arch/arm/kernel/signal.c

   1 /*
   2  *  linux/arch/arm/kernel/signal.c
   3  *
   4  *  Copyright (C) 1995-2002 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/config.h>
  11 #include <linux/errno.h>
  12 #include <linux/signal.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/personality.h>
  15 #include <linux/suspend.h>
  16
  17 #include <asm/cacheflush.h>
  18 #include <asm/ucontext.h>
  19 #include <asm/uaccess.h>
  20 #include <asm/unistd.h>
  21
  22 #include "ptrace.h"
  23
  24 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  25
  26 /*
  27  * For ARM syscalls, we encode the syscall number into the instruction.
  28  */
  29 #define SWI_SYS_SIGRETURN       (0xef000000|(__NR_sigreturn))
  30 #define SWI_SYS_RT_SIGRETURN    (0xef000000|(__NR_rt_sigreturn))
  31
  32 /*
  33  * For Thumb syscalls, we pass the syscall number via r7.  We therefore
  34  * need two 16-bit instructions.
  35  */
  36 #define SWI_THUMB_SIGRETURN     (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE))
  37 #define SWI_THUMB_RT_SIGRETURN  (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE))
  38
  39 static const unsigned long retcodes[4] = {
  40         SWI_SYS_SIGRETURN,      SWI_THUMB_SIGRETURN,
  41         SWI_SYS_RT_SIGRETURN,   SWI_THUMB_RT_SIGRETURN
  42 };
  43
  44 static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall);
  45
  46 /*
  47  * atomically swap in the new signal mask, and wait for a signal.
  48  */
  49 asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs)
  50 {
  51         sigset_t saveset;
  52
  53         mask &= _BLOCKABLE;
  54         spin_lock_irq(&current->sighand->siglock);
  55         saveset = current->blocked;
  56         siginitset(&current->blocked, mask);
  57         recalc_sigpending();
  58         spin_unlock_irq(&current->sighand->siglock);
  59         regs->ARM_r0 = -EINTR;
  60
  61         while (1) {
  62                 current->state = TASK_INTERRUPTIBLE;
  63                 schedule();
  64                 if (do_signal(&saveset, regs, 0))
  65                         return regs->ARM_r0;
  66         }
  67 }
  68
  69 asmlinkage int
  70 sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
  71 {
  72         sigset_t saveset, newset;
  73
  74         /* XXX: Don't preclude handling different sized sigset_t's. */
  75         if (sigsetsize != sizeof(sigset_t))
  76                 return -EINVAL;
  77
  78         if (copy_from_user(&newset, unewset, sizeof(newset)))
  79                 return -EFAULT;
  80         sigdelsetmask(&newset, ~_BLOCKABLE);
  81
  82         spin_lock_irq(&current->sighand->siglock);
  83         saveset = current->blocked;
  84         current->blocked = newset;
  85         recalc_sigpending();
  86         spin_unlock_irq(&current->sighand->siglock);
  87         regs->ARM_r0 = -EINTR;
  88
  89         while (1) {
  90                 current->state = TASK_INTERRUPTIBLE;
  91                 schedule();
  92                 if (do_signal(&saveset, regs, 0))
  93                         return regs->ARM_r0;
  94         }
  95 }
  96
  97 asmlinkage int
  98 sys_sigaction(int sig, const struct old_sigaction __user *act,
  99               struct old_sigaction __user *oact)
 100 {
 101         struct k_sigaction new_ka, old_ka;
 102         int ret;
 103
 104         if (act) {
 105                 old_sigset_t mask;
 106                 if (verify_area(VERIFY_READ, act, sizeof(*act)) ||
 107                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
 108                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
 109                         return -EFAULT;
 110                 __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 111                 __get_user(mask, &act->sa_mask);
 112                 siginitset(&new_ka.sa.sa_mask, mask);
 113         }
 114
 115         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 116
 117         if (!ret && oact) {
 118                 if (verify_area(VERIFY_WRITE, oact, sizeof(*oact)) ||
 119                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
 120                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
 121                         return -EFAULT;
 122                 __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 123                 __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
 124         }
 125
 126         return ret;
 127 }
 128
 129 /*
 130  * Do a signal return; undo the signal stack.
 131  */
 132 struct sigframe
 133 {
 134         struct sigcontext sc;
 135         unsigned long extramask[_NSIG_WORDS-1];
 136         unsigned long retcode;
 137 };
 138
 139 struct rt_sigframe
 140 {
 141         struct siginfo __user *pinfo;
 142         void __user *puc;
 143         struct siginfo info;
 144         struct ucontext uc;
 145         unsigned long retcode;
 146 };
 147
 148 static int
 149 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 150 {
 151         int err = 0;
 152
 153         __get_user_error(regs->ARM_r0, &sc->arm_r0, err);
 154         __get_user_error(regs->ARM_r1, &sc->arm_r1, err);
 155         __get_user_error(regs->ARM_r2, &sc->arm_r2, err);
 156         __get_user_error(regs->ARM_r3, &sc->arm_r3, err);
 157         __get_user_error(regs->ARM_r4, &sc->arm_r4, err);
 158         __get_user_error(regs->ARM_r5, &sc->arm_r5, err);
 159         __get_user_error(regs->ARM_r6, &sc->arm_r6, err);
 160         __get_user_error(regs->ARM_r7, &sc->arm_r7, err);
 161         __get_user_error(regs->ARM_r8, &sc->arm_r8, err);
 162         __get_user_error(regs->ARM_r9, &sc->arm_r9, err);
 163         __get_user_error(regs->ARM_r10, &sc->arm_r10, err);
 164         __get_user_error(regs->ARM_fp, &sc->arm_fp, err);
 165         __get_user_error(regs->ARM_ip, &sc->arm_ip, err);
 166         __get_user_error(regs->ARM_sp, &sc->arm_sp, err);
 167         __get_user_error(regs->ARM_lr, &sc->arm_lr, err);
 168         __get_user_error(regs->ARM_pc, &sc->arm_pc, err);
 169         __get_user_error(regs->ARM_cpsr, &sc->arm_cpsr, err);
 170
 171         err |= !valid_user_regs(regs);
 172
 173         return err;
 174 }
 175
 176 asmlinkage int sys_sigreturn(struct pt_regs *regs)
 177 {
 178         struct sigframe __user *frame;
 179         sigset_t set;
 180
 181         /* Always make any pending restarted system calls return -EINTR */
 182         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 183
 184         /*
 185          * Since we stacked the signal on a 64-bit boundary,
 186          * then 'sp' should be word aligned here.  If it's
 187          * not, then the user is trying to mess with us.
 188          */
 189         if (regs->ARM_sp & 7)
 190                 goto badframe;
 191
 192         frame = (struct sigframe __user *)regs->ARM_sp;
 193
 194         if (verify_area(VERIFY_READ, frame, sizeof (*frame)))
 195                 goto badframe;
 196         if (__get_user(set.sig[0], &frame->sc.oldmask)
 197             || (_NSIG_WORDS > 1
 198                 && __copy_from_user(&set.sig[1], &frame->extramask,
 199                                     sizeof(frame->extramask))))
 200                 goto badframe;
 201
 202         sigdelsetmask(&set, ~_BLOCKABLE);
 203         spin_lock_irq(&current->sighand->siglock);
 204         current->blocked = set;
 205         recalc_sigpending();
 206         spin_unlock_irq(&current->sighand->siglock);
 207
 208         if (restore_sigcontext(regs, &frame->sc))
 209                 goto badframe;
 210
 211         /* Send SIGTRAP if we're single-stepping */
 212         if (current->ptrace & PT_SINGLESTEP) {
 213                 ptrace_cancel_bpt(current);
 214                 send_sig(SIGTRAP, current, 1);
 215         }
 216
 217         return regs->ARM_r0;
 218
 219 badframe:
 220         force_sig(SIGSEGV, current);
 221         return 0;
 222 }
 223
 224 asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 225 {
 226         struct rt_sigframe __user *frame;
 227         sigset_t set;
 228
 229         /* Always make any pending restarted system calls return -EINTR */
 230         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 231
 232         /*
 233          * Since we stacked the signal on a 64-bit boundary,
 234          * then 'sp' should be word aligned here.  If it's
 235          * not, then the user is trying to mess with us.
 236          */
 237         if (regs->ARM_sp & 7)
 238                 goto badframe;
 239
 240         frame = (struct rt_sigframe __user *)regs->ARM_sp;
 241
 242         if (verify_area(VERIFY_READ, frame, sizeof (*frame)))
 243                 goto badframe;
 244         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 245                 goto badframe;
 246
 247         sigdelsetmask(&set, ~_BLOCKABLE);
 248         spin_lock_irq(&current->sighand->siglock);
 249         current->blocked = set;
 250         recalc_sigpending();
 251         spin_unlock_irq(&current->sighand->siglock);
 252
 253         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 254                 goto badframe;
 255
 256         /* Send SIGTRAP if we're single-stepping */
 257         if (current->ptrace & PT_SINGLESTEP) {
 258                 ptrace_cancel_bpt(current);
 259                 send_sig(SIGTRAP, current, 1);
 260         }
 261
 262         return regs->ARM_r0;
 263
 264 badframe:
 265         force_sig(SIGSEGV, current);
 266         return 0;
 267 }
 268
 269 static int
 270 setup_sigcontext(struct sigcontext __user *sc, /*struct _fpstate *fpstate,*/
 271                  struct pt_regs *regs, unsigned long mask)
 272 {
 273         int err = 0;
 274
 275         __put_user_error(regs->ARM_r0, &sc->arm_r0, err);
 276         __put_user_error(regs->ARM_r1, &sc->arm_r1, err);
 277         __put_user_error(regs->ARM_r2, &sc->arm_r2, err);
 278         __put_user_error(regs->ARM_r3, &sc->arm_r3, err);
 279         __put_user_error(regs->ARM_r4, &sc->arm_r4, err);
 280         __put_user_error(regs->ARM_r5, &sc->arm_r5, err);
 281         __put_user_error(regs->ARM_r6, &sc->arm_r6, err);
 282         __put_user_error(regs->ARM_r7, &sc->arm_r7, err);
 283         __put_user_error(regs->ARM_r8, &sc->arm_r8, err);
 284         __put_user_error(regs->ARM_r9, &sc->arm_r9, err);
 285         __put_user_error(regs->ARM_r10, &sc->arm_r10, err);
 286         __put_user_error(regs->ARM_fp, &sc->arm_fp, err);
 287         __put_user_error(regs->ARM_ip, &sc->arm_ip, err);
 288         __put_user_error(regs->ARM_sp, &sc->arm_sp, err);
 289         __put_user_error(regs->ARM_lr, &sc->arm_lr, err);
 290         __put_user_error(regs->ARM_pc, &sc->arm_pc, err);
 291         __put_user_error(regs->ARM_cpsr, &sc->arm_cpsr, err);
 292
 293         __put_user_error(current->thread.trap_no, &sc->trap_no, err);
 294         __put_user_error(current->thread.error_code, &sc->error_code, err);
 295         __put_user_error(current->thread.address, &sc->fault_address, err);
 296         __put_user_error(mask, &sc->oldmask, err);
 297
 298         return err;
 299 }
 300
 301 static inline void __user *
 302 get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize)
 303 {
 304         unsigned long sp = regs->ARM_sp;
 305
 306         /*
 307          * This is the X/Open sanctioned signal stack switching.
 308          */
 309         if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 310                 sp = current->sas_ss_sp + current->sas_ss_size;
 311
 312         /*
 313          * ATPCS B01 mandates 8-byte alignment
 314          */
 315         return (void __user *)((sp - framesize) & ~7);
 316 }
 317
 318 static int
 319 setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 320              unsigned long __user *rc, void __user *frame, int usig)
 321 {
 322         unsigned long handler = (unsigned long)ka->sa.sa_handler;
 323         unsigned long retcode;
 324         int thumb = 0;
 325         unsigned long cpsr = regs->ARM_cpsr & ~PSR_f;
 326
 327         /*
 328          * Maybe we need to deliver a 32-bit signal to a 26-bit task.
 329          */
 330         if (ka->sa.sa_flags & SA_THIRTYTWO)
 331                 cpsr = (cpsr & ~MODE_MASK) | USR_MODE;
 332
 333 #ifdef CONFIG_ARM_THUMB
 334         if (elf_hwcap & HWCAP_THUMB) {
 335                 /*
 336                  * The LSB of the handler determines if we're going to
 337                  * be using THUMB or ARM mode for this signal handler.
 338                  */
 339                 thumb = handler & 1;
 340
 341                 if (thumb)
 342                         cpsr |= PSR_T_BIT;
 343                 else
 344                         cpsr &= ~PSR_T_BIT;
 345         }
 346 #endif
 347
 348         if (ka->sa.sa_flags & SA_RESTORER) {
 349                 retcode = (unsigned long)ka->sa.sa_restorer;
 350         } else {
 351                 unsigned int idx = thumb;
 352
 353                 if (ka->sa.sa_flags & SA_SIGINFO)
 354                         idx += 2;
 355
 356                 if (__put_user(retcodes[idx], rc))
 357                         return 1;
 358
 359                 /*
 360                  * Ensure that the instruction cache sees
 361                  * the return code written onto the stack.
 362                  */
 363                 flush_icache_range((unsigned long)rc,
 364                                    (unsigned long)(rc + 1));
 365
 366                 retcode = ((unsigned long)rc) + thumb;
 367         }
 368
 369         regs->ARM_r0 = usig;
 370         regs->ARM_sp = (unsigned long)frame;
 371         regs->ARM_lr = retcode;
 372         regs->ARM_pc = handler;
 373         regs->ARM_cpsr = cpsr;
 374
 375         return 0;
 376 }
 377
 378 static int
 379 setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs)
 380 {
 381         struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 382         int err = 0;
 383
 384         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 385                 return 1;
 386
 387         err |= setup_sigcontext(&frame->sc, /*&frame->fpstate,*/ regs, set->sig[0]);
 388
 389         if (_NSIG_WORDS > 1) {
 390                 err |= __copy_to_user(frame->extramask, &set->sig[1],
 391                                       sizeof(frame->extramask));
 392         }
 393
 394         if (err == 0)
 395                 err = setup_return(regs, ka, &frame->retcode, frame, usig);
 396
 397         return err;
 398 }
 399
 400 static int
 401 setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 402                sigset_t *set, struct pt_regs *regs)
 403 {
 404         struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame));
 405         int err = 0;
 406
 407         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 408                 return 1;
 409
 410         __put_user_error(&frame->info, &frame->pinfo, err);
 411         __put_user_error(&frame->uc, &frame->puc, err);
 412         err |= copy_siginfo_to_user(&frame->info, info);
 413
 414         /* Clear all the bits of the ucontext we don't use.  */
 415         err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
 416
 417         err |= setup_sigcontext(&frame->uc.uc_mcontext, /*&frame->fpstate,*/
 418                                 regs, set->sig[0]);
 419         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 420
 421         if (err == 0)
 422                 err = setup_return(regs, ka, &frame->retcode, frame, usig);
 423
 424         if (err == 0) {
 425                 /*
 426                  * For realtime signals we must also set the second and third
 427                  * arguments for the signal handler.
 428                  *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 429                  */
 430                 regs->ARM_r1 = (unsigned long)frame->pinfo;
 431                 regs->ARM_r2 = (unsigned long)frame->puc;
 432         }
 433
 434         return err;
 435 }
 436
 437 static inline void restart_syscall(struct pt_regs *regs)
 438 {
 439         regs->ARM_r0 = regs->ARM_ORIG_r0;
 440         regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 441 }
 442
 443 /*
 444  * OK, we're invoking a handler
 445  */
 446 static void
 447 handle_signal(unsigned long sig, siginfo_t *info, sigset_t *oldset,
 448               struct pt_regs * regs, int syscall)
 449 {
 450         struct thread_info *thread = current_thread_info();
 451         struct task_struct *tsk = current;
 452         struct k_sigaction *ka = &tsk->sighand->action[sig-1];
 453         int usig = sig;
 454         int ret;
 455
 456         /*
 457          * If we were from a system call, check for system call restarting...
 458          */
 459         if (syscall) {
 460                 switch (regs->ARM_r0) {
 461                 case -ERESTART_RESTARTBLOCK:
 462                 case -ERESTARTNOHAND:
 463                         regs->ARM_r0 = -EINTR;
 464                         break;
 465                 case -ERESTARTSYS:
 466                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 467                                 regs->ARM_r0 = -EINTR;
 468                                 break;
 469                         }
 470                         /* fallthrough */
 471                 case -ERESTARTNOINTR:
 472                         restart_syscall(regs);
 473                 }
 474         }
 475
 476         /*
 477          * translate the signal
 478          */
 479         if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
 480                 usig = thread->exec_domain->signal_invmap[usig];
 481
 482         /*
 483          * Set up the stack frame
 484          */
 485         if (ka->sa.sa_flags & SA_SIGINFO)
 486                 ret = setup_rt_frame(usig, ka, info, oldset, regs);
 487         else
 488                 ret = setup_frame(usig, ka, oldset, regs);
 489
 490         /*
 491          * Check that the resulting registers are actually sane.
 492          */
 493         ret |= !valid_user_regs(regs);
 494
 495         /*
 496          * Block the signal if we were unsuccessful.
 497          */
 498         if (ret != 0 || !(ka->sa.sa_flags & SA_NODEFER)) {
 499                 spin_lock_irq(&tsk->sighand->siglock);
 500                 sigorsets(&tsk->blocked, &tsk->blocked,
 501                           &ka->sa.sa_mask);
 502                 sigaddset(&tsk->blocked, sig);
 503                 recalc_sigpending();
 504                 spin_unlock_irq(&tsk->sighand->siglock);
 505         }
 506
 507         if (ret == 0) {
 508                 if (ka->sa.sa_flags & SA_ONESHOT)
 509                         ka->sa.sa_handler = SIG_DFL;
 510                 return;
 511         }
 512
 513         if (sig == SIGSEGV)
 514                 ka->sa.sa_handler = SIG_DFL;
 515         force_sig(SIGSEGV, tsk);
 516 }
 517
 518 /*
 519  * Note that 'init' is a special process: it doesn't get signals it doesn't
 520  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 521  * mistake.
 522  *
 523  * Note that we go through the signals twice: once to check the signals that
 524  * the kernel can handle, and then we build all the user-level signal handling
 525  * stack-frames in one go after that.
 526  */
 527 static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
 528 {
 529         siginfo_t info;
 530         int signr;
 531
 532         /*
 533          * We want the common case to go fast, which
 534          * is why we may in certain cases get here from
 535          * kernel mode. Just return without doing anything
 536          * if so.
 537          */
 538         if (!user_mode(regs))
 539                 return 0;
 540
 541         if (current->flags & PF_FREEZE) {
 542                 refrigerator(0);
 543                 goto no_signal;
 544         }
 545
 546         if (current->ptrace & PT_SINGLESTEP)
 547                 ptrace_cancel_bpt(current);
 548
 549         signr = get_signal_to_deliver(&info, regs, NULL);
 550         if (signr > 0) {
 551                 handle_signal(signr, &info, oldset, regs, syscall);
 552                 if (current->ptrace & PT_SINGLESTEP)
 553                         ptrace_set_bpt(current);
 554                 return 1;
 555         }
 556
 557  no_signal:
 558         /*
 559          * No signal to deliver to the process - restart the syscall.
 560          */
 561         if (syscall) {
 562                 if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
 563                         if (thumb_mode(regs)) {
 564                                 regs->ARM_r7 = __NR_restart_syscall;
 565                                 regs->ARM_pc -= 2;
 566                         } else {
 567                                 u32 *usp;
 568
 569                                 regs->ARM_sp -= 12;
 570                                 usp = (u32 *)regs->ARM_sp;
 571
 572                                 put_user(regs->ARM_pc, &usp[0]);
 573                                 /* swi __NR_restart_syscall */
 574                                 put_user(0xef000000 | __NR_restart_syscall, &usp[1]);
 575                                 /* ldr  pc, [sp], #12 */
 576                                 put_user(0xe49df00c, &usp[2]);
 577
 578                                 flush_icache_range((unsigned long)usp,
 579                                                    (unsigned long)(usp + 3));
 580
 581                                 regs->ARM_pc = regs->ARM_sp + 4;
 582                         }
 583                 }
 584                 if (regs->ARM_r0 == -ERESTARTNOHAND ||
 585                     regs->ARM_r0 == -ERESTARTSYS ||
 586                     regs->ARM_r0 == -ERESTARTNOINTR) {
 587                         restart_syscall(regs);
 588                 }
 589         }
 590         if (current->ptrace & PT_SINGLESTEP)
 591                 ptrace_set_bpt(current);
 592         return 0;
 593 }
 594
 595 asmlinkage void
 596 do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 597 {
 598         if (thread_flags & _TIF_SIGPENDING)
 599                 do_signal(&current->blocked, regs, syscall);
 600 }