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
  22 #include "ptrace.h"
  23 #include "signal.h"
  24
  25 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  26
  27 /*
  28  * For ARM syscalls, we encode the syscall number into the instruction.
  29  */
  30 #define SWI_SYS_SIGRETURN       (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
  31 #define SWI_SYS_RT_SIGRETURN    (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
  32 #define SWI_SYS_RESTART         (0xef000000|__NR_restart_syscall|__NR_OABI_SYSCALL_BASE)
  33
  34 /*
  35  * With EABI, the syscall number has to be loaded into r7.
  36  */
  37 #define MOV_R7_NR_SIGRETURN     (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  38 #define MOV_R7_NR_RT_SIGRETURN  (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  39
  40 /*
  41  * For Thumb syscalls, we pass the syscall number via r7.  We therefore
  42  * need two 16-bit instructions.
  43  */
  44 #define SWI_THUMB_SIGRETURN     (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  45 #define SWI_THUMB_RT_SIGRETURN  (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  46
  47 const unsigned long sigreturn_codes[7] = {
  48         MOV_R7_NR_SIGRETURN,    SWI_SYS_SIGRETURN,    SWI_THUMB_SIGRETURN,
  49         MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
  50 };
  51
  52 /*
  53  * Either we support OABI only, or we have EABI with the OABI
  54  * compat layer enabled.  In the later case we don't know if
  55  * user space is EABI or not, and if not we must not clobber r7.
  56  * Always using the OABI syscall solves that issue and works for
  57  * all those cases.
  58  */
  59 const unsigned long syscall_restart_code[2] = {
  60         SWI_SYS_RESTART,        /* swi  __NR_restart_syscall */
  61         0xe49df004,             /* ldr  pc, [sp], #4 */
  62 };
  63
  64 /*
  65  * atomically swap in the new signal mask, and wait for a signal.
  66  */
  67 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask)
  68 {
  69         mask &= _BLOCKABLE;
  70         spin_lock_irq(&current->sighand->siglock);
  71         current->saved_sigmask = current->blocked;
  72         siginitset(&current->blocked, mask);
  73         recalc_sigpending();
  74         spin_unlock_irq(&current->sighand->siglock);
  75
  76         current->state = TASK_INTERRUPTIBLE;
  77         schedule();
  78         set_restore_sigmask();
  79         return -ERESTARTNOHAND;
  80 }
  81
  82 asmlinkage int
  83 sys_sigaction(int sig, const struct old_sigaction __user *act,
  84               struct old_sigaction __user *oact)
  85 {
  86         struct k_sigaction new_ka, old_ka;
  87         int ret;
  88
  89         if (act) {
  90                 old_sigset_t mask;
  91                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  92                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  93                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
  94                         return -EFAULT;
  95                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
  96                 __get_user(mask, &act->sa_mask);
  97                 siginitset(&new_ka.sa.sa_mask, mask);
  98         }
  99
 100         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 101
 102         if (!ret && oact) {
 103                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
 104                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 105                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 106                         return -EFAULT;
 107                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 108                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 109         }
 110
 111         return ret;
 112 }
 113
 114 #ifdef CONFIG_CRUNCH
 115 static int preserve_crunch_context(struct crunch_sigframe __user *frame)
 116 {
 117         char kbuf[sizeof(*frame) + 8];
 118         struct crunch_sigframe *kframe;
 119
 120         /* the crunch context must be 64 bit aligned */
 121         kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 122         kframe->magic = CRUNCH_MAGIC;
 123         kframe->size = CRUNCH_STORAGE_SIZE;
 124         crunch_task_copy(current_thread_info(), &kframe->storage);
 125         return __copy_to_user(frame, kframe, sizeof(*frame));
 126 }
 127
 128 static int restore_crunch_context(struct crunch_sigframe __user *frame)
 129 {
 130         char kbuf[sizeof(*frame) + 8];
 131         struct crunch_sigframe *kframe;
 132
 133         /* the crunch context must be 64 bit aligned */
 134         kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 135         if (__copy_from_user(kframe, frame, sizeof(*frame)))
 136                 return -1;
 137         if (kframe->magic != CRUNCH_MAGIC ||
 138             kframe->size != CRUNCH_STORAGE_SIZE)
 139                 return -1;
 140         crunch_task_restore(current_thread_info(), &kframe->storage);
 141         return 0;
 142 }
 143 #endif
 144
 145 #ifdef CONFIG_IWMMXT
 146
 147 static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame)
 148 {
 149         char kbuf[sizeof(*frame) + 8];
 150         struct iwmmxt_sigframe *kframe;
 151
 152         /* the iWMMXt context must be 64 bit aligned */
 153         kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 154         kframe->magic = IWMMXT_MAGIC;
 155         kframe->size = IWMMXT_STORAGE_SIZE;
 156         iwmmxt_task_copy(current_thread_info(), &kframe->storage);
 157         return __copy_to_user(frame, kframe, sizeof(*frame));
 158 }
 159
 160 static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame)
 161 {
 162         char kbuf[sizeof(*frame) + 8];
 163         struct iwmmxt_sigframe *kframe;
 164
 165         /* the iWMMXt context must be 64 bit aligned */
 166         kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 167         if (__copy_from_user(kframe, frame, sizeof(*frame)))
 168                 return -1;
 169         if (kframe->magic != IWMMXT_MAGIC ||
 170             kframe->size != IWMMXT_STORAGE_SIZE)
 171                 return -1;
 172         iwmmxt_task_restore(current_thread_info(), &kframe->storage);
 173         return 0;
 174 }
 175
 176 #endif
 177
 178 /*
 179  * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
 180  */
 181 struct sigframe {
 182         struct ucontext uc;
 183         unsigned long retcode[2];
 184 };
 185
 186 struct rt_sigframe {
 187         struct siginfo info;
 188         struct sigframe sig;
 189 };
 190
 191 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
 192 {
 193         struct aux_sigframe __user *aux;
 194         sigset_t set;
 195         int err;
 196
 197         err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
 198         if (err == 0) {
 199                 sigdelsetmask(&set, ~_BLOCKABLE);
 200                 spin_lock_irq(&current->sighand->siglock);
 201                 current->blocked = set;
 202                 recalc_sigpending();
 203                 spin_unlock_irq(&current->sighand->siglock);
 204         }
 205
 206         __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 207         __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 208         __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 209         __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 210         __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 211         __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 212         __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 213         __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 214         __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 215         __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 216         __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 217         __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 218         __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 219         __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 220         __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 221         __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 222         __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 223
 224         err |= !valid_user_regs(regs);
 225
 226         aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
 227 #ifdef CONFIG_CRUNCH
 228         if (err == 0)
 229                 err |= restore_crunch_context(&aux->crunch);
 230 #endif
 231 #ifdef CONFIG_IWMMXT
 232         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 233                 err |= restore_iwmmxt_context(&aux->iwmmxt);
 234 #endif
 235 #ifdef CONFIG_VFP
 236 //      if (err == 0)
 237 //              err |= vfp_restore_state(&sf->aux.vfp);
 238 #endif
 239
 240         return err;
 241 }
 242
 243 asmlinkage int sys_sigreturn(struct pt_regs *regs)
 244 {
 245         struct sigframe __user *frame;
 246
 247         /* Always make any pending restarted system calls return -EINTR */
 248         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 249
 250         /*
 251          * Since we stacked the signal on a 64-bit boundary,
 252          * then 'sp' should be word aligned here.  If it's
 253          * not, then the user is trying to mess with us.
 254          */
 255         if (regs->ARM_sp & 7)
 256                 goto badframe;
 257
 258         frame = (struct sigframe __user *)regs->ARM_sp;
 259
 260         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 261                 goto badframe;
 262
 263         if (restore_sigframe(regs, frame))
 264                 goto badframe;
 265
 266         single_step_trap(current);
 267
 268         return regs->ARM_r0;
 269
 270 badframe:
 271         force_sig(SIGSEGV, current);
 272         return 0;
 273 }
 274
 275 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 276 {
 277         struct rt_sigframe __user *frame;
 278
 279         /* Always make any pending restarted system calls return -EINTR */
 280         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 281
 282         /*
 283          * Since we stacked the signal on a 64-bit boundary,
 284          * then 'sp' should be word aligned here.  If it's
 285          * not, then the user is trying to mess with us.
 286          */
 287         if (regs->ARM_sp & 7)
 288                 goto badframe;
 289
 290         frame = (struct rt_sigframe __user *)regs->ARM_sp;
 291
 292         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 293                 goto badframe;
 294
 295         if (restore_sigframe(regs, &frame->sig))
 296                 goto badframe;
 297
 298         if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
 299                 goto badframe;
 300
 301         single_step_trap(current);
 302
 303         return regs->ARM_r0;
 304
 305 badframe:
 306         force_sig(SIGSEGV, current);
 307         return 0;
 308 }
 309
 310 static int
 311 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
 312 {
 313         struct aux_sigframe __user *aux;
 314         int err = 0;
 315
 316         __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 317         __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 318         __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 319         __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 320         __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 321         __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 322         __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 323         __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 324         __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 325         __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 326         __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 327         __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 328         __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 329         __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 330         __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 331         __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 332         __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 333
 334         __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err);
 335         __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err);
 336         __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err);
 337         __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
 338
 339         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 340
 341         aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
 342 #ifdef CONFIG_CRUNCH
 343         if (err == 0)
 344                 err |= preserve_crunch_context(&aux->crunch);
 345 #endif
 346 #ifdef CONFIG_IWMMXT
 347         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 348                 err |= preserve_iwmmxt_context(&aux->iwmmxt);
 349 #endif
 350 #ifdef CONFIG_VFP
 351 //      if (err == 0)
 352 //              err |= vfp_save_state(&sf->aux.vfp);
 353 #endif
 354         __put_user_error(0, &aux->end_magic, err);
 355
 356         return err;
 357 }
 358
 359 static inline void __user *
 360 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 361 {
 362         unsigned long sp = regs->ARM_sp;
 363         void __user *frame;
 364
 365         /*
 366          * This is the X/Open sanctioned signal stack switching.
 367          */
 368         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 369                 sp = current->sas_ss_sp + current->sas_ss_size;
 370
 371         /*
 372          * ATPCS B01 mandates 8-byte alignment
 373          */
 374         frame = (void __user *)((sp - framesize) & ~7);
 375
 376         /*
 377          * Check that we can actually write to the signal frame.
 378          */
 379         if (!access_ok(VERIFY_WRITE, frame, framesize))
 380                 frame = NULL;
 381
 382         return frame;
 383 }
 384
 385 static int
 386 setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 387              unsigned long __user *rc, void __user *frame, int usig)
 388 {
 389         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 390         unsigned long retcode;
 391         int thumb = 0;
 392         unsigned long cpsr = regs->ARM_cpsr & ~PSR_f;
 393
 394         /*
 395          * Maybe we need to deliver a 32-bit signal to a 26-bit task.
 396          */
 397         if (ka->sa.sa_flags & SA_THIRTYTWO)
 398                 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
 399
 400 #ifdef CONFIG_ARM_THUMB
 401         if (elf_hwcap & HWCAP_THUMB) {
 402                 /*
 403                  * The LSB of the handler determines if we're going to
 404                  * be using THUMB or ARM mode for this signal handler.
 405                  */
 406                 thumb = handler & 1;
 407
 408                 if (thumb) {
 409                         cpsr |= PSR_T_BIT;
 410 #if __LINUX_ARM_ARCH__ >= 7
 411                         /* clear the If-Then Thumb-2 execution state */
 412                         cpsr &= ~PSR_IT_MASK;
 413 #endif
 414                 } else
 415                         cpsr &= ~PSR_T_BIT;
 416         }
 417 #endif
 418
 419         if (ka->sa.sa_flags & SA_RESTORER) {
 420                 retcode = (unsigned long)ka->sa.sa_restorer;
 421         } else {
 422                 unsigned int idx = thumb << 1;
 423
 424                 if (ka->sa.sa_flags & SA_SIGINFO)
 425                         idx += 3;
 426
 427                 if (__put_user(sigreturn_codes[idx],   rc) ||
 428                     __put_user(sigreturn_codes[idx+1], rc+1))
 429                         return 1;
 430
 431                 if (cpsr & MODE32_BIT) {
 432                         /*
 433                          * 32-bit code can use the new high-page
 434                          * signal return code support.
 435                          */
 436                         retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb;
 437                 } else {
 438                         /*
 439                          * Ensure that the instruction cache sees
 440                          * the return code written onto the stack.
 441                          */
 442                         flush_icache_range((unsigned long)rc,
 443                                            (unsigned long)(rc + 2));
 444
 445                         retcode = ((unsigned long)rc) + thumb;
 446                 }
 447         }
 448
 449         regs->ARM_r0 = usig;
 450         regs->ARM_sp = (unsigned long)frame;
 451         regs->ARM_lr = retcode;
 452         regs->ARM_pc = handler;
 453         regs->ARM_cpsr = cpsr;
 454
 455         return 0;
 456 }
 457
 458 static int
 459 setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
 460 {
 461         struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 462         int err = 0;
 463
 464         if (!frame)
 465                 return 1;
 466
 467         /*
 468          * Set uc.uc_flags to a value which sc.trap_no would never have.
 469          */
 470         __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
 471
 472         err |= setup_sigframe(frame, regs, set);
 473         if (err == 0)
 474                 err = setup_return(regs, ka, frame->retcode, frame, usig);
 475
 476         return err;
 477 }
 478
 479 static int
 480 setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 481                sigset_t *set, struct pt_regs *regs)
 482 {
 483         struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 484         stack_t stack;
 485         int err = 0;
 486
 487         if (!frame)
 488                 return 1;
 489
 490         err |= copy_siginfo_to_user(&frame->info, info);
 491
 492         __put_user_error(0, &frame->sig.uc.uc_flags, err);
 493         __put_user_error(NULL, &frame->sig.uc.uc_link, err);
 494
 495         memset(&stack, 0, sizeof(stack));
 496         stack.ss_sp = (void __user *)current->sas_ss_sp;
 497         stack.ss_flags = sas_ss_flags(regs->ARM_sp);
 498         stack.ss_size = current->sas_ss_size;
 499         err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
 500
 501         err |= setup_sigframe(&frame->sig, regs, set);
 502         if (err == 0)
 503                 err = setup_return(regs, ka, frame->sig.retcode, frame, usig);
 504
 505         if (err == 0) {
 506                 /*
 507                  * For realtime signals we must also set the second and third
 508                  * arguments for the signal handler.
 509                  *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 510                  */
 511                 regs->ARM_r1 = (unsigned long)&frame->info;
 512                 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
 513         }
 514
 515         return err;
 516 }
 517
 518 static inline void setup_syscall_restart(struct pt_regs *regs)
 519 {
 520         regs->ARM_r0 = regs->ARM_ORIG_r0;
 521         regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 522 }
 523
 524 /*
 525  * OK, we're invoking a handler
 526  */
 527 static int
 528 handle_signal(unsigned long sig, struct k_sigaction *ka,
 529               siginfo_t *info, sigset_t *oldset,
 530               struct pt_regs * regs, int syscall)
 531 {
 532         struct thread_info *thread = current_thread_info();
 533         struct task_struct *tsk = current;
 534         int usig = sig;
 535         int ret;
 536
 537         /*
 538          * If we were from a system call, check for system call restarting...
 539          */
 540         if (syscall) {
 541                 switch (regs->ARM_r0) {
 542                 case -ERESTART_RESTARTBLOCK:
 543                 case -ERESTARTNOHAND:
 544                         regs->ARM_r0 = -EINTR;
 545                         break;
 546                 case -ERESTARTSYS:
 547                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 548                                 regs->ARM_r0 = -EINTR;
 549                                 break;
 550                         }
 551                         /* fallthrough */
 552                 case -ERESTARTNOINTR:
 553                         setup_syscall_restart(regs);
 554                 }
 555         }
 556
 557         /*
 558          * translate the signal
 559          */
 560         if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
 561                 usig = thread->exec_domain->signal_invmap[usig];
 562
 563         /*
 564          * Set up the stack frame
 565          */
 566         if (ka->sa.sa_flags & SA_SIGINFO)
 567                 ret = setup_rt_frame(usig, ka, info, oldset, regs);
 568         else
 569                 ret = setup_frame(usig, ka, oldset, regs);
 570
 571         /*
 572          * Check that the resulting registers are actually sane.
 573          */
 574         ret |= !valid_user_regs(regs);
 575
 576         if (ret != 0) {
 577                 force_sigsegv(sig, tsk);
 578                 return ret;
 579         }
 580
 581         /*
 582          * Block the signal if we were successful.
 583          */
 584         spin_lock_irq(&tsk->sighand->siglock);
 585         sigorsets(&tsk->blocked, &tsk->blocked,
 586                   &ka->sa.sa_mask);
 587         if (!(ka->sa.sa_flags & SA_NODEFER))
 588                 sigaddset(&tsk->blocked, sig);
 589         recalc_sigpending();
 590         spin_unlock_irq(&tsk->sighand->siglock);
 591
 592         return 0;
 593 }
 594
 595 /*
 596  * Note that 'init' is a special process: it doesn't get signals it doesn't
 597  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 598  * mistake.
 599  *
 600  * Note that we go through the signals twice: once to check the signals that
 601  * the kernel can handle, and then we build all the user-level signal handling
 602  * stack-frames in one go after that.
 603  */
 604 static void do_signal(struct pt_regs *regs, int syscall)
 605 {
 606         struct k_sigaction ka;
 607         siginfo_t info;
 608         int signr;
 609
 610         /*
 611          * We want the common case to go fast, which
 612          * is why we may in certain cases get here from
 613          * kernel mode. Just return without doing anything
 614          * if so.
 615          */
 616         if (!user_mode(regs))
 617                 return;
 618
 619         if (try_to_freeze())
 620                 goto no_signal;
 621
 622         single_step_clear(current);
 623
 624         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 625         if (signr > 0) {
 626                 sigset_t *oldset;
 627
 628                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
 629                         oldset = &current->saved_sigmask;
 630                 else
 631                         oldset = &current->blocked;
 632                 if (handle_signal(signr, &ka, &info, oldset, regs, syscall) == 0) {
 633                         /*
 634                          * A signal was successfully delivered; the saved
 635                          * sigmask will have been stored in the signal frame,
 636                          * and will be restored by sigreturn, so we can simply
 637                          * clear the TIF_RESTORE_SIGMASK flag.
 638                          */
 639                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 640                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 641                 }
 642                 single_step_set(current);
 643                 return;
 644         }
 645
 646  no_signal:
 647         /*
 648          * No signal to deliver to the process - restart the syscall.
 649          */
 650         if (syscall) {
 651                 if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
 652                         if (thumb_mode(regs)) {
 653                                 regs->ARM_r7 = __NR_restart_syscall - __NR_SYSCALL_BASE;
 654                                 regs->ARM_pc -= 2;
 655                         } else {
 656 #if defined(CONFIG_AEABI) && !defined(CONFIG_OABI_COMPAT)
 657                                 regs->ARM_r7 = __NR_restart_syscall;
 658                                 regs->ARM_pc -= 4;
 659 #else
 660                                 u32 __user *usp;
 661
 662                                 regs->ARM_sp -= 4;
 663                                 usp = (u32 __user *)regs->ARM_sp;
 664
 665                                 if (put_user(regs->ARM_pc, usp) == 0) {
 666                                         regs->ARM_pc = KERN_RESTART_CODE;
 667                                 } else {
 668                                         regs->ARM_sp += 4;
 669                                         force_sigsegv(0, current);
 670                                 }
 671 #endif
 672                         }
 673                 }
 674                 if (regs->ARM_r0 == -ERESTARTNOHAND ||
 675                     regs->ARM_r0 == -ERESTARTSYS ||
 676                     regs->ARM_r0 == -ERESTARTNOINTR) {
 677                         setup_syscall_restart(regs);
 678                 }
 679
 680                 /* If there's no signal to deliver, we just put the saved sigmask
 681                  * back.
 682                  */
 683                 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 684                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 685                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 686                 }
 687         }
 688         single_step_set(current);
 689 }
 690
 691 asmlinkage void
 692 do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 693 {
 694         if (thread_flags & _TIF_SIGPENDING)
 695                 do_signal(regs, syscall);
 696
 697         if (thread_flags & _TIF_NOTIFY_RESUME) {
 698                 clear_thread_flag(TIF_NOTIFY_RESUME);
 699                 tracehook_notify_resume(regs);
 700                 if (current->replacement_session_keyring)
 701                         key_replace_session_keyring();
 702         }
 703 }