arch/sh/kernel/signal_32.c

   1 /*
   2  *  linux/arch/sh/kernel/signal.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   7  *
   8  *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
   9  *
  10  */
  11 #include <linux/sched.h>
  12 #include <linux/mm.h>
  13 #include <linux/smp.h>
  14 #include <linux/kernel.h>
  15 #include <linux/signal.h>
  16 #include <linux/errno.h>
  17 #include <linux/wait.h>
  18 #include <linux/ptrace.h>
  19 #include <linux/unistd.h>
  20 #include <linux/stddef.h>
  21 #include <linux/tty.h>
  22 #include <linux/elf.h>
  23 #include <linux/personality.h>
  24 #include <linux/binfmts.h>
  25 #include <linux/freezer.h>
  26 #include <linux/io.h>
  27 #include <linux/tracehook.h>
  28 #include <asm/ucontext.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/pgtable.h>
  31 #include <asm/cacheflush.h>
  32 #include <asm/syscalls.h>
  33 #include <asm/fpu.h>
  34
  35 struct fdpic_func_descriptor {
  36         unsigned long   text;
  37         unsigned long   GOT;
  38 };
  39
  40 /*
  41  * The following define adds a 64 byte gap between the signal
  42  * stack frame and previous contents of the stack.  This allows
  43  * frame unwinding in a function epilogue but only if a frame
  44  * pointer is used in the function.  This is necessary because
  45  * current gcc compilers (<4.3) do not generate unwind info on
  46  * SH for function epilogues.
  47  */
  48 #define UNWINDGUARD 64
  49
  50 /*
  51  * Atomically swap in the new signal mask, and wait for a signal.
  52  */
  53 asmlinkage int
  54 sys_sigsuspend(old_sigset_t mask)
  55 {
  56         sigset_t blocked;
  57         siginitset(&blocked, mask);
  58         return sigsuspend(&blocked);
  59 }
  60
  61 asmlinkage int
  62 sys_sigaction(int sig, const struct old_sigaction __user *act,
  63               struct old_sigaction __user *oact)
  64 {
  65         struct k_sigaction new_ka, old_ka;
  66         int ret;
  67
  68         if (act) {
  69                 old_sigset_t mask;
  70                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  71                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  72                     __get_user(new_ka.sa.sa_restorer, &act->sa_restorer) ||
  73                     __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
  74                     __get_user(mask, &act->sa_mask))
  75                         return -EFAULT;
  76                 siginitset(&new_ka.sa.sa_mask, mask);
  77         }
  78
  79         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  80
  81         if (!ret && oact) {
  82                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  83                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  84                     __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer) ||
  85                     __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
  86                     __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
  87                         return -EFAULT;
  88         }
  89
  90         return ret;
  91 }
  92
  93 asmlinkage int
  94 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
  95                 unsigned long r6, unsigned long r7,
  96                 struct pt_regs __regs)
  97 {
  98         struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
  99
 100         return do_sigaltstack(uss, uoss, regs->regs[15]);
 101 }
 102
 103
 104 /*
 105  * Do a signal return; undo the signal stack.
 106  */
 107
 108 #define MOVW(n)  (0x9300|((n)-2))       /* Move mem word at PC+n to R3 */
 109 #if defined(CONFIG_CPU_SH2)
 110 #define TRAP_NOARG 0xc320               /* Syscall w/no args (NR in R3) */
 111 #else
 112 #define TRAP_NOARG 0xc310               /* Syscall w/no args (NR in R3) */
 113 #endif
 114 #define OR_R0_R0 0x200b                 /* or r0,r0 (insert to avoid hardware bug) */
 115
 116 struct sigframe
 117 {
 118         struct sigcontext sc;
 119         unsigned long extramask[_NSIG_WORDS-1];
 120         u16 retcode[8];
 121 };
 122
 123 struct rt_sigframe
 124 {
 125         struct siginfo info;
 126         struct ucontext uc;
 127         u16 retcode[8];
 128 };
 129
 130 #ifdef CONFIG_SH_FPU
 131 static inline int restore_sigcontext_fpu(struct sigcontext __user *sc)
 132 {
 133         struct task_struct *tsk = current;
 134
 135         if (!(boot_cpu_data.flags & CPU_HAS_FPU))
 136                 return 0;
 137
 138         set_used_math();
 139         return __copy_from_user(&tsk->thread.xstate->hardfpu, &sc->sc_fpregs[0],
 140                                 sizeof(long)*(16*2+2));
 141 }
 142
 143 static inline int save_sigcontext_fpu(struct sigcontext __user *sc,
 144                                       struct pt_regs *regs)
 145 {
 146         struct task_struct *tsk = current;
 147
 148         if (!(boot_cpu_data.flags & CPU_HAS_FPU))
 149                 return 0;
 150
 151         if (!used_math())
 152                 return __put_user(0, &sc->sc_ownedfp);
 153
 154         if (__put_user(1, &sc->sc_ownedfp))
 155                 return -EFAULT;
 156
 157         /* This will cause a "finit" to be triggered by the next
 158            attempted FPU operation by the 'current' process.
 159            */
 160         clear_used_math();
 161
 162         unlazy_fpu(tsk, regs);
 163         return __copy_to_user(&sc->sc_fpregs[0], &tsk->thread.xstate->hardfpu,
 164                               sizeof(long)*(16*2+2));
 165 }
 166 #endif /* CONFIG_SH_FPU */
 167
 168 static int
 169 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *r0_p)
 170 {
 171         unsigned int err = 0;
 172
 173 #define COPY(x)         err |= __get_user(regs->x, &sc->sc_##x)
 174                         COPY(regs[1]);
 175         COPY(regs[2]);  COPY(regs[3]);
 176         COPY(regs[4]);  COPY(regs[5]);
 177         COPY(regs[6]);  COPY(regs[7]);
 178         COPY(regs[8]);  COPY(regs[9]);
 179         COPY(regs[10]); COPY(regs[11]);
 180         COPY(regs[12]); COPY(regs[13]);
 181         COPY(regs[14]); COPY(regs[15]);
 182         COPY(gbr);      COPY(mach);
 183         COPY(macl);     COPY(pr);
 184         COPY(sr);       COPY(pc);
 185 #undef COPY
 186
 187 #ifdef CONFIG_SH_FPU
 188         if (boot_cpu_data.flags & CPU_HAS_FPU) {
 189                 int owned_fp;
 190                 struct task_struct *tsk = current;
 191
 192                 regs->sr |= SR_FD; /* Release FPU */
 193                 clear_fpu(tsk, regs);
 194                 clear_used_math();
 195                 err |= __get_user (owned_fp, &sc->sc_ownedfp);
 196                 if (owned_fp)
 197                         err |= restore_sigcontext_fpu(sc);
 198         }
 199 #endif
 200
 201         regs->tra = -1;         /* disable syscall checks */
 202         err |= __get_user(*r0_p, &sc->sc_regs[0]);
 203         return err;
 204 }
 205
 206 asmlinkage int sys_sigreturn(unsigned long r4, unsigned long r5,
 207                              unsigned long r6, unsigned long r7,
 208                              struct pt_regs __regs)
 209 {
 210         struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
 211         struct sigframe __user *frame = (struct sigframe __user *)regs->regs[15];
 212         sigset_t set;
 213         int r0;
 214
 215         /* Always make any pending restarted system calls return -EINTR */
 216         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 217
 218         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 219                 goto badframe;
 220
 221         if (__get_user(set.sig[0], &frame->sc.oldmask)
 222             || (_NSIG_WORDS > 1
 223                 && __copy_from_user(&set.sig[1], &frame->extramask,
 224                                     sizeof(frame->extramask))))
 225                 goto badframe;
 226
 227         set_current_blocked(&set);
 228
 229         if (restore_sigcontext(regs, &frame->sc, &r0))
 230                 goto badframe;
 231         return r0;
 232
 233 badframe:
 234         force_sig(SIGSEGV, current);
 235         return 0;
 236 }
 237
 238 asmlinkage int sys_rt_sigreturn(unsigned long r4, unsigned long r5,
 239                                 unsigned long r6, unsigned long r7,
 240                                 struct pt_regs __regs)
 241 {
 242         struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
 243         struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->regs[15];
 244         sigset_t set;
 245         int r0;
 246
 247         /* Always make any pending restarted system calls return -EINTR */
 248         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 249
 250         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 251                 goto badframe;
 252
 253         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 254                 goto badframe;
 255
 256         set_current_blocked(&set);
 257
 258         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
 259                 goto badframe;
 260
 261         if (do_sigaltstack(&frame->uc.uc_stack, NULL,
 262                            regs->regs[15]) == -EFAULT)
 263                 goto badframe;
 264
 265         return r0;
 266
 267 badframe:
 268         force_sig(SIGSEGV, current);
 269         return 0;
 270 }
 271
 272 /*
 273  * Set up a signal frame.
 274  */
 275
 276 static int
 277 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 278                  unsigned long mask)
 279 {
 280         int err = 0;
 281
 282 #define COPY(x)         err |= __put_user(regs->x, &sc->sc_##x)
 283         COPY(regs[0]);  COPY(regs[1]);
 284         COPY(regs[2]);  COPY(regs[3]);
 285         COPY(regs[4]);  COPY(regs[5]);
 286         COPY(regs[6]);  COPY(regs[7]);
 287         COPY(regs[8]);  COPY(regs[9]);
 288         COPY(regs[10]); COPY(regs[11]);
 289         COPY(regs[12]); COPY(regs[13]);
 290         COPY(regs[14]); COPY(regs[15]);
 291         COPY(gbr);      COPY(mach);
 292         COPY(macl);     COPY(pr);
 293         COPY(sr);       COPY(pc);
 294 #undef COPY
 295
 296 #ifdef CONFIG_SH_FPU
 297         err |= save_sigcontext_fpu(sc, regs);
 298 #endif
 299
 300         /* non-iBCS2 extensions.. */
 301         err |= __put_user(mask, &sc->oldmask);
 302
 303         return err;
 304 }
 305
 306 /*
 307  * Determine which stack to use..
 308  */
 309 static inline void __user *
 310 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 311 {
 312         if (ka->sa.sa_flags & SA_ONSTACK) {
 313                 if (sas_ss_flags(sp) == 0)
 314                         sp = current->sas_ss_sp + current->sas_ss_size;
 315         }
 316
 317         return (void __user *)((sp - (frame_size+UNWINDGUARD)) & -8ul);
 318 }
 319
 320 /* These symbols are defined with the addresses in the vsyscall page.
 321    See vsyscall-trapa.S.  */
 322 extern void __kernel_sigreturn(void);
 323 extern void __kernel_rt_sigreturn(void);
 324
 325 static int setup_frame(int sig, struct k_sigaction *ka,
 326                         sigset_t *set, struct pt_regs *regs)
 327 {
 328         struct sigframe __user *frame;
 329         int err = 0;
 330         int signal;
 331
 332         frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));
 333
 334         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 335                 goto give_sigsegv;
 336
 337         signal = current_thread_info()->exec_domain
 338                 && current_thread_info()->exec_domain->signal_invmap
 339                 && sig < 32
 340                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 341                 : sig;
 342
 343         err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
 344
 345         if (_NSIG_WORDS > 1)
 346                 err |= __copy_to_user(frame->extramask, &set->sig[1],
 347                                       sizeof(frame->extramask));
 348
 349         /* Set up to return from userspace.  If provided, use a stub
 350            already in userspace.  */
 351         if (ka->sa.sa_flags & SA_RESTORER) {
 352                 regs->pr = (unsigned long) ka->sa.sa_restorer;
 353 #ifdef CONFIG_VSYSCALL
 354         } else if (likely(current->mm->context.vdso)) {
 355                 regs->pr = VDSO_SYM(&__kernel_sigreturn);
 356 #endif
 357         } else {
 358                 /* Generate return code (system call to sigreturn) */
 359                 err |= __put_user(MOVW(7), &frame->retcode[0]);
 360                 err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
 361                 err |= __put_user(OR_R0_R0, &frame->retcode[2]);
 362                 err |= __put_user(OR_R0_R0, &frame->retcode[3]);
 363                 err |= __put_user(OR_R0_R0, &frame->retcode[4]);
 364                 err |= __put_user(OR_R0_R0, &frame->retcode[5]);
 365                 err |= __put_user(OR_R0_R0, &frame->retcode[6]);
 366                 err |= __put_user((__NR_sigreturn), &frame->retcode[7]);
 367                 regs->pr = (unsigned long) frame->retcode;
 368                 flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
 369         }
 370
 371         if (err)
 372                 goto give_sigsegv;
 373
 374         /* Set up registers for signal handler */
 375         regs->regs[15] = (unsigned long) frame;
 376         regs->regs[4] = signal; /* Arg for signal handler */
 377         regs->regs[5] = 0;
 378         regs->regs[6] = (unsigned long) &frame->sc;
 379
 380         if (current->personality & FDPIC_FUNCPTRS) {
 381                 struct fdpic_func_descriptor __user *funcptr =
 382                         (struct fdpic_func_descriptor __user *)ka->sa.sa_handler;
 383
 384                 err |= __get_user(regs->pc, &funcptr->text);
 385                 err |= __get_user(regs->regs[12], &funcptr->GOT);
 386         } else
 387                 regs->pc = (unsigned long)ka->sa.sa_handler;
 388
 389         if (err)
 390                 goto give_sigsegv;
 391
 392         set_fs(USER_DS);
 393
 394         pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
 395                  current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
 396
 397         return 0;
 398
 399 give_sigsegv:
 400         force_sigsegv(sig, current);
 401         return -EFAULT;
 402 }
 403
 404 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 405                            sigset_t *set, struct pt_regs *regs)
 406 {
 407         struct rt_sigframe __user *frame;
 408         int err = 0;
 409         int signal;
 410
 411         frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));
 412
 413         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 414                 goto give_sigsegv;
 415
 416         signal = current_thread_info()->exec_domain
 417                 && current_thread_info()->exec_domain->signal_invmap
 418                 && sig < 32
 419                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 420                 : sig;
 421
 422         err |= copy_siginfo_to_user(&frame->info, info);
 423
 424         /* Create the ucontext.  */
 425         err |= __put_user(0, &frame->uc.uc_flags);
 426         err |= __put_user(NULL, &frame->uc.uc_link);
 427         err |= __put_user((void *)current->sas_ss_sp,
 428                           &frame->uc.uc_stack.ss_sp);
 429         err |= __put_user(sas_ss_flags(regs->regs[15]),
 430                           &frame->uc.uc_stack.ss_flags);
 431         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 432         err |= setup_sigcontext(&frame->uc.uc_mcontext,
 433                                 regs, set->sig[0]);
 434         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 435
 436         /* Set up to return from userspace.  If provided, use a stub
 437            already in userspace.  */
 438         if (ka->sa.sa_flags & SA_RESTORER) {
 439                 regs->pr = (unsigned long) ka->sa.sa_restorer;
 440 #ifdef CONFIG_VSYSCALL
 441         } else if (likely(current->mm->context.vdso)) {
 442                 regs->pr = VDSO_SYM(&__kernel_rt_sigreturn);
 443 #endif
 444         } else {
 445                 /* Generate return code (system call to rt_sigreturn) */
 446                 err |= __put_user(MOVW(7), &frame->retcode[0]);
 447                 err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
 448                 err |= __put_user(OR_R0_R0, &frame->retcode[2]);
 449                 err |= __put_user(OR_R0_R0, &frame->retcode[3]);
 450                 err |= __put_user(OR_R0_R0, &frame->retcode[4]);
 451                 err |= __put_user(OR_R0_R0, &frame->retcode[5]);
 452                 err |= __put_user(OR_R0_R0, &frame->retcode[6]);
 453                 err |= __put_user((__NR_rt_sigreturn), &frame->retcode[7]);
 454                 regs->pr = (unsigned long) frame->retcode;
 455                 flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
 456         }
 457
 458         if (err)
 459                 goto give_sigsegv;
 460
 461         /* Set up registers for signal handler */
 462         regs->regs[15] = (unsigned long) frame;
 463         regs->regs[4] = signal; /* Arg for signal handler */
 464         regs->regs[5] = (unsigned long) &frame->info;
 465         regs->regs[6] = (unsigned long) &frame->uc;
 466
 467         if (current->personality & FDPIC_FUNCPTRS) {
 468                 struct fdpic_func_descriptor __user *funcptr =
 469                         (struct fdpic_func_descriptor __user *)ka->sa.sa_handler;
 470
 471                 err |= __get_user(regs->pc, &funcptr->text);
 472                 err |= __get_user(regs->regs[12], &funcptr->GOT);
 473         } else
 474                 regs->pc = (unsigned long)ka->sa.sa_handler;
 475
 476         if (err)
 477                 goto give_sigsegv;
 478
 479         set_fs(USER_DS);
 480
 481         pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
 482                  current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
 483
 484         return 0;
 485
 486 give_sigsegv:
 487         force_sigsegv(sig, current);
 488         return -EFAULT;
 489 }
 490
 491 static inline void
 492 handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
 493                        struct sigaction *sa)
 494 {
 495         /* If we're not from a syscall, bail out */
 496         if (regs->tra < 0)
 497                 return;
 498
 499         /* check for system call restart.. */
 500         switch (regs->regs[0]) {
 501                 case -ERESTART_RESTARTBLOCK:
 502                 case -ERESTARTNOHAND:
 503                 no_system_call_restart:
 504                         regs->regs[0] = -EINTR;
 505                         break;
 506
 507                 case -ERESTARTSYS:
 508                         if (!(sa->sa_flags & SA_RESTART))
 509                                 goto no_system_call_restart;
 510                 /* fallthrough */
 511                 case -ERESTARTNOINTR:
 512                         regs->regs[0] = save_r0;
 513                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
 514                         break;
 515         }
 516 }
 517
 518 /*
 519  * OK, we're invoking a handler
 520  */
 521 static void
 522 handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
 523               struct pt_regs *regs, unsigned int save_r0)
 524 {
 525         sigset_t *oldset = sigmask_to_save();
 526         int ret;
 527
 528         /* Set up the stack frame */
 529         if (ka->sa.sa_flags & SA_SIGINFO)
 530                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 531         else
 532                 ret = setup_frame(sig, ka, oldset, regs);
 533
 534         if (ret)
 535                 return;
 536         signal_delivered(sig, info, ka, regs,
 537                         test_thread_flag(TIF_SINGLESTEP));
 538 }
 539
 540 /*
 541  * Note that 'init' is a special process: it doesn't get signals it doesn't
 542  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 543  * mistake.
 544  *
 545  * Note that we go through the signals twice: once to check the signals that
 546  * the kernel can handle, and then we build all the user-level signal handling
 547  * stack-frames in one go after that.
 548  */
 549 static void do_signal(struct pt_regs *regs, unsigned int save_r0)
 550 {
 551         siginfo_t info;
 552         int signr;
 553         struct k_sigaction ka;
 554
 555         /*
 556          * We want the common case to go fast, which
 557          * is why we may in certain cases get here from
 558          * kernel mode. Just return without doing anything
 559          * if so.
 560          */
 561         if (!user_mode(regs))
 562                 return;
 563
 564         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 565         if (signr > 0) {
 566                 handle_syscall_restart(save_r0, regs, &ka.sa);
 567
 568                 /* Whee!  Actually deliver the signal.  */
 569                 handle_signal(signr, &ka, &info, regs, save_r0);
 570                 return;
 571         }
 572
 573         /* Did we come from a system call? */
 574         if (regs->tra >= 0) {
 575                 /* Restart the system call - no handlers present */
 576                 if (regs->regs[0] == -ERESTARTNOHAND ||
 577                     regs->regs[0] == -ERESTARTSYS ||
 578                     regs->regs[0] == -ERESTARTNOINTR) {
 579                         regs->regs[0] = save_r0;
 580                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
 581                 } else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
 582                         regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
 583                         regs->regs[3] = __NR_restart_syscall;
 584                 }
 585         }
 586
 587         /*
 588          * If there's no signal to deliver, we just put the saved sigmask
 589          * back.
 590          */
 591         restore_saved_sigmask();
 592 }
 593
 594 asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
 595                                  unsigned long thread_info_flags)
 596 {
 597         /* deal with pending signal delivery */
 598         if (thread_info_flags & _TIF_SIGPENDING)
 599                 do_signal(regs, save_r0);
 600
 601         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 602                 clear_thread_flag(TIF_NOTIFY_RESUME);
 603                 tracehook_notify_resume(regs);
 604         }
 605 }