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 38typedef 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 47typedef 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 */ 58SYSCALL_DEFINE3(sigsuspend, int, history0, int, history1, old_sigset_t, mask) 59{ 60 mask &= _BLOCKABLE; 61 spin_lock_irq(¤t->sighand->siglock); 62 current->saved_sigmask = current->blocked; 63 siginitset(¤t->blocked, mask); 64 recalc_sigpending(); 65 spin_unlock_irq(¤t->sighand->siglock); 66 67 set_current_state(TASK_INTERRUPTIBLE); 68 schedule(); 69 set_thread_flag(TIF_RESTORE_SIGMASK); 70 71 return -ERESTARTNOHAND; 72} 73 74SYSCALL_DEFINE3(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 105SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss, 106 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/* Returns non-zero on fault. */ 113static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs) 114{ 115 _sigregs user_sregs; 116 117 save_access_regs(current->thread.acrs); 118 119 /* Copy a 'clean' PSW mask to the user to avoid leaking 120 information about whether PER is currently on. */ 121 user_sregs.regs.psw.mask = PSW_MASK_MERGE(psw_user_bits, regs->psw.mask); 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 */ 137static 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 regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask, 149 user_sregs.regs.psw.mask); 150 regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr; 151 memcpy(®s->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs)); 152 memcpy(¤t->thread.acrs, &user_sregs.regs.acrs, 153 sizeof(sregs->regs.acrs)); 154 restore_access_regs(current->thread.acrs); 155 156 memcpy(¤t->thread.fp_regs, &user_sregs.fpregs, 157 sizeof(s390_fp_regs)); 158 current->thread.fp_regs.fpc &= FPC_VALID_MASK; 159 160 restore_fp_regs(¤t->thread.fp_regs); 161 regs->svcnr = 0; /* disable syscall checks */ 162 return 0; 163} 164 165SYSCALL_DEFINE0(sigreturn) 166{ 167 struct pt_regs *regs = task_pt_regs(current); 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 187badframe: 188 force_sig(SIGSEGV, current); 189 return 0; 190} 191 192SYSCALL_DEFINE0(rt_sigreturn) 193{ 194 struct pt_regs *regs = task_pt_regs(current); 195 rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15]; 196 sigset_t set; 197 198 if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) 199 goto badframe; 200 if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set))) 201 goto badframe; 202 203 sigdelsetmask(&set, ~_BLOCKABLE); 204 spin_lock_irq(¤t->sighand->siglock); 205 current->blocked = set; 206 recalc_sigpending(); 207 spin_unlock_irq(¤t->sighand->siglock); 208 209 if (restore_sigregs(regs, &frame->uc.uc_mcontext)) 210 goto badframe; 211 212 if (do_sigaltstack(&frame->uc.uc_stack, NULL, 213 regs->gprs[15]) == -EFAULT) 214 goto badframe; 215 return regs->gprs[2]; 216 217badframe: 218 force_sig(SIGSEGV, current); 219 return 0; 220} 221 222/* 223 * Set up a signal frame. 224 */ 225 226 227/* 228 * Determine which stack to use.. 229 */ 230static inline void __user * 231get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) 232{ 233 unsigned long sp; 234 235 /* Default to using normal stack */ 236 sp = regs->gprs[15]; 237 238 /* Overflow on alternate signal stack gives SIGSEGV. */ 239 if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL)) 240 return (void __user *) -1UL; 241 242 /* This is the X/Open sanctioned signal stack switching. */ 243 if (ka->sa.sa_flags & SA_ONSTACK) { 244 if (! sas_ss_flags(sp)) 245 sp = current->sas_ss_sp + current->sas_ss_size; 246 } 247 248 /* This is the legacy signal stack switching. */ 249 else if (!user_mode(regs) && 250 !(ka->sa.sa_flags & SA_RESTORER) && 251 ka->sa.sa_restorer) { 252 sp = (unsigned long) ka->sa.sa_restorer; 253 } 254 255 return (void __user *)((sp - frame_size) & -8ul); 256} 257 258static inline int map_signal(int sig) 259{ 260 if (current_thread_info()->exec_domain 261 && current_thread_info()->exec_domain->signal_invmap 262 && sig < 32) 263 return current_thread_info()->exec_domain->signal_invmap[sig]; 264 else 265 return sig; 266} 267 268static int setup_frame(int sig, struct k_sigaction *ka, 269 sigset_t *set, struct pt_regs * regs) 270{ 271 sigframe __user *frame; 272 273 frame = get_sigframe(ka, regs, sizeof(sigframe)); 274 if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe))) 275 goto give_sigsegv; 276 277 if (frame == (void __user *) -1UL) 278 goto give_sigsegv; 279 280 if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE)) 281 goto give_sigsegv; 282 283 if (save_sigregs(regs, &frame->sregs)) 284 goto give_sigsegv; 285 if (__put_user(&frame->sregs, &frame->sc.sregs)) 286 goto give_sigsegv; 287 288 /* Set up to return from userspace. If provided, use a stub 289 already in userspace. */ 290 if (ka->sa.sa_flags & SA_RESTORER) { 291 regs->gprs[14] = (unsigned long) 292 ka->sa.sa_restorer | PSW_ADDR_AMODE; 293 } else { 294 regs->gprs[14] = (unsigned long) 295 frame->retcode | PSW_ADDR_AMODE; 296 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, 297 (u16 __user *)(frame->retcode))) 298 goto give_sigsegv; 299 } 300 301 /* Set up backchain. */ 302 if (__put_user(regs->gprs[15], (addr_t __user *) frame)) 303 goto give_sigsegv; 304 305 /* Set up registers for signal handler */ 306 regs->gprs[15] = (unsigned long) frame; 307 regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE; 308 309 regs->gprs[2] = map_signal(sig); 310 regs->gprs[3] = (unsigned long) &frame->sc; 311 312 /* We forgot to include these in the sigcontext. 313 To avoid breaking binary compatibility, they are passed as args. */ 314 regs->gprs[4] = current->thread.trap_no; 315 regs->gprs[5] = current->thread.prot_addr; 316 regs->gprs[6] = task_thread_info(current)->last_break; 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 323give_sigsegv: 324 force_sigsegv(sig, current); 325 return -EFAULT; 326} 327 328static 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 regs->gprs[5] = task_thread_info(current)->last_break; 381 return 0; 382 383give_sigsegv: 384 force_sigsegv(sig, current); 385 return -EFAULT; 386} 387 388/* 389 * OK, we're invoking a handler 390 */ 391 392static int 393handle_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 */ 425void 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->svcnr) { 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->svcnr = 0; /* 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 (is_compat_task()) { 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 * Let tracing know that we've done the handler setup. 506 */ 507 tracehook_signal_handler(signr, &info, &ka, regs, 508 current->thread.per_info.single_step); 509 } 510 return; 511 } 512 513 /* 514 * If there's no signal to deliver, we just put the saved sigmask back. 515 */ 516 if (test_thread_flag(TIF_RESTORE_SIGMASK)) { 517 clear_thread_flag(TIF_RESTORE_SIGMASK); 518 sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); 519 } 520 521 /* Restart a different system call. */ 522 if (retval == -ERESTART_RESTARTBLOCK 523 && regs->psw.addr == continue_addr) { 524 regs->gprs[2] = __NR_restart_syscall; 525 set_thread_flag(TIF_RESTART_SVC); 526 } 527} 528 529void do_notify_resume(struct pt_regs *regs) 530{ 531 clear_thread_flag(TIF_NOTIFY_RESUME); 532 tracehook_notify_resume(regs); 533 if (current->replacement_session_keyring) 534 key_replace_session_keyring(); 535} 536