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