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 sigcontext sc;
 197         unsigned long extramask[_NSIG_WORDS-1];
 198         unsigned long retcode[2];
 199         struct aux_sigframe aux __attribute__((aligned(8)));
 200 };
 201
 202 struct rt_sigframe {
 203         struct siginfo __user *pinfo;
 204         void __user *puc;
 205         struct siginfo info;
 206         struct ucontext uc;
 207         unsigned long retcode[2];
 208         struct aux_sigframe aux __attribute__((aligned(8)));
 209 };
 210
 211 static int
 212 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc,
 213                    struct aux_sigframe __user *aux)
 214 {
 215         int err = 0;
 216
 217         __get_user_error(regs->ARM_r0, &sc->arm_r0, err);
 218         __get_user_error(regs->ARM_r1, &sc->arm_r1, err);
 219         __get_user_error(regs->ARM_r2, &sc->arm_r2, err);
 220         __get_user_error(regs->ARM_r3, &sc->arm_r3, err);
 221         __get_user_error(regs->ARM_r4, &sc->arm_r4, err);
 222         __get_user_error(regs->ARM_r5, &sc->arm_r5, err);
 223         __get_user_error(regs->ARM_r6, &sc->arm_r6, err);
 224         __get_user_error(regs->ARM_r7, &sc->arm_r7, err);
 225         __get_user_error(regs->ARM_r8, &sc->arm_r8, err);
 226         __get_user_error(regs->ARM_r9, &sc->arm_r9, err);
 227         __get_user_error(regs->ARM_r10, &sc->arm_r10, err);
 228         __get_user_error(regs->ARM_fp, &sc->arm_fp, err);
 229         __get_user_error(regs->ARM_ip, &sc->arm_ip, err);
 230         __get_user_error(regs->ARM_sp, &sc->arm_sp, err);
 231         __get_user_error(regs->ARM_lr, &sc->arm_lr, err);
 232         __get_user_error(regs->ARM_pc, &sc->arm_pc, err);
 233         __get_user_error(regs->ARM_cpsr, &sc->arm_cpsr, err);
 234
 235         err |= !valid_user_regs(regs);
 236
 237 #ifdef CONFIG_IWMMXT
 238         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 239                 err |= restore_iwmmxt_context(&aux->iwmmxt);
 240 #endif
 241 #ifdef CONFIG_VFP
 242 //      if (err == 0)
 243 //              err |= vfp_restore_state(&aux->vfp);
 244 #endif
 245
 246         return err;
 247 }
 248
 249 asmlinkage int sys_sigreturn(struct pt_regs *regs)
 250 {
 251         struct sigframe __user *frame;
 252         sigset_t set;
 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         if (__get_user(set.sig[0], &frame->sc.oldmask)
 270             || (_NSIG_WORDS > 1
 271                 && __copy_from_user(&set.sig[1], &frame->extramask,
 272                                     sizeof(frame->extramask))))
 273                 goto badframe;
 274
 275         sigdelsetmask(&set, ~_BLOCKABLE);
 276         spin_lock_irq(&current->sighand->siglock);
 277         current->blocked = set;
 278         recalc_sigpending();
 279         spin_unlock_irq(&current->sighand->siglock);
 280
 281         if (restore_sigcontext(regs, &frame->sc, &frame->aux))
 282                 goto badframe;
 283
 284         /* Send SIGTRAP if we're single-stepping */
 285         if (current->ptrace & PT_SINGLESTEP) {
 286                 ptrace_cancel_bpt(current);
 287                 send_sig(SIGTRAP, current, 1);
 288         }
 289
 290         return regs->ARM_r0;
 291
 292 badframe:
 293         force_sig(SIGSEGV, current);
 294         return 0;
 295 }
 296
 297 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 298 {
 299         struct rt_sigframe __user *frame;
 300         sigset_t set;
 301
 302         /* Always make any pending restarted system calls return -EINTR */
 303         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 304
 305         /*
 306          * Since we stacked the signal on a 64-bit boundary,
 307          * then 'sp' should be word aligned here.  If it's
 308          * not, then the user is trying to mess with us.
 309          */
 310         if (regs->ARM_sp & 7)
 311                 goto badframe;
 312
 313         frame = (struct rt_sigframe __user *)regs->ARM_sp;
 314
 315         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 316                 goto badframe;
 317         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 318                 goto badframe;
 319
 320         sigdelsetmask(&set, ~_BLOCKABLE);
 321         spin_lock_irq(&current->sighand->siglock);
 322         current->blocked = set;
 323         recalc_sigpending();
 324         spin_unlock_irq(&current->sighand->siglock);
 325
 326         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &frame->aux))
 327                 goto badframe;
 328
 329         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
 330                 goto badframe;
 331
 332         /* Send SIGTRAP if we're single-stepping */
 333         if (current->ptrace & PT_SINGLESTEP) {
 334                 ptrace_cancel_bpt(current);
 335                 send_sig(SIGTRAP, current, 1);
 336         }
 337
 338         return regs->ARM_r0;
 339
 340 badframe:
 341         force_sig(SIGSEGV, current);
 342         return 0;
 343 }
 344
 345 static int
 346 setup_sigcontext(struct sigcontext __user *sc, struct aux_sigframe __user *aux,
 347                  struct pt_regs *regs, unsigned long mask)
 348 {
 349         int err = 0;
 350
 351         __put_user_error(regs->ARM_r0, &sc->arm_r0, err);
 352         __put_user_error(regs->ARM_r1, &sc->arm_r1, err);
 353         __put_user_error(regs->ARM_r2, &sc->arm_r2, err);
 354         __put_user_error(regs->ARM_r3, &sc->arm_r3, err);
 355         __put_user_error(regs->ARM_r4, &sc->arm_r4, err);
 356         __put_user_error(regs->ARM_r5, &sc->arm_r5, err);
 357         __put_user_error(regs->ARM_r6, &sc->arm_r6, err);
 358         __put_user_error(regs->ARM_r7, &sc->arm_r7, err);
 359         __put_user_error(regs->ARM_r8, &sc->arm_r8, err);
 360         __put_user_error(regs->ARM_r9, &sc->arm_r9, err);
 361         __put_user_error(regs->ARM_r10, &sc->arm_r10, err);
 362         __put_user_error(regs->ARM_fp, &sc->arm_fp, err);
 363         __put_user_error(regs->ARM_ip, &sc->arm_ip, err);
 364         __put_user_error(regs->ARM_sp, &sc->arm_sp, err);
 365         __put_user_error(regs->ARM_lr, &sc->arm_lr, err);
 366         __put_user_error(regs->ARM_pc, &sc->arm_pc, err);
 367         __put_user_error(regs->ARM_cpsr, &sc->arm_cpsr, err);
 368
 369         __put_user_error(current->thread.trap_no, &sc->trap_no, err);
 370         __put_user_error(current->thread.error_code, &sc->error_code, err);
 371         __put_user_error(current->thread.address, &sc->fault_address, err);
 372         __put_user_error(mask, &sc->oldmask, err);
 373
 374 #ifdef CONFIG_IWMMXT
 375         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 376                 err |= preserve_iwmmxt_context(&aux->iwmmxt);
 377 #endif
 378 #ifdef CONFIG_VFP
 379 //      if (err == 0)
 380 //              err |= vfp_save_state(&aux->vfp);
 381 #endif
 382
 383         return err;
 384 }
 385
 386 static inline void __user *
 387 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 388 {
 389         unsigned long sp = regs->ARM_sp;
 390         void __user *frame;
 391
 392         /*
 393          * This is the X/Open sanctioned signal stack switching.
 394          */
 395         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 396                 sp = current->sas_ss_sp + current->sas_ss_size;
 397
 398         /*
 399          * ATPCS B01 mandates 8-byte alignment
 400          */
 401         frame = (void __user *)((sp - framesize) & ~7);
 402
 403         /*
 404          * Check that we can actually write to the signal frame.
 405          */
 406         if (!access_ok(VERIFY_WRITE, frame, framesize))
 407                 frame = NULL;
 408
 409         return frame;
 410 }
 411
 412 static int
 413 setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 414              unsigned long __user *rc, void __user *frame, int usig)
 415 {
 416         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 417         unsigned long retcode;
 418         int thumb = 0;
 419         unsigned long cpsr = regs->ARM_cpsr & ~PSR_f;
 420
 421         /*
 422          * Maybe we need to deliver a 32-bit signal to a 26-bit task.
 423          */
 424         if (ka->sa.sa_flags & SA_THIRTYTWO)
 425                 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
 426
 427 #ifdef CONFIG_ARM_THUMB
 428         if (elf_hwcap & HWCAP_THUMB) {
 429                 /*
 430                  * The LSB of the handler determines if we're going to
 431                  * be using THUMB or ARM mode for this signal handler.
 432                  */
 433                 thumb = handler & 1;
 434
 435                 if (thumb)
 436                         cpsr |= PSR_T_BIT;
 437                 else
 438                         cpsr &= ~PSR_T_BIT;
 439         }
 440 #endif
 441
 442         if (ka->sa.sa_flags & SA_RESTORER) {
 443                 retcode = (unsigned long)ka->sa.sa_restorer;
 444         } else {
 445                 unsigned int idx = thumb << 1;
 446
 447                 if (ka->sa.sa_flags & SA_SIGINFO)
 448                         idx += 3;
 449
 450                 if (__put_user(sigreturn_codes[idx],   rc) ||
 451                     __put_user(sigreturn_codes[idx+1], rc+1))
 452                         return 1;
 453
 454                 if (cpsr & MODE32_BIT) {
 455                         /*
 456                          * 32-bit code can use the new high-page
 457                          * signal return code support.
 458                          */
 459                         retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb;
 460                 } else {
 461                         /*
 462                          * Ensure that the instruction cache sees
 463                          * the return code written onto the stack.
 464                          */
 465                         flush_icache_range((unsigned long)rc,
 466                                            (unsigned long)(rc + 2));
 467
 468                         retcode = ((unsigned long)rc) + thumb;
 469                 }
 470         }
 471
 472         regs->ARM_r0 = usig;
 473         regs->ARM_sp = (unsigned long)frame;
 474         regs->ARM_lr = retcode;
 475         regs->ARM_pc = handler;
 476         regs->ARM_cpsr = cpsr;
 477
 478         return 0;
 479 }
 480
 481 static int
 482 setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
 483 {
 484         struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 485         int err = 0;
 486
 487         if (!frame)
 488                 return 1;
 489
 490         err |= setup_sigcontext(&frame->sc, &frame->aux, regs, set->sig[0]);
 491
 492         if (_NSIG_WORDS > 1) {
 493                 err |= __copy_to_user(frame->extramask, &set->sig[1],
 494                                       sizeof(frame->extramask));
 495         }
 496
 497         if (err == 0)
 498                 err = setup_return(regs, ka, frame->retcode, frame, usig);
 499
 500         return err;
 501 }
 502
 503 static int
 504 setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 505                sigset_t *set, struct pt_regs *regs)
 506 {
 507         struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 508         stack_t stack;
 509         int err = 0;
 510
 511         if (!frame)
 512                 return 1;
 513
 514         __put_user_error(&frame->info, &frame->pinfo, err);
 515         __put_user_error(&frame->uc, &frame->puc, err);
 516         err |= copy_siginfo_to_user(&frame->info, info);
 517
 518         __put_user_error(0, &frame->uc.uc_flags, err);
 519         __put_user_error(NULL, &frame->uc.uc_link, err);
 520
 521         memset(&stack, 0, sizeof(stack));
 522         stack.ss_sp = (void __user *)current->sas_ss_sp;
 523         stack.ss_flags = sas_ss_flags(regs->ARM_sp);
 524         stack.ss_size = current->sas_ss_size;
 525         err |= __copy_to_user(&frame->uc.uc_stack, &stack, sizeof(stack));
 526
 527         err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->aux,
 528                                 regs, set->sig[0]);
 529         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 530
 531         if (err == 0)
 532                 err = setup_return(regs, ka, frame->retcode, frame, usig);
 533
 534         if (err == 0) {
 535                 /*
 536                  * For realtime signals we must also set the second and third
 537                  * arguments for the signal handler.
 538                  *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 539                  */
 540                 regs->ARM_r1 = (unsigned long)&frame->info;
 541                 regs->ARM_r2 = (unsigned long)&frame->uc;
 542         }
 543
 544         return err;
 545 }
 546
 547 static inline void restart_syscall(struct pt_regs *regs)
 548 {
 549         regs->ARM_r0 = regs->ARM_ORIG_r0;
 550         regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 551 }
 552
 553 /*
 554  * OK, we're invoking a handler
 555  */
 556 static void
 557 handle_signal(unsigned long sig, struct k_sigaction *ka,
 558               siginfo_t *info, sigset_t *oldset,
 559               struct pt_regs * regs, int syscall)
 560 {
 561         struct thread_info *thread = current_thread_info();
 562         struct task_struct *tsk = current;
 563         int usig = sig;
 564         int ret;
 565
 566         /*
 567          * If we were from a system call, check for system call restarting...
 568          */
 569         if (syscall) {
 570                 switch (regs->ARM_r0) {
 571                 case -ERESTART_RESTARTBLOCK:
 572                 case -ERESTARTNOHAND:
 573                         regs->ARM_r0 = -EINTR;
 574                         break;
 575                 case -ERESTARTSYS:
 576                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 577                                 regs->ARM_r0 = -EINTR;
 578                                 break;
 579                         }
 580                         /* fallthrough */
 581                 case -ERESTARTNOINTR:
 582                         restart_syscall(regs);
 583                 }
 584         }
 585
 586         /*
 587          * translate the signal
 588          */
 589         if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
 590                 usig = thread->exec_domain->signal_invmap[usig];
 591
 592         /*
 593          * Set up the stack frame
 594          */
 595         if (ka->sa.sa_flags & SA_SIGINFO)
 596                 ret = setup_rt_frame(usig, ka, info, oldset, regs);
 597         else
 598                 ret = setup_frame(usig, ka, oldset, regs);
 599
 600         /*
 601          * Check that the resulting registers are actually sane.
 602          */
 603         ret |= !valid_user_regs(regs);
 604
 605         if (ret != 0) {
 606                 force_sigsegv(sig, tsk);
 607                 return;
 608         }
 609
 610         /*
 611          * Block the signal if we were successful.
 612          */
 613         spin_lock_irq(&tsk->sighand->siglock);
 614         sigorsets(&tsk->blocked, &tsk->blocked,
 615                   &ka->sa.sa_mask);
 616         if (!(ka->sa.sa_flags & SA_NODEFER))
 617                 sigaddset(&tsk->blocked, sig);
 618         recalc_sigpending();
 619         spin_unlock_irq(&tsk->sighand->siglock);
 620
 621 }
 622
 623 /*
 624  * Note that 'init' is a special process: it doesn't get signals it doesn't
 625  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 626  * mistake.
 627  *
 628  * Note that we go through the signals twice: once to check the signals that
 629  * the kernel can handle, and then we build all the user-level signal handling
 630  * stack-frames in one go after that.
 631  */
 632 static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
 633 {
 634         struct k_sigaction ka;
 635         siginfo_t info;
 636         int signr;
 637
 638         /*
 639          * We want the common case to go fast, which
 640          * is why we may in certain cases get here from
 641          * kernel mode. Just return without doing anything
 642          * if so.
 643          */
 644         if (!user_mode(regs))
 645                 return 0;
 646
 647         if (try_to_freeze())
 648                 goto no_signal;
 649
 650         if (current->ptrace & PT_SINGLESTEP)
 651                 ptrace_cancel_bpt(current);
 652
 653         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 654         if (signr > 0) {
 655                 handle_signal(signr, &ka, &info, oldset, regs, syscall);
 656                 if (current->ptrace & PT_SINGLESTEP)
 657                         ptrace_set_bpt(current);
 658                 return 1;
 659         }
 660
 661  no_signal:
 662         /*
 663          * No signal to deliver to the process - restart the syscall.
 664          */
 665         if (syscall) {
 666                 if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
 667                         if (thumb_mode(regs)) {
 668                                 regs->ARM_r7 = __NR_restart_syscall;
 669                                 regs->ARM_pc -= 2;
 670                         } else {
 671                                 u32 __user *usp;
 672
 673                                 regs->ARM_sp -= 12;
 674                                 usp = (u32 __user *)regs->ARM_sp;
 675
 676                                 put_user(regs->ARM_pc, &usp[0]);
 677                                 /* swi __NR_restart_syscall */
 678                                 put_user(0xef000000 | __NR_restart_syscall, &usp[1]);
 679                                 /* ldr  pc, [sp], #12 */
 680                                 put_user(0xe49df00c, &usp[2]);
 681
 682                                 flush_icache_range((unsigned long)usp,
 683                                                    (unsigned long)(usp + 3));
 684
 685                                 regs->ARM_pc = regs->ARM_sp + 4;
 686                         }
 687                 }
 688                 if (regs->ARM_r0 == -ERESTARTNOHAND ||
 689                     regs->ARM_r0 == -ERESTARTSYS ||
 690                     regs->ARM_r0 == -ERESTARTNOINTR) {
 691                         restart_syscall(regs);
 692                 }
 693         }
 694         if (current->ptrace & PT_SINGLESTEP)
 695                 ptrace_set_bpt(current);
 696         return 0;
 697 }
 698
 699 asmlinkage void
 700 do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 701 {
 702         if (thread_flags & _TIF_SIGPENDING)
 703                 do_signal(&current->blocked, regs, syscall);
 704 }