arch/cris/arch-v32/kernel/signal.c

   1 /*
   2  * Copyright (C) 2003, Axis Communications AB.
   3  */
   4
   5 #include <linux/sched.h>
   6 #include <linux/mm.h>
   7 #include <linux/slab.h>
   8 #include <linux/kernel.h>
   9 #include <linux/signal.h>
  10 #include <linux/errno.h>
  11 #include <linux/wait.h>
  12 #include <linux/ptrace.h>
  13 #include <linux/unistd.h>
  14 #include <linux/stddef.h>
  15 #include <linux/syscalls.h>
  16 #include <linux/vmalloc.h>
  17
  18 #include <asm/io.h>
  19 #include <asm/processor.h>
  20 #include <asm/ucontext.h>
  21 #include <asm/uaccess.h>
  22 #include <arch/ptrace.h>
  23 #include <arch/hwregs/cpu_vect.h>
  24
  25 extern unsigned long cris_signal_return_page;
  26
  27 /*
  28  * A syscall in CRIS is really a "break 13" instruction, which is 2
  29  * bytes. The registers is manipulated so upon return the instruction
  30  * will be executed again.
  31  *
  32  * This relies on that PC points to the instruction after the break call.
  33  */
  34 #define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2;
  35
  36 /* Signal frames. */
  37 struct signal_frame {
  38         struct sigcontext sc;
  39         unsigned long extramask[_NSIG_WORDS - 1];
  40         unsigned char retcode[8];       /* Trampoline code. */
  41 };
  42
  43 struct rt_signal_frame {
  44         struct siginfo *pinfo;
  45         void *puc;
  46         struct siginfo info;
  47         struct ucontext uc;
  48         unsigned char retcode[8];       /* Trampoline code. */
  49 };
  50
  51 void do_signal(int restart, struct pt_regs *regs);
  52 void keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
  53                       struct pt_regs *regs);
  54 /*
  55  * Swap in the new signal mask, and wait for a signal. Define some
  56  * dummy arguments to be able to reach the regs argument.
  57  */
  58 int
  59 sys_sigsuspend(old_sigset_t mask)
  60 {
  61         sigset_t blocked;
  62         siginitset(&blocked, mask);
  63         return sigsuspend(&blocked);
  64 }
  65
  66 int
  67 sys_sigaction(int signal, const struct old_sigaction *act,
  68               struct old_sigaction *oact)
  69 {
  70         int retval;
  71         struct k_sigaction newk;
  72         struct k_sigaction oldk;
  73
  74         if (act) {
  75                 old_sigset_t mask;
  76
  77                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  78                     __get_user(newk.sa.sa_handler, &act->sa_handler) ||
  79                     __get_user(newk.sa.sa_restorer, &act->sa_restorer) ||
  80                     __get_user(newk.sa.sa_flags, &act->sa_flags) ||
  81                     __get_user(mask, &act->sa_mask))
  82                         return -EFAULT;
  83
  84                 siginitset(&newk.sa.sa_mask, mask);
  85         }
  86
  87         retval = do_sigaction(signal, act ? &newk : NULL, oact ? &oldk : NULL);
  88
  89         if (!retval && oact) {
  90                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  91                     __put_user(oldk.sa.sa_handler, &oact->sa_handler) ||
  92                     __put_user(oldk.sa.sa_restorer, &oact->sa_restorer) ||
  93                     __put_user(oldk.sa.sa_flags, &oact->sa_flags) ||
  94                     __put_user(oldk.sa.sa_mask.sig[0], &oact->sa_mask))
  95                         return -EFAULT;
  96
  97         }
  98
  99         return retval;
 100 }
 101
 102 int
 103 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
 104 {
 105         return do_sigaltstack(uss, uoss, rdusp());
 106 }
 107
 108 static int
 109 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 110 {
 111         unsigned int err = 0;
 112         unsigned long old_usp;
 113
 114         /* Always make any pending restarted system calls return -EINTR */
 115         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 116
 117         /*
 118          * Restore the registers from &sc->regs. sc is already checked
 119          * for VERIFY_READ since the signal_frame was previously
 120          * checked in sys_sigreturn().
 121          */
 122         if (__copy_from_user(regs, sc, sizeof(struct pt_regs)))
 123                 goto badframe;
 124
 125         /* Make that the user-mode flag is set. */
 126         regs->ccs |= (1 << (U_CCS_BITNR + CCS_SHIFT));
 127
 128         /* Restore the old USP. */
 129         err |= __get_user(old_usp, &sc->usp);
 130         wrusp(old_usp);
 131
 132         return err;
 133
 134 badframe:
 135         return 1;
 136 }
 137
 138 /* Define some dummy arguments to be able to reach the regs argument. */
 139 asmlinkage int
 140 sys_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp,
 141               struct pt_regs *regs)
 142 {
 143         sigset_t set;
 144         struct signal_frame __user *frame;
 145         unsigned long oldspc = regs->spc;
 146         unsigned long oldccs = regs->ccs;
 147
 148         frame = (struct signal_frame *) rdusp();
 149
 150         /*
 151          * Since the signal is stacked on a dword boundary, the frame
 152          * should be dword aligned here as well. It it's not, then the
 153          * user is trying some funny business.
 154          */
 155         if (((long)frame) & 3)
 156                 goto badframe;
 157
 158         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 159                 goto badframe;
 160
 161         if (__get_user(set.sig[0], &frame->sc.oldmask) ||
 162             (_NSIG_WORDS > 1 && __copy_from_user(&set.sig[1],
 163                                                  frame->extramask,
 164                                                  sizeof(frame->extramask))))
 165                 goto badframe;
 166
 167         set_current_blocked(&set);
 168
 169         if (restore_sigcontext(regs, &frame->sc))
 170                 goto badframe;
 171
 172         keep_debug_flags(oldccs, oldspc, regs);
 173
 174         return regs->r10;
 175
 176 badframe:
 177         force_sig(SIGSEGV, current);
 178         return 0;
 179 }
 180
 181 /* Define some dummy variables to be able to reach the regs argument. */
 182 asmlinkage int
 183 sys_rt_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp,
 184                  struct pt_regs *regs)
 185 {
 186         sigset_t set;
 187         struct rt_signal_frame __user *frame;
 188         unsigned long oldspc = regs->spc;
 189         unsigned long oldccs = regs->ccs;
 190
 191         frame = (struct rt_signal_frame *) rdusp();
 192
 193         /*
 194          * Since the signal is stacked on a dword boundary, the frame
 195          * should be dword aligned here as well. It it's not, then the
 196          * user is trying some funny business.
 197          */
 198         if (((long)frame) & 3)
 199                 goto badframe;
 200
 201         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 202                 goto badframe;
 203
 204         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 205                 goto badframe;
 206
 207         set_current_blocked(&set);
 208
 209         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 210                 goto badframe;
 211
 212         if (do_sigaltstack(&frame->uc.uc_stack, NULL, rdusp()) == -EFAULT)
 213                 goto badframe;
 214
 215         keep_debug_flags(oldccs, oldspc, regs);
 216
 217         return regs->r10;
 218
 219 badframe:
 220         force_sig(SIGSEGV, current);
 221         return 0;
 222 }
 223
 224 /* Setup a signal frame. */
 225 static int
 226 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 227                  unsigned long mask)
 228 {
 229         int err;
 230         unsigned long usp;
 231
 232         err = 0;
 233         usp = rdusp();
 234
 235         /*
 236          * Copy the registers. They are located first in sc, so it's
 237          * possible to use sc directly.
 238          */
 239         err |= __copy_to_user(sc, regs, sizeof(struct pt_regs));
 240
 241         err |= __put_user(mask, &sc->oldmask);
 242         err |= __put_user(usp, &sc->usp);
 243
 244         return err;
 245 }
 246
 247 /* Figure out where to put the new signal frame - usually on the stack. */
 248 static inline void __user *
 249 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 250 {
 251         unsigned long sp;
 252
 253         sp = rdusp();
 254
 255         /* This is the X/Open sanctioned signal stack switching. */
 256         if (ka->sa.sa_flags & SA_ONSTACK) {
 257                 if (!on_sig_stack(sp))
 258                         sp = current->sas_ss_sp + current->sas_ss_size;
 259         }
 260
 261         /* Make sure the frame is dword-aligned. */
 262         sp &= ~3;
 263
 264         return (void __user *)(sp - frame_size);
 265 }
 266
 267 /* Grab and setup a signal frame.
 268  *
 269  * Basically a lot of state-info is stacked, and arranged for the
 270  * user-mode program to return to the kernel using either a trampiline
 271  * which performs the syscall sigreturn(), or a provided user-mode
 272  * trampoline.
 273   */
 274 static int
 275 setup_frame(int sig, struct k_sigaction *ka,  sigset_t *set,
 276             struct pt_regs * regs)
 277 {
 278         int err;
 279         unsigned long return_ip;
 280         struct signal_frame __user *frame;
 281
 282         err = 0;
 283         frame = get_sigframe(ka, regs, sizeof(*frame));
 284
 285         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 286                 goto give_sigsegv;
 287
 288         err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
 289
 290         if (err)
 291                 goto give_sigsegv;
 292
 293         if (_NSIG_WORDS > 1) {
 294                 err |= __copy_to_user(frame->extramask, &set->sig[1],
 295                                       sizeof(frame->extramask));
 296         }
 297
 298         if (err)
 299                 goto give_sigsegv;
 300
 301         /*
 302          * Set up to return from user-space. If provided, use a stub
 303          * already located in user-space.
 304          */
 305         if (ka->sa.sa_flags & SA_RESTORER) {
 306                 return_ip = (unsigned long)ka->sa.sa_restorer;
 307         } else {
 308                 /* Trampoline - the desired return ip is in the signal return page. */
 309                 return_ip = cris_signal_return_page;
 310
 311                 /*
 312                  * This is movu.w __NR_sigreturn, r9; break 13;
 313                  *
 314                  * WE DO NOT USE IT ANY MORE! It's only left here for historical
 315                  * reasons and because gdb uses it as a signature to notice
 316                  * signal handler stack frames.
 317                  */
 318                 err |= __put_user(0x9c5f,         (short __user*)(frame->retcode+0));
 319                 err |= __put_user(__NR_sigreturn, (short __user*)(frame->retcode+2));
 320                 err |= __put_user(0xe93d,         (short __user*)(frame->retcode+4));
 321         }
 322
 323         if (err)
 324                 goto give_sigsegv;
 325
 326         /*
 327          * Set up registers for signal handler.
 328          *
 329          * Where the code enters now.
 330          * Where the code enter later.
 331          * First argument, signo.
 332          */
 333         regs->erp = (unsigned long) ka->sa.sa_handler;
 334         regs->srp = return_ip;
 335         regs->r10 = sig;
 336
 337         /* Actually move the USP to reflect the stacked frame. */
 338         wrusp((unsigned long)frame);
 339
 340         return 0;
 341
 342 give_sigsegv:
 343         force_sigsegv(sig, current);
 344         return -EFAULT;
 345 }
 346
 347 static int
 348 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 349                sigset_t *set, struct pt_regs * regs)
 350 {
 351         int err;
 352         unsigned long return_ip;
 353         struct rt_signal_frame __user *frame;
 354
 355         err = 0;
 356         frame = get_sigframe(ka, regs, sizeof(*frame));
 357
 358         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 359                 goto give_sigsegv;
 360
 361         /* TODO: what is the current->exec_domain stuff and invmap ? */
 362
 363         err |= __put_user(&frame->info, &frame->pinfo);
 364         err |= __put_user(&frame->uc, &frame->puc);
 365         err |= copy_siginfo_to_user(&frame->info, info);
 366
 367         if (err)
 368                 goto give_sigsegv;
 369
 370         /* Clear all the bits of the ucontext we don't use.  */
 371         err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
 372         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
 373         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 374
 375         if (err)
 376                 goto give_sigsegv;
 377
 378         /*
 379          * Set up to return from user-space. If provided, use a stub
 380          * already located in user-space.
 381          */
 382         if (ka->sa.sa_flags & SA_RESTORER) {
 383                 return_ip = (unsigned long) ka->sa.sa_restorer;
 384         } else {
 385                 /* Trampoline - the desired return ip is in the signal return page. */
 386                 return_ip = cris_signal_return_page + 6;
 387
 388                 /*
 389                  * This is movu.w __NR_rt_sigreturn, r9; break 13;
 390                  *
 391                  * WE DO NOT USE IT ANY MORE! It's only left here for historical
 392                  * reasons and because gdb uses it as a signature to notice
 393                  * signal handler stack frames.
 394                  */
 395                 err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0));
 396
 397                 err |= __put_user(__NR_rt_sigreturn,
 398                                   (short __user*)(frame->retcode+2));
 399
 400                 err |= __put_user(0xe93d, (short __user*)(frame->retcode+4));
 401         }
 402
 403         if (err)
 404                 goto give_sigsegv;
 405
 406         /*
 407          * Set up registers for signal handler.
 408          *
 409          * Where the code enters now.
 410          * Where the code enters later.
 411          * First argument is signo.
 412          * Second argument is (siginfo_t *).
 413          * Third argument is unused.
 414          */
 415         regs->erp = (unsigned long) ka->sa.sa_handler;
 416         regs->srp = return_ip;
 417         regs->r10 = sig;
 418         regs->r11 = (unsigned long) &frame->info;
 419         regs->r12 = 0;
 420
 421         /* Actually move the usp to reflect the stacked frame. */
 422         wrusp((unsigned long)frame);
 423
 424         return 0;
 425
 426 give_sigsegv:
 427         force_sigsegv(sig, current);
 428         return -EFAULT;
 429 }
 430
 431 /* Invoke a signal handler to, well, handle the signal. */
 432 static inline void
 433 handle_signal(int canrestart, unsigned long sig,
 434               siginfo_t *info, struct k_sigaction *ka,
 435               struct pt_regs * regs)
 436 {
 437         sigset_t *oldset = sigmask_to_save();
 438         int ret;
 439
 440         /* Check if this got called from a system call. */
 441         if (canrestart) {
 442                 /* If so, check system call restarting. */
 443                 switch (regs->r10) {
 444                         case -ERESTART_RESTARTBLOCK:
 445                         case -ERESTARTNOHAND:
 446                                 /*
 447                                  * This means that the syscall should
 448                                  * only be restarted if there was no
 449                                  * handler for the signal, and since
 450                                  * this point isn't reached unless
 451                                  * there is a handler, there's no need
 452                                  * to restart.
 453                                  */
 454                                 regs->r10 = -EINTR;
 455                                 break;
 456
 457                         case -ERESTARTSYS:
 458                                 /*
 459                                  * This means restart the syscall if
 460                                  * there is no handler, or the handler
 461                                  * was registered with SA_RESTART.
 462                                  */
 463                                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 464                                         regs->r10 = -EINTR;
 465                                         break;
 466                                 }
 467
 468                                 /* Fall through. */
 469
 470                         case -ERESTARTNOINTR:
 471                                 /*
 472                                  * This means that the syscall should
 473                                  * be called again after the signal
 474                                  * handler returns.
 475                                  */
 476                                 RESTART_CRIS_SYS(regs);
 477                                 break;
 478                 }
 479         }
 480
 481         /* Set up the stack frame. */
 482         if (ka->sa.sa_flags & SA_SIGINFO)
 483                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 484         else
 485                 ret = setup_frame(sig, ka, oldset, regs);
 486
 487         if (ret == 0)
 488                 signal_delivered(sig, info, ka, regs, 0);
 489 }
 490
 491 /*
 492  * Note that 'init' is a special process: it doesn't get signals it doesn't
 493  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 494  * mistake.
 495  *
 496  * Also note that the regs structure given here as an argument, is the latest
 497  * pushed pt_regs. It may or may not be the same as the first pushed registers
 498  * when the initial usermode->kernelmode transition took place. Therefore
 499  * we can use user_mode(regs) to see if we came directly from kernel or user
 500  * mode below.
 501  */
 502 void
 503 do_signal(int canrestart, struct pt_regs *regs)
 504 {
 505         int signr;
 506         siginfo_t info;
 507         struct k_sigaction ka;
 508
 509         /*
 510          * The common case should go fast, which is why this point is
 511          * reached from kernel-mode. If that's the case, just return
 512          * without doing anything.
 513          */
 514         if (!user_mode(regs))
 515                 return;
 516
 517         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 518
 519         if (signr > 0) {
 520                 /* Whee!  Actually deliver the signal.  */
 521                 handle_signal(canrestart, signr, &info, &ka, regs);
 522                 return;
 523         }
 524
 525         /* Got here from a system call? */
 526         if (canrestart) {
 527                 /* Restart the system call - no handlers present. */
 528                 if (regs->r10 == -ERESTARTNOHAND ||
 529                     regs->r10 == -ERESTARTSYS ||
 530                     regs->r10 == -ERESTARTNOINTR) {
 531                         RESTART_CRIS_SYS(regs);
 532                 }
 533
 534                 if (regs->r10 == -ERESTART_RESTARTBLOCK){
 535                         regs->r9 = __NR_restart_syscall;
 536                         regs->erp -= 2;
 537                 }
 538         }
 539
 540         /* if there's no signal to deliver, we just put the saved sigmask
 541          * back */
 542         restore_saved_sigmask();
 543 }
 544
 545 asmlinkage void
 546 ugdb_trap_user(struct thread_info *ti, int sig)
 547 {
 548         if (((user_regs(ti)->exs & 0xff00) >> 8) != SINGLE_STEP_INTR_VECT) {
 549                 /* Zero single-step PC if the reason we stopped wasn't a single
 550                    step exception. This is to avoid relying on it when it isn't
 551                    reliable. */
 552                 user_regs(ti)->spc = 0;
 553         }
 554         /* FIXME: Filter out false h/w breakpoint hits (i.e. EDA
 555            not within any configured h/w breakpoint range). Synchronize with
 556            what already exists for kernel debugging.  */
 557         if (((user_regs(ti)->exs & 0xff00) >> 8) == BREAK_8_INTR_VECT) {
 558                 /* Break 8: subtract 2 from ERP unless in a delay slot. */
 559                 if (!(user_regs(ti)->erp & 0x1))
 560                         user_regs(ti)->erp -= 2;
 561         }
 562         sys_kill(ti->task->pid, sig);
 563 }
 564
 565 void
 566 keep_debug_flags(unsigned long oldccs, unsigned long oldspc,
 567                  struct pt_regs *regs)
 568 {
 569         if (oldccs & (1 << Q_CCS_BITNR)) {
 570                 /* Pending single step due to single-stepping the break 13
 571                    in the signal trampoline: keep the Q flag. */
 572                 regs->ccs |= (1 << Q_CCS_BITNR);
 573                 /* S flag should be set - complain if it's not. */
 574                 if (!(oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT)))) {
 575                         printk("Q flag but no S flag?");
 576                 }
 577                 regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
 578                 /* Assume the SPC is valid and interesting. */
 579                 regs->spc = oldspc;
 580
 581         } else if (oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT))) {
 582                 /* If a h/w bp was set in the signal handler we need
 583                    to keep the S flag. */
 584                 regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT));
 585                 /* Don't keep the old SPC though; if we got here due to
 586                    a single-step, the Q flag should have been set. */
 587         } else if (regs->spc) {
 588                 /* If we were single-stepping *before* the signal was taken,
 589                    we don't want to restore that state now, because GDB will
 590                    have forgotten all about it. */
 591                 regs->spc = 0;
 592                 regs->ccs &= ~(1 << (S_CCS_BITNR + CCS_SHIFT));
 593         }
 594 }
 595
 596 /* Set up the trampolines on the signal return page. */
 597 int __init
 598 cris_init_signal(void)
 599 {
 600         u16* data = kmalloc(PAGE_SIZE, GFP_KERNEL);
 601
 602         /* This is movu.w __NR_sigreturn, r9; break 13; */
 603         data[0] = 0x9c5f;
 604         data[1] = __NR_sigreturn;
 605         data[2] = 0xe93d;
 606         /* This is movu.w __NR_rt_sigreturn, r9; break 13; */
 607         data[3] = 0x9c5f;
 608         data[4] = __NR_rt_sigreturn;
 609         data[5] = 0xe93d;
 610
 611         /* Map to userspace with appropriate permissions (no write access...) */
 612         cris_signal_return_page = (unsigned long)
 613           __ioremap_prot(virt_to_phys(data), PAGE_SIZE, PAGE_SIGNAL_TRAMPOLINE);
 614
 615         return 0;
 616 }
 617
 618 __initcall(cris_init_signal);