arch/arm/kernel/signal.c

   1 /*
   2  *  linux/arch/arm/kernel/signal.c
   3  *
   4  *  Copyright (C) 1995-2009 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/errno.h>
  11 #include <linux/signal.h>
  12 #include <linux/personality.h>
  13 #include <linux/freezer.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/tracehook.h>
  16
  17 #include <asm/elf.h>
  18 #include <asm/cacheflush.h>
  19 #include <asm/ucontext.h>
  20 #include <asm/unistd.h>
  21 #include <asm/vfp.h>
  22
  23 #include "signal.h"
  24
  25 #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         sigset_t blocked;
  70
  71         current->saved_sigmask = current->blocked;
  72
  73         mask &= _BLOCKABLE;
  74         siginitset(&blocked, mask);
  75         set_current_blocked(&blocked);
  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         const unsigned long magic = VFP_MAGIC;
 184         const unsigned long size = VFP_STORAGE_SIZE;
 185         int err = 0;
 186
 187         __put_user_error(magic, &frame->magic, err);
 188         __put_user_error(size, &frame->size, err);
 189
 190         if (err)
 191                 return -EFAULT;
 192
 193         return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc);
 194 }
 195
 196 static int restore_vfp_context(struct vfp_sigframe __user *frame)
 197 {
 198         unsigned long magic;
 199         unsigned long size;
 200         int err = 0;
 201
 202         __get_user_error(magic, &frame->magic, err);
 203         __get_user_error(size, &frame->size, err);
 204
 205         if (err)
 206                 return -EFAULT;
 207         if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
 208                 return -EINVAL;
 209
 210         return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc);
 211 }
 212
 213 #endif
 214
 215 /*
 216  * Do a signal return; undo the signal stack.  These are aligned to 64-bit.
 217  */
 218 struct sigframe {
 219         struct ucontext uc;
 220         unsigned long retcode[2];
 221 };
 222
 223 struct rt_sigframe {
 224         struct siginfo info;
 225         struct sigframe sig;
 226 };
 227
 228 static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf)
 229 {
 230         struct aux_sigframe __user *aux;
 231         sigset_t set;
 232         int err;
 233
 234         err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
 235         if (err == 0) {
 236                 sigdelsetmask(&set, ~_BLOCKABLE);
 237                 set_current_blocked(&set);
 238         }
 239
 240         __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 241         __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 242         __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 243         __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 244         __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 245         __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 246         __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 247         __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 248         __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 249         __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 250         __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 251         __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 252         __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 253         __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 254         __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 255         __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 256         __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 257
 258         err |= !valid_user_regs(regs);
 259
 260         aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
 261 #ifdef CONFIG_CRUNCH
 262         if (err == 0)
 263                 err |= restore_crunch_context(&aux->crunch);
 264 #endif
 265 #ifdef CONFIG_IWMMXT
 266         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 267                 err |= restore_iwmmxt_context(&aux->iwmmxt);
 268 #endif
 269 #ifdef CONFIG_VFP
 270         if (err == 0)
 271                 err |= restore_vfp_context(&aux->vfp);
 272 #endif
 273
 274         return err;
 275 }
 276
 277 asmlinkage int sys_sigreturn(struct pt_regs *regs)
 278 {
 279         struct sigframe __user *frame;
 280
 281         /* Always make any pending restarted system calls return -EINTR */
 282         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 283
 284         /*
 285          * Since we stacked the signal on a 64-bit boundary,
 286          * then 'sp' should be word aligned here.  If it's
 287          * not, then the user is trying to mess with us.
 288          */
 289         if (regs->ARM_sp & 7)
 290                 goto badframe;
 291
 292         frame = (struct sigframe __user *)regs->ARM_sp;
 293
 294         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 295                 goto badframe;
 296
 297         if (restore_sigframe(regs, frame))
 298                 goto badframe;
 299
 300         return regs->ARM_r0;
 301
 302 badframe:
 303         force_sig(SIGSEGV, current);
 304         return 0;
 305 }
 306
 307 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 308 {
 309         struct rt_sigframe __user *frame;
 310
 311         /* Always make any pending restarted system calls return -EINTR */
 312         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 313
 314         /*
 315          * Since we stacked the signal on a 64-bit boundary,
 316          * then 'sp' should be word aligned here.  If it's
 317          * not, then the user is trying to mess with us.
 318          */
 319         if (regs->ARM_sp & 7)
 320                 goto badframe;
 321
 322         frame = (struct rt_sigframe __user *)regs->ARM_sp;
 323
 324         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 325                 goto badframe;
 326
 327         if (restore_sigframe(regs, &frame->sig))
 328                 goto badframe;
 329
 330         if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT)
 331                 goto badframe;
 332
 333         return regs->ARM_r0;
 334
 335 badframe:
 336         force_sig(SIGSEGV, current);
 337         return 0;
 338 }
 339
 340 static int
 341 setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set)
 342 {
 343         struct aux_sigframe __user *aux;
 344         int err = 0;
 345
 346         __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err);
 347         __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err);
 348         __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err);
 349         __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err);
 350         __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err);
 351         __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err);
 352         __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err);
 353         __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err);
 354         __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err);
 355         __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err);
 356         __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err);
 357         __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err);
 358         __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err);
 359         __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err);
 360         __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err);
 361         __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err);
 362         __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err);
 363
 364         __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err);
 365         __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err);
 366         __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err);
 367         __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
 368
 369         err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 370
 371         aux = (struct aux_sigframe __user *) sf->uc.uc_regspace;
 372 #ifdef CONFIG_CRUNCH
 373         if (err == 0)
 374                 err |= preserve_crunch_context(&aux->crunch);
 375 #endif
 376 #ifdef CONFIG_IWMMXT
 377         if (err == 0 && test_thread_flag(TIF_USING_IWMMXT))
 378                 err |= preserve_iwmmxt_context(&aux->iwmmxt);
 379 #endif
 380 #ifdef CONFIG_VFP
 381         if (err == 0)
 382                 err |= preserve_vfp_context(&aux->vfp);
 383 #endif
 384         __put_user_error(0, &aux->end_magic, err);
 385
 386         return err;
 387 }
 388
 389 static inline void __user *
 390 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 391 {
 392         unsigned long sp = regs->ARM_sp;
 393         void __user *frame;
 394
 395         /*
 396          * This is the X/Open sanctioned signal stack switching.
 397          */
 398         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 399                 sp = current->sas_ss_sp + current->sas_ss_size;
 400
 401         /*
 402          * ATPCS B01 mandates 8-byte alignment
 403          */
 404         frame = (void __user *)((sp - framesize) & ~7);
 405
 406         /*
 407          * Check that we can actually write to the signal frame.
 408          */
 409         if (!access_ok(VERIFY_WRITE, frame, framesize))
 410                 frame = NULL;
 411
 412         return frame;
 413 }
 414
 415 static int
 416 setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 417              unsigned long __user *rc, void __user *frame, int usig)
 418 {
 419         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 420         unsigned long retcode;
 421         int thumb = 0;
 422         unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT);
 423
 424         cpsr |= PSR_ENDSTATE;
 425
 426         /*
 427          * Maybe we need to deliver a 32-bit signal to a 26-bit task.
 428          */
 429         if (ka->sa.sa_flags & SA_THIRTYTWO)
 430                 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
 431
 432 #ifdef CONFIG_ARM_THUMB
 433         if (elf_hwcap & HWCAP_THUMB) {
 434                 /*
 435                  * The LSB of the handler determines if we're going to
 436                  * be using THUMB or ARM mode for this signal handler.
 437                  */
 438                 thumb = handler & 1;
 439
 440                 if (thumb) {
 441                         cpsr |= PSR_T_BIT;
 442 #if __LINUX_ARM_ARCH__ >= 7
 443                         /* clear the If-Then Thumb-2 execution state */
 444                         cpsr &= ~PSR_IT_MASK;
 445 #endif
 446                 } else
 447                         cpsr &= ~PSR_T_BIT;
 448         }
 449 #endif
 450
 451         if (ka->sa.sa_flags & SA_RESTORER) {
 452                 retcode = (unsigned long)ka->sa.sa_restorer;
 453         } else {
 454                 unsigned int idx = thumb << 1;
 455
 456                 if (ka->sa.sa_flags & SA_SIGINFO)
 457                         idx += 3;
 458
 459                 if (__put_user(sigreturn_codes[idx],   rc) ||
 460                     __put_user(sigreturn_codes[idx+1], rc+1))
 461                         return 1;
 462
 463                 if (cpsr & MODE32_BIT) {
 464                         /*
 465                          * 32-bit code can use the new high-page
 466                          * signal return code support.
 467                          */
 468                         retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb;
 469                 } else {
 470                         /*
 471                          * Ensure that the instruction cache sees
 472                          * the return code written onto the stack.
 473                          */
 474                         flush_icache_range((unsigned long)rc,
 475                                            (unsigned long)(rc + 2));
 476
 477                         retcode = ((unsigned long)rc) + thumb;
 478                 }
 479         }
 480
 481         regs->ARM_r0 = usig;
 482         regs->ARM_sp = (unsigned long)frame;
 483         regs->ARM_lr = retcode;
 484         regs->ARM_pc = handler;
 485         regs->ARM_cpsr = cpsr;
 486
 487         return 0;
 488 }
 489
 490 static int
 491 setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
 492 {
 493         struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 494         int err = 0;
 495
 496         if (!frame)
 497                 return 1;
 498
 499         /*
 500          * Set uc.uc_flags to a value which sc.trap_no would never have.
 501          */
 502         __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
 503
 504         err |= setup_sigframe(frame, regs, set);
 505         if (err == 0)
 506                 err = setup_return(regs, ka, frame->retcode, frame, usig);
 507
 508         return err;
 509 }
 510
 511 static int
 512 setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 513                sigset_t *set, struct pt_regs *regs)
 514 {
 515         struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 516         stack_t stack;
 517         int err = 0;
 518
 519         if (!frame)
 520                 return 1;
 521
 522         err |= copy_siginfo_to_user(&frame->info, info);
 523
 524         __put_user_error(0, &frame->sig.uc.uc_flags, err);
 525         __put_user_error(NULL, &frame->sig.uc.uc_link, err);
 526
 527         memset(&stack, 0, sizeof(stack));
 528         stack.ss_sp = (void __user *)current->sas_ss_sp;
 529         stack.ss_flags = sas_ss_flags(regs->ARM_sp);
 530         stack.ss_size = current->sas_ss_size;
 531         err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
 532
 533         err |= setup_sigframe(&frame->sig, regs, set);
 534         if (err == 0)
 535                 err = setup_return(regs, ka, frame->sig.retcode, frame, usig);
 536
 537         if (err == 0) {
 538                 /*
 539                  * For realtime signals we must also set the second and third
 540                  * arguments for the signal handler.
 541                  *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 542                  */
 543                 regs->ARM_r1 = (unsigned long)&frame->info;
 544                 regs->ARM_r2 = (unsigned long)&frame->sig.uc;
 545         }
 546
 547         return err;
 548 }
 549
 550 /*
 551  * OK, we're invoking a handler
 552  */
 553 static int
 554 handle_signal(unsigned long sig, struct k_sigaction *ka,
 555               siginfo_t *info, sigset_t *oldset,
 556               struct pt_regs * regs)
 557 {
 558         struct thread_info *thread = current_thread_info();
 559         struct task_struct *tsk = current;
 560         int usig = sig;
 561         int ret;
 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 ret;
 585         }
 586
 587         /*
 588          * Block the signal if we were successful.
 589          */
 590         block_sigmask(ka, sig);
 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         unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
 607         struct k_sigaction ka;
 608         siginfo_t info;
 609         int signr;
 610
 611         /*
 612          * We want the common case to go fast, which
 613          * is why we may in certain cases get here from
 614          * kernel mode. Just return without doing anything
 615          * if so.
 616          */
 617         if (!user_mode(regs))
 618                 return;
 619
 620         /*
 621          * If we were from a system call, check for system call restarting...
 622          */
 623         if (syscall) {
 624                 continue_addr = regs->ARM_pc;
 625                 restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4);
 626                 retval = regs->ARM_r0;
 627
 628                 /*
 629                  * Prepare for system call restart.  We do this here so that a
 630                  * debugger will see the already changed PSW.
 631                  */
 632                 switch (retval) {
 633                 case -ERESTARTNOHAND:
 634                 case -ERESTARTSYS:
 635                 case -ERESTARTNOINTR:
 636                         regs->ARM_r0 = regs->ARM_ORIG_r0;
 637                         regs->ARM_pc = restart_addr;
 638                         break;
 639                 case -ERESTART_RESTARTBLOCK:
 640                         regs->ARM_r0 = -EINTR;
 641                         break;
 642                 }
 643         }
 644
 645         if (try_to_freeze())
 646                 goto no_signal;
 647
 648         /*
 649          * Get the signal to deliver.  When running under ptrace, at this
 650          * point the debugger may change all our registers ...
 651          */
 652         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 653         if (signr > 0) {
 654                 sigset_t *oldset;
 655
 656                 /*
 657                  * Depending on the signal settings we may need to revert the
 658                  * decision to restart the system call.  But skip this if a
 659                  * debugger has chosen to restart at a different PC.
 660                  */
 661                 if (regs->ARM_pc == restart_addr) {
 662                         if (retval == -ERESTARTNOHAND
 663                             || (retval == -ERESTARTSYS
 664                                 && !(ka.sa.sa_flags & SA_RESTART))) {
 665                                 regs->ARM_r0 = -EINTR;
 666                                 regs->ARM_pc = continue_addr;
 667                         }
 668                 }
 669
 670                 if (test_thread_flag(TIF_RESTORE_SIGMASK))
 671                         oldset = &current->saved_sigmask;
 672                 else
 673                         oldset = &current->blocked;
 674                 if (handle_signal(signr, &ka, &info, oldset, regs) == 0) {
 675                         /*
 676                          * A signal was successfully delivered; the saved
 677                          * sigmask will have been stored in the signal frame,
 678                          * and will be restored by sigreturn, so we can simply
 679                          * clear the TIF_RESTORE_SIGMASK flag.
 680                          */
 681                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 682                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 683                 }
 684                 return;
 685         }
 686
 687  no_signal:
 688         if (syscall) {
 689                 /*
 690                  * Handle restarting a different system call.  As above,
 691                  * if a debugger has chosen to restart at a different PC,
 692                  * ignore the restart.
 693                  */
 694                 if (retval == -ERESTART_RESTARTBLOCK
 695                     && regs->ARM_pc == continue_addr) {
 696                         if (thumb_mode(regs)) {
 697                                 regs->ARM_r7 = __NR_restart_syscall - __NR_SYSCALL_BASE;
 698                                 regs->ARM_pc -= 2;
 699                         } else {
 700 #if defined(CONFIG_AEABI) && !defined(CONFIG_OABI_COMPAT)
 701                                 regs->ARM_r7 = __NR_restart_syscall;
 702                                 regs->ARM_pc -= 4;
 703 #else
 704                                 u32 __user *usp;
 705
 706                                 regs->ARM_sp -= 4;
 707                                 usp = (u32 __user *)regs->ARM_sp;
 708
 709                                 if (put_user(regs->ARM_pc, usp) == 0) {
 710                                         regs->ARM_pc = KERN_RESTART_CODE;
 711                                 } else {
 712                                         regs->ARM_sp += 4;
 713                                         force_sigsegv(0, current);
 714                                 }
 715 #endif
 716                         }
 717                 }
 718
 719                 /* If there's no signal to deliver, we just put the saved sigmask
 720                  * back.
 721                  */
 722                 if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 723                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 724                         sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 725                 }
 726         }
 727 }
 728
 729 asmlinkage void
 730 do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 731 {
 732         if (thread_flags & _TIF_SIGPENDING)
 733                 do_signal(regs, syscall);
 734
 735         if (thread_flags & _TIF_NOTIFY_RESUME) {
 736                 clear_thread_flag(TIF_NOTIFY_RESUME);
 737                 tracehook_notify_resume(regs);
 738                 if (current->replacement_session_keyring)
 739                         key_replace_session_keyring();
 740         }
 741 }