaction *ka, 264 sigset_t *set, struct pt_regs * regs) 265 { 266 sigframe __user *frame; 267 268 frame = get_sigframe(ka, regs, sizeof(sigframe)); 269 if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe))) 270 goto give_sigsegv; 271 272 if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE)) 273 goto give_sigsegv; 274 275 if (save_sigregs(regs, &frame->sregs)) 276 goto give_sigsegv; 277 if (__put_user(&frame->sregs, &frame->sc.sregs)) 278 goto give_sigsegv; 279 280 /* Set up to return from userspace. If provided, use a stub 281 already in userspace. */ 282 if (ka->sa.sa_flags & SA_RESTORER) { 283 regs->gprs[14] = (unsigned long) 284 ka->sa.sa_restorer | PSW_ADDR_AMODE; 285 } else { 286 regs->gprs[14] = (unsigned long) 287 frame->retcode | PSW_ADDR_AMODE; 288 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, 289 (u16 __user *)(frame->retcode))) 290 goto give_sigsegv; 291 } 292 293 /* Set up backchain. */ 294 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 295 goto give_sigsegv; 296 297 /* Set up registers for signal handler */ 298 regs->gprs[15] = (unsigned long) frame; 299 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 300 301 regs->gprs[2] = map_signal(sig); 302 regs->gprs[3] = (unsigned long) &frame->sc; 303 304 /* We forgot to include these in the sigcontext. 305 To avoid breaking binary compatibility, they are passed as args. */ 306 regs->gprs[4] = current->thread.trap_no; 307 regs->gprs[5] = current->thread.prot_addr; 308 309 /* Place signal number on stack to allow backtrace from handler. */ 310 if (__put_user(regs->gprs[2], (int __user *) &frame->signo)) 311 goto give_sigsegv; 312 return 0; 313 314 give_sigsegv: 315 force_sigsegv(sig, current); 316 return -EFAULT; 317 } 318 319 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 320 sigset_t *set, struct pt_regs * regs) 321 { 322 int err = 0; 323 rt_sigframe __user *frame; 324 325 frame = get_sigframe(ka, regs, sizeof(rt_sigframe)); 326 if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe))) 327 goto give_sigsegv; 328 329 if (copy_siginfo_to_user(&frame->info, info)) 330 goto give_sigsegv; 331 332 /* Create the ucontext. */ 333 err |= __put_user(0, &frame->uc.uc_flags); 334 err |= __put_user(NULL, &frame->uc.uc_link); 335 err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 336 err |= __put_user(sas_ss_flags(regs->gprs[15]), 337 &frame->uc.uc_stack.ss_flags); 338 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 339 err |= save_sigregs(regs, &frame->uc.uc_mcontext); 340 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 341 if (err) 342 goto give_sigsegv; 343 344 /* Set up to return from userspace. If provided, use a stub 345 already in userspace. */ 346 if (ka->sa.sa_flags & SA_RESTORER) { 347 regs->gprs[14] = (unsigned long) 348 ka->sa.sa_restorer | PSW_ADDR_AMODE; 349 } else { 350 regs->gprs[14] = (unsigned long) 351 frame->retcode | PSW_ADDR_AMODE; 352 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, 353 (u16 __user *)(frame->retcode))) 354 goto give_sigsegv; 355 } 356 357 /* Set up backchain. */ 358 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 359 goto give_sigsegv; 360 361 /* Set up registers for signal handler */ 362 regs->gprs[15] = (unsigned long) frame; 363 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 364 365 regs->gprs[2] = map_signal(sig); 366 regs->gprs[3] = (unsigned long) &frame->info; 367 regs->gprs[4] = (unsigned long) &frame->uc; 368 return 0; 369 370 give_sigsegv: 371 force_sigsegv(sig, current); 372 return -EFAULT; 373 } 374 375 /* 376 * OK, we're invoking a handler 377 */ 378 379 static int 380 handle_signal(unsigned long sig, struct k_sigaction *ka, 381 siginfo_t *info, sigset_t *oldset, struct pt_regs * regs) 382 { 383 int ret; 384 385 /* Set up the stack frame */ 386 if (ka->sa.sa_flags & SA_SIGINFO) 387 ret = setup_rt_frame(sig, ka, info, oldset, regs); 388 else 389 ret = setup_frame(sig, ka, oldset, regs); 390 391 if (ret == 0) { 392 spin_lock_irq(¤t->sighand->siglock); 393 sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); 394 if (!(ka->sa.sa_flags & SA_NODEFER)) 395 sigaddset(¤t->blocked,sig); 396 recalc_sigpending(); 397 spin_unlock_irq(¤t->sighand->siglock); 398 } 399 400 return ret; 401 } 402 403 /* 404 * Note that 'init' is a special process: it doesn't get signals it doesn't 405 * want to handle. Thus you cannot kill init even with a SIGKILL even by 406 * mistake. 407 * 408 * Note that we go through the signals twice: once to check the signals that 409 * the kernel can handle, and then we build all the user-level signal handling 410 * stack-frames in one go after that. 411 */ 412 void do_signal(struct pt_regs *regs) 413 { 414 unsigned long retval = 0, continue_addr = 0, restart_addr = 0; 415 siginfo_t info; 416 int signr; 417 struct k_sigaction ka; 418 sigset_t *oldset; 419 420 /* 421 * We want the common case to go fast, which 422 * is why we may in certain cases get here from 423 * kernel mode. Just return without doing anything 424 * if so. 425 */ 426 if (!user_mode(regs)) 427 return; 428 429 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 430 oldset = ¤t->saved_sigmask; 431 else 432 oldset = ¤t->blocked; 433 434 /* Are we from a system call? */ 435 if (regs->trap == __LC_SVC_OLD_PSW) { 436 continue_addr = regs->psw.addr; 437 restart_addr = continue_addr - regs->ilc; 438 retval = regs->gprs[2]; 439 440 /* Prepare for system call restart. We do this here so that a 441 debugger will see the already changed PSW. */ 442 switch (retval) { 443 case -ERESTARTNOHAND: 444 case -ERESTARTSYS: 445 case -ERESTARTNOINTR: 446 regs->gprs[2] = regs->orig_gpr2; 447 regs->psw.addr = restart_addr; 448 break; 449 case -ERESTART_RESTARTBLOCK: 450 regs->gprs[2] = -EINTR; 451 } 452 regs->trap = -1; /* Don't deal with this again. */ 453 } 454 455 /* Get signal to deliver. When running under ptrace, at this point 456 the debugger may change all our registers ... */ 457 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 458 459 /* Depending on the signal settings we may need to revert the 460 decision to restart the system call. */ 461 if (signr > 0 && regs->psw.addr == restart_addr) { 462 if (retval == -ERESTARTNOHAND 463 || (retval == -ERESTARTSYS 464 && !(current->sighand->action[signr-1].sa.sa_flags 465 & SA_RESTART))) { 466 regs->gprs[2] = -EINTR; 467 regs->psw.addr = continue_addr; 468 } 469 } 470 471 if (signr > 0) { 472 /* Whee! Actually deliver the signal. */ 473 #ifdef CONFIG_COMPAT 474 if (test_thread_flag(TIF_31BIT)) { 475 extern int handle_signal32(unsigned long sig, 476 struct k_sigaction *ka, 477 siginfo_t *info, 478 sigset_t *oldset, 479 struct pt_regs *regs); 480 if (handle_signal32( 481 signr, &ka, &info, oldset, regs) == 0) { 482 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 483 clear_thread_flag(TIF_RESTORE_SIGMASK); 484 } 485 return; 486 } 487 #endif 488 if (handle_signal(signr, &ka, &info, oldset, regs) == 0) { 489 /* 490 * A signal was successfully delivered; the saved 491 * sigmask will have been stored in the signal frame, 492 * and will be restored by sigreturn, so we can simply 493 * clear the TIF_RESTORE_SIGMASK flag. 494 */ 495 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 496 clear_thread_flag(TIF_RESTORE_SIGMASK); 497 } 498 return; 499 } 500 501 /* 502 * If there's no signal to deliver, we just put the saved sigmask back. 503 */ 504 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 505 clear_thread_flag(TIF_RESTORE_SIGMASK); 506 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 507 } 508 509 /* Restart a different system call. */ 510 if (retval == -ERESTART_RESTARTBLOCK 511 && regs->psw.addr == continue_addr) { 512 regs->gprs[2] = __NR_restart_syscall; 513 set_thread_flag(TIF_RESTART_SVC); 514 } 515 } 516