arch/s390/kernel/signal.c

   1 /*
   2  *    Copyright IBM Corp. 1999, 2006
   3  *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
   4  *
   5  *    Based on Intel version
   6  *
   7  *  Copyright (C) 1991, 1992  Linus Torvalds
   8  *
   9  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  10  */
  11
  12 #include <linux/sched.h>
  13 #include <linux/mm.h>
  14 #include <linux/smp.h>
  15 #include <linux/kernel.h>
  16 #include <linux/signal.h>
  17 #include <linux/errno.h>
  18 #include <linux/wait.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/unistd.h>
  21 #include <linux/stddef.h>
  22 #include <linux/tty.h>
  23 #include <linux/personality.h>
  24 #include <linux/binfmts.h>
  25 #include <linux/tracehook.h>
  26 #include <linux/syscalls.h>
  27 #include <linux/compat.h>
  28 #include <asm/ucontext.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/lowcore.h>
  31 #include <asm/switch_to.h>
  32 #include "entry.h"
  33
  34 typedef struct
  35 {
  36         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  37         struct sigcontext sc;
  38         _sigregs sregs;
  39         int signo;
  40         __u8 retcode[S390_SYSCALL_SIZE];
  41 } sigframe;
  42
  43 typedef struct
  44 {
  45         __u8 callee_used_stack[__SIGNAL_FRAMESIZE];
  46         __u8 retcode[S390_SYSCALL_SIZE];
  47         struct siginfo info;
  48         struct ucontext uc;
  49 } rt_sigframe;
  50
  51 /*
  52  * Atomically swap in the new signal mask, and wait for a signal.
  53  */
  54 SYSCALL_DEFINE3(sigsuspend, int, history0, int, history1, old_sigset_t, mask)
  55 {
  56         sigset_t blocked;
  57         siginitset(&blocked, mask);
  58         return sigsuspend(&blocked);
  59 }
  60
  61 SYSCALL_DEFINE3(sigaction, int, sig, const struct old_sigaction __user *, act,
  62                 struct old_sigaction __user *, oact)
  63 {
  64         struct k_sigaction new_ka, old_ka;
  65         int ret;
  66
  67         if (act) {
  68                 old_sigset_t mask;
  69                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  70                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  71                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
  72                     __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
  73                     __get_user(mask, &act->sa_mask))
  74                         return -EFAULT;
  75                 siginitset(&new_ka.sa.sa_mask, mask);
  76         }
  77
  78         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  79
  80         if (!ret && oact) {
  81                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  82                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  83                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
  84                     __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
  85                     __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
  86                         return -EFAULT;
  87         }
  88
  89         return ret;
  90 }
  91
  92 SYSCALL_DEFINE2(sigaltstack, const stack_t __user *, uss,
  93                 stack_t __user *, uoss)
  94 {
  95         struct pt_regs *regs = task_pt_regs(current);
  96         return do_sigaltstack(uss, uoss, regs->gprs[15]);
  97 }
  98
  99 /* Returns non-zero on fault. */
 100 static int save_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 101 {
 102         _sigregs user_sregs;
 103
 104         save_access_regs(current->thread.acrs);
 105
 106         /* Copy a 'clean' PSW mask to the user to avoid leaking
 107            information about whether PER is currently on.  */
 108         user_sregs.regs.psw.mask = psw_user_bits |
 109                 (regs->psw.mask & PSW_MASK_USER);
 110         user_sregs.regs.psw.addr = regs->psw.addr;
 111         memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
 112         memcpy(&user_sregs.regs.acrs, current->thread.acrs,
 113                sizeof(sregs->regs.acrs));
 114         /*
 115          * We have to store the fp registers to current->thread.fp_regs
 116          * to merge them with the emulated registers.
 117          */
 118         save_fp_regs(&current->thread.fp_regs);
 119         memcpy(&user_sregs.fpregs, &current->thread.fp_regs,
 120                sizeof(s390_fp_regs));
 121         return __copy_to_user(sregs, &user_sregs, sizeof(_sigregs));
 122 }
 123
 124 /* Returns positive number on error */
 125 static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
 126 {
 127         int err;
 128         _sigregs user_sregs;
 129
 130         /* Alwys make any pending restarted system call return -EINTR */
 131         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 132
 133         err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
 134         if (err)
 135                 return err;
 136         /* Use regs->psw.mask instead of psw_user_bits to preserve PER bit. */
 137         regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
 138                 (user_sregs.regs.psw.mask & PSW_MASK_USER);
 139         /* Check for invalid user address space control. */
 140         if ((regs->psw.mask & PSW_MASK_ASC) >= (psw_kernel_bits & PSW_MASK_ASC))
 141                 regs->psw.mask = (psw_user_bits & PSW_MASK_ASC) |
 142                         (regs->psw.mask & ~PSW_MASK_ASC);
 143         /* Check for invalid amode */
 144         if (regs->psw.mask & PSW_MASK_EA)
 145                 regs->psw.mask |= PSW_MASK_BA;
 146         regs->psw.addr = user_sregs.regs.psw.addr;
 147         memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 148         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 149                sizeof(sregs->regs.acrs));
 150         restore_access_regs(current->thread.acrs);
 151
 152         memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
 153                sizeof(s390_fp_regs));
 154         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 155
 156         restore_fp_regs(&current->thread.fp_regs);
 157         clear_thread_flag(TIF_SYSCALL); /* No longer in a system call */
 158         return 0;
 159 }
 160
 161 SYSCALL_DEFINE0(sigreturn)
 162 {
 163         struct pt_regs *regs = task_pt_regs(current);
 164         sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 165         sigset_t set;
 166
 167         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 168                 goto badframe;
 169         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 170                 goto badframe;
 171         set_current_blocked(&set);
 172         if (restore_sigregs(regs, &frame->sregs))
 173                 goto badframe;
 174         return regs->gprs[2];
 175 badframe:
 176         force_sig(SIGSEGV, current);
 177         return 0;
 178 }
 179
 180 SYSCALL_DEFINE0(rt_sigreturn)
 181 {
 182         struct pt_regs *regs = task_pt_regs(current);
 183         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 184         sigset_t set;
 185
 186         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 187                 goto badframe;
 188         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 189                 goto badframe;
 190         set_current_blocked(&set);
 191         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 192                 goto badframe;
 193         if (do_sigaltstack(&frame->uc.uc_stack, NULL,
 194                            regs->gprs[15]) == -EFAULT)
 195                 goto badframe;
 196         return regs->gprs[2];
 197 badframe:
 198         force_sig(SIGSEGV, current);
 199         return 0;
 200 }
 201
 202 /*
 203  * Set up a signal frame.
 204  */
 205
 206
 207 /*
 208  * Determine which stack to use..
 209  */
 210 static inline void __user *
 211 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 212 {
 213         unsigned long sp;
 214
 215         /* Default to using normal stack */
 216         sp = regs->gprs[15];
 217
 218         /* Overflow on alternate signal stack gives SIGSEGV. */
 219         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 220                 return (void __user *) -1UL;
 221
 222         /* This is the X/Open sanctioned signal stack switching.  */
 223         if (ka->sa.sa_flags & SA_ONSTACK) {
 224                 if (! sas_ss_flags(sp))
 225                         sp = current->sas_ss_sp + current->sas_ss_size;
 226         }
 227
 228         return (void __user *)((sp - frame_size) & -8ul);
 229 }
 230
 231 static inline int map_signal(int sig)
 232 {
 233         if (current_thread_info()->exec_domain
 234             && current_thread_info()->exec_domain->signal_invmap
 235             && sig < 32)
 236                 return current_thread_info()->exec_domain->signal_invmap[sig];
 237         else
 238                 return sig;
 239 }
 240
 241 static int setup_frame(int sig, struct k_sigaction *ka,
 242                        sigset_t *set, struct pt_regs * regs)
 243 {
 244         sigframe __user *frame;
 245
 246         frame = get_sigframe(ka, regs, sizeof(sigframe));
 247         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 248                 goto give_sigsegv;
 249
 250         if (frame == (void __user *) -1UL)
 251                 goto give_sigsegv;
 252
 253         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 254                 goto give_sigsegv;
 255
 256         if (save_sigregs(regs, &frame->sregs))
 257                 goto give_sigsegv;
 258         if (__put_user(&frame->sregs, &frame->sc.sregs))
 259                 goto give_sigsegv;
 260
 261         /* Set up to return from userspace.  If provided, use a stub
 262            already in userspace.  */
 263         if (ka->sa.sa_flags & SA_RESTORER) {
 264                 regs->gprs[14] = (unsigned long)
 265                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 266         } else {
 267                 regs->gprs[14] = (unsigned long)
 268                         frame->retcode | PSW_ADDR_AMODE;
 269                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 270                                (u16 __user *)(frame->retcode)))
 271                         goto give_sigsegv;
 272         }
 273
 274         /* Set up backchain. */
 275         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 276                 goto give_sigsegv;
 277
 278         /* Set up registers for signal handler */
 279         regs->gprs[15] = (unsigned long) frame;
 280         /* Force default amode and default user address space control. */
 281         regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
 282                 (psw_user_bits & PSW_MASK_ASC) |
 283                 (regs->psw.mask & ~PSW_MASK_ASC);
 284         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 285
 286         regs->gprs[2] = map_signal(sig);
 287         regs->gprs[3] = (unsigned long) &frame->sc;
 288
 289         /* We forgot to include these in the sigcontext.
 290            To avoid breaking binary compatibility, they are passed as args. */
 291         if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
 292             sig == SIGTRAP || sig == SIGFPE) {
 293                 /* set extra registers only for synchronous signals */
 294                 regs->gprs[4] = regs->int_code & 127;
 295                 regs->gprs[5] = regs->int_parm_long;
 296                 regs->gprs[6] = task_thread_info(current)->last_break;
 297         }
 298
 299         /* Place signal number on stack to allow backtrace from handler.  */
 300         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 301                 goto give_sigsegv;
 302         return 0;
 303
 304 give_sigsegv:
 305         force_sigsegv(sig, current);
 306         return -EFAULT;
 307 }
 308
 309 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 310                            sigset_t *set, struct pt_regs * regs)
 311 {
 312         int err = 0;
 313         rt_sigframe __user *frame;
 314
 315         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 316         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 317                 goto give_sigsegv;
 318
 319         if (frame == (void __user *) -1UL)
 320                 goto give_sigsegv;
 321
 322         if (copy_siginfo_to_user(&frame->info, info))
 323                 goto give_sigsegv;
 324
 325         /* Create the ucontext.  */
 326         err |= __put_user(0, &frame->uc.uc_flags);
 327         err |= __put_user(NULL, &frame->uc.uc_link);
 328         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 329         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 330                           &frame->uc.uc_stack.ss_flags);
 331         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 332         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 333         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 334         if (err)
 335                 goto give_sigsegv;
 336
 337         /* Set up to return from userspace.  If provided, use a stub
 338            already in userspace.  */
 339         if (ka->sa.sa_flags & SA_RESTORER) {
 340                 regs->gprs[14] = (unsigned long)
 341                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 342         } else {
 343                 regs->gprs[14] = (unsigned long)
 344                         frame->retcode | PSW_ADDR_AMODE;
 345                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 346                                (u16 __user *)(frame->retcode)))
 347                         goto give_sigsegv;
 348         }
 349
 350         /* Set up backchain. */
 351         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 352                 goto give_sigsegv;
 353
 354         /* Set up registers for signal handler */
 355         regs->gprs[15] = (unsigned long) frame;
 356         /* Force default amode and default user address space control. */
 357         regs->psw.mask = PSW_MASK_EA | PSW_MASK_BA |
 358                 (psw_user_bits & PSW_MASK_ASC) |
 359                 (regs->psw.mask & ~PSW_MASK_ASC);
 360         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 361
 362         regs->gprs[2] = map_signal(sig);
 363         regs->gprs[3] = (unsigned long) &frame->info;
 364         regs->gprs[4] = (unsigned long) &frame->uc;
 365         regs->gprs[5] = task_thread_info(current)->last_break;
 366         return 0;
 367
 368 give_sigsegv:
 369         force_sigsegv(sig, current);
 370         return -EFAULT;
 371 }
 372
 373 static void handle_signal(unsigned long sig, struct k_sigaction *ka,
 374                          siginfo_t *info, sigset_t *oldset,
 375                          struct pt_regs *regs)
 376 {
 377         int ret;
 378
 379         /* Set up the stack frame */
 380         if (ka->sa.sa_flags & SA_SIGINFO)
 381                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 382         else
 383                 ret = setup_frame(sig, ka, oldset, regs);
 384         if (ret)
 385                 return;
 386         signal_delivered(sig, info, ka, regs,
 387                                  test_thread_flag(TIF_SINGLE_STEP));
 388 }
 389
 390 /*
 391  * Note that 'init' is a special process: it doesn't get signals it doesn't
 392  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 393  * mistake.
 394  *
 395  * Note that we go through the signals twice: once to check the signals that
 396  * the kernel can handle, and then we build all the user-level signal handling
 397  * stack-frames in one go after that.
 398  */
 399 void do_signal(struct pt_regs *regs)
 400 {
 401         siginfo_t info;
 402         int signr;
 403         struct k_sigaction ka;
 404         sigset_t *oldset = sigmask_to_save();
 405
 406         /*
 407          * Get signal to deliver. When running under ptrace, at this point
 408          * the debugger may change all our registers, including the system
 409          * call information.
 410          */
 411         current_thread_info()->system_call =
 412                 test_thread_flag(TIF_SYSCALL) ? regs->int_code : 0;
 413         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 414
 415         if (signr > 0) {
 416                 /* Whee!  Actually deliver the signal.  */
 417                 if (current_thread_info()->system_call) {
 418                         regs->int_code = current_thread_info()->system_call;
 419                         /* Check for system call restarting. */
 420                         switch (regs->gprs[2]) {
 421                         case -ERESTART_RESTARTBLOCK:
 422                         case -ERESTARTNOHAND:
 423                                 regs->gprs[2] = -EINTR;
 424                                 break;
 425                         case -ERESTARTSYS:
 426                                 if (!(ka.sa.sa_flags & SA_RESTART)) {
 427                                         regs->gprs[2] = -EINTR;
 428                                         break;
 429                                 }
 430                         /* fallthrough */
 431                         case -ERESTARTNOINTR:
 432                                 regs->gprs[2] = regs->orig_gpr2;
 433                                 regs->psw.addr =
 434                                         __rewind_psw(regs->psw,
 435                                                      regs->int_code >> 16);
 436                                 break;
 437                         }
 438                 }
 439                 /* No longer in a system call */
 440                 clear_thread_flag(TIF_SYSCALL);
 441
 442                 if (is_compat_task())
 443                         handle_signal32(signr, &ka, &info, oldset, regs);
 444                 else
 445                         handle_signal(signr, &ka, &info, oldset, regs);
 446                 return;
 447         }
 448
 449         /* No handlers present - check for system call restart */
 450         clear_thread_flag(TIF_SYSCALL);
 451         if (current_thread_info()->system_call) {
 452                 regs->int_code = current_thread_info()->system_call;
 453                 switch (regs->gprs[2]) {
 454                 case -ERESTART_RESTARTBLOCK:
 455                         /* Restart with sys_restart_syscall */
 456                         regs->int_code = __NR_restart_syscall;
 457                 /* fallthrough */
 458                 case -ERESTARTNOHAND:
 459                 case -ERESTARTSYS:
 460                 case -ERESTARTNOINTR:
 461                         /* Restart system call with magic TIF bit. */
 462                         regs->gprs[2] = regs->orig_gpr2;
 463                         set_thread_flag(TIF_SYSCALL);
 464                         if (test_thread_flag(TIF_SINGLE_STEP))
 465                                 set_thread_flag(TIF_PER_TRAP);
 466                         break;
 467                 }
 468         }
 469
 470         /*
 471          * If there's no signal to deliver, we just put the saved sigmask back.
 472          */
 473         restore_saved_sigmask();
 474 }
 475
 476 void do_notify_resume(struct pt_regs *regs)
 477 {
 478         clear_thread_flag(TIF_NOTIFY_RESUME);
 479         tracehook_notify_resume(regs);
 480 }