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 amode */
 140         if (regs->psw.mask & PSW_MASK_EA)
 141                 regs->psw.mask |= PSW_MASK_BA;
 142         regs->psw.addr = user_sregs.regs.psw.addr;
 143         memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 144         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 145                sizeof(sregs->regs.acrs));
 146         restore_access_regs(current->thread.acrs);
 147
 148         memcpy(&current->thread.fp_regs, &user_sregs.fpregs,
 149                sizeof(s390_fp_regs));
 150         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 151
 152         restore_fp_regs(&current->thread.fp_regs);
 153         clear_thread_flag(TIF_SYSCALL); /* No longer in a system call */
 154         return 0;
 155 }
 156
 157 SYSCALL_DEFINE0(sigreturn)
 158 {
 159         struct pt_regs *regs = task_pt_regs(current);
 160         sigframe __user *frame = (sigframe __user *)regs->gprs[15];
 161         sigset_t set;
 162
 163         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 164                 goto badframe;
 165         if (__copy_from_user(&set.sig, &frame->sc.oldmask, _SIGMASK_COPY_SIZE))
 166                 goto badframe;
 167         set_current_blocked(&set);
 168         if (restore_sigregs(regs, &frame->sregs))
 169                 goto badframe;
 170         return regs->gprs[2];
 171 badframe:
 172         force_sig(SIGSEGV, current);
 173         return 0;
 174 }
 175
 176 SYSCALL_DEFINE0(rt_sigreturn)
 177 {
 178         struct pt_regs *regs = task_pt_regs(current);
 179         rt_sigframe __user *frame = (rt_sigframe __user *)regs->gprs[15];
 180         sigset_t set;
 181
 182         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 183                 goto badframe;
 184         if (__copy_from_user(&set.sig, &frame->uc.uc_sigmask, sizeof(set)))
 185                 goto badframe;
 186         set_current_blocked(&set);
 187         if (restore_sigregs(regs, &frame->uc.uc_mcontext))
 188                 goto badframe;
 189         if (do_sigaltstack(&frame->uc.uc_stack, NULL,
 190                            regs->gprs[15]) == -EFAULT)
 191                 goto badframe;
 192         return regs->gprs[2];
 193 badframe:
 194         force_sig(SIGSEGV, current);
 195         return 0;
 196 }
 197
 198 /*
 199  * Set up a signal frame.
 200  */
 201
 202
 203 /*
 204  * Determine which stack to use..
 205  */
 206 static inline void __user *
 207 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 208 {
 209         unsigned long sp;
 210
 211         /* Default to using normal stack */
 212         sp = regs->gprs[15];
 213
 214         /* Overflow on alternate signal stack gives SIGSEGV. */
 215         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 216                 return (void __user *) -1UL;
 217
 218         /* This is the X/Open sanctioned signal stack switching.  */
 219         if (ka->sa.sa_flags & SA_ONSTACK) {
 220                 if (! sas_ss_flags(sp))
 221                         sp = current->sas_ss_sp + current->sas_ss_size;
 222         }
 223
 224         return (void __user *)((sp - frame_size) & -8ul);
 225 }
 226
 227 static inline int map_signal(int sig)
 228 {
 229         if (current_thread_info()->exec_domain
 230             && current_thread_info()->exec_domain->signal_invmap
 231             && sig < 32)
 232                 return current_thread_info()->exec_domain->signal_invmap[sig];
 233         else
 234                 return sig;
 235 }
 236
 237 static int setup_frame(int sig, struct k_sigaction *ka,
 238                        sigset_t *set, struct pt_regs * regs)
 239 {
 240         sigframe __user *frame;
 241
 242         frame = get_sigframe(ka, regs, sizeof(sigframe));
 243         if (!access_ok(VERIFY_WRITE, frame, sizeof(sigframe)))
 244                 goto give_sigsegv;
 245
 246         if (frame == (void __user *) -1UL)
 247                 goto give_sigsegv;
 248
 249         if (__copy_to_user(&frame->sc.oldmask, &set->sig, _SIGMASK_COPY_SIZE))
 250                 goto give_sigsegv;
 251
 252         if (save_sigregs(regs, &frame->sregs))
 253                 goto give_sigsegv;
 254         if (__put_user(&frame->sregs, &frame->sc.sregs))
 255                 goto give_sigsegv;
 256
 257         /* Set up to return from userspace.  If provided, use a stub
 258            already in userspace.  */
 259         if (ka->sa.sa_flags & SA_RESTORER) {
 260                 regs->gprs[14] = (unsigned long)
 261                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 262         } else {
 263                 regs->gprs[14] = (unsigned long)
 264                         frame->retcode | PSW_ADDR_AMODE;
 265                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn,
 266                                (u16 __user *)(frame->retcode)))
 267                         goto give_sigsegv;
 268         }
 269
 270         /* Set up backchain. */
 271         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 272                 goto give_sigsegv;
 273
 274         /* Set up registers for signal handler */
 275         regs->gprs[15] = (unsigned long) frame;
 276         regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA;    /* 64 bit amode */
 277         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 278
 279         regs->gprs[2] = map_signal(sig);
 280         regs->gprs[3] = (unsigned long) &frame->sc;
 281
 282         /* We forgot to include these in the sigcontext.
 283            To avoid breaking binary compatibility, they are passed as args. */
 284         if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
 285             sig == SIGTRAP || sig == SIGFPE) {
 286                 /* set extra registers only for synchronous signals */
 287                 regs->gprs[4] = regs->int_code & 127;
 288                 regs->gprs[5] = regs->int_parm_long;
 289                 regs->gprs[6] = task_thread_info(current)->last_break;
 290         }
 291
 292         /* Place signal number on stack to allow backtrace from handler.  */
 293         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
 294                 goto give_sigsegv;
 295         return 0;
 296
 297 give_sigsegv:
 298         force_sigsegv(sig, current);
 299         return -EFAULT;
 300 }
 301
 302 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 303                            sigset_t *set, struct pt_regs * regs)
 304 {
 305         int err = 0;
 306         rt_sigframe __user *frame;
 307
 308         frame = get_sigframe(ka, regs, sizeof(rt_sigframe));
 309         if (!access_ok(VERIFY_WRITE, frame, sizeof(rt_sigframe)))
 310                 goto give_sigsegv;
 311
 312         if (frame == (void __user *) -1UL)
 313                 goto give_sigsegv;
 314
 315         if (copy_siginfo_to_user(&frame->info, info))
 316                 goto give_sigsegv;
 317
 318         /* Create the ucontext.  */
 319         err |= __put_user(0, &frame->uc.uc_flags);
 320         err |= __put_user(NULL, &frame->uc.uc_link);
 321         err |= __put_user((void __user *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 322         err |= __put_user(sas_ss_flags(regs->gprs[15]),
 323                           &frame->uc.uc_stack.ss_flags);
 324         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 325         err |= save_sigregs(regs, &frame->uc.uc_mcontext);
 326         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 327         if (err)
 328                 goto give_sigsegv;
 329
 330         /* Set up to return from userspace.  If provided, use a stub
 331            already in userspace.  */
 332         if (ka->sa.sa_flags & SA_RESTORER) {
 333                 regs->gprs[14] = (unsigned long)
 334                         ka->sa.sa_restorer | PSW_ADDR_AMODE;
 335         } else {
 336                 regs->gprs[14] = (unsigned long)
 337                         frame->retcode | PSW_ADDR_AMODE;
 338                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
 339                                (u16 __user *)(frame->retcode)))
 340                         goto give_sigsegv;
 341         }
 342
 343         /* Set up backchain. */
 344         if (__put_user(regs->gprs[15], (addr_t __user *) frame))
 345                 goto give_sigsegv;
 346
 347         /* Set up registers for signal handler */
 348         regs->gprs[15] = (unsigned long) frame;
 349         regs->psw.mask |= PSW_MASK_EA | PSW_MASK_BA;    /* 64 bit amode */
 350         regs->psw.addr = (unsigned long) ka->sa.sa_handler | PSW_ADDR_AMODE;
 351
 352         regs->gprs[2] = map_signal(sig);
 353         regs->gprs[3] = (unsigned long) &frame->info;
 354         regs->gprs[4] = (unsigned long) &frame->uc;
 355         regs->gprs[5] = task_thread_info(current)->last_break;
 356         return 0;
 357
 358 give_sigsegv:
 359         force_sigsegv(sig, current);
 360         return -EFAULT;
 361 }
 362
 363 static void handle_signal(unsigned long sig, struct k_sigaction *ka,
 364                          siginfo_t *info, sigset_t *oldset,
 365                          struct pt_regs *regs)
 366 {
 367         int ret;
 368
 369         /* Set up the stack frame */
 370         if (ka->sa.sa_flags & SA_SIGINFO)
 371                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 372         else
 373                 ret = setup_frame(sig, ka, oldset, regs);
 374         if (ret)
 375                 return;
 376         signal_delivered(sig, info, ka, regs,
 377                                  test_thread_flag(TIF_SINGLE_STEP));
 378 }
 379
 380 /*
 381  * Note that 'init' is a special process: it doesn't get signals it doesn't
 382  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 383  * mistake.
 384  *
 385  * Note that we go through the signals twice: once to check the signals that
 386  * the kernel can handle, and then we build all the user-level signal handling
 387  * stack-frames in one go after that.
 388  */
 389 void do_signal(struct pt_regs *regs)
 390 {
 391         siginfo_t info;
 392         int signr;
 393         struct k_sigaction ka;
 394         sigset_t *oldset = sigmask_to_save();
 395
 396         /*
 397          * Get signal to deliver. When running under ptrace, at this point
 398          * the debugger may change all our registers, including the system
 399          * call information.
 400          */
 401         current_thread_info()->system_call =
 402                 test_thread_flag(TIF_SYSCALL) ? regs->int_code : 0;
 403         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 404
 405         if (signr > 0) {
 406                 /* Whee!  Actually deliver the signal.  */
 407                 if (current_thread_info()->system_call) {
 408                         regs->int_code = current_thread_info()->system_call;
 409                         /* Check for system call restarting. */
 410                         switch (regs->gprs[2]) {
 411                         case -ERESTART_RESTARTBLOCK:
 412                         case -ERESTARTNOHAND:
 413                                 regs->gprs[2] = -EINTR;
 414                                 break;
 415                         case -ERESTARTSYS:
 416                                 if (!(ka.sa.sa_flags & SA_RESTART)) {
 417                                         regs->gprs[2] = -EINTR;
 418                                         break;
 419                                 }
 420                         /* fallthrough */
 421                         case -ERESTARTNOINTR:
 422                                 regs->gprs[2] = regs->orig_gpr2;
 423                                 regs->psw.addr =
 424                                         __rewind_psw(regs->psw,
 425                                                      regs->int_code >> 16);
 426                                 break;
 427                         }
 428                 }
 429                 /* No longer in a system call */
 430                 clear_thread_flag(TIF_SYSCALL);
 431
 432                 if (is_compat_task())
 433                         handle_signal32(signr, &ka, &info, oldset, regs);
 434                 else
 435                         handle_signal(signr, &ka, &info, oldset, regs);
 436                 return;
 437         }
 438
 439         /* No handlers present - check for system call restart */
 440         clear_thread_flag(TIF_SYSCALL);
 441         if (current_thread_info()->system_call) {
 442                 regs->int_code = current_thread_info()->system_call;
 443                 switch (regs->gprs[2]) {
 444                 case -ERESTART_RESTARTBLOCK:
 445                         /* Restart with sys_restart_syscall */
 446                         regs->int_code = __NR_restart_syscall;
 447                 /* fallthrough */
 448                 case -ERESTARTNOHAND:
 449                 case -ERESTARTSYS:
 450                 case -ERESTARTNOINTR:
 451                         /* Restart system call with magic TIF bit. */
 452                         regs->gprs[2] = regs->orig_gpr2;
 453                         set_thread_flag(TIF_SYSCALL);
 454                         break;
 455                 }
 456         }
 457
 458         /*
 459          * If there's no signal to deliver, we just put the saved sigmask back.
 460          */
 461         restore_saved_sigmask();
 462 }
 463
 464 void do_notify_resume(struct pt_regs *regs)
 465 {
 466         clear_thread_flag(TIF_NOTIFY_RESUME);
 467         tracehook_notify_resume(regs);
 468 }