arch/frv/kernel/signal.c

   1 /* signal.c: FRV specific bits of signal handling
   2  *
   3  * Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  * - Derived from arch/m68k/kernel/signal.c
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <linux/sched.h>
  14 #include <linux/mm.h>
  15 #include <linux/smp.h>
  16 #include <linux/kernel.h>
  17 #include <linux/signal.h>
  18 #include <linux/errno.h>
  19 #include <linux/wait.h>
  20 #include <linux/ptrace.h>
  21 #include <linux/unistd.h>
  22 #include <linux/personality.h>
  23 #include <linux/tracehook.h>
  24 #include <asm/ucontext.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/cacheflush.h>
  27
  28 #define DEBUG_SIG 0
  29
  30 struct fdpic_func_descriptor {
  31         unsigned long   text;
  32         unsigned long   GOT;
  33 };
  34
  35 /*
  36  * Do a signal return; undo the signal stack.
  37  */
  38
  39 struct sigframe
  40 {
  41         __sigrestore_t pretcode;
  42         int sig;
  43         struct sigcontext sc;
  44         unsigned long extramask[_NSIG_WORDS-1];
  45         uint32_t retcode[2];
  46 };
  47
  48 struct rt_sigframe
  49 {
  50         __sigrestore_t pretcode;
  51         int sig;
  52         struct siginfo __user *pinfo;
  53         void __user *puc;
  54         struct siginfo info;
  55         struct ucontext uc;
  56         uint32_t retcode[2];
  57 };
  58
  59 static int restore_sigcontext(struct sigcontext __user *sc, int *_gr8)
  60 {
  61         struct user_context *user = current->thread.user;
  62         unsigned long tbr, psr;
  63
  64         /* Always make any pending restarted system calls return -EINTR */
  65         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  66
  67         tbr = user->i.tbr;
  68         psr = user->i.psr;
  69         if (copy_from_user(user, &sc->sc_context, sizeof(sc->sc_context)))
  70                 goto badframe;
  71         user->i.tbr = tbr;
  72         user->i.psr = psr;
  73
  74         restore_user_regs(user);
  75
  76         user->i.syscallno = -1;         /* disable syscall checks */
  77
  78         *_gr8 = user->i.gr[8];
  79         return 0;
  80
  81  badframe:
  82         return 1;
  83 }
  84
  85 asmlinkage int sys_sigreturn(void)
  86 {
  87         struct sigframe __user *frame = (struct sigframe __user *) __frame->sp;
  88         sigset_t set;
  89         int gr8;
  90
  91         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  92                 goto badframe;
  93         if (__get_user(set.sig[0], &frame->sc.sc_oldmask))
  94                 goto badframe;
  95
  96         if (_NSIG_WORDS > 1 &&
  97             __copy_from_user(&set.sig[1], &frame->extramask, sizeof(frame->extramask)))
  98                 goto badframe;
  99
 100         set_current_blocked(&set);
 101
 102         if (restore_sigcontext(&frame->sc, &gr8))
 103                 goto badframe;
 104         return gr8;
 105
 106  badframe:
 107         force_sig(SIGSEGV, current);
 108         return 0;
 109 }
 110
 111 asmlinkage int sys_rt_sigreturn(void)
 112 {
 113         struct rt_sigframe __user *frame = (struct rt_sigframe __user *) __frame->sp;
 114         sigset_t set;
 115         int gr8;
 116
 117         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 118                 goto badframe;
 119         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 120                 goto badframe;
 121
 122         set_current_blocked(&set);
 123
 124         if (restore_sigcontext(&frame->uc.uc_mcontext, &gr8))
 125                 goto badframe;
 126
 127         if (restore_altstack(&frame->uc.uc_stack))
 128                 goto badframe;
 129
 130         return gr8;
 131
 132 badframe:
 133         force_sig(SIGSEGV, current);
 134         return 0;
 135 }
 136
 137 /*
 138  * Set up a signal frame
 139  */
 140 static int setup_sigcontext(struct sigcontext __user *sc, unsigned long mask)
 141 {
 142         save_user_regs(current->thread.user);
 143
 144         if (copy_to_user(&sc->sc_context, current->thread.user, sizeof(sc->sc_context)) != 0)
 145                 goto badframe;
 146
 147         /* non-iBCS2 extensions.. */
 148         if (__put_user(mask, &sc->sc_oldmask) < 0)
 149                 goto badframe;
 150
 151         return 0;
 152
 153  badframe:
 154         return 1;
 155 }
 156
 157 /*****************************************************************************/
 158 /*
 159  * Determine which stack to use..
 160  */
 161 static inline void __user *get_sigframe(struct k_sigaction *ka,
 162                                         size_t frame_size)
 163 {
 164         unsigned long sp;
 165
 166         /* Default to using normal stack */
 167         sp = __frame->sp;
 168
 169         /* This is the X/Open sanctioned signal stack switching.  */
 170         if (ka->sa.sa_flags & SA_ONSTACK) {
 171                 if (! sas_ss_flags(sp))
 172                         sp = current->sas_ss_sp + current->sas_ss_size;
 173         }
 174
 175         return (void __user *) ((sp - frame_size) & ~7UL);
 176
 177 } /* end get_sigframe() */
 178
 179 /*****************************************************************************/
 180 /*
 181  *
 182  */
 183 static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set)
 184 {
 185         struct sigframe __user *frame;
 186         int rsig;
 187
 188         set_fs(USER_DS);
 189
 190         frame = get_sigframe(ka, sizeof(*frame));
 191
 192         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 193                 goto give_sigsegv;
 194
 195         rsig = sig;
 196         if (sig < 32 &&
 197             __current_thread_info->exec_domain &&
 198             __current_thread_info->exec_domain->signal_invmap)
 199                 rsig = __current_thread_info->exec_domain->signal_invmap[sig];
 200
 201         if (__put_user(rsig, &frame->sig) < 0)
 202                 goto give_sigsegv;
 203
 204         if (setup_sigcontext(&frame->sc, set->sig[0]))
 205                 goto give_sigsegv;
 206
 207         if (_NSIG_WORDS > 1) {
 208                 if (__copy_to_user(frame->extramask, &set->sig[1],
 209                                    sizeof(frame->extramask)))
 210                         goto give_sigsegv;
 211         }
 212
 213         /* Set up to return from userspace.  If provided, use a stub
 214          * already in userspace.  */
 215         if (ka->sa.sa_flags & SA_RESTORER) {
 216                 if (__put_user(ka->sa.sa_restorer, &frame->pretcode) < 0)
 217                         goto give_sigsegv;
 218         }
 219         else {
 220                 /* Set up the following code on the stack:
 221                  *      setlos  #__NR_sigreturn,gr7
 222                  *      tira    gr0,0
 223                  */
 224                 if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
 225                     __put_user(0x8efc0000|__NR_sigreturn, &frame->retcode[0]) ||
 226                     __put_user(0xc0700000, &frame->retcode[1]))
 227                         goto give_sigsegv;
 228
 229                 flush_icache_range((unsigned long) frame->retcode,
 230                                    (unsigned long) (frame->retcode + 2));
 231         }
 232
 233         /* Set up registers for the signal handler */
 234         if (current->personality & FDPIC_FUNCPTRS) {
 235                 struct fdpic_func_descriptor __user *funcptr =
 236                         (struct fdpic_func_descriptor __user *) ka->sa.sa_handler;
 237                 struct fdpic_func_descriptor desc;
 238                 if (copy_from_user(&desc, funcptr, sizeof(desc)))
 239                         goto give_sigsegv;
 240                 __frame->pc = desc.text;
 241                 __frame->gr15 = desc.GOT;
 242         } else {
 243                 __frame->pc   = (unsigned long) ka->sa.sa_handler;
 244                 __frame->gr15 = 0;
 245         }
 246
 247         __frame->sp   = (unsigned long) frame;
 248         __frame->lr   = (unsigned long) &frame->retcode;
 249         __frame->gr8  = sig;
 250
 251 #if DEBUG_SIG
 252         printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
 253                sig, current->comm, current->pid, frame, __frame->pc,
 254                frame->pretcode);
 255 #endif
 256
 257         return 0;
 258
 259 give_sigsegv:
 260         force_sigsegv(sig, current);
 261         return -EFAULT;
 262
 263 } /* end setup_frame() */
 264
 265 /*****************************************************************************/
 266 /*
 267  *
 268  */
 269 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 270                           sigset_t *set)
 271 {
 272         struct rt_sigframe __user *frame;
 273         int rsig;
 274
 275         set_fs(USER_DS);
 276
 277         frame = get_sigframe(ka, sizeof(*frame));
 278
 279         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 280                 goto give_sigsegv;
 281
 282         rsig = sig;
 283         if (sig < 32 &&
 284             __current_thread_info->exec_domain &&
 285             __current_thread_info->exec_domain->signal_invmap)
 286                 rsig = __current_thread_info->exec_domain->signal_invmap[sig];
 287
 288         if (__put_user(rsig,            &frame->sig) ||
 289             __put_user(&frame->info,    &frame->pinfo) ||
 290             __put_user(&frame->uc,      &frame->puc))
 291                 goto give_sigsegv;
 292
 293         if (copy_siginfo_to_user(&frame->info, info))
 294                 goto give_sigsegv;
 295
 296         /* Create the ucontext.  */
 297         if (__put_user(0, &frame->uc.uc_flags) ||
 298             __put_user(NULL, &frame->uc.uc_link) ||
 299             __save_altstack(&frame->uc.uc_stack, __frame->sp))
 300                 goto give_sigsegv;
 301
 302         if (setup_sigcontext(&frame->uc.uc_mcontext, set->sig[0]))
 303                 goto give_sigsegv;
 304
 305         if (__copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)))
 306                 goto give_sigsegv;
 307
 308         /* Set up to return from userspace.  If provided, use a stub
 309          * already in userspace.  */
 310         if (ka->sa.sa_flags & SA_RESTORER) {
 311                 if (__put_user(ka->sa.sa_restorer, &frame->pretcode))
 312                         goto give_sigsegv;
 313         }
 314         else {
 315                 /* Set up the following code on the stack:
 316                  *      setlos  #__NR_sigreturn,gr7
 317                  *      tira    gr0,0
 318                  */
 319                 if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
 320                     __put_user(0x8efc0000|__NR_rt_sigreturn, &frame->retcode[0]) ||
 321                     __put_user(0xc0700000, &frame->retcode[1]))
 322                         goto give_sigsegv;
 323
 324                 flush_icache_range((unsigned long) frame->retcode,
 325                                    (unsigned long) (frame->retcode + 2));
 326         }
 327
 328         /* Set up registers for signal handler */
 329         if (current->personality & FDPIC_FUNCPTRS) {
 330                 struct fdpic_func_descriptor __user *funcptr =
 331                         (struct fdpic_func_descriptor __user *) ka->sa.sa_handler;
 332                 struct fdpic_func_descriptor desc;
 333                 if (copy_from_user(&desc, funcptr, sizeof(desc)))
 334                         goto give_sigsegv;
 335                 __frame->pc = desc.text;
 336                 __frame->gr15 = desc.GOT;
 337         } else {
 338                 __frame->pc   = (unsigned long) ka->sa.sa_handler;
 339                 __frame->gr15 = 0;
 340         }
 341
 342         __frame->sp  = (unsigned long) frame;
 343         __frame->lr  = (unsigned long) &frame->retcode;
 344         __frame->gr8 = sig;
 345         __frame->gr9 = (unsigned long) &frame->info;
 346
 347 #if DEBUG_SIG
 348         printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
 349                sig, current->comm, current->pid, frame, __frame->pc,
 350                frame->pretcode);
 351 #endif
 352
 353         return 0;
 354
 355 give_sigsegv:
 356         force_sigsegv(sig, current);
 357         return -EFAULT;
 358
 359 } /* end setup_rt_frame() */
 360
 361 /*****************************************************************************/
 362 /*
 363  * OK, we're invoking a handler
 364  */
 365 static void handle_signal(unsigned long sig, siginfo_t *info,
 366                          struct k_sigaction *ka)
 367 {
 368         sigset_t *oldset = sigmask_to_save();
 369         int ret;
 370
 371         /* Are we from a system call? */
 372         if (__frame->syscallno != -1) {
 373                 /* If so, check system call restarting.. */
 374                 switch (__frame->gr8) {
 375                 case -ERESTART_RESTARTBLOCK:
 376                 case -ERESTARTNOHAND:
 377                         __frame->gr8 = -EINTR;
 378                         break;
 379
 380                 case -ERESTARTSYS:
 381                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 382                                 __frame->gr8 = -EINTR;
 383                                 break;
 384                         }
 385
 386                         /* fallthrough */
 387                 case -ERESTARTNOINTR:
 388                         __frame->gr8 = __frame->orig_gr8;
 389                         __frame->pc -= 4;
 390                 }
 391                 __frame->syscallno = -1;
 392         }
 393
 394         /* Set up the stack frame */
 395         if (ka->sa.sa_flags & SA_SIGINFO)
 396                 ret = setup_rt_frame(sig, ka, info, oldset);
 397         else
 398                 ret = setup_frame(sig, ka, oldset);
 399
 400         if (ret)
 401                 return;
 402
 403         signal_delivered(sig, info, ka, __frame,
 404                                  test_thread_flag(TIF_SINGLESTEP));
 405 } /* end handle_signal() */
 406
 407 /*****************************************************************************/
 408 /*
 409  * Note that 'init' is a special process: it doesn't get signals it doesn't
 410  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 411  * mistake.
 412  */
 413 static void do_signal(void)
 414 {
 415         struct k_sigaction ka;
 416         siginfo_t info;
 417         int signr;
 418
 419         signr = get_signal_to_deliver(&info, &ka, __frame, NULL);
 420         if (signr > 0) {
 421                 handle_signal(signr, &info, &ka);
 422                 return;
 423         }
 424
 425         /* Did we come from a system call? */
 426         if (__frame->syscallno != -1) {
 427                 /* Restart the system call - no handlers present */
 428                 switch (__frame->gr8) {
 429                 case -ERESTARTNOHAND:
 430                 case -ERESTARTSYS:
 431                 case -ERESTARTNOINTR:
 432                         __frame->gr8 = __frame->orig_gr8;
 433                         __frame->pc -= 4;
 434                         break;
 435
 436                 case -ERESTART_RESTARTBLOCK:
 437                         __frame->gr7 = __NR_restart_syscall;
 438                         __frame->pc -= 4;
 439                         break;
 440                 }
 441                 __frame->syscallno = -1;
 442         }
 443
 444         /* if there's no signal to deliver, we just put the saved sigmask
 445          * back */
 446         restore_saved_sigmask();
 447 } /* end do_signal() */
 448
 449 /*****************************************************************************/
 450 /*
 451  * notification of userspace execution resumption
 452  * - triggered by the TIF_WORK_MASK flags
 453  */
 454 asmlinkage void do_notify_resume(__u32 thread_info_flags)
 455 {
 456         /* pending single-step? */
 457         if (thread_info_flags & _TIF_SINGLESTEP)
 458                 clear_thread_flag(TIF_SINGLESTEP);
 459
 460         /* deal with pending signal delivery */
 461         if (thread_info_flags & _TIF_SIGPENDING)
 462                 do_signal();
 463
 464         /* deal with notification on about to resume userspace execution */
 465         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 466                 clear_thread_flag(TIF_NOTIFY_RESUME);
 467                 tracehook_notify_resume(__frame);
 468         }
 469
 470 } /* end do_notify_resume() */