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 #include "signal.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  * With EABI, the syscall number has to be loaded into r7.
  34  */
  35 #define MOV_R7_NR_SIGRETURN     (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  36 #define MOV_R7_NR_RT_SIGRETURN  (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  37
  38 /*
  39  * For Thumb syscalls, we pass the syscall number via r7.  We therefore
  40  * need two 16-bit instructions.
  41  */
  42 #define SWI_THUMB_SIGRETURN     (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  43 #define SWI_THUMB_RT_SIGRETURN  (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  44
  45 const unsigned long sigreturn_codes[7] = {
  46         MOV_R7_NR_SIGRETURN,    SWI_SYS_SIGRETURN,    SWI_THUMB_SIGRETURN,
  47         MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
  48 };
  49
  50 static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall);
  51
  52 /*
  53  * atomically swap in the new signal mask, and wait for a signal.
  54  */
  55 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs)
  56 {
  57         sigset_t saveset;
  58
  59         mask &= _BLOCKABLE;
  60         spin_lock_irq(&current->sighand->siglock);
  61         saveset = current->blocked;
  62         siginitset(&current->blocked, mask);
  63         recalc_sigpending();
  64         spin_unlock_irq(&current->sighand->siglock);
  65         regs->ARM_r0 = -EINTR;
  66
  67         while (1) {
  68                 current->state = TASK_INTERRUPTIBLE;
  69                 schedule();
  70                 if (do_signal(&saveset, regs, 0))
  71                         return regs->ARM_r0;
  72         }
  73 }
  74
  75 asmlinkage int
  76 sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
  77 {
  78         sigset_t saveset, newset;
  79
  80         /* XXX: Don't preclude handling different sized sigset_t's. */
  81         if (sigsetsize != sizeof(sigset_t))
  82                 return -EINVAL;
  83
  84         if (copy_from_user(&newset, unewset, sizeof(newset)))
  85                 return -EFAULT;
  86         sigdelsetmask(&newset, ~_BLOCKABLE);
  87
  88         spin_lock_irq(&current->sighand->siglock);
  89         saveset = current->blocked;
  90         current->blocked = newset;
  91         recalc_sigpending();
  92         spin_unlock_irq(&current->sighand->siglock);
  93         regs->ARM_r0 = -EINTR;
  94
  95         while (1) {
  96                 current->state = TASK_INTERRUPTIBLE;
  97                 schedule();
  98                 if (do_signal(&saveset, regs, 0))
  99                         return regs->ARM_r0;
 100         }
 101 }
 102
 103 asmlinkage int
 104 sys_sigaction(int sig, const struct old_sigaction __user *act,
 105               struct old_sigaction __user *oact)
 106 {
 107         struct k_sigaction new_ka, old_ka;
 108         int ret;
 109
 110         if (act) {
 111                 old_sigset_t mask;
 112                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
 113                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
 114                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
 115                         return -EFAULT;
 116                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 117                 __get_user(mask, &act->sa_mask);
 118                 siginitset(&new_ka.sa.sa_mask, mask);
 119         }
 120
 121         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 122
 123         if (!ret && oact) {
 124                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
 125                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 126                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 127                         return -EFAULT;
 128                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 129                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 130         }
 131
 132         return ret;
 133 }
 134
 135 #ifdef CONFIG_IWMMXT
 136
 137 /* iwmmxt_area is 0x98 bytes long, preceeded by 8 bytes of signature */
 138 #define IWMMXT_STORAGE_SIZE     (0x98 + 8)
 139 #define IWMMXT_MAGIC0           0x12ef842a
 140 #define IWMMXT_MAGIC1           0x1c07ca71
 141
 142 struct iwmmxt_sigframe {
 143         unsigned long   magic0;
 144         unsigned long   magic1;
 145         unsigned long   storage[0x98/4];
 146 };
 147
 148 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
 149 {
 150         char kbuf[sizeof(*frame) + 8];
 151         struct iwmmxt_sigframe *kframe;
 152
 153         /* the iWMMXt context must be 64 bit aligned */
 154         kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 155         kframe->magic0 = IWMMXT_MAGIC0;
 156         kframe->magic1 = IWMMXT_MAGIC1;
 157         iwmmxt_task_copy(current_thread_info(), &kframe->storage);
 158         return __copy_to_user(frame, kframe, sizeof(*frame));
 159 }
 160
 161 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
 162 {
 163         char kbuf[sizeof(*frame) + 8];
 164         struct iwmmxt_sigframe *kframe;
 165
 166         /* the iWMMXt context must be 64 bit aligned */
 167         kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 168         if (__copy_from_user(kframe, frame, sizeof(*frame)))
 169                 return -1;
 170         if (kframe->magic0 != IWMMXT_MAGIC0 ||
 171             kframe->magic1 != IWMMXT_MAGIC1)
 172                 return -1;
 173         iwmmxt_task_restore(current_thread_info(), &kframe->storage);
 174         return 0;
 175 }
 176
 177 #endif
 178
 179 /*
 180  * Auxiliary signal frame.  This saves stuff like FP state.
 181  * The layout of this structure is not part of the user ABI.
 182  */
 183 struct aux_sigframe {
 184 #ifdef CONFIG_IWMMXT
 185         struct iwmmxt_sigframe  iwmmxt;
 186 #endif
 187 #ifdef CONFIG_VFP
 188         union vfp_state         vfp;
 189 #endif
 190 };
 191
 192 /*
 193  * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
 194  */
 195 struct sigframe {
 196         struct ucontext uc;
 197         unsigned long retcode[2];
 198         struct aux_sigframe aux __attribute__((aligned(8)));
 199 };
 200
 201 struct rt_sigframe {
 202         struct siginfo info;
 203         struct sigframe sig;
 204 };
 205
 206 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
 207 {
 208         sigset_t set;
 209         int err;
 210
 211         err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
 212         if (err == 0) {
 213                 sigdelsetmask(&set, ~_BLOCKABLE);
 214                 spin_lock_irq(&current->sighand->siglock);
 215                 current->blocked = set;
 216                 recalc_sigpending();
 217                 spin_unlock_irq(&current->sighand->siglock);
 218         }
 219
 220         __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 221         __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 222         __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 223         __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 224         __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 225         __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 226         __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 227         __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 228         __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 229         __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 230         __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 231         __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 232         __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 233         __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 234         __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 235         __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 236         __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 237
 238         err |= !valid_user_regs(regs);
 239
 240 #ifdef CONFIG_IWMMXT
 241         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 242                 err |= restore_iwmmxt_context(&sf->aux.iwmmxt);
 243 #endif
 244 #ifdef CONFIG_VFP
 245 //      if (err == 0)
 246 //              err |= vfp_restore_state(&sf->aux.vfp);
 247 #endif
 248
 249         return err;
 250 }
 251
 252 asmlinkage int sys_sigreturn(struct pt_regs *regs)
 253 {
 254         struct sigframe __user *frame;
 255
 256         /* Always make any pending restarted system calls return -EINTR */
 257         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 258
 259         /*
 260          * Since we stacked the signal on a 64-bit boundary,
 261          * then 'sp' should be word aligned here.  If it's
 262          * not, then the user is trying to mess with us.
 263          */
 264         if (regs->ARM_sp & 7)
 265                 goto badframe;
 266
 267         frame = (struct sigframe __user *)regs->ARM_sp;
 268
 269         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 270                 goto badframe;
 271
 272         if (restore_sigframe(regs, frame))
 273                 goto badframe;
 274
 275         /* Send SIGTRAP if we're single-stepping */
 276         if (current->ptrace & PT_SINGLESTEP) {
 277                 ptrace_cancel_bpt(current);
 278                 send_sig(SIGTRAP, current, 1);
 279         }
 280
 281         return regs->ARM_r0;
 282
 283 badframe:
 284         force_sig(SIGSEGV, current);
 285         return 0;
 286 }
 287
 288 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 289 {
 290         struct rt_sigframe __user *frame;
 291
 292         /* Always make any pending restarted system calls return -EINTR */
 293         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 294
 295         /*
 296          * Since we stacked the signal on a 64-bit boundary,
 297          * then 'sp' should be word aligned here.  If it's
 298          * not, then the user is trying to mess with us.
 299          */
 300         if (regs->ARM_sp & 7)
 301                 goto badframe;
 302
 303         frame = (struct rt_sigframe __user *)regs->ARM_sp;
 304
 305         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 306                 goto badframe;
 307
 308         if (restore_sigframe(regs, &frame->sig))
 309                 goto badframe;
 310
 311         if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
 312                 goto badframe;
 313
 314         /* Send SIGTRAP if we're single-stepping */
 315         if (current->ptrace & PT_SINGLESTEP) {
 316                 ptrace_cancel_bpt(current);
 317                 send_sig(SIGTRAP, current, 1);
 318         }
 319
 320         return regs->ARM_r0;
 321
 322 badframe:
 323         force_sig(SIGSEGV, current);
 324         return 0;
 325 }
 326
 327 static int
 328 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
 329 {
 330         int err = 0;
 331
 332         __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 333         __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 334         __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 335         __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 336         __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 337         __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 338         __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 339         __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 340         __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 341         __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 342         __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 343         __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 344         __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 345         __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 346         __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 347         __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 348         __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 349
 350         __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err);
 351         __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err);
 352         __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err);
 353         __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
 354
 355         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 356
 357 #ifdef CONFIG_IWMMXT
 358         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 359                 err |= preserve_iwmmxt_context(&sf->aux.iwmmxt);
 360 #endif
 361 #ifdef CONFIG_VFP
 362 //      if (err == 0)
 363 //              err |= vfp_save_state(&sf->aux.vfp);
 364 #endif
 365
 366         return err;
 367 }
 368
 369 static inline void __user *
 370 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 371 {
 372         unsigned long sp = regs->ARM_sp;
 373         void __user *frame;
 374
 375         /*
 376          * This is the X/Open sanctioned signal stack switching.
 377          */
 378         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 379                 sp = current->sas_ss_sp + current->sas_ss_size;
 380
 381         /*
 382          * ATPCS B01 mandates 8-byte alignment
 383          */
 384         frame = (void __user *)((sp - framesize) & ~7);
 385
 386         /*
 387          * Check that we can actually write to the signal frame.
 388          */
 389         if (!access_ok(VERIFY_WRITE, frame, framesize))
 390                 frame = NULL;
 391
 392         return frame;
 393 }
 394
 395 static int
 396 setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 397              unsigned long __user *rc, void __user *frame, int usig)
 398 {
 399         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 400         unsigned long retcode;
 401         int thumb = 0;
 402         unsigned long cpsr = regs->ARM_cpsr & ~PSR_f;
 403
 404         /*
 405          * Maybe we need to deliver a 32-bit signal to a 26-bit task.
 406          */
 407         if (ka->sa.sa_flags & SA_THIRTYTWO)
 408                 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
 409
 410 #ifdef CONFIG_ARM_THUMB
 411         if (elf_hwcap & HWCAP_THUMB) {
 412                 /*
 413                  * The LSB of the handler determines if we're going to
 414                  * be using THUMB or ARM mode for this signal handler.
 415                  */
 416                 thumb = handler & 1;
 417
 418                 if (thumb)
 419                         cpsr |= PSR_T_BIT;
 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 static inline void restart_syscall(struct pt_regs *regs)
 525 {
 526         regs->ARM_r0 = regs->ARM_ORIG_r0;
 527         regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 528 }
 529
 530 /*
 531  * OK, we're invoking a handler
 532  */
 533 static void
 534 handle_signal(unsigned long sig, struct k_sigaction *ka,
 535               siginfo_t *info, sigset_t *oldset,
 536               struct pt_regs * regs, int syscall)
 537 {
 538         struct thread_info *thread = current_thread_info();
 539         struct task_struct *tsk = current;
 540         int usig = sig;
 541         int ret;
 542
 543         /*
 544          * If we were from a system call, check for system call restarting...
 545          */
 546         if (syscall) {
 547                 switch (regs->ARM_r0) {
 548                 case -ERESTART_RESTARTBLOCK:
 549                 case -ERESTARTNOHAND:
 550                         regs->ARM_r0 = -EINTR;
 551                         break;
 552                 case -ERESTARTSYS:
 553                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 554                                 regs->ARM_r0 = -EINTR;
 555                                 break;
 556                         }
 557                         /* fallthrough */
 558                 case -ERESTARTNOINTR:
 559                         restart_syscall(regs);
 560                 }
 561         }
 562
 563         /*
 564          * translate the signal
 565          */
 566         if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
 567                 usig = thread->exec_domain->signal_invmap[usig];
 568
 569         /*
 570          * Set up the stack frame
 571          */
 572         if (ka->sa.sa_flags & SA_SIGINFO)
 573                 ret = setup_rt_frame(usig, ka, info, oldset, regs);
 574         else
 575                 ret = setup_frame(usig, ka, oldset, regs);
 576
 577         /*
 578          * Check that the resulting registers are actually sane.
 579          */
 580         ret |= !valid_user_regs(regs);
 581
 582         if (ret != 0) {
 583                 force_sigsegv(sig, tsk);
 584                 return;
 585         }
 586
 587         /*
 588          * Block the signal if we were successful.
 589          */
 590         spin_lock_irq(&tsk->sighand->siglock);
 591         sigorsets(&tsk->blocked, &tsk->blocked,
 592                   &ka->sa.sa_mask);
 593         if (!(ka->sa.sa_flags & SA_NODEFER))
 594                 sigaddset(&tsk->blocked, sig);
 595         recalc_sigpending();
 596         spin_unlock_irq(&tsk->sighand->siglock);
 597
 598 }
 599
 600 /*
 601  * Note that 'init' is a special process: it doesn't get signals it doesn't
 602  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 603  * mistake.
 604  *
 605  * Note that we go through the signals twice: once to check the signals that
 606  * the kernel can handle, and then we build all the user-level signal handling
 607  * stack-frames in one go after that.
 608  */
 609 static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
 610 {
 611         struct k_sigaction ka;
 612         siginfo_t info;
 613         int signr;
 614
 615         /*
 616          * We want the common case to go fast, which
 617          * is why we may in certain cases get here from
 618          * kernel mode. Just return without doing anything
 619          * if so.
 620          */
 621         if (!user_mode(regs))
 622                 return 0;
 623
 624         if (try_to_freeze())
 625                 goto no_signal;
 626
 627         if (current->ptrace & PT_SINGLESTEP)
 628                 ptrace_cancel_bpt(current);
 629
 630         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 631         if (signr > 0) {
 632                 handle_signal(signr, &ka, &info, oldset, regs, syscall);
 633                 if (current->ptrace & PT_SINGLESTEP)
 634                         ptrace_set_bpt(current);
 635                 return 1;
 636         }
 637
 638  no_signal:
 639         /*
 640          * No signal to deliver to the process - restart the syscall.
 641          */
 642         if (syscall) {
 643                 if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
 644                         if (thumb_mode(regs)) {
 645                                 regs->ARM_r7 = __NR_restart_syscall;
 646                                 regs->ARM_pc -= 2;
 647                         } else {
 648                                 u32 __user *usp;
 649
 650                                 regs->ARM_sp -= 12;
 651                                 usp = (u32 __user *)regs->ARM_sp;
 652
 653                                 put_user(regs->ARM_pc, &usp[0]);
 654                                 /* swi __NR_restart_syscall */
 655                                 put_user(0xef000000 | __NR_restart_syscall, &usp[1]);
 656                                 /* ldr  pc, [sp], #12 */
 657                                 put_user(0xe49df00c, &usp[2]);
 658
 659                                 flush_icache_range((unsigned long)usp,
 660                                                    (unsigned long)(usp + 3));
 661
 662                                 regs->ARM_pc = regs->ARM_sp + 4;
 663                         }
 664                 }
 665                 if (regs->ARM_r0 == -ERESTARTNOHAND ||
 666                     regs->ARM_r0 == -ERESTARTSYS ||
 667                     regs->ARM_r0 == -ERESTARTNOINTR) {
 668                         restart_syscall(regs);
 669                 }
 670         }
 671         if (current->ptrace & PT_SINGLESTEP)
 672                 ptrace_set_bpt(current);
 673         return 0;
 674 }
 675
 676 asmlinkage void
 677 do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 678 {
 679         if (thread_flags & _TIF_SIGPENDING)
 680                 do_signal(&current->blocked, regs, syscall);
 681 }