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 "ptrace.h"
  24 #include "signal.h"
  25
  26 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  27
  28 /*
  29  * For ARM syscalls, we encode the syscall number into the instruction.
  30  */
  31 #define SWI_SYS_SIGRETURN       (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE))
  32 #define SWI_SYS_RT_SIGRETURN    (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE))
  33 #define SWI_SYS_RESTART         (0xef000000|__NR_restart_syscall|__NR_OABI_SYSCALL_BASE)
  34
  35 /*
  36  * With EABI, the syscall number has to be loaded into r7.
  37  */
  38 #define MOV_R7_NR_SIGRETURN     (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  39 #define MOV_R7_NR_RT_SIGRETURN  (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  40
  41 /*
  42  * For Thumb syscalls, we pass the syscall number via r7.  We therefore
  43  * need two 16-bit instructions.
  44  */
  45 #define SWI_THUMB_SIGRETURN     (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  46 #define SWI_THUMB_RT_SIGRETURN  (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  47
  48 const unsigned long sigreturn_codes[7] = {
  49         MOV_R7_NR_SIGRETURN,    SWI_SYS_SIGRETURN,    SWI_THUMB_SIGRETURN,
  50         MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
  51 };
  52
  53 /*
  54  * Either we support OABI only, or we have EABI with the OABI
  55  * compat layer enabled.  In the later case we don't know if
  56  * user space is EABI or not, and if not we must not clobber r7.
  57  * Always using the OABI syscall solves that issue and works for
  58  * all those cases.
  59  */
  60 const unsigned long syscall_restart_code[2] = {
  61         SWI_SYS_RESTART,        /* swi  __NR_restart_syscall */
  62         0xe49df004,             /* ldr  pc, [sp], #4 */
  63 };
  64
  65 /*
  66  * atomically swap in the new signal mask, and wait for a signal.
  67  */
  68 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask)
  69 {
  70         mask &= _BLOCKABLE;
  71         spin_lock_irq(&current->sighand->siglock);
  72         current->saved_sigmask = current->blocked;
  73         siginitset(&current->blocked, mask);
  74         recalc_sigpending();
  75         spin_unlock_irq(&current->sighand->siglock);
  76
  77         current->state = TASK_INTERRUPTIBLE;
  78         schedule();
  79         set_restore_sigmask();
  80         return -ERESTARTNOHAND;
  81 }
  82
  83 asmlinkage int
  84 sys_sigaction(int sig, const struct old_sigaction __user *act,
  85               struct old_sigaction __user *oact)
  86 {
  87         struct k_sigaction new_ka, old_ka;
  88         int ret;
  89
  90         if (act) {
  91                 old_sigset_t mask;
  92                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  93                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  94                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
  95                         return -EFAULT;
  96                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
  97                 __get_user(mask, &act->sa_mask);
  98                 siginitset(&new_ka.sa.sa_mask, mask);
  99         }
 100
 101         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 102
 103         if (!ret && oact) {
 104                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
 105                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 106                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 107                         return -EFAULT;
 108                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 109                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 110         }
 111
 112         return ret;
 113 }
 114
 115 #ifdef CONFIG_CRUNCH
 116 static int preserve_crunch_context(struct crunch_sigframe __user *frame)
 117 {
 118         char kbuf[sizeof(*frame) + 8];
 119         struct crunch_sigframe *kframe;
 120
 121         /* the crunch context must be 64 bit aligned */
 122         kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 123         kframe->magic = CRUNCH_MAGIC;
 124         kframe->size = CRUNCH_STORAGE_SIZE;
 125         crunch_task_copy(current_thread_info(), &kframe->storage);
 126         return __copy_to_user(frame, kframe, sizeof(*frame));
 127 }
 128
 129 static int restore_crunch_context(struct crunch_sigframe __user *frame)
 130 {
 131         char kbuf[sizeof(*frame) + 8];
 132         struct crunch_sigframe *kframe;
 133
 134         /* the crunch context must be 64 bit aligned */
 135         kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7);
 136         if (__copy_from_user(kframe, frame, sizeof(*frame)))
 137                 return -1;
 138         if (kframe->magic != CRUNCH_MAGIC ||
 139             kframe->size != CRUNCH_STORAGE_SIZE)
 140                 return -1;
 141         crunch_task_restore(current_thread_info(), &kframe->storage);
 142         return 0;
 143 }
 144 #endif
 145
 146 #ifdef CONFIG_IWMMXT
 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->magic = IWMMXT_MAGIC;
 156         kframe->size = IWMMXT_STORAGE_SIZE;
 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->magic != IWMMXT_MAGIC ||
 171             kframe->size != IWMMXT_STORAGE_SIZE)
 172                 return -1;
 173         iwmmxt_task_restore(current_thread_info(), &kframe->storage);
 174         return 0;
 175 }
 176
 177 #endif
 178
 179 #ifdef CONFIG_VFP
 180
 181 static int preserve_vfp_context(struct vfp_sigframe __user *frame)
 182 {
 183         struct thread_info *thread = current_thread_info();
 184         struct vfp_hard_struct *h = &thread->vfpstate.hard;
 185         const unsigned long magic = VFP_MAGIC;
 186         const unsigned long size = VFP_STORAGE_SIZE;
 187         int err = 0;
 188
 189         vfp_sync_hwstate(thread);
 190         __put_user_error(magic, &frame->magic, err);
 191         __put_user_error(size, &frame->size, err);
 192
 193         /*
 194          * Copy the floating point registers. There can be unused
 195          * registers see asm/hwcap.h for details.
 196          */
 197         err |= __copy_to_user(&frame->ufp.fpregs, &h->fpregs,
 198                               sizeof(h->fpregs));
 199         /*
 200          * Copy the status and control register.
 201          */
 202         __put_user_error(h->fpscr, &frame->ufp.fpscr, err);
 203
 204         /*
 205          * Copy the exception registers.
 206          */
 207         __put_user_error(h->fpexc, &frame->ufp_exc.fpexc, err);
 208         __put_user_error(h->fpinst, &frame->ufp_exc.fpinst, err);
 209         __put_user_error(h->fpinst2, &frame->ufp_exc.fpinst2, err);
 210
 211         return err ? -EFAULT : 0;
 212 }
 213
 214 static int restore_vfp_context(struct vfp_sigframe __user *frame)
 215 {
 216         struct thread_info *thread = current_thread_info();
 217         struct vfp_hard_struct *h = &thread->vfpstate.hard;
 218         unsigned long magic;
 219         unsigned long size;
 220         unsigned long fpexc;
 221         int err = 0;
 222
 223         __get_user_error(magic, &frame->magic, err);
 224         __get_user_error(size, &frame->size, err);
 225
 226         if (err)
 227                 return -EFAULT;
 228         if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
 229                 return -EINVAL;
 230
 231         /*
 232          * Copy the floating point registers. There can be unused
 233          * registers see asm/hwcap.h for details.
 234          */
 235         err |= __copy_from_user(&h->fpregs, &frame->ufp.fpregs,
 236                                 sizeof(h->fpregs));
 237         /*
 238          * Copy the status and control register.
 239          */
 240         __get_user_error(h->fpscr, &frame->ufp.fpscr, err);
 241
 242         /*
 243          * Sanitise and restore the exception registers.
 244          */
 245         __get_user_error(fpexc, &frame->ufp_exc.fpexc, err);
 246         /* Ensure the VFP is enabled. */
 247         fpexc |= FPEXC_EN;
 248         /* Ensure FPINST2 is invalid and the exception flag is cleared. */
 249         fpexc &= ~(FPEXC_EX | FPEXC_FP2V);
 250         h->fpexc = fpexc;
 251
 252         __get_user_error(h->fpinst, &frame->ufp_exc.fpinst, err);
 253         __get_user_error(h->fpinst2, &frame->ufp_exc.fpinst2, err);
 254
 255         if (!err)
 256                 vfp_flush_hwstate(thread);
 257
 258         return err ? -EFAULT : 0;
 259 }
 260
 261 #endif
 262
 263 /*
 264  * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
 265  */
 266 struct sigframe {
 267         struct ucontext uc;
 268         unsigned long retcode[2];
 269 };
 270
 271 struct rt_sigframe {
 272         struct siginfo info;
 273         struct sigframe sig;
 274 };
 275
 276 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
 277 {
 278         struct aux_sigframe __user *aux;
 279         sigset_t set;
 280         int err;
 281
 282         err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
 283         if (err == 0) {
 284                 sigdelsetmask(&set, ~_BLOCKABLE);
 285                 spin_lock_irq(&current->sighand->siglock);
 286                 current->blocked = set;
 287                 recalc_sigpending();
 288                 spin_unlock_irq(&current->sighand->siglock);
 289         }
 290
 291         __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 292         __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 293         __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 294         __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 295         __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 296         __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 297         __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 298         __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 299         __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 300         __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 301         __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 302         __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 303         __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 304         __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 305         __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 306         __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 307         __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 308
 309         err |= !valid_user_regs(regs);
 310
 311         aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
 312 #ifdef CONFIG_CRUNCH
 313         if (err == 0)
 314                 err |= restore_crunch_context(&aux->crunch);
 315 #endif
 316 #ifdef CONFIG_IWMMXT
 317         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 318                 err |= restore_iwmmxt_context(&aux->iwmmxt);
 319 #endif
 320 #ifdef CONFIG_VFP
 321         if (err == 0)
 322                 err |= restore_vfp_context(&aux->vfp);
 323 #endif
 324
 325         return err;
 326 }
 327
 328 asmlinkage int sys_sigreturn(struct pt_regs *regs)
 329 {
 330         struct sigframe __user *frame;
 331
 332         /* Always make any pending restarted system calls return -EINTR */
 333         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 334
 335         /*
 336          * Since we stacked the signal on a 64-bit boundary,
 337          * then 'sp' should be word aligned here.  If it's
 338          * not, then the user is trying to mess with us.
 339          */
 340         if (regs->ARM_sp & 7)
 341                 goto badframe;
 342
 343         frame = (struct sigframe __user *)regs->ARM_sp;
 344
 345         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 346                 goto badframe;
 347
 348         if (restore_sigframe(regs, frame))
 349                 goto badframe;
 350
 351         single_step_trap(current);
 352
 353         return regs->ARM_r0;
 354
 355 badframe:
 356         force_sig(SIGSEGV, current);
 357         return 0;
 358 }
 359
 360 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 361 {
 362         struct rt_sigframe __user *frame;
 363
 364         /* Always make any pending restarted system calls return -EINTR */
 365         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 366
 367         /*
 368          * Since we stacked the signal on a 64-bit boundary,
 369          * then 'sp' should be word aligned here.  If it's
 370          * not, then the user is trying to mess with us.
 371          */
 372         if (regs->ARM_sp & 7)
 373                 goto badframe;
 374
 375         frame = (struct rt_sigframe __user *)regs->ARM_sp;
 376
 377         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 378                 goto badframe;
 379
 380         if (restore_sigframe(regs, &frame->sig))
 381                 goto badframe;
 382
 383         if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
 384                 goto badframe;
 385
 386         single_step_trap(current);
 387
 388         return regs->ARM_r0;
 389
 390 badframe:
 391         force_sig(SIGSEGV, current);
 392         return 0;
 393 }
 394
 395 static int
 396 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
 397 {
 398         struct aux_sigframe __user *aux;
 399         int err = 0;
 400
 401         __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 402         __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 403         __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 404         __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 405         __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 406         __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 407         __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 408         __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 409         __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 410         __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 411         __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 412         __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 413         __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 414         __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 415         __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 416         __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 417         __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 418
 419         __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err);
 420         __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err);
 421         __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err);
 422         __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
 423
 424         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 425
 426         aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
 427 #ifdef CONFIG_CRUNCH
 428         if (err == 0)
 429                 err |= preserve_crunch_context(&aux->crunch);
 430 #endif
 431 #ifdef CONFIG_IWMMXT
 432         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 433                 err |= preserve_iwmmxt_context(&aux->iwmmxt);
 434 #endif
 435 #ifdef CONFIG_VFP
 436         if (err == 0)
 437                 err |= preserve_vfp_context(&aux->vfp);
 438 #endif
 439         __put_user_error(0, &aux->end_magic, err);
 440
 441         return err;
 442 }
 443
 444 static inline void __user *
 445 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 446 {
 447         unsigned long sp = regs->ARM_sp;
 448         void __user *frame;
 449
 450         /*
 451          * This is the X/Open sanctioned signal stack switching.
 452          */
 453         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 454                 sp = current->sas_ss_sp + current->sas_ss_size;
 455
 456         /*
 457          * ATPCS B01 mandates 8-byte alignment
 458          */
 459         frame = (void __user *)((sp - framesize) & ~7);
 460
 461         /*
 462          * Check that we can actually write to the signal frame.
 463          */
 464         if (!access_ok(VERIFY_WRITE, frame, framesize))
 465                 frame = NULL;
 466
 467         return frame;
 468 }
 469
 470 static int
 471 setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 472              unsigned long __user *rc, void __user *frame, int usig)
 473 {
 474         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 475         unsigned long retcode;
 476         int thumb = 0;
 477         unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
 478
 479         cpsr |= PSR_ENDSTATE;
 480
 481         /*
 482          * Maybe we need to deliver a 32-bit signal to a 26-bit task.
 483          */
 484         if (ka->sa.sa_flags & SA_THIRTYTWO)
 485                 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
 486
 487 #ifdef CONFIG_ARM_THUMB
 488         if (elf_hwcap & HWCAP_THUMB) {
 489                 /*
 490                  * The LSB of the handler determines if we're going to
 491                  * be using THUMB or ARM mode for this signal handler.
 492                  */
 493                 thumb = handler & 1;
 494
 495                 if (thumb) {
 496                         cpsr |= PSR_T_BIT;
 497 #if __LINUX_ARM_ARCH__ >= 7
 498                         /* clear the If-Then Thumb-2 execution state */
 499                         cpsr &= ~PSR_IT_MASK;
 500 #endif
 501                 } else
 502                         cpsr &= ~PSR_T_BIT;
 503         }
 504 #endif
 505
 506         if (ka->sa.sa_flags & SA_RESTORER) {
 507                 retcode = (unsigned long)ka->sa.sa_restorer;
 508         } else {
 509                 unsigned int idx = thumb << 1;
 510
 511                 if (ka->sa.sa_flags & SA_SIGINFO)
 512                         idx += 3;
 513
 514                 if (__put_user(sigreturn_codes[idx],   rc) ||
 515                     __put_user(sigreturn_codes[idx+1], rc+1))
 516                         return 1;
 517
 518                 if (cpsr & MODE32_BIT) {
 519                         /*
 520                          * 32-bit code can use the new high-page
 521                          * signal return code support.
 522                          */
 523                         retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb;
 524                 } else {
 525                         /*
 526                          * Ensure that the instruction cache sees
 527                          * the return code written onto the stack.
 528                          */
 529                         flush_icache_range((unsigned long)rc,
 530                                            (unsigned long)(rc + 2));
 531
 532                         retcode = ((unsigned long)rc) + thumb;
 533                 }
 534         }
 535
 536         regs->ARM_r0 = usig;
 537         regs->ARM_sp = (unsigned long)frame;
 538         regs->ARM_lr = retcode;
 539         regs->ARM_pc = handler;
 540         regs->ARM_cpsr = cpsr;
 541
 542         return 0;
 543 }
 544
 545 static int
 546 setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
 547 {
 548         struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 549         int err = 0;
 550
 551         if (!frame)
 552                 return 1;
 553
 554         /*
 555          * Set uc.uc_flags to a value which sc.trap_no would never have.
 556          */
 557         __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
 558
 559         err |= setup_sigframe(frame, regs, set);
 560         if (err == 0)
 561                 err = setup_return(regs, ka, frame->retcode, frame, usig);
 562
 563         return err;
 564 }
 565
 566 static int
 567 setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 568                sigset_t *set, struct pt_regs *regs)
 569 {
 570         struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 571         stack_t stack;
 572         int err = 0;
 573
 574         if (!frame)
 575                 return 1;
 576
 577         err |= copy_siginfo_to_user(&frame->info, info);
 578
 579         __put_user_error(0, &frame->sig.uc.uc_flags, err);
 580         __put_user_error(NULL, &frame->sig.uc.uc_link, err);
 581
 582         memset(&stack, 0, sizeof(stack));
 583         stack.ss_sp = (void __user *)current->sas_ss_sp;
 584         stack.ss_flags = sas_ss_flags(regs->ARM_sp);
 585         stack.ss_size = current->sas_ss_size;
 586         err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
 587
 588         err |= setup_sigframe(&frame->sig, regs, set);
 589         if (err == 0)
 590                 err = setup_return(regs, ka, frame->sig.retcode, frame, usig);
 591
 592         if (err == 0) {
 593                 /*
 594                  * For realtime signals we must also set the second and third
 595                  * arguments for the signal handler.
 596                  *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 597                  */
 598                 regs->ARM_r1 = (unsigned long)&frame->info;
 599                 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
 600         }
 601
 602         return err;
 603 }
 604
 605 static inline void setup_syscall_restart(struct pt_regs *regs)
 606 {
 607         regs->ARM_r0 = regs->ARM_ORIG_r0;
 608         regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 609 }
 610
 611 /*
 612  * OK, we're invoking a handler
 613  */
 614 static int
 615 handle_signal(unsigned long sig, struct k_sigaction *ka,
 616               siginfo_t *info, sigset_t *oldset,
 617               struct pt_regs * regs, int syscall)
 618 {
 619         struct thread_info *thread = current_thread_info();
 620         struct task_struct *tsk = current;
 621         int usig = sig;
 622         int ret;
 623
 624         /*
 625          * If we were from a system call, check for system call restarting...
 626          */
 627         if (syscall) {
 628                 switch (regs->ARM_r0) {
 629                 case -ERESTART_RESTARTBLOCK:
 630                 case -ERESTARTNOHAND:
 631                         regs->ARM_r0 = -EINTR;
 632                         break;
 633                 case -ERESTARTSYS:
 634                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 635                                 regs->ARM_r0 = -EINTR;
 636                                 break;
 637                         }
 638                         /* fallthrough */
 639                 case -ERESTARTNOINTR:
 640                         setup_syscall_restart(regs);
 641                 }
 642         }
 643
 644         /*
 645          * translate the signal
 646          */
 647         if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
 648                 usig = thread->exec_domain->signal_invmap[usig];
 649
 650         /*
 651          * Set up the stack frame
 652          */
 653         if (ka->sa.sa_flags & SA_SIGINFO)
 654                 ret = setup_rt_frame(usig, ka, info, oldset, regs);
 655         else
 656                 ret = setup_frame(usig, ka, oldset, regs);
 657
 658         /*
 659          * Check that the resulting registers are actually sane.
 660          */
 661         ret |= !valid_user_regs(regs);
 662
 663         if (ret != 0) {
 664                 force_sigsegv(sig, tsk);
 665                 return ret;
 666         }
 667
 668         /*
 669          * Block the signal if we were successful.
 670          */
 671         spin_lock_irq(&tsk->sighand->siglock);
 672         sigorsets(&tsk->blocked, &tsk->blocked,
 673                   &ka->sa.sa_mask);
 674         if (!(ka->sa.sa_flags & SA_NODEFER))
 675                 sigaddset(&tsk->blocked, sig);
 676         recalc_sigpending();
 677         spin_unlock_irq(&tsk->sighand->siglock);
 678
 679         return 0;
 680 }
 681
 682 /*
 683  * Note that 'init' is a special process: it doesn't get signals it doesn't
 684  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 685  * mistake.
 686  *
 687  * Note that we go through the signals twice: once to check the signals that
 688  * the kernel can handle, and then we build all the user-level signal handling
 689  * stack-frames in one go after that.
 690  */
 691 static void do_signal(struct pt_regs *regs, int syscall)
 692 {
 693         struct k_sigaction ka;
 694         siginfo_t info;
 695         int signr;
 696
 697         /*
 698          * We want the common case to go fast, which
 699          * is why we may in certain cases get here from
 700          * kernel mode. Just return without doing anything
 701          * if so.
 702          */
 703         if (!user_mode(regs))
 704                 return;
 705
 706         if (try_to_freeze())
 707                 goto no_signal;
 708
 709         single_step_clear(current);
 710
 711         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 712         if (signr > 0) {
 713                 sigset_t *oldset;
 714
 715                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
 716                         oldset = &current->saved_sigmask;
 717                 else
 718                         oldset = &current->blocked;
 719                 if (handle_signal(signr, &ka, &info, oldset, regs, syscall) == 0) {
 720                         /*
 721                          * A signal was successfully delivered; the saved
 722                          * sigmask will have been stored in the signal frame,
 723                          * and will be restored by sigreturn, so we can simply
 724                          * clear the TIF_RESTORE_SIGMASK flag.
 725                          */
 726                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 727                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 728                 }
 729                 single_step_set(current);
 730                 return;
 731         }
 732
 733  no_signal:
 734         /*
 735          * No signal to deliver to the process - restart the syscall.
 736          */
 737         if (syscall) {
 738                 if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
 739                         if (thumb_mode(regs)) {
 740                                 regs->ARM_r7 = __NR_restart_syscall - __NR_SYSCALL_BASE;
 741                                 regs->ARM_pc -= 2;
 742                         } else {
 743 #if defined(CONFIG_AEABI) && !defined(CONFIG_OABI_COMPAT)
 744                                 regs->ARM_r7 = __NR_restart_syscall;
 745                                 regs->ARM_pc -= 4;
 746 #else
 747                                 u32 __user *usp;
 748
 749                                 regs->ARM_sp -= 4;
 750                                 usp = (u32 __user *)regs->ARM_sp;
 751
 752                                 if (put_user(regs->ARM_pc, usp) == 0) {
 753                                         regs->ARM_pc = KERN_RESTART_CODE;
 754                                 } else {
 755                                         regs->ARM_sp += 4;
 756                                         force_sigsegv(0, current);
 757                                 }
 758 #endif
 759                         }
 760                 }
 761                 if (regs->ARM_r0 == -ERESTARTNOHAND ||
 762                     regs->ARM_r0 == -ERESTARTSYS ||
 763                     regs->ARM_r0 == -ERESTARTNOINTR) {
 764                         setup_syscall_restart(regs);
 765                 }
 766
 767                 /* If there's no signal to deliver, we just put the saved sigmask
 768                  * back.
 769                  */
 770                 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 771                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 772                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 773                 }
 774         }
 775         single_step_set(current);
 776 }
 777
 778 asmlinkage void
 779 do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 780 {
 781         if (thread_flags & _TIF_SIGPENDING)
 782                 do_signal(regs, syscall);
 783
 784         if (thread_flags & _TIF_NOTIFY_RESUME) {
 785                 clear_thread_flag(TIF_NOTIFY_RESUME);
 786                 tracehook_notify_resume(regs);
 787                 if (current->replacement_session_keyring)
 788                         key_replace_session_keyring();
 789         }
 790 }