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 <linux/syscalls.h> 29 #include <linux/compat.h> 30 #include <asm/ucontext.h> 31 #include <asm/uaccess.h> 32 #include <asm/lowcore.h> 33 #include "entry.h" 34 35 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) 36 37 38 typedef struct 39 { 40 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 41 struct sigcontext sc; 42 _sigregs sregs; 43 int signo; 44 __u8 retcode[S390_SYSCALL_SIZE]; 45 } sigframe; 46 47 typedef struct 48 { 49 __u8 callee_used_stack[__SIGNAL_FRAMESIZE]; 50 __u8 retcode[S390_SYSCALL_SIZE]; 51 struct siginfo info; 52 struct ucontext uc; 53 } rt_sigframe; 54 55 /* 56 * Atomically swap in the new signal mask, and wait for a signal. 57 */ 58 SYSCALL_DEFINE3(sigsuspend, int, history0, int, history1, old_sigset_t, mask) 59 { 60 sigset_t blocked; 61 62 current->saved_sigmask = current->blocked; 63 mask &= _BLOCKABLE; 64 siginitset(&blocked, mask); 65 set_current_blocked(&blocked); 66 set_current_state(TASK_INTERRUPTIBLE); 67 schedule(); 68 set_restore_sigmask(); 69 return -ERESTARTNOHAND; 70 } 71 72 SYSCALL_DEFINE3(sigaction, int, sig, const struct old_sigaction __user *, act, 73 struct old_sigaction __user *, oact) 74 { 75 struct k_sigaction new_ka, old_ka; 76 int ret; 77 78 if (act) { 79 old_sigset_t mask; 80 if (!access_ok(VERIFY_READ, act, sizeof(*act)) || 81 __get_user(new_ka.sa.sa_handler, &act->sa_handler) || 82 __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) || 83 __get_user(new_ka.sa.sa_flags, &act->sa_flags) || 84 __get_user(mask, &act->sa_mask)) 85 return -EFAULT; 86 siginitset(&new_ka.sa.sa_mask, mask); 87 } 88 89 ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); 90 91 if (!ret && oact) { 92 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || 93 __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || 94 __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) || 95 __put_user(old_ka.sa.sa_flags, &oact->sa_flags) || 96 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask)) 97 return -EFAULT; 98 } 99 100 return ret; 101 } 102 103 SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss, 104 stack_t __user *, uoss) 105 { 106 struct pt_regs *regs = task_pt_regs(current); 107 return do_sigaltstack(uss, uoss, regs->gprs[15]); 108 } 109 110 /* Returns non-zero on fault. */ 111 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 112 { 113 _sigregs user_sregs; 114 115 save_access_regs(current->thread.acrs); 116 117 /* Copy a 'clean' PSW mask to the user to avoid leaking 118 information about whether PER is currently on. */ 119 user_sregs.regs.psw.mask = psw_user_bits | 120 (regs->psw.mask & PSW_MASK_USER); 121 user_sregs.regs.psw.addr = regs->psw.addr; 122 memcpy(&user_sregs.regs.gprs, ®s->gprs, sizeof(sregs->regs.gprs)); 123 memcpy(&user_sregs.regs.acrs, current->thread.acrs, 124 sizeof(sregs->regs.acrs)); 125 /* 126 * We have to store the fp registers to current->thread.fp_regs 127 * to merge them with the emulated registers. 128 */ 129 save_fp_regs(¤t->thread.fp_regs); 130 memcpy(&user_sregs.fpregs, ¤t->thread.fp_regs, 131 sizeof(s390_fp_regs)); 132 return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs)); 133 } 134 135 /* Returns positive number on error */ 136 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 137 { 138 int err; 139 _sigregs user_sregs; 140 141 /* Alwys make any pending restarted system call return -EINTR */ 142 current_thread_info()->restart_block.fn = do_no_restart_syscall; 143 144 err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs)); 145 if (err) 146 return err; 147 /* Use regs->psw.mask instead of psw_user_bits to preserve PER bit. */ 148 regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) | 149 (user_sregs.regs.psw.mask & PSW_MASK_USER); 150 /* Check for invalid amode */ 151 if (regs->psw.mask & PSW_MASK_EA) 152 regs->psw.mask |= PSW_MASK_BA; 153 regs->psw.addr = user_sregs.regs.psw.addr; 154 memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs)); 155 memcpy(¤t->thread.acrs, &user_sregs.regs.acrs, 156 sizeof(sregs->regs.acrs)); 157 restore_access_regs(current->thread.acrs); 158 159 memcpy(¤t->thread.fp_regs, &user_sregs.fpregs, 160 sizeof(s390_fp_regs)); 161 current->thread.fp_regs.fpc &= FPC_VALID_MASK; 162 163 restore_fp_regs(¤t->thread.fp_regs); 164 clear_thread_flag(TIF_SYSCALL); /* No longer in a system call */ 165 return 0; 166 } 167 168 SYSCALL_DEFINE0(sigreturn) 169 { 170 struct pt_regs *regs = task_pt_regs(current); 171 sigframe __user *frame = (sigframe __user *)regs->gprs[15]; 172 sigset_t set; 173 174 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 175 goto badframe; 176 if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE)) 177 goto badframe; 178 sigdelsetmask(&set, ~_BLOCKABLE); 179 set_current_blocked(&set); 180 if (restore_sigregs(regs, &frame->sregs)) 181 goto badframe; 182 return regs->gprs[2]; 183 badframe: 184 force_sig(SIGSEGV, current); 185 return 0; 186 } 187 188 SYSCALL_DEFINE0(rt_sigreturn) 189 { 190 struct pt_regs *regs = task_pt_regs(current); 191 rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15]; 192 sigset_t set; 193 194 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 195 goto badframe; 196 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set))) 197 goto badframe; 198 sigdelsetmask(&set, ~_BLOCKABLE); 199 set_current_blocked(&set); 200 if (restore_sigregs(regs, &frame->uc.uc_mcontext)) 201 goto badframe; 202 if (do_sigaltstack(&frame->uc.uc_stack, NULL, 203 regs->gprs[15]) == -EFAULT) 204 goto badframe; 205 return regs->gprs[2]; 206 badframe: 207 force_sig(SIGSEGV, current); 208 return 0; 209 } 210 211 /* 212 * Set up a signal frame. 213 */ 214 215 216 /* 217 * Determine which stack to use.. 218 */ 219 static inline void __user * 220 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 221 { 222 unsigned long sp; 223 224 /* Default to using normal stack */ 225 sp = regs->gprs[15]; 226 227 /* Overflow on alternate signal stack gives SIGSEGV. */ 228 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL)) 229 return (void __user *) -1UL; 230 231 /* This is the X/Open sanctioned signal stack switching. */ 232 if (ka->sa.sa_flags & SA_ONSTACK) { 233 if (! sas_ss_flags(sp)) 234 sp = current->sas_ss_sp + current->sas_ss_size; 235 } 236 237 /* This is the legacy signal stack switching. */ 238 else if (!user_mode(regs) && 239 !(ka->sa.sa_flags & SA_RESTORER) && 240 ka->sa.sa_restorer) { 241 sp = (unsigned long) ka->sa.sa_restorer; 242 } 243 244 return (void __user *)((sp - frame_size) & -8ul); 245 } 246 247 static inline int map_signal(int sig) 248 { 249 if (current_thread_info()->exec_domain 250 && current_thread_info()->exec_domain->signal_invmap 251 && sig < 32) 252 return current_thread_info()->exec_domain->signal_invmap[sig]; 253 else 254 return sig; 255 } 256 257 static int setup_frame(int sig, struct k_sigaction *ka, 258 sigset_t *set, struct pt_regs * regs) 259 { 260 sigframe __user *frame; 261 262 frame = get_sigframe(ka, regs, sizeof(sigframe)); 263 if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe))) 264 goto give_sigsegv; 265 266 if (frame == (void __user *) -1UL) 267 goto give_sigsegv; 268 269 if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE)) 270 goto give_sigsegv; 271 272 if (save_sigregs(regs, &frame->sregs)) 273 goto give_sigsegv; 274 if (__put_user(&frame->sregs, &frame->sc.sregs)) 275 goto give_sigsegv; 276 277 /* Set up to return from userspace. If provided, use a stub 278 already in userspace. */ 279 if (ka->sa.sa_flags & SA_RESTORER) { 280 regs->gprs[14] = (unsigned long) 281 ka->sa.sa_restorer | PSW_ADDR_AMODE; 282 } else { 283 regs->gprs[14] = (unsigned long) 284 frame->retcode | PSW_ADDR_AMODE; 285 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, 286 (u16 __user *)(frame->retcode))) 287 goto give_sigsegv; 288 } 289 290 /* Set up backchain. */ 291 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 292 goto give_sigsegv; 293 294 /* Set up registers for signal handler */ 295 regs->gprs[15] = (unsigned long) frame; 296 regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA; /* 64 bit amode */ 297 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 298 299 regs->gprs[2] = map_signal(sig); 300 regs->gprs[3] = (unsigned long) &frame->sc; 301 302 /* We forgot to include these in the sigcontext. 303 To avoid breaking binary compatibility, they are passed as args. */ 304 if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL || 305 sig == SIGTRAP || sig == SIGFPE) { 306 /* set extra registers only for synchronous signals */ 307 regs->gprs[4] = regs->int_code & 127; 308 regs->gprs[5] = regs->int_parm_long; 309 regs->gprs[6] = task_thread_info(current)->last_break; 310 } 311 312 /* Place signal number on stack to allow backtrace from handler. */ 313 if (__put_user(regs->gprs[2], (int __user *) &frame->signo)) 314 goto give_sigsegv; 315 return 0; 316 317 give_sigsegv: 318 force_sigsegv(sig, current); 319 return -EFAULT; 320 } 321 322 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 323 sigset_t *set, struct pt_regs * regs) 324 { 325 int err = 0; 326 rt_sigframe __user *frame; 327 328 frame = get_sigframe(ka, regs, sizeof(rt_sigframe)); 329 if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe))) 330 goto give_sigsegv; 331 332 if (frame == (void __user *) -1UL) 333 goto give_sigsegv; 334 335 if (copy_siginfo_to_user(&frame->info, info)) 336 goto give_sigsegv; 337 338 /* Create the ucontext. */ 339 err |= __put_user(0, &frame->uc.uc_flags); 340 err |= __put_user(NULL, &frame->uc.uc_link); 341 err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp); 342 err |= __put_user(sas_ss_flags(regs->gprs[15]), 343 &frame->uc.uc_stack.ss_flags); 344 err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); 345 err |= save_sigregs(regs, &frame->uc.uc_mcontext); 346 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 347 if (err) 348 goto give_sigsegv; 349 350 /* Set up to return from userspace. If provided, use a stub 351 already in userspace. */ 352 if (ka->sa.sa_flags & SA_RESTORER) { 353 regs->gprs[14] = (unsigned long) 354 ka->sa.sa_restorer | PSW_ADDR_AMODE; 355 } else { 356 regs->gprs[14] = (unsigned long) 357 frame->retcode | PSW_ADDR_AMODE; 358 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, 359 (u16 __user *)(frame->retcode))) 360 goto give_sigsegv; 361 } 362 363 /* Set up backchain. */ 364 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 365 goto give_sigsegv; 366 367 /* Set up registers for signal handler */ 368 regs->gprs[15] = (unsigned long) frame; 369 regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA; /* 64 bit amode */ 370 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 371 372 regs->gprs[2] = map_signal(sig); 373 regs->gprs[3] = (unsigned long) &frame->info; 374 regs->gprs[4] = (unsigned long) &frame->uc; 375 regs->gprs[5] = task_thread_info(current)->last_break; 376 return 0; 377 378 give_sigsegv: 379 force_sigsegv(sig, current); 380 return -EFAULT; 381 } 382 383 static int handle_signal(unsigned long sig, struct k_sigaction *ka, 384 siginfo_t *info, sigset_t *oldset, 385 struct pt_regs *regs) 386 { 387 int ret; 388 389 /* Set up the stack frame */ 390 if (ka->sa.sa_flags & SA_SIGINFO) 391 ret = setup_rt_frame(sig, ka, info, oldset, regs); 392 else 393 ret = setup_frame(sig, ka, oldset, regs); 394 if (ret) 395 return ret; 396 block_sigmask(ka, sig); 397 return 0; 398 } 399 400 /* 401 * Note that 'init' is a special process: it doesn't get signals it doesn't 402 * want to handle. Thus you cannot kill init even with a SIGKILL even by 403 * mistake. 404 * 405 * Note that we go through the signals twice: once to check the signals that 406 * the kernel can handle, and then we build all the user-level signal handling 407 * stack-frames in one go after that. 408 */ 409 void do_signal(struct pt_regs *regs) 410 { 411 siginfo_t info; 412 int signr; 413 struct k_sigaction ka; 414 sigset_t *oldset; 415 416 /* 417 * We want the common case to go fast, which 418 * is why we may in certain cases get here from 419 * kernel mode. Just return without doing anything 420 * if so. 421 */ 422 if (!user_mode(regs)) 423 return; 424 425 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 426 oldset = ¤t->saved_sigmask; 427 else 428 oldset = ¤t->blocked; 429 430 /* 431 * Get signal to deliver. When running under ptrace, at this point 432 * the debugger may change all our registers, including the system 433 * call information. 434 */ 435 current_thread_info()->system_call = 436 test_thread_flag(TIF_SYSCALL) ? regs->int_code : 0; 437 signr = get_signal_to_deliver(&info, &ka, regs, NULL); 438 439 if (signr > 0) { 440 /* Whee! Actually deliver the signal. */ 441 if (current_thread_info()->system_call) { 442 regs->int_code = current_thread_info()->system_call; 443 /* Check for system call restarting. */ 444 switch (regs->gprs[2]) { 445 case -ERESTART_RESTARTBLOCK: 446 case -ERESTARTNOHAND: 447 regs->gprs[2] = -EINTR; 448 break; 449 case -ERESTARTSYS: 450 if (!(ka.sa.sa_flags & SA_RESTART)) { 451 regs->gprs[2] = -EINTR; 452 break; 453 } 454 /* fallthrough */ 455 case -ERESTARTNOINTR: 456 regs->gprs[2] = regs->orig_gpr2; 457 regs->psw.addr = 458 __rewind_psw(regs->psw, 459 regs->int_code >> 16); 460 break; 461 } 462 } 463 /* No longer in a system call */ 464 clear_thread_flag(TIF_SYSCALL); 465 466 if ((is_compat_task() ? 467 handle_signal32(signr, &ka, &info, oldset, regs) : 468 handle_signal(signr, &ka, &info, oldset, regs)) == 0) { 469 /* 470 * A signal was successfully delivered; the saved 471 * sigmask will have been stored in the signal frame, 472 * and will be restored by sigreturn, so we can simply 473 * clear the TIF_RESTORE_SIGMASK flag. 474 */ 475 if (test_thread_flag(TIF_RESTORE_SIGMASK)) 476 clear_thread_flag(TIF_RESTORE_SIGMASK); 477 478 /* 479 * Let tracing know that we've done the handler setup. 480 */ 481 tracehook_signal_handler(signr, &info, &ka, regs, 482 test_thread_flag(TIF_SINGLE_STEP)); 483 } 484 return; 485 } 486 487 /* No handlers present - check for system call restart */ 488 clear_thread_flag(TIF_SYSCALL); 489 if (current_thread_info()->system_call) { 490 regs->int_code = current_thread_info()->system_call; 491 switch (regs->gprs[2]) { 492 case -ERESTART_RESTARTBLOCK: 493 /* Restart with sys_restart_syscall */ 494 regs->int_code = __NR_restart_syscall; 495 /* fallthrough */ 496 case -ERESTARTNOHAND: 497 case -ERESTARTSYS: 498 case -ERESTARTNOINTR: 499 /* Restart system call with magic TIF bit. */ 500 regs->gprs[2] = regs->orig_gpr2; 501 set_thread_flag(TIF_SYSCALL); 502 break; 503 } 504 } 505 506 /* 507 * If there's no signal to deliver, we just put the saved sigmask back. 508 */ 509 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 510 clear_thread_flag(TIF_RESTORE_SIGMASK); 511 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 512 } 513 } 514 515 void do_notify_resume(struct pt_regs *regs) 516 { 517 clear_thread_flag(TIF_NOTIFY_RESUME); 518 tracehook_notify_resume(regs); 519 if (current->replacement_session_keyring) 520 key_replace_session_keyring(); 521 } 522