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