arch/arm26/kernel/signal.c

   1 /*
   2  *  linux/arch/arm26/kernel/signal.c
   3  *
   4  *  Copyright (C) 1995-2002 Russell King
   5  *  Copyright (C) 2003 Ian Molton (ARM26)
   6  *
   7  * FIXME!!! This is probably very broken (13/05/2003)
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13 #include <linux/sched.h>
  14 #include <linux/mm.h>
  15 #include <linux/smp.h>
  16 #include <linux/smp_lock.h>
  17 #include <linux/kernel.h>
  18 #include <linux/errno.h>
  19 #include <linux/signal.h>
  20 #include <linux/wait.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/personality.h>
  23 #include <linux/tty.h>
  24 #include <linux/binfmts.h>
  25 #include <linux/elf.h>
  26
  27 #include <asm/pgalloc.h>
  28 #include <asm/ucontext.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/unistd.h>
  31
  32 #include "ptrace.h"
  33
  34 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  35
  36 /*
  37  * For ARM syscalls, we encode the syscall number into the instruction.
  38  */
  39 #define SWI_SYS_SIGRETURN       (0xef000000|(__NR_sigreturn))
  40 #define SWI_SYS_RT_SIGRETURN    (0xef000000|(__NR_rt_sigreturn))
  41
  42 static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall);
  43
  44 /*
  45  * atomically swap in the new signal mask, and wait for a signal.
  46  */
  47 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs)
  48 {
  49         sigset_t saveset;
  50
  51         mask &= _BLOCKABLE;
  52         spin_lock_irq(&current->sighand->siglock);
  53         saveset = current->blocked;
  54         siginitset(&current->blocked, mask);
  55         recalc_sigpending();
  56         spin_unlock_irq(&current->sighand->siglock);
  57         regs->ARM_r0 = -EINTR;
  58
  59         while (1) {
  60                 current->state = TASK_INTERRUPTIBLE;
  61                 schedule();
  62                 if (do_signal(&saveset, regs, 0))
  63                         return regs->ARM_r0;
  64         }
  65 }
  66
  67 asmlinkage int
  68 sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize, struct pt_regs *regs)
  69 {
  70         sigset_t saveset, newset;
  71
  72         /* XXX: Don't preclude handling different sized sigset_t's. */
  73         if (sigsetsize != sizeof(sigset_t))
  74                 return -EINVAL;
  75
  76         if (copy_from_user(&newset, unewset, sizeof(newset)))
  77                 return -EFAULT;
  78         sigdelsetmask(&newset, ~_BLOCKABLE);
  79
  80         spin_lock_irq(&current->sighand->siglock);
  81         saveset = current->blocked;
  82         current->blocked = newset;
  83         recalc_sigpending();
  84         spin_unlock_irq(&current->sighand->siglock);
  85         regs->ARM_r0 = -EINTR;
  86
  87         while (1) {
  88                 current->state = TASK_INTERRUPTIBLE;
  89                 schedule();
  90                 if (do_signal(&saveset, regs, 0))
  91                         return regs->ARM_r0;
  92         }
  93 }
  94
  95 asmlinkage int
  96 sys_sigaction(int sig, const struct old_sigaction *act,
  97               struct old_sigaction *oact)
  98 {
  99         struct k_sigaction new_ka, old_ka;
 100         int ret;
 101
 102         if (act) {
 103                 old_sigset_t mask;
 104                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
 105                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
 106                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
 107                         return -EFAULT;
 108                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 109                 __get_user(mask, &act->sa_mask);
 110                 siginitset(&new_ka.sa.sa_mask, mask);
 111         }
 112
 113         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 114
 115         if (!ret && oact) {
 116                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
 117                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 118                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 119                         return -EFAULT;
 120                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 121                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 122         }
 123
 124         return ret;
 125 }
 126
 127 /*
 128  * Do a signal return; undo the signal stack.
 129  */
 130 struct sigframe
 131 {
 132         struct sigcontext sc;
 133         unsigned long extramask[_NSIG_WORDS-1];
 134         unsigned long retcode;
 135 };
 136
 137 struct rt_sigframe
 138 {
 139         struct siginfo *pinfo;
 140         void *puc;
 141         struct siginfo info;
 142         struct ucontext uc;
 143         unsigned long retcode;
 144 };
 145
 146 static int
 147 restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc)
 148 {
 149         int err = 0;
 150
 151         __get_user_error(regs->ARM_r0, &sc->arm_r0, err);
 152         __get_user_error(regs->ARM_r1, &sc->arm_r1, err);
 153         __get_user_error(regs->ARM_r2, &sc->arm_r2, err);
 154         __get_user_error(regs->ARM_r3, &sc->arm_r3, err);
 155         __get_user_error(regs->ARM_r4, &sc->arm_r4, err);
 156         __get_user_error(regs->ARM_r5, &sc->arm_r5, err);
 157         __get_user_error(regs->ARM_r6, &sc->arm_r6, err);
 158         __get_user_error(regs->ARM_r7, &sc->arm_r7, err);
 159         __get_user_error(regs->ARM_r8, &sc->arm_r8, err);
 160         __get_user_error(regs->ARM_r9, &sc->arm_r9, err);
 161         __get_user_error(regs->ARM_r10, &sc->arm_r10, err);
 162         __get_user_error(regs->ARM_fp, &sc->arm_fp, err);
 163         __get_user_error(regs->ARM_ip, &sc->arm_ip, err);
 164         __get_user_error(regs->ARM_sp, &sc->arm_sp, err);
 165         __get_user_error(regs->ARM_lr, &sc->arm_lr, err);
 166         __get_user_error(regs->ARM_pc, &sc->arm_pc, err);
 167
 168         err |= !valid_user_regs(regs);
 169
 170         return err;
 171 }
 172
 173 asmlinkage int sys_sigreturn(struct pt_regs *regs)
 174 {
 175         struct sigframe *frame;
 176         sigset_t set;
 177
 178         /*
 179          * Since we stacked the signal on a 64-bit boundary,
 180          * then 'sp' should be word aligned here.  If it's
 181          * not, then the user is trying to mess with us.
 182          */
 183         if (regs->ARM_sp & 7)
 184                 goto badframe;
 185
 186         frame = (struct sigframe *)regs->ARM_sp;
 187
 188         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 189                 goto badframe;
 190         if (__get_user(set.sig[0], &frame->sc.oldmask)
 191             || (_NSIG_WORDS > 1
 192                 && __copy_from_user(&set.sig[1], &frame->extramask,
 193                                     sizeof(frame->extramask))))
 194                 goto badframe;
 195
 196         sigdelsetmask(&set, ~_BLOCKABLE);
 197         spin_lock_irq(&current->sighand->siglock);
 198         current->blocked = set;
 199         recalc_sigpending();
 200         spin_unlock_irq(&current->sighand->siglock);
 201
 202         if (restore_sigcontext(regs, &frame->sc))
 203                 goto badframe;
 204
 205         /* Send SIGTRAP if we're single-stepping */
 206         if (current->ptrace & PT_SINGLESTEP) {
 207                 ptrace_cancel_bpt(current);
 208                 send_sig(SIGTRAP, current, 1);
 209         }
 210
 211         return regs->ARM_r0;
 212
 213 badframe:
 214         force_sig(SIGSEGV, current);
 215         return 0;
 216 }
 217
 218 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 219 {
 220         struct rt_sigframe *frame;
 221         sigset_t set;
 222
 223         /*
 224          * Since we stacked the signal on a 64-bit boundary,
 225          * then 'sp' should be word aligned here.  If it's
 226          * not, then the user is trying to mess with us.
 227          */
 228         if (regs->ARM_sp & 7)
 229                 goto badframe;
 230
 231         frame = (struct rt_sigframe *)regs->ARM_sp;
 232
 233         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 234                 goto badframe;
 235         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 236                 goto badframe;
 237
 238         sigdelsetmask(&set, ~_BLOCKABLE);
 239         spin_lock_irq(&current->sighand->siglock);
 240         current->blocked = set;
 241         recalc_sigpending();
 242         spin_unlock_irq(&current->sighand->siglock);
 243
 244         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 245                 goto badframe;
 246
 247         /* Send SIGTRAP if we're single-stepping */
 248         if (current->ptrace & PT_SINGLESTEP) {
 249                 ptrace_cancel_bpt(current);
 250                 send_sig(SIGTRAP, current, 1);
 251         }
 252
 253         return regs->ARM_r0;
 254
 255 badframe:
 256         force_sig(SIGSEGV, current);
 257         return 0;
 258 }
 259
 260 static int
 261 setup_sigcontext(struct sigcontext *sc, /*struct _fpstate *fpstate,*/
 262                  struct pt_regs *regs, unsigned long mask)
 263 {
 264         int err = 0;
 265
 266         __put_user_error(regs->ARM_r0, &sc->arm_r0, err);
 267         __put_user_error(regs->ARM_r1, &sc->arm_r1, err);
 268         __put_user_error(regs->ARM_r2, &sc->arm_r2, err);
 269         __put_user_error(regs->ARM_r3, &sc->arm_r3, err);
 270         __put_user_error(regs->ARM_r4, &sc->arm_r4, err);
 271         __put_user_error(regs->ARM_r5, &sc->arm_r5, err);
 272         __put_user_error(regs->ARM_r6, &sc->arm_r6, err);
 273         __put_user_error(regs->ARM_r7, &sc->arm_r7, err);
 274         __put_user_error(regs->ARM_r8, &sc->arm_r8, err);
 275         __put_user_error(regs->ARM_r9, &sc->arm_r9, err);
 276         __put_user_error(regs->ARM_r10, &sc->arm_r10, err);
 277         __put_user_error(regs->ARM_fp, &sc->arm_fp, err);
 278         __put_user_error(regs->ARM_ip, &sc->arm_ip, err);
 279         __put_user_error(regs->ARM_sp, &sc->arm_sp, err);
 280         __put_user_error(regs->ARM_lr, &sc->arm_lr, err);
 281         __put_user_error(regs->ARM_pc, &sc->arm_pc, err);
 282
 283         __put_user_error(current->thread.trap_no, &sc->trap_no, err);
 284         __put_user_error(current->thread.error_code, &sc->error_code, err);
 285         __put_user_error(current->thread.address, &sc->fault_address, err);
 286         __put_user_error(mask, &sc->oldmask, err);
 287
 288         return err;
 289 }
 290
 291 static inline void *
 292 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 293 {
 294         unsigned long sp = regs->ARM_sp;
 295
 296         /*
 297          * This is the X/Open sanctioned signal stack switching.
 298          */
 299         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 300                 sp = current->sas_ss_sp + current->sas_ss_size;
 301
 302         /*
 303          * ATPCS B01 mandates 8-byte alignment
 304          */
 305         return (void *)((sp - framesize) & ~7);
 306 }
 307
 308 static int
 309 setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 310              unsigned long *rc, void *frame, int usig)
 311 {
 312         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 313         unsigned long retcode;
 314
 315         if (ka->sa.sa_flags & SA_RESTORER) {
 316                 retcode = (unsigned long)ka->sa.sa_restorer;
 317         } else {
 318
 319                 if (__put_user((ka->sa.sa_flags & SA_SIGINFO)?SWI_SYS_RT_SIGRETURN:SWI_SYS_SIGRETURN, rc))
 320                         return 1;
 321
 322                 retcode = ((unsigned long)rc);
 323         }
 324
 325         regs->ARM_r0 = usig;
 326         regs->ARM_sp = (unsigned long)frame;
 327         regs->ARM_lr = retcode;
 328         regs->ARM_pc = handler & ~3;
 329
 330         return 0;
 331 }
 332
 333 static int
 334 setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
 335 {
 336         struct sigframe *frame = get_sigframe(ka, regs, sizeof(*frame));
 337         int err = 0;
 338
 339         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 340                 return 1;
 341
 342         err |= setup_sigcontext(&frame->sc, /*&frame->fpstate,*/ regs, set->sig[0]);
 343
 344         if (_NSIG_WORDS > 1) {
 345                 err |= __copy_to_user(frame->extramask, &set->sig[1],
 346                                       sizeof(frame->extramask));
 347         }
 348
 349         if (err == 0)
 350                 err = setup_return(regs, ka, &frame->retcode, frame, usig);
 351
 352         return err;
 353 }
 354
 355 static int
 356 setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 357                sigset_t *set, struct pt_regs *regs)
 358 {
 359         struct rt_sigframe *frame = get_sigframe(ka, regs, sizeof(*frame));
 360         int err = 0;
 361
 362         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 363                 return 1;
 364
 365         __put_user_error(&frame->info, &frame->pinfo, err);
 366         __put_user_error(&frame->uc, &frame->puc, err);
 367         err |= copy_siginfo_to_user(&frame->info, info);
 368
 369         /* Clear all the bits of the ucontext we don't use.  */
 370         err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
 371
 372         err |= setup_sigcontext(&frame->uc.uc_mcontext, /*&frame->fpstate,*/
 373                                 regs, set->sig[0]);
 374         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 375
 376         if (err == 0)
 377                 err = setup_return(regs, ka, &frame->retcode, frame, usig);
 378
 379         if (err == 0) {
 380                 /*
 381                  * For realtime signals we must also set the second and third
 382                  * arguments for the signal handler.
 383                  *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 384                  */
 385                 regs->ARM_r1 = (unsigned long)frame->pinfo;
 386                 regs->ARM_r2 = (unsigned long)frame->puc;
 387         }
 388
 389         return err;
 390 }
 391
 392 static inline void restart_syscall(struct pt_regs *regs)
 393 {
 394         regs->ARM_r0 = regs->ARM_ORIG_r0;
 395         regs->ARM_pc -= 4;
 396 }
 397
 398 /*
 399  * OK, we're invoking a handler
 400  */
 401 static void
 402 handle_signal(unsigned long sig, siginfo_t *info, sigset_t *oldset,
 403               struct pt_regs * regs, int syscall)
 404 {
 405         struct thread_info *thread = current_thread_info();
 406         struct task_struct *tsk = current;
 407         struct k_sigaction *ka = &tsk->sighand->action[sig-1];
 408         int usig = sig;
 409         int ret;
 410
 411         /*
 412          * If we were from a system call, check for system call restarting...
 413          */
 414         if (syscall) {
 415                 switch (regs->ARM_r0) {
 416                 case -ERESTART_RESTARTBLOCK:
 417                         current_thread_info()->restart_block.fn =
 418                                 do_no_restart_syscall;
 419                 case -ERESTARTNOHAND:
 420                         regs->ARM_r0 = -EINTR;
 421                         break;
 422                 case -ERESTARTSYS:
 423                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 424                                 regs->ARM_r0 = -EINTR;
 425                                 break;
 426                         }
 427                         /* fallthrough */
 428                 case -ERESTARTNOINTR:
 429                         restart_syscall(regs);
 430                 }
 431         }
 432
 433         /*
 434          * translate the signal
 435          */
 436         if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
 437                 usig = thread->exec_domain->signal_invmap[usig];
 438
 439         /*
 440          * Set up the stack frame
 441          */
 442         if (ka->sa.sa_flags & SA_SIGINFO)
 443                 ret = setup_rt_frame(usig, ka, info, oldset, regs);
 444         else
 445                 ret = setup_frame(usig, ka, oldset, regs);
 446
 447         /*
 448          * Check that the resulting registers are actually sane.
 449          */
 450         ret |= !valid_user_regs(regs);
 451
 452         if (ret == 0) {
 453                 if (ka->sa.sa_flags & SA_ONESHOT)
 454                         ka->sa.sa_handler = SIG_DFL;
 455
 456                 spin_lock_irq(&tsk->sighand->siglock);
 457                 sigorsets(&tsk->blocked, &tsk->blocked,
 458                           &ka->sa.sa_mask);
 459                 if (!(ka->sa.sa_flags & SA_NODEFER))
 460                         sigaddset(&tsk->blocked, sig);
 461                 recalc_sigpending();
 462                 spin_unlock_irq(&tsk->sighand->siglock);
 463                 return;
 464         }
 465
 466         force_sigsegv(sig, tsk);
 467 }
 468
 469 /*
 470  * Note that 'init' is a special process: it doesn't get signals it doesn't
 471  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 472  * mistake.
 473  *
 474  * Note that we go through the signals twice: once to check the signals that
 475  * the kernel can handle, and then we build all the user-level signal handling
 476  * stack-frames in one go after that.
 477  */
 478 static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
 479 {
 480         siginfo_t info;
 481         int signr;
 482         struct k_sigaction ka;
 483
 484         /*
 485          * We want the common case to go fast, which
 486          * is why we may in certain cases get here from
 487          * kernel mode. Just return without doing anything
 488          * if so.
 489          */
 490         if (!user_mode(regs))
 491                 return 0;
 492
 493         if (current->ptrace & PT_SINGLESTEP)
 494                 ptrace_cancel_bpt(current);
 495
 496         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 497         if (signr > 0) {
 498                 handle_signal(signr, &info, oldset, regs, syscall);
 499                 if (current->ptrace & PT_SINGLESTEP)
 500                         ptrace_set_bpt(current);
 501                 return 1;
 502         }
 503
 504         /*
 505          * No signal to deliver to the process - restart the syscall.
 506          */
 507         if (syscall) {
 508                 if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
 509                         u32 *usp;
 510
 511                         regs->ARM_sp -= 12;
 512                         usp = (u32 *)regs->ARM_sp;
 513
 514                         put_user(regs->ARM_pc, &usp[0]);
 515                         /* swi __NR_restart_syscall */
 516                         put_user(0xef000000 | __NR_restart_syscall, &usp[1]);
 517                         /* ldr  pc, [sp], #12 */
 518 // FIXME!!! is #12 correct there?
 519                         put_user(0xe49df00c, &usp[2]);
 520
 521                         regs->ARM_pc = regs->ARM_sp + 4;
 522                 }
 523                 if (regs->ARM_r0 == -ERESTARTNOHAND ||
 524                     regs->ARM_r0 == -ERESTARTSYS ||
 525                     regs->ARM_r0 == -ERESTARTNOINTR) {
 526                         restart_syscall(regs);
 527                 }
 528         }
 529         if (current->ptrace & PT_SINGLESTEP)
 530                 ptrace_set_bpt(current);
 531         return 0;
 532 }
 533
 534 asmlinkage void
 535 do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 536 {
 537         if (thread_flags & _TIF_SIGPENDING)
 538                 do_signal(&current->blocked, regs, syscall);
 539 }