arch/s390/kernel/signal.c

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