arch/arm/kernel/signal.c

   1 /*
   2  *  linux/arch/arm/kernel/signal.c
   3  *
   4  *  Copyright (C) 1995-2009 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/errno.h>
  11 #include <linux/signal.h>
  12 #include <linux/personality.h>
  13 #include <linux/uaccess.h>
  14 #include <linux/tracehook.h>
  15
  16 #include <asm/elf.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/ucontext.h>
  19 #include <asm/unistd.h>
  20 #include <asm/vfp.h>
  21
  22 #include "signal.h"
  23
  24 /*
  25  * For ARM syscalls, we encode the syscall number into the instruction.
  26  */
  27 #define SWI_SYS_SIGRETURN       (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
  28 #define SWI_SYS_RT_SIGRETURN    (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
  29
  30 /*
  31  * With EABI, the syscall number has to be loaded into r7.
  32  */
  33 #define MOV_R7_NR_SIGRETURN     (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  34 #define MOV_R7_NR_RT_SIGRETURN  (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  35
  36 /*
  37  * For Thumb syscalls, we pass the syscall number via r7.  We therefore
  38  * need two 16-bit instructions.
  39  */
  40 #define SWI_THUMB_SIGRETURN     (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  41 #define SWI_THUMB_RT_SIGRETURN  (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  42
  43 const unsigned long sigreturn_codes[7] = {
  44         MOV_R7_NR_SIGRETURN,    SWI_SYS_SIGRETURN,    SWI_THUMB_SIGRETURN,
  45         MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
  46 };
  47
  48 /*
  49  * atomically swap in the new signal mask, and wait for a signal.
  50  */
  51 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask)
  52 {
  53         sigset_t blocked;
  54         siginitset(&blocked, mask);
  55         return sigsuspend(&blocked);
  56 }
  57
  58 asmlinkage int
  59 sys_sigaction(int sig, const struct old_sigaction __user *act,
  60               struct old_sigaction __user *oact)
  61 {
  62         struct k_sigaction new_ka, old_ka;
  63         int ret;
  64
  65         if (act) {
  66                 old_sigset_t mask;
  67                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  68                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  69                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
  70                     __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
  71                     __get_user(mask, &act->sa_mask))
  72                         return -EFAULT;
  73                 siginitset(&new_ka.sa.sa_mask, mask);
  74         }
  75
  76         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  77
  78         if (!ret && oact) {
  79                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  80                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  81                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
  82                     __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
  83                     __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
  84                         return -EFAULT;
  85         }
  86
  87         return ret;
  88 }
  89
  90 #ifdef CONFIG_CRUNCH
  91 static int preserve_crunch_context(struct crunch_sigframe __user *frame)
  92 {
  93         char kbuf[sizeof(*frame) + 8];
  94         struct crunch_sigframe *kframe;
  95
  96         /* the crunch context must be 64 bit aligned */
  97         kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
  98         kframe->magic = CRUNCH_MAGIC;
  99         kframe->size = CRUNCH_STORAGE_SIZE;
 100         crunch_task_copy(current_thread_info(), &kframe->storage);
 101         return __copy_to_user(frame, kframe, sizeof(*frame));
 102 }
 103
 104 static int restore_crunch_context(struct crunch_sigframe __user *frame)
 105 {
 106         char kbuf[sizeof(*frame) + 8];
 107         struct crunch_sigframe *kframe;
 108
 109         /* the crunch context must be 64 bit aligned */
 110         kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 111         if (__copy_from_user(kframe, frame, sizeof(*frame)))
 112                 return -1;
 113         if (kframe->magic != CRUNCH_MAGIC ||
 114             kframe->size != CRUNCH_STORAGE_SIZE)
 115                 return -1;
 116         crunch_task_restore(current_thread_info(), &kframe->storage);
 117         return 0;
 118 }
 119 #endif
 120
 121 #ifdef CONFIG_IWMMXT
 122
 123 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
 124 {
 125         char kbuf[sizeof(*frame) + 8];
 126         struct iwmmxt_sigframe *kframe;
 127
 128         /* the iWMMXt context must be 64 bit aligned */
 129         kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 130         kframe->magic = IWMMXT_MAGIC;
 131         kframe->size = IWMMXT_STORAGE_SIZE;
 132         iwmmxt_task_copy(current_thread_info(), &kframe->storage);
 133         return __copy_to_user(frame, kframe, sizeof(*frame));
 134 }
 135
 136 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
 137 {
 138         char kbuf[sizeof(*frame) + 8];
 139         struct iwmmxt_sigframe *kframe;
 140
 141         /* the iWMMXt context must be 64 bit aligned */
 142         kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 143         if (__copy_from_user(kframe, frame, sizeof(*frame)))
 144                 return -1;
 145         if (kframe->magic != IWMMXT_MAGIC ||
 146             kframe->size != IWMMXT_STORAGE_SIZE)
 147                 return -1;
 148         iwmmxt_task_restore(current_thread_info(), &kframe->storage);
 149         return 0;
 150 }
 151
 152 #endif
 153
 154 #ifdef CONFIG_VFP
 155
 156 static int preserve_vfp_context(struct vfp_sigframe __user *frame)
 157 {
 158         const unsigned long magic = VFP_MAGIC;
 159         const unsigned long size = VFP_STORAGE_SIZE;
 160         int err = 0;
 161
 162         __put_user_error(magic, &frame->magic, err);
 163         __put_user_error(size, &frame->size, err);
 164
 165         if (err)
 166                 return -EFAULT;
 167
 168         return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc);
 169 }
 170
 171 static int restore_vfp_context(struct vfp_sigframe __user *frame)
 172 {
 173         unsigned long magic;
 174         unsigned long size;
 175         int err = 0;
 176
 177         __get_user_error(magic, &frame->magic, err);
 178         __get_user_error(size, &frame->size, err);
 179
 180         if (err)
 181                 return -EFAULT;
 182         if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
 183                 return -EINVAL;
 184
 185         return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc);
 186 }
 187
 188 #endif
 189
 190 /*
 191  * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
 192  */
 193 struct sigframe {
 194         struct ucontext uc;
 195         unsigned long retcode[2];
 196 };
 197
 198 struct rt_sigframe {
 199         struct siginfo info;
 200         struct sigframe sig;
 201 };
 202
 203 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
 204 {
 205         struct aux_sigframe __user *aux;
 206         sigset_t set;
 207         int err;
 208
 209         err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
 210         if (err == 0)
 211                 set_current_blocked(&set);
 212
 213         __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 214         __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 215         __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 216         __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 217         __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 218         __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 219         __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 220         __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 221         __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 222         __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 223         __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 224         __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 225         __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 226         __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 227         __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 228         __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 229         __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 230
 231         err |= !valid_user_regs(regs);
 232
 233         aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
 234 #ifdef CONFIG_CRUNCH
 235         if (err == 0)
 236                 err |= restore_crunch_context(&aux->crunch);
 237 #endif
 238 #ifdef CONFIG_IWMMXT
 239         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 240                 err |= restore_iwmmxt_context(&aux->iwmmxt);
 241 #endif
 242 #ifdef CONFIG_VFP
 243         if (err == 0)
 244                 err |= restore_vfp_context(&aux->vfp);
 245 #endif
 246
 247         return err;
 248 }
 249
 250 asmlinkage int sys_sigreturn(struct pt_regs *regs)
 251 {
 252         struct sigframe __user *frame;
 253
 254         /* Always make any pending restarted system calls return -EINTR */
 255         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 256
 257         /*
 258          * Since we stacked the signal on a 64-bit boundary,
 259          * then 'sp' should be word aligned here.  If it's
 260          * not, then the user is trying to mess with us.
 261          */
 262         if (regs->ARM_sp & 7)
 263                 goto badframe;
 264
 265         frame = (struct sigframe __user *)regs->ARM_sp;
 266
 267         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 268                 goto badframe;
 269
 270         if (restore_sigframe(regs, frame))
 271                 goto badframe;
 272
 273         return regs->ARM_r0;
 274
 275 badframe:
 276         force_sig(SIGSEGV, current);
 277         return 0;
 278 }
 279
 280 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 281 {
 282         struct rt_sigframe __user *frame;
 283
 284         /* Always make any pending restarted system calls return -EINTR */
 285         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 286
 287         /*
 288          * Since we stacked the signal on a 64-bit boundary,
 289          * then 'sp' should be word aligned here.  If it's
 290          * not, then the user is trying to mess with us.
 291          */
 292         if (regs->ARM_sp & 7)
 293                 goto badframe;
 294
 295         frame = (struct rt_sigframe __user *)regs->ARM_sp;
 296
 297         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 298                 goto badframe;
 299
 300         if (restore_sigframe(regs, &frame->sig))
 301                 goto badframe;
 302
 303         if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
 304                 goto badframe;
 305
 306         return regs->ARM_r0;
 307
 308 badframe:
 309         force_sig(SIGSEGV, current);
 310         return 0;
 311 }
 312
 313 static int
 314 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
 315 {
 316         struct aux_sigframe __user *aux;
 317         int err = 0;
 318
 319         __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 320         __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 321         __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 322         __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 323         __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 324         __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 325         __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 326         __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 327         __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 328         __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 329         __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 330         __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 331         __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 332         __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 333         __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 334         __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 335         __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 336
 337         __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err);
 338         __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err);
 339         __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err);
 340         __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
 341
 342         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 343
 344         aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
 345 #ifdef CONFIG_CRUNCH
 346         if (err == 0)
 347                 err |= preserve_crunch_context(&aux->crunch);
 348 #endif
 349 #ifdef CONFIG_IWMMXT
 350         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 351                 err |= preserve_iwmmxt_context(&aux->iwmmxt);
 352 #endif
 353 #ifdef CONFIG_VFP
 354         if (err == 0)
 355                 err |= preserve_vfp_context(&aux->vfp);
 356 #endif
 357         __put_user_error(0, &aux->end_magic, err);
 358
 359         return err;
 360 }
 361
 362 static inline void __user *
 363 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 364 {
 365         unsigned long sp = regs->ARM_sp;
 366         void __user *frame;
 367
 368         /*
 369          * This is the X/Open sanctioned signal stack switching.
 370          */
 371         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 372                 sp = current->sas_ss_sp + current->sas_ss_size;
 373
 374         /*
 375          * ATPCS B01 mandates 8-byte alignment
 376          */
 377         frame = (void __user *)((sp - framesize) & ~7);
 378
 379         /*
 380          * Check that we can actually write to the signal frame.
 381          */
 382         if (!access_ok(VERIFY_WRITE, frame, framesize))
 383                 frame = NULL;
 384
 385         return frame;
 386 }
 387
 388 static int
 389 setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 390              unsigned long __user *rc, void __user *frame, int usig)
 391 {
 392         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 393         unsigned long retcode;
 394         int thumb = 0;
 395         unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
 396
 397         cpsr |= PSR_ENDSTATE;
 398
 399         /*
 400          * Maybe we need to deliver a 32-bit signal to a 26-bit task.
 401          */
 402         if (ka->sa.sa_flags & SA_THIRTYTWO)
 403                 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
 404
 405 #ifdef CONFIG_ARM_THUMB
 406         if (elf_hwcap & HWCAP_THUMB) {
 407                 /*
 408                  * The LSB of the handler determines if we're going to
 409                  * be using THUMB or ARM mode for this signal handler.
 410                  */
 411                 thumb = handler & 1;
 412
 413                 if (thumb) {
 414                         cpsr |= PSR_T_BIT;
 415 #if __LINUX_ARM_ARCH__ >= 7
 416                         /* clear the If-Then Thumb-2 execution state */
 417                         cpsr &= ~PSR_IT_MASK;
 418 #endif
 419                 } else
 420                         cpsr &= ~PSR_T_BIT;
 421         }
 422 #endif
 423
 424         if (ka->sa.sa_flags & SA_RESTORER) {
 425                 retcode = (unsigned long)ka->sa.sa_restorer;
 426         } else {
 427                 unsigned int idx = thumb << 1;
 428
 429                 if (ka->sa.sa_flags & SA_SIGINFO)
 430                         idx += 3;
 431
 432                 if (__put_user(sigreturn_codes[idx],   rc) ||
 433                     __put_user(sigreturn_codes[idx+1], rc+1))
 434                         return 1;
 435
 436                 if (cpsr & MODE32_BIT) {
 437                         /*
 438                          * 32-bit code can use the new high-page
 439                          * signal return code support.
 440                          */
 441                         retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb;
 442                 } else {
 443                         /*
 444                          * Ensure that the instruction cache sees
 445                          * the return code written onto the stack.
 446                          */
 447                         flush_icache_range((unsigned long)rc,
 448                                            (unsigned long)(rc + 2));
 449
 450                         retcode = ((unsigned long)rc) + thumb;
 451                 }
 452         }
 453
 454         regs->ARM_r0 = usig;
 455         regs->ARM_sp = (unsigned long)frame;
 456         regs->ARM_lr = retcode;
 457         regs->ARM_pc = handler;
 458         regs->ARM_cpsr = cpsr;
 459
 460         return 0;
 461 }
 462
 463 static int
 464 setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
 465 {
 466         struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 467         int err = 0;
 468
 469         if (!frame)
 470                 return 1;
 471
 472         /*
 473          * Set uc.uc_flags to a value which sc.trap_no would never have.
 474          */
 475         __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
 476
 477         err |= setup_sigframe(frame, regs, set);
 478         if (err == 0)
 479                 err = setup_return(regs, ka, frame->retcode, frame, usig);
 480
 481         return err;
 482 }
 483
 484 static int
 485 setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 486                sigset_t *set, struct pt_regs *regs)
 487 {
 488         struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 489         stack_t stack;
 490         int err = 0;
 491
 492         if (!frame)
 493                 return 1;
 494
 495         err |= copy_siginfo_to_user(&frame->info, info);
 496
 497         __put_user_error(0, &frame->sig.uc.uc_flags, err);
 498         __put_user_error(NULL, &frame->sig.uc.uc_link, err);
 499
 500         memset(&stack, 0, sizeof(stack));
 501         stack.ss_sp = (void __user *)current->sas_ss_sp;
 502         stack.ss_flags = sas_ss_flags(regs->ARM_sp);
 503         stack.ss_size = current->sas_ss_size;
 504         err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
 505
 506         err |= setup_sigframe(&frame->sig, regs, set);
 507         if (err == 0)
 508                 err = setup_return(regs, ka, frame->sig.retcode, frame, usig);
 509
 510         if (err == 0) {
 511                 /*
 512                  * For realtime signals we must also set the second and third
 513                  * arguments for the signal handler.
 514                  *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 515                  */
 516                 regs->ARM_r1 = (unsigned long)&frame->info;
 517                 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
 518         }
 519
 520         return err;
 521 }
 522
 523 /*
 524  * OK, we're invoking a handler
 525  */
 526 static void
 527 handle_signal(unsigned long sig, struct k_sigaction *ka,
 528               siginfo_t *info, struct pt_regs *regs)
 529 {
 530         struct thread_info *thread = current_thread_info();
 531         struct task_struct *tsk = current;
 532         sigset_t *oldset = sigmask_to_save();
 533         int usig = sig;
 534         int ret;
 535
 536         /*
 537          * translate the signal
 538          */
 539         if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
 540                 usig = thread->exec_domain->signal_invmap[usig];
 541
 542         /*
 543          * Set up the stack frame
 544          */
 545         if (ka->sa.sa_flags & SA_SIGINFO)
 546                 ret = setup_rt_frame(usig, ka, info, oldset, regs);
 547         else
 548                 ret = setup_frame(usig, ka, oldset, regs);
 549
 550         /*
 551          * Check that the resulting registers are actually sane.
 552          */
 553         ret |= !valid_user_regs(regs);
 554
 555         if (ret != 0) {
 556                 force_sigsegv(sig, tsk);
 557                 return;
 558         }
 559         signal_delivered(sig, info, ka, regs, 0);
 560 }
 561
 562 /*
 563  * Note that 'init' is a special process: it doesn't get signals it doesn't
 564  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 565  * mistake.
 566  *
 567  * Note that we go through the signals twice: once to check the signals that
 568  * the kernel can handle, and then we build all the user-level signal handling
 569  * stack-frames in one go after that.
 570  */
 571 static int do_signal(struct pt_regs *regs, int syscall)
 572 {
 573         unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
 574         struct k_sigaction ka;
 575         siginfo_t info;
 576         int signr;
 577         int restart = 0;
 578
 579         /*
 580          * If we were from a system call, check for system call restarting...
 581          */
 582         if (syscall) {
 583                 continue_addr = regs->ARM_pc;
 584                 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
 585                 retval = regs->ARM_r0;
 586
 587                 /*
 588                  * Prepare for system call restart.  We do this here so that a
 589                  * debugger will see the already changed PSW.
 590                  */
 591                 switch (retval) {
 592                 case -ERESTART_RESTARTBLOCK:
 593                         restart -= 2;
 594                 case -ERESTARTNOHAND:
 595                 case -ERESTARTSYS:
 596                 case -ERESTARTNOINTR:
 597                         restart++;
 598                         regs->ARM_r0 = regs->ARM_ORIG_r0;
 599                         regs->ARM_pc = restart_addr;
 600                         break;
 601                 }
 602         }
 603
 604         /*
 605          * Get the signal to deliver.  When running under ptrace, at this
 606          * point the debugger may change all our registers ...
 607          */
 608         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 609         /*
 610          * Depending on the signal settings we may need to revert the
 611          * decision to restart the system call.  But skip this if a
 612          * debugger has chosen to restart at a different PC.
 613          */
 614         if (regs->ARM_pc != restart_addr)
 615                 restart = 0;
 616         if (signr > 0) {
 617                 if (unlikely(restart)) {
 618                         if (retval == -ERESTARTNOHAND ||
 619                             retval == -ERESTART_RESTARTBLOCK
 620                             || (retval == -ERESTARTSYS
 621                                 && !(ka.sa.sa_flags & SA_RESTART))) {
 622                                 regs->ARM_r0 = -EINTR;
 623                                 regs->ARM_pc = continue_addr;
 624                         }
 625                 }
 626
 627                 handle_signal(signr, &ka, &info, regs);
 628                 return 0;
 629         }
 630
 631         restore_saved_sigmask();
 632         if (unlikely(restart))
 633                 regs->ARM_pc = continue_addr;
 634         return restart;
 635 }
 636
 637 asmlinkage int
 638 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 639 {
 640         do {
 641                 if (likely(thread_flags & _TIF_NEED_RESCHED)) {
 642                         schedule();
 643                 } else {
 644                         if (unlikely(!user_mode(regs)))
 645                                 return 0;
 646                         local_irq_enable();
 647                         if (thread_flags & _TIF_SIGPENDING) {
 648                                 int restart = do_signal(regs, syscall);
 649                                 if (unlikely(restart)) {
 650                                         /*
 651                                          * Restart without handlers.
 652                                          * Deal with it without leaving
 653                                          * the kernel space.
 654                                          */
 655                                         return restart;
 656                                 }
 657                                 syscall = 0;
 658                         } else {
 659                                 clear_thread_flag(TIF_NOTIFY_RESUME);
 660                                 tracehook_notify_resume(regs);
 661                         }
 662                 }
 663                 local_irq_disable();
 664                 thread_flags = current_thread_info()->flags;
 665         } while (thread_flags & _TIF_WORK_MASK);
 666         return 0;
 667 }