arch/arm/kernel/signal.c

   1 /*
   2  *  linux/arch/arm/kernel/signal.c
   3  *
   4  *  Copyright (C) 1995-2002 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/config.h>
  11 #include <linux/errno.h>
  12 #include <linux/signal.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/personality.h>
  15
  16 #include <asm/cacheflush.h>
  17 #include <asm/ucontext.h>
  18 #include <asm/uaccess.h>
  19 #include <asm/unistd.h>
  20
  21 #include "ptrace.h"
  22
  23 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  24
  25 /*
  26  * For ARM syscalls, we encode the syscall number into the instruction.
  27  */
  28 #define SWI_SYS_SIGRETURN       (0xef000000|(__NR_sigreturn))
  29 #define SWI_SYS_RT_SIGRETURN    (0xef000000|(__NR_rt_sigreturn))
  30
  31 /*
  32  * For Thumb syscalls, we pass the syscall number via r7.  We therefore
  33  * need two 16-bit instructions.
  34  */
  35 #define SWI_THUMB_SIGRETURN     (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  36 #define SWI_THUMB_RT_SIGRETURN  (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  37
  38 static const unsigned long retcodes[4] = {
  39         SWI_SYS_SIGRETURN,      SWI_THUMB_SIGRETURN,
  40         SWI_SYS_RT_SIGRETURN,   SWI_THUMB_RT_SIGRETURN
  41 };
  42
  43 static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall);
  44
  45 /*
  46  * atomically swap in the new signal mask, and wait for a signal.
  47  */
  48 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs)
  49 {
  50         sigset_t saveset;
  51
  52         mask &= _BLOCKABLE;
  53         spin_lock_irq(&current->sighand->siglock);
  54         saveset = current->blocked;
  55         siginitset(&current->blocked, mask);
  56         recalc_sigpending();
  57         spin_unlock_irq(&current->sighand->siglock);
  58         regs->ARM_r0 = -EINTR;
  59
  60         while (1) {
  61                 current->state = TASK_INTERRUPTIBLE;
  62                 schedule();
  63                 if (do_signal(&saveset, regs, 0))
  64                         return regs->ARM_r0;
  65         }
  66 }
  67
  68 asmlinkage int
  69 sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
  70 {
  71         sigset_t saveset, newset;
  72
  73         /* XXX: Don't preclude handling different sized sigset_t's. */
  74         if (sigsetsize != sizeof(sigset_t))
  75                 return -EINVAL;
  76
  77         if (copy_from_user(&newset, unewset, sizeof(newset)))
  78                 return -EFAULT;
  79         sigdelsetmask(&newset, ~_BLOCKABLE);
  80
  81         spin_lock_irq(&current->sighand->siglock);
  82         saveset = current->blocked;
  83         current->blocked = newset;
  84         recalc_sigpending();
  85         spin_unlock_irq(&current->sighand->siglock);
  86         regs->ARM_r0 = -EINTR;
  87
  88         while (1) {
  89                 current->state = TASK_INTERRUPTIBLE;
  90                 schedule();
  91                 if (do_signal(&saveset, regs, 0))
  92                         return regs->ARM_r0;
  93         }
  94 }
  95
  96 asmlinkage int
  97 sys_sigaction(int sig, const struct old_sigaction __user *act,
  98               struct old_sigaction __user *oact)
  99 {
 100         struct k_sigaction new_ka, old_ka;
 101         int ret;
 102
 103         if (act) {
 104                 old_sigset_t mask;
 105                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
 106                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
 107                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
 108                         return -EFAULT;
 109                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 110                 __get_user(mask, &act->sa_mask);
 111                 siginitset(&new_ka.sa.sa_mask, mask);
 112         }
 113
 114         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 115
 116         if (!ret && oact) {
 117                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
 118                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 119                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 120                         return -EFAULT;
 121                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 122                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 123         }
 124
 125         return ret;
 126 }
 127
 128 #ifdef CONFIG_IWMMXT
 129
 130 /* iwmmxt_area is 0x98 bytes long, preceeded by 8 bytes of signature */
 131 #define IWMMXT_STORAGE_SIZE     (0x98 + 8)
 132 #define IWMMXT_MAGIC0           0x12ef842a
 133 #define IWMMXT_MAGIC1           0x1c07ca71
 134
 135 struct iwmmxt_sigframe {
 136         unsigned long   magic0;
 137         unsigned long   magic1;
 138         unsigned long   storage[0x98/4];
 139 };
 140
 141 static int page_present(struct mm_struct *mm, void __user *uptr, int wr)
 142 {
 143         unsigned long addr = (unsigned long)uptr;
 144         pgd_t *pgd = pgd_offset(mm, addr);
 145         if (pgd_present(*pgd)) {
 146                 pmd_t *pmd = pmd_offset(pgd, addr);
 147                 if (pmd_present(*pmd)) {
 148                         pte_t *pte = pte_offset_map(pmd, addr);
 149                         return (pte_present(*pte) && (!wr || pte_write(*pte)));
 150                 }
 151         }
 152         return 0;
 153 }
 154
 155 static int copy_locked(void __user *uptr, void *kptr, size_t size, int write,
 156                        void (*copyfn)(void *, void __user *))
 157 {
 158         unsigned char v, __user *userptr = uptr;
 159         int err = 0;
 160
 161         do {
 162                 struct mm_struct *mm;
 163
 164                 if (write) {
 165                         __put_user_error(0, userptr, err);
 166                         __put_user_error(0, userptr + size - 1, err);
 167                 } else {
 168                         __get_user_error(v, userptr, err);
 169                         __get_user_error(v, userptr + size - 1, err);
 170                 }
 171
 172                 if (err)
 173                         break;
 174
 175                 mm = current->mm;
 176                 spin_lock(&mm->page_table_lock);
 177                 if (page_present(mm, userptr, write) &&
 178                     page_present(mm, userptr + size - 1, write)) {
 179                         copyfn(kptr, uptr);
 180                 } else
 181                         err = 1;
 182                 spin_unlock(&mm->page_table_lock);
 183         } while (err);
 184
 185         return err;
 186 }
 187
 188 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
 189 {
 190         int err = 0;
 191
 192         /* the iWMMXt context must be 64 bit aligned */
 193         WARN_ON((unsigned long)frame & 7);
 194
 195         __put_user_error(IWMMXT_MAGIC0, &frame->magic0, err);
 196         __put_user_error(IWMMXT_MAGIC1, &frame->magic1, err);
 197
 198         /*
 199          * iwmmxt_task_copy() doesn't check user permissions.
 200          * Let's do a dummy write on the upper boundary to ensure
 201          * access to user mem is OK all way up.
 202          */
 203         err |= copy_locked(&frame->storage, current_thread_info(),
 204                            sizeof(frame->storage), 1, iwmmxt_task_copy);
 205         return err;
 206 }
 207
 208 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
 209 {
 210         unsigned long magic0, magic1;
 211         int err = 0;
 212
 213         /* the iWMMXt context is 64 bit aligned */
 214         WARN_ON((unsigned long)frame & 7);
 215
 216         /*
 217          * Validate iWMMXt context signature.
 218          * Also, iwmmxt_task_restore() doesn't check user permissions.
 219          * Let's do a dummy write on the upper boundary to ensure
 220          * access to user mem is OK all way up.
 221          */
 222         __get_user_error(magic0, &frame->magic0, err);
 223         __get_user_error(magic1, &frame->magic1, err);
 224         if (!err && magic0 == IWMMXT_MAGIC0 && magic1 == IWMMXT_MAGIC1)
 225                 err = copy_locked(&frame->storage, current_thread_info(),
 226                                   sizeof(frame->storage), 0, iwmmxt_task_restore);
 227         return err;
 228 }
 229
 230 #endif
 231
 232 /*
 233  * Auxiliary signal frame.  This saves stuff like FP state.
 234  * The layout of this structure is not part of the user ABI.
 235  */
 236 struct aux_sigframe {
 237 #ifdef CONFIG_IWMMXT
 238         struct iwmmxt_sigframe  iwmmxt;
 239 #endif
 240 #ifdef CONFIG_VFP
 241         union vfp_state         vfp;
 242 #endif
 243 };
 244
 245 /*
 246  * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
 247  */
 248 struct sigframe {
 249         struct sigcontext sc;
 250         unsigned long extramask[_NSIG_WORDS-1];
 251         unsigned long retcode;
 252         struct aux_sigframe aux __attribute__((aligned(8)));
 253 };
 254
 255 struct rt_sigframe {
 256         struct siginfo __user *pinfo;
 257         void __user *puc;
 258         struct siginfo info;
 259         struct ucontext uc;
 260         unsigned long retcode;
 261         struct aux_sigframe aux __attribute__((aligned(8)));
 262 };
 263
 264 static int
 265 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
 266                    struct aux_sigframe __user *aux)
 267 {
 268         int err = 0;
 269
 270         __get_user_error(regs->ARM_r0, &sc->arm_r0, err);
 271         __get_user_error(regs->ARM_r1, &sc->arm_r1, err);
 272         __get_user_error(regs->ARM_r2, &sc->arm_r2, err);
 273         __get_user_error(regs->ARM_r3, &sc->arm_r3, err);
 274         __get_user_error(regs->ARM_r4, &sc->arm_r4, err);
 275         __get_user_error(regs->ARM_r5, &sc->arm_r5, err);
 276         __get_user_error(regs->ARM_r6, &sc->arm_r6, err);
 277         __get_user_error(regs->ARM_r7, &sc->arm_r7, err);
 278         __get_user_error(regs->ARM_r8, &sc->arm_r8, err);
 279         __get_user_error(regs->ARM_r9, &sc->arm_r9, err);
 280         __get_user_error(regs->ARM_r10, &sc->arm_r10, err);
 281         __get_user_error(regs->ARM_fp, &sc->arm_fp, err);
 282         __get_user_error(regs->ARM_ip, &sc->arm_ip, err);
 283         __get_user_error(regs->ARM_sp, &sc->arm_sp, err);
 284         __get_user_error(regs->ARM_lr, &sc->arm_lr, err);
 285         __get_user_error(regs->ARM_pc, &sc->arm_pc, err);
 286         __get_user_error(regs->ARM_cpsr, &sc->arm_cpsr, err);
 287
 288         err |= !valid_user_regs(regs);
 289
 290 #ifdef CONFIG_IWMMXT
 291         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 292                 err |= restore_iwmmxt_context(&aux->iwmmxt);
 293 #endif
 294 #ifdef CONFIG_VFP
 295 //      if (err == 0)
 296 //              err |= vfp_restore_state(&aux->vfp);
 297 #endif
 298
 299         return err;
 300 }
 301
 302 asmlinkage int sys_sigreturn(struct pt_regs *regs)
 303 {
 304         struct sigframe __user *frame;
 305         sigset_t set;
 306
 307         /* Always make any pending restarted system calls return -EINTR */
 308         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 309
 310         /*
 311          * Since we stacked the signal on a 64-bit boundary,
 312          * then 'sp' should be word aligned here.  If it's
 313          * not, then the user is trying to mess with us.
 314          */
 315         if (regs->ARM_sp & 7)
 316                 goto badframe;
 317
 318         frame = (struct sigframe __user *)regs->ARM_sp;
 319
 320         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 321                 goto badframe;
 322         if (__get_user(set.sig[0], &frame->sc.oldmask)
 323             || (_NSIG_WORDS > 1
 324                 && __copy_from_user(&set.sig[1], &frame->extramask,
 325                                     sizeof(frame->extramask))))
 326                 goto badframe;
 327
 328         sigdelsetmask(&set, ~_BLOCKABLE);
 329         spin_lock_irq(&current->sighand->siglock);
 330         current->blocked = set;
 331         recalc_sigpending();
 332         spin_unlock_irq(&current->sighand->siglock);
 333
 334         if (restore_sigcontext(regs, &frame->sc, &frame->aux))
 335                 goto badframe;
 336
 337         /* Send SIGTRAP if we're single-stepping */
 338         if (current->ptrace & PT_SINGLESTEP) {
 339                 ptrace_cancel_bpt(current);
 340                 send_sig(SIGTRAP, current, 1);
 341         }
 342
 343         return regs->ARM_r0;
 344
 345 badframe:
 346         force_sig(SIGSEGV, current);
 347         return 0;
 348 }
 349
 350 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 351 {
 352         struct rt_sigframe __user *frame;
 353         sigset_t set;
 354
 355         /* Always make any pending restarted system calls return -EINTR */
 356         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 357
 358         /*
 359          * Since we stacked the signal on a 64-bit boundary,
 360          * then 'sp' should be word aligned here.  If it's
 361          * not, then the user is trying to mess with us.
 362          */
 363         if (regs->ARM_sp & 7)
 364                 goto badframe;
 365
 366         frame = (struct rt_sigframe __user *)regs->ARM_sp;
 367
 368         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 369                 goto badframe;
 370         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 371                 goto badframe;
 372
 373         sigdelsetmask(&set, ~_BLOCKABLE);
 374         spin_lock_irq(&current->sighand->siglock);
 375         current->blocked = set;
 376         recalc_sigpending();
 377         spin_unlock_irq(&current->sighand->siglock);
 378
 379         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &frame->aux))
 380                 goto badframe;
 381
 382         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
 383                 goto badframe;
 384
 385         /* Send SIGTRAP if we're single-stepping */
 386         if (current->ptrace & PT_SINGLESTEP) {
 387                 ptrace_cancel_bpt(current);
 388                 send_sig(SIGTRAP, current, 1);
 389         }
 390
 391         return regs->ARM_r0;
 392
 393 badframe:
 394         force_sig(SIGSEGV, current);
 395         return 0;
 396 }
 397
 398 static int
 399 setup_sigcontext(struct sigcontext __user *sc, struct aux_sigframe __user *aux,
 400                  struct pt_regs *regs, unsigned long mask)
 401 {
 402         int err = 0;
 403
 404         __put_user_error(regs->ARM_r0, &sc->arm_r0, err);
 405         __put_user_error(regs->ARM_r1, &sc->arm_r1, err);
 406         __put_user_error(regs->ARM_r2, &sc->arm_r2, err);
 407         __put_user_error(regs->ARM_r3, &sc->arm_r3, err);
 408         __put_user_error(regs->ARM_r4, &sc->arm_r4, err);
 409         __put_user_error(regs->ARM_r5, &sc->arm_r5, err);
 410         __put_user_error(regs->ARM_r6, &sc->arm_r6, err);
 411         __put_user_error(regs->ARM_r7, &sc->arm_r7, err);
 412         __put_user_error(regs->ARM_r8, &sc->arm_r8, err);
 413         __put_user_error(regs->ARM_r9, &sc->arm_r9, err);
 414         __put_user_error(regs->ARM_r10, &sc->arm_r10, err);
 415         __put_user_error(regs->ARM_fp, &sc->arm_fp, err);
 416         __put_user_error(regs->ARM_ip, &sc->arm_ip, err);
 417         __put_user_error(regs->ARM_sp, &sc->arm_sp, err);
 418         __put_user_error(regs->ARM_lr, &sc->arm_lr, err);
 419         __put_user_error(regs->ARM_pc, &sc->arm_pc, err);
 420         __put_user_error(regs->ARM_cpsr, &sc->arm_cpsr, err);
 421
 422         __put_user_error(current->thread.trap_no, &sc->trap_no, err);
 423         __put_user_error(current->thread.error_code, &sc->error_code, err);
 424         __put_user_error(current->thread.address, &sc->fault_address, err);
 425         __put_user_error(mask, &sc->oldmask, err);
 426
 427 #ifdef CONFIG_IWMMXT
 428         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 429                 err |= preserve_iwmmxt_context(&aux->iwmmxt);
 430 #endif
 431 #ifdef CONFIG_VFP
 432 //      if (err == 0)
 433 //              err |= vfp_save_state(&aux->vfp);
 434 #endif
 435
 436         return err;
 437 }
 438
 439 static inline void __user *
 440 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 441 {
 442         unsigned long sp = regs->ARM_sp;
 443         void __user *frame;
 444
 445         /*
 446          * This is the X/Open sanctioned signal stack switching.
 447          */
 448         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 449                 sp = current->sas_ss_sp + current->sas_ss_size;
 450
 451         /*
 452          * ATPCS B01 mandates 8-byte alignment
 453          */
 454         frame = (void __user *)((sp - framesize) & ~7);
 455
 456         /*
 457          * Check that we can actually write to the signal frame.
 458          */
 459         if (!access_ok(VERIFY_WRITE, frame, framesize))
 460                 frame = NULL;
 461
 462         return frame;
 463 }
 464
 465 static int
 466 setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 467              unsigned long __user *rc, void __user *frame, int usig)
 468 {
 469         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 470         unsigned long retcode;
 471         int thumb = 0;
 472         unsigned long cpsr = regs->ARM_cpsr & ~PSR_f;
 473
 474         /*
 475          * Maybe we need to deliver a 32-bit signal to a 26-bit task.
 476          */
 477         if (ka->sa.sa_flags & SA_THIRTYTWO)
 478                 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
 479
 480 #ifdef CONFIG_ARM_THUMB
 481         if (elf_hwcap & HWCAP_THUMB) {
 482                 /*
 483                  * The LSB of the handler determines if we're going to
 484                  * be using THUMB or ARM mode for this signal handler.
 485                  */
 486                 thumb = handler & 1;
 487
 488                 if (thumb)
 489                         cpsr |= PSR_T_BIT;
 490                 else
 491                         cpsr &= ~PSR_T_BIT;
 492         }
 493 #endif
 494
 495         if (ka->sa.sa_flags & SA_RESTORER) {
 496                 retcode = (unsigned long)ka->sa.sa_restorer;
 497         } else {
 498                 unsigned int idx = thumb;
 499
 500                 if (ka->sa.sa_flags & SA_SIGINFO)
 501                         idx += 2;
 502
 503                 if (__put_user(retcodes[idx], rc))
 504                         return 1;
 505
 506                 /*
 507                  * Ensure that the instruction cache sees
 508                  * the return code written onto the stack.
 509                  */
 510                 flush_icache_range((unsigned long)rc,
 511                                    (unsigned long)(rc + 1));
 512
 513                 retcode = ((unsigned long)rc) + thumb;
 514         }
 515
 516         regs->ARM_r0 = usig;
 517         regs->ARM_sp = (unsigned long)frame;
 518         regs->ARM_lr = retcode;
 519         regs->ARM_pc = handler;
 520         regs->ARM_cpsr = cpsr;
 521
 522         return 0;
 523 }
 524
 525 static int
 526 setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
 527 {
 528         struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 529         int err = 0;
 530
 531         if (!frame)
 532                 return 1;
 533
 534         err |= setup_sigcontext(&frame->sc, &frame->aux, regs, set->sig[0]);
 535
 536         if (_NSIG_WORDS > 1) {
 537                 err |= __copy_to_user(frame->extramask, &set->sig[1],
 538                                       sizeof(frame->extramask));
 539         }
 540
 541         if (err == 0)
 542                 err = setup_return(regs, ka, &frame->retcode, frame, usig);
 543
 544         return err;
 545 }
 546
 547 static int
 548 setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 549                sigset_t *set, struct pt_regs *regs)
 550 {
 551         struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 552         stack_t stack;
 553         int err = 0;
 554
 555         if (!frame)
 556                 return 1;
 557
 558         __put_user_error(&frame->info, &frame->pinfo, err);
 559         __put_user_error(&frame->uc, &frame->puc, err);
 560         err |= copy_siginfo_to_user(&frame->info, info);
 561
 562         __put_user_error(0, &frame->uc.uc_flags, err);
 563         __put_user_error(NULL, &frame->uc.uc_link, err);
 564
 565         memset(&stack, 0, sizeof(stack));
 566         stack.ss_sp = (void __user *)current->sas_ss_sp;
 567         stack.ss_flags = sas_ss_flags(regs->ARM_sp);
 568         stack.ss_size = current->sas_ss_size;
 569         err |= __copy_to_user(&frame->uc.uc_stack, &stack, sizeof(stack));
 570
 571         err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->aux,
 572                                 regs, set->sig[0]);
 573         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 574
 575         if (err == 0)
 576                 err = setup_return(regs, ka, &frame->retcode, frame, usig);
 577
 578         if (err == 0) {
 579                 /*
 580                  * For realtime signals we must also set the second and third
 581                  * arguments for the signal handler.
 582                  *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 583                  */
 584                 regs->ARM_r1 = (unsigned long)&frame->info;
 585                 regs->ARM_r2 = (unsigned long)&frame->uc;
 586         }
 587
 588         return err;
 589 }
 590
 591 static inline void restart_syscall(struct pt_regs *regs)
 592 {
 593         regs->ARM_r0 = regs->ARM_ORIG_r0;
 594         regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 595 }
 596
 597 /*
 598  * OK, we're invoking a handler
 599  */
 600 static void
 601 handle_signal(unsigned long sig, struct k_sigaction *ka,
 602               siginfo_t *info, sigset_t *oldset,
 603               struct pt_regs * regs, int syscall)
 604 {
 605         struct thread_info *thread = current_thread_info();
 606         struct task_struct *tsk = current;
 607         int usig = sig;
 608         int ret;
 609
 610         /*
 611          * If we were from a system call, check for system call restarting...
 612          */
 613         if (syscall) {
 614                 switch (regs->ARM_r0) {
 615                 case -ERESTART_RESTARTBLOCK:
 616                 case -ERESTARTNOHAND:
 617                         regs->ARM_r0 = -EINTR;
 618                         break;
 619                 case -ERESTARTSYS:
 620                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 621                                 regs->ARM_r0 = -EINTR;
 622                                 break;
 623                         }
 624                         /* fallthrough */
 625                 case -ERESTARTNOINTR:
 626                         restart_syscall(regs);
 627                 }
 628         }
 629
 630         /*
 631          * translate the signal
 632          */
 633         if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
 634                 usig = thread->exec_domain->signal_invmap[usig];
 635
 636         /*
 637          * Set up the stack frame
 638          */
 639         if (ka->sa.sa_flags & SA_SIGINFO)
 640                 ret = setup_rt_frame(usig, ka, info, oldset, regs);
 641         else
 642                 ret = setup_frame(usig, ka, oldset, regs);
 643
 644         /*
 645          * Check that the resulting registers are actually sane.
 646          */
 647         ret |= !valid_user_regs(regs);
 648
 649         /*
 650          * Block the signal if we were unsuccessful.
 651          */
 652         if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
 653                 spin_lock_irq(&tsk->sighand->siglock);
 654                 sigorsets(&tsk->blocked, &tsk->blocked,
 655                           &ka->sa.sa_mask);
 656                 sigaddset(&tsk->blocked, sig);
 657                 recalc_sigpending();
 658                 spin_unlock_irq(&tsk->sighand->siglock);
 659         }
 660
 661         if (ret == 0)
 662                 return;
 663
 664         force_sigsegv(sig, tsk);
 665 }
 666
 667 /*
 668  * Note that 'init' is a special process: it doesn't get signals it doesn't
 669  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 670  * mistake.
 671  *
 672  * Note that we go through the signals twice: once to check the signals that
 673  * the kernel can handle, and then we build all the user-level signal handling
 674  * stack-frames in one go after that.
 675  */
 676 static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
 677 {
 678         struct k_sigaction ka;
 679         siginfo_t info;
 680         int signr;
 681
 682         /*
 683          * We want the common case to go fast, which
 684          * is why we may in certain cases get here from
 685          * kernel mode. Just return without doing anything
 686          * if so.
 687          */
 688         if (!user_mode(regs))
 689                 return 0;
 690
 691         if (try_to_freeze(0))
 692                 goto no_signal;
 693
 694         if (current->ptrace & PT_SINGLESTEP)
 695                 ptrace_cancel_bpt(current);
 696
 697         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 698         if (signr > 0) {
 699                 handle_signal(signr, &ka, &info, oldset, regs, syscall);
 700                 if (current->ptrace & PT_SINGLESTEP)
 701                         ptrace_set_bpt(current);
 702                 return 1;
 703         }
 704
 705  no_signal:
 706         /*
 707          * No signal to deliver to the process - restart the syscall.
 708          */
 709         if (syscall) {
 710                 if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
 711                         if (thumb_mode(regs)) {
 712                                 regs->ARM_r7 = __NR_restart_syscall;
 713                                 regs->ARM_pc -= 2;
 714                         } else {
 715                                 u32 __user *usp;
 716
 717                                 regs->ARM_sp -= 12;
 718                                 usp = (u32 __user *)regs->ARM_sp;
 719
 720                                 put_user(regs->ARM_pc, &usp[0]);
 721                                 /* swi __NR_restart_syscall */
 722                                 put_user(0xef000000 | __NR_restart_syscall, &usp[1]);
 723                                 /* ldr  pc, [sp], #12 */
 724                                 put_user(0xe49df00c, &usp[2]);
 725
 726                                 flush_icache_range((unsigned long)usp,
 727                                                    (unsigned long)(usp + 3));
 728
 729                                 regs->ARM_pc = regs->ARM_sp + 4;
 730                         }
 731                 }
 732                 if (regs->ARM_r0 == -ERESTARTNOHAND ||
 733                     regs->ARM_r0 == -ERESTARTSYS ||
 734                     regs->ARM_r0 == -ERESTARTNOINTR) {
 735                         restart_syscall(regs);
 736                 }
 737         }
 738         if (current->ptrace & PT_SINGLESTEP)
 739                 ptrace_set_bpt(current);
 740         return 0;
 741 }
 742
 743 asmlinkage void
 744 do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 745 {
 746         if (thread_flags & _TIF_SIGPENDING)
 747                 do_signal(&current->blocked, regs, syscall);
 748 }