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/freezer.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/tracehook.h>
  16
  17 #include <asm/elf.h>
  18 #include <asm/cacheflush.h>
  19 #include <asm/ucontext.h>
  20 #include <asm/unistd.h>
  21 #include <asm/vfp.h>
  22
  23 #include "signal.h"
  24
  25 /*
  26  * For ARM syscalls, we encode the syscall number into the instruction.
  27  */
  28 #define SWI_SYS_SIGRETURN       (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
  29 #define SWI_SYS_RT_SIGRETURN    (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
  30
  31 /*
  32  * With EABI, the syscall number has to be loaded into r7.
  33  */
  34 #define MOV_R7_NR_SIGRETURN     (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  35 #define MOV_R7_NR_RT_SIGRETURN  (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  36
  37 /*
  38  * For Thumb syscalls, we pass the syscall number via r7.  We therefore
  39  * need two 16-bit instructions.
  40  */
  41 #define SWI_THUMB_SIGRETURN     (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  42 #define SWI_THUMB_RT_SIGRETURN  (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  43
  44 const unsigned long sigreturn_codes[7] = {
  45         MOV_R7_NR_SIGRETURN,    SWI_SYS_SIGRETURN,    SWI_THUMB_SIGRETURN,
  46         MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
  47 };
  48
  49 /*
  50  * atomically swap in the new signal mask, and wait for a signal.
  51  */
  52 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask)
  53 {
  54         sigset_t blocked;
  55         siginitset(&blocked, mask);
  56         return sigsuspend(&blocked);
  57 }
  58
  59 asmlinkage int
  60 sys_sigaction(int sig, const struct old_sigaction __user *act,
  61               struct old_sigaction __user *oact)
  62 {
  63         struct k_sigaction new_ka, old_ka;
  64         int ret;
  65
  66         if (act) {
  67                 old_sigset_t mask;
  68                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  69                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  70                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
  71                     __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
  72                     __get_user(mask, &act->sa_mask))
  73                         return -EFAULT;
  74                 siginitset(&new_ka.sa.sa_mask, mask);
  75         }
  76
  77         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  78
  79         if (!ret && oact) {
  80                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  81                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  82                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
  83                     __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
  84                     __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
  85                         return -EFAULT;
  86         }
  87
  88         return ret;
  89 }
  90
  91 #ifdef CONFIG_CRUNCH
  92 static int preserve_crunch_context(struct crunch_sigframe __user *frame)
  93 {
  94         char kbuf[sizeof(*frame) + 8];
  95         struct crunch_sigframe *kframe;
  96
  97         /* the crunch context must be 64 bit aligned */
  98         kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
  99         kframe->magic = CRUNCH_MAGIC;
 100         kframe->size = CRUNCH_STORAGE_SIZE;
 101         crunch_task_copy(current_thread_info(), &kframe->storage);
 102         return __copy_to_user(frame, kframe, sizeof(*frame));
 103 }
 104
 105 static int restore_crunch_context(struct crunch_sigframe __user *frame)
 106 {
 107         char kbuf[sizeof(*frame) + 8];
 108         struct crunch_sigframe *kframe;
 109
 110         /* the crunch context must be 64 bit aligned */
 111         kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 112         if (__copy_from_user(kframe, frame, sizeof(*frame)))
 113                 return -1;
 114         if (kframe->magic != CRUNCH_MAGIC ||
 115             kframe->size != CRUNCH_STORAGE_SIZE)
 116                 return -1;
 117         crunch_task_restore(current_thread_info(), &kframe->storage);
 118         return 0;
 119 }
 120 #endif
 121
 122 #ifdef CONFIG_IWMMXT
 123
 124 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
 125 {
 126         char kbuf[sizeof(*frame) + 8];
 127         struct iwmmxt_sigframe *kframe;
 128
 129         /* the iWMMXt context must be 64 bit aligned */
 130         kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 131         kframe->magic = IWMMXT_MAGIC;
 132         kframe->size = IWMMXT_STORAGE_SIZE;
 133         iwmmxt_task_copy(current_thread_info(), &kframe->storage);
 134         return __copy_to_user(frame, kframe, sizeof(*frame));
 135 }
 136
 137 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
 138 {
 139         char kbuf[sizeof(*frame) + 8];
 140         struct iwmmxt_sigframe *kframe;
 141
 142         /* the iWMMXt context must be 64 bit aligned */
 143         kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 144         if (__copy_from_user(kframe, frame, sizeof(*frame)))
 145                 return -1;
 146         if (kframe->magic != IWMMXT_MAGIC ||
 147             kframe->size != IWMMXT_STORAGE_SIZE)
 148                 return -1;
 149         iwmmxt_task_restore(current_thread_info(), &kframe->storage);
 150         return 0;
 151 }
 152
 153 #endif
 154
 155 #ifdef CONFIG_VFP
 156
 157 static int preserve_vfp_context(struct vfp_sigframe __user *frame)
 158 {
 159         const unsigned long magic = VFP_MAGIC;
 160         const unsigned long size = VFP_STORAGE_SIZE;
 161         int err = 0;
 162
 163         __put_user_error(magic, &frame->magic, err);
 164         __put_user_error(size, &frame->size, err);
 165
 166         if (err)
 167                 return -EFAULT;
 168
 169         return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc);
 170 }
 171
 172 static int restore_vfp_context(struct vfp_sigframe __user *frame)
 173 {
 174         unsigned long magic;
 175         unsigned long size;
 176         int err = 0;
 177
 178         __get_user_error(magic, &frame->magic, err);
 179         __get_user_error(size, &frame->size, err);
 180
 181         if (err)
 182                 return -EFAULT;
 183         if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
 184                 return -EINVAL;
 185
 186         return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc);
 187 }
 188
 189 #endif
 190
 191 /*
 192  * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
 193  */
 194 struct sigframe {
 195         struct ucontext uc;
 196         unsigned long retcode[2];
 197 };
 198
 199 struct rt_sigframe {
 200         struct siginfo info;
 201         struct sigframe sig;
 202 };
 203
 204 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
 205 {
 206         struct aux_sigframe __user *aux;
 207         sigset_t set;
 208         int err;
 209
 210         err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
 211         if (err == 0)
 212                 set_current_blocked(&set);
 213
 214         __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 215         __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 216         __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 217         __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 218         __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 219         __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 220         __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 221         __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 222         __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 223         __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 224         __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 225         __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 226         __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 227         __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 228         __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 229         __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 230         __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 231
 232         err |= !valid_user_regs(regs);
 233
 234         aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
 235 #ifdef CONFIG_CRUNCH
 236         if (err == 0)
 237                 err |= restore_crunch_context(&aux->crunch);
 238 #endif
 239 #ifdef CONFIG_IWMMXT
 240         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 241                 err |= restore_iwmmxt_context(&aux->iwmmxt);
 242 #endif
 243 #ifdef CONFIG_VFP
 244         if (err == 0)
 245                 err |= restore_vfp_context(&aux->vfp);
 246 #endif
 247
 248         return err;
 249 }
 250
 251 asmlinkage int sys_sigreturn(struct pt_regs *regs)
 252 {
 253         struct sigframe __user *frame;
 254
 255         /* Always make any pending restarted system calls return -EINTR */
 256         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 257
 258         /*
 259          * Since we stacked the signal on a 64-bit boundary,
 260          * then 'sp' should be word aligned here.  If it's
 261          * not, then the user is trying to mess with us.
 262          */
 263         if (regs->ARM_sp & 7)
 264                 goto badframe;
 265
 266         frame = (struct sigframe __user *)regs->ARM_sp;
 267
 268         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 269                 goto badframe;
 270
 271         if (restore_sigframe(regs, frame))
 272                 goto badframe;
 273
 274         return regs->ARM_r0;
 275
 276 badframe:
 277         force_sig(SIGSEGV, current);
 278         return 0;
 279 }
 280
 281 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 282 {
 283         struct rt_sigframe __user *frame;
 284
 285         /* Always make any pending restarted system calls return -EINTR */
 286         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 287
 288         /*
 289          * Since we stacked the signal on a 64-bit boundary,
 290          * then 'sp' should be word aligned here.  If it's
 291          * not, then the user is trying to mess with us.
 292          */
 293         if (regs->ARM_sp & 7)
 294                 goto badframe;
 295
 296         frame = (struct rt_sigframe __user *)regs->ARM_sp;
 297
 298         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 299                 goto badframe;
 300
 301         if (restore_sigframe(regs, &frame->sig))
 302                 goto badframe;
 303
 304         if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
 305                 goto badframe;
 306
 307         return regs->ARM_r0;
 308
 309 badframe:
 310         force_sig(SIGSEGV, current);
 311         return 0;
 312 }
 313
 314 static int
 315 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
 316 {
 317         struct aux_sigframe __user *aux;
 318         int err = 0;
 319
 320         __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 321         __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 322         __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 323         __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 324         __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 325         __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 326         __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 327         __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 328         __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 329         __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 330         __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 331         __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 332         __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 333         __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 334         __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 335         __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 336         __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 337
 338         __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err);
 339         __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err);
 340         __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err);
 341         __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
 342
 343         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 344
 345         aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
 346 #ifdef CONFIG_CRUNCH
 347         if (err == 0)
 348                 err |= preserve_crunch_context(&aux->crunch);
 349 #endif
 350 #ifdef CONFIG_IWMMXT
 351         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 352                 err |= preserve_iwmmxt_context(&aux->iwmmxt);
 353 #endif
 354 #ifdef CONFIG_VFP
 355         if (err == 0)
 356                 err |= preserve_vfp_context(&aux->vfp);
 357 #endif
 358         __put_user_error(0, &aux->end_magic, err);
 359
 360         return err;
 361 }
 362
 363 static inline void __user *
 364 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 365 {
 366         unsigned long sp = regs->ARM_sp;
 367         void __user *frame;
 368
 369         /*
 370          * This is the X/Open sanctioned signal stack switching.
 371          */
 372         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 373                 sp = current->sas_ss_sp + current->sas_ss_size;
 374
 375         /*
 376          * ATPCS B01 mandates 8-byte alignment
 377          */
 378         frame = (void __user *)((sp - framesize) & ~7);
 379
 380         /*
 381          * Check that we can actually write to the signal frame.
 382          */
 383         if (!access_ok(VERIFY_WRITE, frame, framesize))
 384                 frame = NULL;
 385
 386         return frame;
 387 }
 388
 389 static int
 390 setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 391              unsigned long __user *rc, void __user *frame, int usig)
 392 {
 393         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 394         unsigned long retcode;
 395         int thumb = 0;
 396         unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
 397
 398         cpsr |= PSR_ENDSTATE;
 399
 400         /*
 401          * Maybe we need to deliver a 32-bit signal to a 26-bit task.
 402          */
 403         if (ka->sa.sa_flags & SA_THIRTYTWO)
 404                 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
 405
 406 #ifdef CONFIG_ARM_THUMB
 407         if (elf_hwcap & HWCAP_THUMB) {
 408                 /*
 409                  * The LSB of the handler determines if we're going to
 410                  * be using THUMB or ARM mode for this signal handler.
 411                  */
 412                 thumb = handler & 1;
 413
 414                 if (thumb) {
 415                         cpsr |= PSR_T_BIT;
 416 #if __LINUX_ARM_ARCH__ >= 7
 417                         /* clear the If-Then Thumb-2 execution state */
 418                         cpsr &= ~PSR_IT_MASK;
 419 #endif
 420                 } else
 421                         cpsr &= ~PSR_T_BIT;
 422         }
 423 #endif
 424
 425         if (ka->sa.sa_flags & SA_RESTORER) {
 426                 retcode = (unsigned long)ka->sa.sa_restorer;
 427         } else {
 428                 unsigned int idx = thumb << 1;
 429
 430                 if (ka->sa.sa_flags & SA_SIGINFO)
 431                         idx += 3;
 432
 433                 if (__put_user(sigreturn_codes[idx],   rc) ||
 434                     __put_user(sigreturn_codes[idx+1], rc+1))
 435                         return 1;
 436
 437                 if (cpsr & MODE32_BIT) {
 438                         /*
 439                          * 32-bit code can use the new high-page
 440                          * signal return code support.
 441                          */
 442                         retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb;
 443                 } else {
 444                         /*
 445                          * Ensure that the instruction cache sees
 446                          * the return code written onto the stack.
 447                          */
 448                         flush_icache_range((unsigned long)rc,
 449                                            (unsigned long)(rc + 2));
 450
 451                         retcode = ((unsigned long)rc) + thumb;
 452                 }
 453         }
 454
 455         regs->ARM_r0 = usig;
 456         regs->ARM_sp = (unsigned long)frame;
 457         regs->ARM_lr = retcode;
 458         regs->ARM_pc = handler;
 459         regs->ARM_cpsr = cpsr;
 460
 461         return 0;
 462 }
 463
 464 static int
 465 setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
 466 {
 467         struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 468         int err = 0;
 469
 470         if (!frame)
 471                 return 1;
 472
 473         /*
 474          * Set uc.uc_flags to a value which sc.trap_no would never have.
 475          */
 476         __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
 477
 478         err |= setup_sigframe(frame, regs, set);
 479         if (err == 0)
 480                 err = setup_return(regs, ka, frame->retcode, frame, usig);
 481
 482         return err;
 483 }
 484
 485 static int
 486 setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 487                sigset_t *set, struct pt_regs *regs)
 488 {
 489         struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 490         stack_t stack;
 491         int err = 0;
 492
 493         if (!frame)
 494                 return 1;
 495
 496         err |= copy_siginfo_to_user(&frame->info, info);
 497
 498         __put_user_error(0, &frame->sig.uc.uc_flags, err);
 499         __put_user_error(NULL, &frame->sig.uc.uc_link, err);
 500
 501         memset(&stack, 0, sizeof(stack));
 502         stack.ss_sp = (void __user *)current->sas_ss_sp;
 503         stack.ss_flags = sas_ss_flags(regs->ARM_sp);
 504         stack.ss_size = current->sas_ss_size;
 505         err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
 506
 507         err |= setup_sigframe(&frame->sig, regs, set);
 508         if (err == 0)
 509                 err = setup_return(regs, ka, frame->sig.retcode, frame, usig);
 510
 511         if (err == 0) {
 512                 /*
 513                  * For realtime signals we must also set the second and third
 514                  * arguments for the signal handler.
 515                  *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 516                  */
 517                 regs->ARM_r1 = (unsigned long)&frame->info;
 518                 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
 519         }
 520
 521         return err;
 522 }
 523
 524 /*
 525  * OK, we're invoking a handler
 526  */
 527 static void
 528 handle_signal(unsigned long sig, struct k_sigaction *ka,
 529               siginfo_t *info, struct pt_regs *regs)
 530 {
 531         struct thread_info *thread = current_thread_info();
 532         struct task_struct *tsk = current;
 533         sigset_t *oldset = sigmask_to_save();
 534         int usig = sig;
 535         int ret;
 536
 537         /*
 538          * translate the signal
 539          */
 540         if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
 541                 usig = thread->exec_domain->signal_invmap[usig];
 542
 543         /*
 544          * Set up the stack frame
 545          */
 546         if (ka->sa.sa_flags & SA_SIGINFO)
 547                 ret = setup_rt_frame(usig, ka, info, oldset, regs);
 548         else
 549                 ret = setup_frame(usig, ka, oldset, regs);
 550
 551         /*
 552          * Check that the resulting registers are actually sane.
 553          */
 554         ret |= !valid_user_regs(regs);
 555
 556         if (ret != 0) {
 557                 force_sigsegv(sig, tsk);
 558                 return;
 559         }
 560         signal_delivered(sig, info, ka, regs, 0);
 561 }
 562
 563 /*
 564  * Note that 'init' is a special process: it doesn't get signals it doesn't
 565  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 566  * mistake.
 567  *
 568  * Note that we go through the signals twice: once to check the signals that
 569  * the kernel can handle, and then we build all the user-level signal handling
 570  * stack-frames in one go after that.
 571  */
 572 static int do_signal(struct pt_regs *regs, int syscall)
 573 {
 574         unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
 575         struct k_sigaction ka;
 576         siginfo_t info;
 577         int signr;
 578         int restart = 0;
 579
 580         /*
 581          * If we were from a system call, check for system call restarting...
 582          */
 583         if (syscall) {
 584                 continue_addr = regs->ARM_pc;
 585                 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
 586                 retval = regs->ARM_r0;
 587
 588                 /*
 589                  * Prepare for system call restart.  We do this here so that a
 590                  * debugger will see the already changed PSW.
 591                  */
 592                 switch (retval) {
 593                 case -ERESTART_RESTARTBLOCK:
 594                         restart -= 2;
 595                 case -ERESTARTNOHAND:
 596                 case -ERESTARTSYS:
 597                 case -ERESTARTNOINTR:
 598                         restart++;
 599                         regs->ARM_r0 = regs->ARM_ORIG_r0;
 600                         regs->ARM_pc = restart_addr;
 601                         break;
 602                 }
 603         }
 604
 605         /*
 606          * Get the signal to deliver.  When running under ptrace, at this
 607          * point the debugger may change all our registers ...
 608          */
 609         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 610         /*
 611          * Depending on the signal settings we may need to revert the
 612          * decision to restart the system call.  But skip this if a
 613          * debugger has chosen to restart at a different PC.
 614          */
 615         if (regs->ARM_pc != restart_addr)
 616                 restart = 0;
 617         if (signr > 0) {
 618                 if (unlikely(restart)) {
 619                         if (retval == -ERESTARTNOHAND ||
 620                             retval == -ERESTART_RESTARTBLOCK
 621                             || (retval == -ERESTARTSYS
 622                                 && !(ka.sa.sa_flags & SA_RESTART))) {
 623                                 regs->ARM_r0 = -EINTR;
 624                                 regs->ARM_pc = continue_addr;
 625                         }
 626                 }
 627
 628                 handle_signal(signr, &ka, &info, regs);
 629                 return 0;
 630         }
 631
 632         restore_saved_sigmask();
 633         if (unlikely(restart))
 634                 regs->ARM_pc = continue_addr;
 635         return restart;
 636 }
 637
 638 asmlinkage int
 639 do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 640 {
 641         do {
 642                 if (likely(thread_flags & _TIF_NEED_RESCHED)) {
 643                         schedule();
 644                 } else {
 645                         if (unlikely(!user_mode(regs)))
 646                                 return 0;
 647                         local_irq_enable();
 648                         if (thread_flags & _TIF_SIGPENDING) {
 649                                 int restart = do_signal(regs, syscall);
 650                                 if (unlikely(restart)) {
 651                                         /*
 652                                          * Restart without handlers.
 653                                          * Deal with it without leaving
 654                                          * the kernel space.
 655                                          */
 656                                         return restart;
 657                                 }
 658                                 syscall = 0;
 659                         } else {
 660                                 clear_thread_flag(TIF_NOTIFY_RESUME);
 661                                 tracehook_notify_resume(regs);
 662                         }
 663                 }
 664                 local_irq_disable();
 665                 thread_flags = current_thread_info()->flags;
 666         } while (thread_flags & _TIF_WORK_MASK);
 667         return 0;
 668 }