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