arch/alpha/kernel/signal.c

   1 /*
   2  *  linux/arch/alpha/kernel/signal.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  *
   6  *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
   7  */
   8
   9 #include <linux/sched/signal.h>
  10 #include <linux/sched/task_stack.h>
  11 #include <linux/kernel.h>
  12 #include <linux/signal.h>
  13 #include <linux/errno.h>
  14 #include <linux/wait.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/unistd.h>
  17 #include <linux/mm.h>
  18 #include <linux/smp.h>
  19 #include <linux/stddef.h>
  20 #include <linux/tty.h>
  21 #include <linux/binfmts.h>
  22 #include <linux/bitops.h>
  23 #include <linux/syscalls.h>
  24 #include <linux/tracehook.h>
  25
  26 #include <linux/uaccess.h>
  27 #include <asm/sigcontext.h>
  28 #include <asm/ucontext.h>
  29
  30 #include "proto.h"
  31
  32
  33 #define DEBUG_SIG 0
  34
  35 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  36
  37 asmlinkage void ret_from_sys_call(void);
  38
  39 /*
  40  * The OSF/1 sigprocmask calling sequence is different from the
  41  * C sigprocmask() sequence..
  42  */
  43 SYSCALL_DEFINE2(osf_sigprocmask, int, how, unsigned long, newmask)
  44 {
  45         sigset_t oldmask;
  46         sigset_t mask;
  47         unsigned long res;
  48
  49         siginitset(&mask, newmask & _BLOCKABLE);
  50         res = sigprocmask(how, &mask, &oldmask);
  51         if (!res) {
  52                 force_successful_syscall_return();
  53                 res = oldmask.sig[0];
  54         }
  55         return res;
  56 }
  57
  58 SYSCALL_DEFINE3(osf_sigaction, int, sig,
  59                 const struct osf_sigaction __user *, act,
  60                 struct osf_sigaction __user *, oact)
  61 {
  62         struct k_sigaction new_ka, old_ka;
  63         int ret;
  64
  65         if (act) {
  66                 old_sigset_t mask;
  67                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  68                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  69                     __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
  70                     __get_user(mask, &act->sa_mask))
  71                         return -EFAULT;
  72                 siginitset(&new_ka.sa.sa_mask, mask);
  73                 new_ka.ka_restorer = NULL;
  74         }
  75
  76         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  77
  78         if (!ret && oact) {
  79                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  80                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  81                     __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
  82                     __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
  83                         return -EFAULT;
  84         }
  85
  86         return ret;
  87 }
  88
  89 SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act,
  90                 struct sigaction __user *, oact,
  91                 size_t, sigsetsize, void __user *, restorer)
  92 {
  93         struct k_sigaction new_ka, old_ka;
  94         int ret;
  95
  96         /* XXX: Don't preclude handling different sized sigset_t's.  */
  97         if (sigsetsize != sizeof(sigset_t))
  98                 return -EINVAL;
  99
 100         if (act) {
 101                 new_ka.ka_restorer = restorer;
 102                 if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
 103                         return -EFAULT;
 104         }
 105
 106         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 107
 108         if (!ret && oact) {
 109                 if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
 110                         return -EFAULT;
 111         }
 112
 113         return ret;
 114 }
 115
 116 /*
 117  * Do a signal return; undo the signal stack.
 118  */
 119
 120 #if _NSIG_WORDS > 1
 121 # error "Non SA_SIGINFO frame needs rearranging"
 122 #endif
 123
 124 struct sigframe
 125 {
 126         struct sigcontext sc;
 127         unsigned int retcode[3];
 128 };
 129
 130 struct rt_sigframe
 131 {
 132         struct siginfo info;
 133         struct ucontext uc;
 134         unsigned int retcode[3];
 135 };
 136
 137 /* If this changes, userland unwinders that Know Things about our signal
 138    frame will break.  Do not undertake lightly.  It also implies an ABI
 139    change wrt the size of siginfo_t, which may cause some pain.  */
 140 extern char compile_time_assert
 141         [offsetof(struct rt_sigframe, uc.uc_mcontext) == 176 ? 1 : -1];
 142
 143 #define INSN_MOV_R30_R16        0x47fe0410
 144 #define INSN_LDI_R0             0x201f0000
 145 #define INSN_CALLSYS            0x00000083
 146
 147 static long
 148 restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 149 {
 150         unsigned long usp;
 151         struct switch_stack *sw = (struct switch_stack *)regs - 1;
 152         long i, err = __get_user(regs->pc, &sc->sc_pc);
 153
 154         current->restart_block.fn = do_no_restart_syscall;
 155
 156         sw->r26 = (unsigned long) ret_from_sys_call;
 157
 158         err |= __get_user(regs->r0, sc->sc_regs+0);
 159         err |= __get_user(regs->r1, sc->sc_regs+1);
 160         err |= __get_user(regs->r2, sc->sc_regs+2);
 161         err |= __get_user(regs->r3, sc->sc_regs+3);
 162         err |= __get_user(regs->r4, sc->sc_regs+4);
 163         err |= __get_user(regs->r5, sc->sc_regs+5);
 164         err |= __get_user(regs->r6, sc->sc_regs+6);
 165         err |= __get_user(regs->r7, sc->sc_regs+7);
 166         err |= __get_user(regs->r8, sc->sc_regs+8);
 167         err |= __get_user(sw->r9, sc->sc_regs+9);
 168         err |= __get_user(sw->r10, sc->sc_regs+10);
 169         err |= __get_user(sw->r11, sc->sc_regs+11);
 170         err |= __get_user(sw->r12, sc->sc_regs+12);
 171         err |= __get_user(sw->r13, sc->sc_regs+13);
 172         err |= __get_user(sw->r14, sc->sc_regs+14);
 173         err |= __get_user(sw->r15, sc->sc_regs+15);
 174         err |= __get_user(regs->r16, sc->sc_regs+16);
 175         err |= __get_user(regs->r17, sc->sc_regs+17);
 176         err |= __get_user(regs->r18, sc->sc_regs+18);
 177         err |= __get_user(regs->r19, sc->sc_regs+19);
 178         err |= __get_user(regs->r20, sc->sc_regs+20);
 179         err |= __get_user(regs->r21, sc->sc_regs+21);
 180         err |= __get_user(regs->r22, sc->sc_regs+22);
 181         err |= __get_user(regs->r23, sc->sc_regs+23);
 182         err |= __get_user(regs->r24, sc->sc_regs+24);
 183         err |= __get_user(regs->r25, sc->sc_regs+25);
 184         err |= __get_user(regs->r26, sc->sc_regs+26);
 185         err |= __get_user(regs->r27, sc->sc_regs+27);
 186         err |= __get_user(regs->r28, sc->sc_regs+28);
 187         err |= __get_user(regs->gp, sc->sc_regs+29);
 188         err |= __get_user(usp, sc->sc_regs+30);
 189         wrusp(usp);
 190
 191         for (i = 0; i < 31; i++)
 192                 err |= __get_user(sw->fp[i], sc->sc_fpregs+i);
 193         err |= __get_user(sw->fp[31], &sc->sc_fpcr);
 194
 195         return err;
 196 }
 197
 198 /* Note that this syscall is also used by setcontext(3) to install
 199    a given sigcontext.  This because it's impossible to set *all*
 200    registers and transfer control from userland.  */
 201
 202 asmlinkage void
 203 do_sigreturn(struct sigcontext __user *sc)
 204 {
 205         struct pt_regs *regs = current_pt_regs();
 206         sigset_t set;
 207
 208         /* Verify that it's a good sigcontext before using it */
 209         if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
 210                 goto give_sigsegv;
 211         if (__get_user(set.sig[0], &sc->sc_mask))
 212                 goto give_sigsegv;
 213
 214         set_current_blocked(&set);
 215
 216         if (restore_sigcontext(sc, regs))
 217                 goto give_sigsegv;
 218
 219         /* Send SIGTRAP if we're single-stepping: */
 220         if (ptrace_cancel_bpt (current)) {
 221                 siginfo_t info;
 222
 223                 info.si_signo = SIGTRAP;
 224                 info.si_errno = 0;
 225                 info.si_code = TRAP_BRKPT;
 226                 info.si_addr = (void __user *) regs->pc;
 227                 info.si_trapno = 0;
 228                 send_sig_info(SIGTRAP, &info, current);
 229         }
 230         return;
 231
 232 give_sigsegv:
 233         force_sig(SIGSEGV, current);
 234 }
 235
 236 asmlinkage void
 237 do_rt_sigreturn(struct rt_sigframe __user *frame)
 238 {
 239         struct pt_regs *regs = current_pt_regs();
 240         sigset_t set;
 241
 242         /* Verify that it's a good ucontext_t before using it */
 243         if (!access_ok(VERIFY_READ, &frame->uc, sizeof(frame->uc)))
 244                 goto give_sigsegv;
 245         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 246                 goto give_sigsegv;
 247
 248         set_current_blocked(&set);
 249
 250         if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
 251                 goto give_sigsegv;
 252
 253         /* Send SIGTRAP if we're single-stepping: */
 254         if (ptrace_cancel_bpt (current)) {
 255                 siginfo_t info;
 256
 257                 info.si_signo = SIGTRAP;
 258                 info.si_errno = 0;
 259                 info.si_code = TRAP_BRKPT;
 260                 info.si_addr = (void __user *) regs->pc;
 261                 info.si_trapno = 0;
 262                 send_sig_info(SIGTRAP, &info, current);
 263         }
 264         return;
 265
 266 give_sigsegv:
 267         force_sig(SIGSEGV, current);
 268 }
 269
 270
 271 /*
 272  * Set up a signal frame.
 273  */
 274
 275 static inline void __user *
 276 get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size)
 277 {
 278         return (void __user *)((sigsp(sp, ksig) - frame_size) & -32ul);
 279 }
 280
 281 static long
 282 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 283                  unsigned long mask, unsigned long sp)
 284 {
 285         struct switch_stack *sw = (struct switch_stack *)regs - 1;
 286         long i, err = 0;
 287
 288         err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
 289         err |= __put_user(mask, &sc->sc_mask);
 290         err |= __put_user(regs->pc, &sc->sc_pc);
 291         err |= __put_user(8, &sc->sc_ps);
 292
 293         err |= __put_user(regs->r0 , sc->sc_regs+0);
 294         err |= __put_user(regs->r1 , sc->sc_regs+1);
 295         err |= __put_user(regs->r2 , sc->sc_regs+2);
 296         err |= __put_user(regs->r3 , sc->sc_regs+3);
 297         err |= __put_user(regs->r4 , sc->sc_regs+4);
 298         err |= __put_user(regs->r5 , sc->sc_regs+5);
 299         err |= __put_user(regs->r6 , sc->sc_regs+6);
 300         err |= __put_user(regs->r7 , sc->sc_regs+7);
 301         err |= __put_user(regs->r8 , sc->sc_regs+8);
 302         err |= __put_user(sw->r9   , sc->sc_regs+9);
 303         err |= __put_user(sw->r10  , sc->sc_regs+10);
 304         err |= __put_user(sw->r11  , sc->sc_regs+11);
 305         err |= __put_user(sw->r12  , sc->sc_regs+12);
 306         err |= __put_user(sw->r13  , sc->sc_regs+13);
 307         err |= __put_user(sw->r14  , sc->sc_regs+14);
 308         err |= __put_user(sw->r15  , sc->sc_regs+15);
 309         err |= __put_user(regs->r16, sc->sc_regs+16);
 310         err |= __put_user(regs->r17, sc->sc_regs+17);
 311         err |= __put_user(regs->r18, sc->sc_regs+18);
 312         err |= __put_user(regs->r19, sc->sc_regs+19);
 313         err |= __put_user(regs->r20, sc->sc_regs+20);
 314         err |= __put_user(regs->r21, sc->sc_regs+21);
 315         err |= __put_user(regs->r22, sc->sc_regs+22);
 316         err |= __put_user(regs->r23, sc->sc_regs+23);
 317         err |= __put_user(regs->r24, sc->sc_regs+24);
 318         err |= __put_user(regs->r25, sc->sc_regs+25);
 319         err |= __put_user(regs->r26, sc->sc_regs+26);
 320         err |= __put_user(regs->r27, sc->sc_regs+27);
 321         err |= __put_user(regs->r28, sc->sc_regs+28);
 322         err |= __put_user(regs->gp , sc->sc_regs+29);
 323         err |= __put_user(sp, sc->sc_regs+30);
 324         err |= __put_user(0, sc->sc_regs+31);
 325
 326         for (i = 0; i < 31; i++)
 327                 err |= __put_user(sw->fp[i], sc->sc_fpregs+i);
 328         err |= __put_user(0, sc->sc_fpregs+31);
 329         err |= __put_user(sw->fp[31], &sc->sc_fpcr);
 330
 331         err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0);
 332         err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1);
 333         err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2);
 334
 335         return err;
 336 }
 337
 338 static int
 339 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 340 {
 341         unsigned long oldsp, r26, err = 0;
 342         struct sigframe __user *frame;
 343
 344         oldsp = rdusp();
 345         frame = get_sigframe(ksig, oldsp, sizeof(*frame));
 346         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 347                 return -EFAULT;
 348
 349         err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp);
 350         if (err)
 351                 return -EFAULT;
 352
 353         /* Set up to return from userspace.  If provided, use a stub
 354            already in userspace.  */
 355         r26 = (unsigned long) ksig->ka.ka_restorer;
 356         if (!r26) {
 357                 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
 358                 err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1);
 359                 err |= __put_user(INSN_CALLSYS, frame->retcode+2);
 360                 imb();
 361                 r26 = (unsigned long) frame->retcode;
 362         }
 363
 364         /* Check that everything was written properly.  */
 365         if (err)
 366                 return err;
 367
 368         /* "Return" to the handler */
 369         regs->r26 = r26;
 370         regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 371         regs->r16 = ksig->sig;                  /* a0: signal number */
 372         regs->r17 = 0;                          /* a1: exception code */
 373         regs->r18 = (unsigned long) &frame->sc; /* a2: sigcontext pointer */
 374         wrusp((unsigned long) frame);
 375
 376 #if DEBUG_SIG
 377         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 378                 current->comm, current->pid, frame, regs->pc, regs->r26);
 379 #endif
 380         return 0;
 381 }
 382
 383 static int
 384 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 385 {
 386         unsigned long oldsp, r26, err = 0;
 387         struct rt_sigframe __user *frame;
 388
 389         oldsp = rdusp();
 390         frame = get_sigframe(ksig, oldsp, sizeof(*frame));
 391         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 392                 return -EFAULT;
 393
 394         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 395
 396         /* Create the ucontext.  */
 397         err |= __put_user(0, &frame->uc.uc_flags);
 398         err |= __put_user(0, &frame->uc.uc_link);
 399         err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask);
 400         err |= __save_altstack(&frame->uc.uc_stack, oldsp);
 401         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs,
 402                                 set->sig[0], oldsp);
 403         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 404         if (err)
 405                 return -EFAULT;
 406
 407         /* Set up to return from userspace.  If provided, use a stub
 408            already in userspace.  */
 409         r26 = (unsigned long) ksig->ka.ka_restorer;
 410         if (!r26) {
 411                 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
 412                 err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn,
 413                                   frame->retcode+1);
 414                 err |= __put_user(INSN_CALLSYS, frame->retcode+2);
 415                 imb();
 416                 r26 = (unsigned long) frame->retcode;
 417         }
 418
 419         if (err)
 420                 return -EFAULT;
 421
 422         /* "Return" to the handler */
 423         regs->r26 = r26;
 424         regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 425         regs->r16 = ksig->sig;                    /* a0: signal number */
 426         regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */
 427         regs->r18 = (unsigned long) &frame->uc;   /* a2: ucontext pointer */
 428         wrusp((unsigned long) frame);
 429
 430 #if DEBUG_SIG
 431         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 432                 current->comm, current->pid, frame, regs->pc, regs->r26);
 433 #endif
 434
 435         return 0;
 436 }
 437
 438
 439 /*
 440  * OK, we're invoking a handler.
 441  */
 442 static inline void
 443 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 444 {
 445         sigset_t *oldset = sigmask_to_save();
 446         int ret;
 447
 448         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 449                 ret = setup_rt_frame(ksig, oldset, regs);
 450         else
 451                 ret = setup_frame(ksig, oldset, regs);
 452
 453         signal_setup_done(ret, ksig, 0);
 454 }
 455
 456 static inline void
 457 syscall_restart(unsigned long r0, unsigned long r19,
 458                 struct pt_regs *regs, struct k_sigaction *ka)
 459 {
 460         switch (regs->r0) {
 461         case ERESTARTSYS:
 462                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 463                 case ERESTARTNOHAND:
 464                         regs->r0 = EINTR;
 465                         break;
 466                 }
 467                 /* fallthrough */
 468         case ERESTARTNOINTR:
 469                 regs->r0 = r0;  /* reset v0 and a3 and replay syscall */
 470                 regs->r19 = r19;
 471                 regs->pc -= 4;
 472                 break;
 473         case ERESTART_RESTARTBLOCK:
 474                 regs->r0 = EINTR;
 475                 break;
 476         }
 477 }
 478
 479
 480 /*
 481  * Note that 'init' is a special process: it doesn't get signals it doesn't
 482  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 483  * mistake.
 484  *
 485  * Note that we go through the signals twice: once to check the signals that
 486  * the kernel can handle, and then we build all the user-level signal handling
 487  * stack-frames in one go after that.
 488  *
 489  * "r0" and "r19" are the registers we need to restore for system call
 490  * restart. "r0" is also used as an indicator whether we can restart at
 491  * all (if we get here from anything but a syscall return, it will be 0)
 492  */
 493 static void
 494 do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
 495 {
 496         unsigned long single_stepping = ptrace_cancel_bpt(current);
 497         struct ksignal ksig;
 498
 499         /* This lets the debugger run, ... */
 500         if (get_signal(&ksig)) {
 501                 /* ... so re-check the single stepping. */
 502                 single_stepping |= ptrace_cancel_bpt(current);
 503                 /* Whee!  Actually deliver the signal.  */
 504                 if (r0)
 505                         syscall_restart(r0, r19, regs, &ksig.ka);
 506                 handle_signal(&ksig, regs);
 507         } else {
 508                 single_stepping |= ptrace_cancel_bpt(current);
 509                 if (r0) {
 510                         switch (regs->r0) {
 511                         case ERESTARTNOHAND:
 512                         case ERESTARTSYS:
 513                         case ERESTARTNOINTR:
 514                                 /* Reset v0 and a3 and replay syscall.  */
 515                                 regs->r0 = r0;
 516                                 regs->r19 = r19;
 517                                 regs->pc -= 4;
 518                                 break;
 519                         case ERESTART_RESTARTBLOCK:
 520                                 /* Set v0 to the restart_syscall and replay */
 521                                 regs->r0 = __NR_restart_syscall;
 522                                 regs->pc -= 4;
 523                                 break;
 524                         }
 525                 }
 526                 restore_saved_sigmask();
 527         }
 528         if (single_stepping)
 529                 ptrace_set_bpt(current);        /* re-set breakpoint */
 530 }
 531
 532 void
 533 do_work_pending(struct pt_regs *regs, unsigned long thread_flags,
 534                  unsigned long r0, unsigned long r19)
 535 {
 536         do {
 537                 if (thread_flags & _TIF_NEED_RESCHED) {
 538                         schedule();
 539                 } else {
 540                         local_irq_enable();
 541                         if (thread_flags & _TIF_SIGPENDING) {
 542                                 do_signal(regs, r0, r19);
 543                                 r0 = 0;
 544                         } else {
 545                                 clear_thread_flag(TIF_NOTIFY_RESUME);
 546                                 tracehook_notify_resume(regs);
 547                         }
 548                 }
 549                 local_irq_disable();
 550                 thread_flags = current_thread_info()->flags;
 551         } while (thread_flags & _TIF_WORK_MASK);
 552 }