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 <linux/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->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 ksignal *ksig,
 162                                         size_t frame_size)
 163 {
 164         unsigned long sp = sigsp(__frame->sp, ksig);
 165
 166         return (void __user *) ((sp - frame_size) & ~7UL);
 167
 168 } /* end get_sigframe() */
 169
 170 /*****************************************************************************/
 171 /*
 172  *
 173  */
 174 static int setup_frame(struct ksignal *ksig, sigset_t *set)
 175 {
 176         struct sigframe __user *frame;
 177         int sig = ksig->sig;
 178
 179         frame = get_sigframe(ksig, sizeof(*frame));
 180
 181         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 182                 return -EFAULT;
 183
 184         if (__put_user(sig, &frame->sig) < 0)
 185                 return -EFAULT;
 186
 187         if (setup_sigcontext(&frame->sc, set->sig[0]))
 188                 return -EFAULT;
 189
 190         if (_NSIG_WORDS > 1) {
 191                 if (__copy_to_user(frame->extramask, &set->sig[1],
 192                                    sizeof(frame->extramask)))
 193                         return -EFAULT;
 194         }
 195
 196         /* Set up to return from userspace.  If provided, use a stub
 197          * already in userspace.  */
 198         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 199                 if (__put_user(ksig->ka.sa.sa_restorer, &frame->pretcode) < 0)
 200                         return -EFAULT;
 201         }
 202         else {
 203                 /* Set up the following code on the stack:
 204                  *      setlos  #__NR_sigreturn,gr7
 205                  *      tira    gr0,0
 206                  */
 207                 if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
 208                     __put_user(0x8efc0000|__NR_sigreturn, &frame->retcode[0]) ||
 209                     __put_user(0xc0700000, &frame->retcode[1]))
 210                         return -EFAULT;
 211
 212                 flush_icache_range((unsigned long) frame->retcode,
 213                                    (unsigned long) (frame->retcode + 2));
 214         }
 215
 216         /* Set up registers for the signal handler */
 217         if (current->personality & FDPIC_FUNCPTRS) {
 218                 struct fdpic_func_descriptor __user *funcptr =
 219                         (struct fdpic_func_descriptor __user *) ksig->ka.sa.sa_handler;
 220                 struct fdpic_func_descriptor desc;
 221                 if (copy_from_user(&desc, funcptr, sizeof(desc)))
 222                         return -EFAULT;
 223                 __frame->pc = desc.text;
 224                 __frame->gr15 = desc.GOT;
 225         } else {
 226                 __frame->pc   = (unsigned long) ksig->ka.sa.sa_handler;
 227                 __frame->gr15 = 0;
 228         }
 229
 230         __frame->sp   = (unsigned long) frame;
 231         __frame->lr   = (unsigned long) &frame->retcode;
 232         __frame->gr8  = sig;
 233
 234 #if DEBUG_SIG
 235         printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
 236                sig, current->comm, current->pid, frame, __frame->pc,
 237                frame->pretcode);
 238 #endif
 239
 240         return 0;
 241 } /* end setup_frame() */
 242
 243 /*****************************************************************************/
 244 /*
 245  *
 246  */
 247 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set)
 248 {
 249         struct rt_sigframe __user *frame;
 250         int sig = ksig->sig;
 251
 252         frame = get_sigframe(ksig, sizeof(*frame));
 253
 254         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 255                 return -EFAULT;
 256
 257         if (__put_user(sig,             &frame->sig) ||
 258             __put_user(&frame->info,    &frame->pinfo) ||
 259             __put_user(&frame->uc,      &frame->puc))
 260                 return -EFAULT;
 261
 262         if (copy_siginfo_to_user(&frame->info, &ksig->info))
 263                 return -EFAULT;
 264
 265         /* Create the ucontext.  */
 266         if (__put_user(0, &frame->uc.uc_flags) ||
 267             __put_user(NULL, &frame->uc.uc_link) ||
 268             __save_altstack(&frame->uc.uc_stack, __frame->sp))
 269                 return -EFAULT;
 270
 271         if (setup_sigcontext(&frame->uc.uc_mcontext, set->sig[0]))
 272                 return -EFAULT;
 273
 274         if (__copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)))
 275                 return -EFAULT;
 276
 277         /* Set up to return from userspace.  If provided, use a stub
 278          * already in userspace.  */
 279         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 280                 if (__put_user(ksig->ka.sa.sa_restorer, &frame->pretcode))
 281                         return -EFAULT;
 282         }
 283         else {
 284                 /* Set up the following code on the stack:
 285                  *      setlos  #__NR_sigreturn,gr7
 286                  *      tira    gr0,0
 287                  */
 288                 if (__put_user((__sigrestore_t)frame->retcode, &frame->pretcode) ||
 289                     __put_user(0x8efc0000|__NR_rt_sigreturn, &frame->retcode[0]) ||
 290                     __put_user(0xc0700000, &frame->retcode[1]))
 291                         return -EFAULT;
 292
 293                 flush_icache_range((unsigned long) frame->retcode,
 294                                    (unsigned long) (frame->retcode + 2));
 295         }
 296
 297         /* Set up registers for signal handler */
 298         if (current->personality & FDPIC_FUNCPTRS) {
 299                 struct fdpic_func_descriptor __user *funcptr =
 300                         (struct fdpic_func_descriptor __user *) ksig->ka.sa.sa_handler;
 301                 struct fdpic_func_descriptor desc;
 302                 if (copy_from_user(&desc, funcptr, sizeof(desc)))
 303                         return -EFAULT;
 304                 __frame->pc = desc.text;
 305                 __frame->gr15 = desc.GOT;
 306         } else {
 307                 __frame->pc   = (unsigned long) ksig->ka.sa.sa_handler;
 308                 __frame->gr15 = 0;
 309         }
 310
 311         __frame->sp  = (unsigned long) frame;
 312         __frame->lr  = (unsigned long) &frame->retcode;
 313         __frame->gr8 = sig;
 314         __frame->gr9 = (unsigned long) &frame->info;
 315
 316 #if DEBUG_SIG
 317         printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
 318                sig, current->comm, current->pid, frame, __frame->pc,
 319                frame->pretcode);
 320 #endif
 321         return 0;
 322
 323 } /* end setup_rt_frame() */
 324
 325 /*****************************************************************************/
 326 /*
 327  * OK, we're invoking a handler
 328  */
 329 static void handle_signal(struct ksignal *ksig)
 330 {
 331         sigset_t *oldset = sigmask_to_save();
 332         int ret;
 333
 334         /* Are we from a system call? */
 335         if (__frame->syscallno != -1) {
 336                 /* If so, check system call restarting.. */
 337                 switch (__frame->gr8) {
 338                 case -ERESTART_RESTARTBLOCK:
 339                 case -ERESTARTNOHAND:
 340                         __frame->gr8 = -EINTR;
 341                         break;
 342
 343                 case -ERESTARTSYS:
 344                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 345                                 __frame->gr8 = -EINTR;
 346                                 break;
 347                         }
 348
 349                         /* fallthrough */
 350                 case -ERESTARTNOINTR:
 351                         __frame->gr8 = __frame->orig_gr8;
 352                         __frame->pc -= 4;
 353                 }
 354                 __frame->syscallno = -1;
 355         }
 356
 357         /* Set up the stack frame */
 358         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 359                 ret = setup_rt_frame(ksig, oldset);
 360         else
 361                 ret = setup_frame(ksig, oldset);
 362
 363         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 364 } /* end handle_signal() */
 365
 366 /*****************************************************************************/
 367 /*
 368  * Note that 'init' is a special process: it doesn't get signals it doesn't
 369  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 370  * mistake.
 371  */
 372 static void do_signal(void)
 373 {
 374         struct ksignal ksig;
 375
 376         if (get_signal(&ksig)) {
 377                 handle_signal(&ksig);
 378                 return;
 379         }
 380
 381         /* Did we come from a system call? */
 382         if (__frame->syscallno != -1) {
 383                 /* Restart the system call - no handlers present */
 384                 switch (__frame->gr8) {
 385                 case -ERESTARTNOHAND:
 386                 case -ERESTARTSYS:
 387                 case -ERESTARTNOINTR:
 388                         __frame->gr8 = __frame->orig_gr8;
 389                         __frame->pc -= 4;
 390                         break;
 391
 392                 case -ERESTART_RESTARTBLOCK:
 393                         __frame->gr7 = __NR_restart_syscall;
 394                         __frame->pc -= 4;
 395                         break;
 396                 }
 397                 __frame->syscallno = -1;
 398         }
 399
 400         /* if there's no signal to deliver, we just put the saved sigmask
 401          * back */
 402         restore_saved_sigmask();
 403 } /* end do_signal() */
 404
 405 /*****************************************************************************/
 406 /*
 407  * notification of userspace execution resumption
 408  * - triggered by the TIF_WORK_MASK flags
 409  */
 410 asmlinkage void do_notify_resume(__u32 thread_info_flags)
 411 {
 412         /* pending single-step? */
 413         if (thread_info_flags & _TIF_SINGLESTEP)
 414                 clear_thread_flag(TIF_SINGLESTEP);
 415
 416         /* deal with pending signal delivery */
 417         if (thread_info_flags & _TIF_SIGPENDING)
 418                 do_signal();
 419
 420         /* deal with notification on about to resume userspace execution */
 421         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 422                 clear_thread_flag(TIF_NOTIFY_RESUME);
 423                 tracehook_notify_resume(__frame);
 424         }
 425
 426 } /* end do_notify_resume() */