arch/alpha/kernel/signal.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/arch/alpha/kernel/signal.c
   4  *
   5  *  Copyright (C) 1995  Linus Torvalds
   6  *
   7  *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
   8  */
   9
  10 #include <linux/sched/signal.h>
  11 #include <linux/sched/task_stack.h>
  12 #include <linux/kernel.h>
  13 #include <linux/signal.h>
  14 #include <linux/errno.h>
  15 #include <linux/wait.h>
  16 #include <linux/ptrace.h>
  17 #include <linux/unistd.h>
  18 #include <linux/mm.h>
  19 #include <linux/smp.h>
  20 #include <linux/stddef.h>
  21 #include <linux/tty.h>
  22 #include <linux/binfmts.h>
  23 #include <linux/bitops.h>
  24 #include <linux/syscalls.h>
  25 #include <linux/tracehook.h>
  26
  27 #include <linux/uaccess.h>
  28 #include <asm/sigcontext.h>
  29 #include <asm/ucontext.h>
  30
  31 #include "proto.h"
  32
  33
  34 #define DEBUG_SIG 0
  35
  36 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  37
  38 asmlinkage void ret_from_sys_call(void);
  39
  40 /*
  41  * The OSF/1 sigprocmask calling sequence is different from the
  42  * C sigprocmask() sequence..
  43  */
  44 SYSCALL_DEFINE2(osf_sigprocmask, int, how, unsigned long, newmask)
  45 {
  46         sigset_t oldmask;
  47         sigset_t mask;
  48         unsigned long res;
  49
  50         siginitset(&mask, newmask & _BLOCKABLE);
  51         res = sigprocmask(how, &mask, &oldmask);
  52         if (!res) {
  53                 force_successful_syscall_return();
  54                 res = oldmask.sig[0];
  55         }
  56         return res;
  57 }
  58
  59 SYSCALL_DEFINE3(osf_sigaction, int, sig,
  60                 const struct osf_sigaction __user *, act,
  61                 struct osf_sigaction __user *, oact)
  62 {
  63         struct k_sigaction new_ka, old_ka;
  64         int ret;
  65
  66         if (act) {
  67                 old_sigset_t mask;
  68                 if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
  69                     __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
  70                     __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
  71                     __get_user(mask, &act->sa_mask))
  72                         return -EFAULT;
  73                 siginitset(&new_ka.sa.sa_mask, mask);
  74                 new_ka.ka_restorer = NULL;
  75         }
  76
  77         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
  78
  79         if (!ret && oact) {
  80                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
  81                     __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
  82                     __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
  83                     __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
  84                         return -EFAULT;
  85         }
  86
  87         return ret;
  88 }
  89
  90 SYSCALL_DEFINE5(rt_sigaction, int, sig, const struct sigaction __user *, act,
  91                 struct sigaction __user *, oact,
  92                 size_t, sigsetsize, void __user *, restorer)
  93 {
  94         struct k_sigaction new_ka, old_ka;
  95         int ret;
  96
  97         /* XXX: Don't preclude handling different sized sigset_t's.  */
  98         if (sigsetsize != sizeof(sigset_t))
  99                 return -EINVAL;
 100
 101         if (act) {
 102                 new_ka.ka_restorer = restorer;
 103                 if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
 104                         return -EFAULT;
 105         }
 106
 107         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 108
 109         if (!ret && oact) {
 110                 if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
 111                         return -EFAULT;
 112         }
 113
 114         return ret;
 115 }
 116
 117 /*
 118  * Do a signal return; undo the signal stack.
 119  */
 120
 121 #if _NSIG_WORDS > 1
 122 # error "Non SA_SIGINFO frame needs rearranging"
 123 #endif
 124
 125 struct sigframe
 126 {
 127         struct sigcontext sc;
 128         unsigned int retcode[3];
 129 };
 130
 131 struct rt_sigframe
 132 {
 133         struct siginfo info;
 134         struct ucontext uc;
 135         unsigned int retcode[3];
 136 };
 137
 138 /* If this changes, userland unwinders that Know Things about our signal
 139    frame will break.  Do not undertake lightly.  It also implies an ABI
 140    change wrt the size of siginfo_t, which may cause some pain.  */
 141 extern char compile_time_assert
 142         [offsetof(struct rt_sigframe, uc.uc_mcontext) == 176 ? 1 : -1];
 143
 144 #define INSN_MOV_R30_R16        0x47fe0410
 145 #define INSN_LDI_R0             0x201f0000
 146 #define INSN_CALLSYS            0x00000083
 147
 148 static long
 149 restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 150 {
 151         unsigned long usp;
 152         struct switch_stack *sw = (struct switch_stack *)regs - 1;
 153         long i, err = __get_user(regs->pc, &sc->sc_pc);
 154
 155         current->restart_block.fn = do_no_restart_syscall;
 156
 157         sw->r26 = (unsigned long) ret_from_sys_call;
 158
 159         err |= __get_user(regs->r0, sc->sc_regs+0);
 160         err |= __get_user(regs->r1, sc->sc_regs+1);
 161         err |= __get_user(regs->r2, sc->sc_regs+2);
 162         err |= __get_user(regs->r3, sc->sc_regs+3);
 163         err |= __get_user(regs->r4, sc->sc_regs+4);
 164         err |= __get_user(regs->r5, sc->sc_regs+5);
 165         err |= __get_user(regs->r6, sc->sc_regs+6);
 166         err |= __get_user(regs->r7, sc->sc_regs+7);
 167         err |= __get_user(regs->r8, sc->sc_regs+8);
 168         err |= __get_user(sw->r9, sc->sc_regs+9);
 169         err |= __get_user(sw->r10, sc->sc_regs+10);
 170         err |= __get_user(sw->r11, sc->sc_regs+11);
 171         err |= __get_user(sw->r12, sc->sc_regs+12);
 172         err |= __get_user(sw->r13, sc->sc_regs+13);
 173         err |= __get_user(sw->r14, sc->sc_regs+14);
 174         err |= __get_user(sw->r15, sc->sc_regs+15);
 175         err |= __get_user(regs->r16, sc->sc_regs+16);
 176         err |= __get_user(regs->r17, sc->sc_regs+17);
 177         err |= __get_user(regs->r18, sc->sc_regs+18);
 178         err |= __get_user(regs->r19, sc->sc_regs+19);
 179         err |= __get_user(regs->r20, sc->sc_regs+20);
 180         err |= __get_user(regs->r21, sc->sc_regs+21);
 181         err |= __get_user(regs->r22, sc->sc_regs+22);
 182         err |= __get_user(regs->r23, sc->sc_regs+23);
 183         err |= __get_user(regs->r24, sc->sc_regs+24);
 184         err |= __get_user(regs->r25, sc->sc_regs+25);
 185         err |= __get_user(regs->r26, sc->sc_regs+26);
 186         err |= __get_user(regs->r27, sc->sc_regs+27);
 187         err |= __get_user(regs->r28, sc->sc_regs+28);
 188         err |= __get_user(regs->gp, sc->sc_regs+29);
 189         err |= __get_user(usp, sc->sc_regs+30);
 190         wrusp(usp);
 191
 192         for (i = 0; i < 31; i++)
 193                 err |= __get_user(sw->fp[i], sc->sc_fpregs+i);
 194         err |= __get_user(sw->fp[31], &sc->sc_fpcr);
 195
 196         return err;
 197 }
 198
 199 /* Note that this syscall is also used by setcontext(3) to install
 200    a given sigcontext.  This because it's impossible to set *all*
 201    registers and transfer control from userland.  */
 202
 203 asmlinkage void
 204 do_sigreturn(struct sigcontext __user *sc)
 205 {
 206         struct pt_regs *regs = current_pt_regs();
 207         sigset_t set;
 208
 209         /* Verify that it's a good sigcontext before using it */
 210         if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
 211                 goto give_sigsegv;
 212         if (__get_user(set.sig[0], &sc->sc_mask))
 213                 goto give_sigsegv;
 214
 215         set_current_blocked(&set);
 216
 217         if (restore_sigcontext(sc, regs))
 218                 goto give_sigsegv;
 219
 220         /* Send SIGTRAP if we're single-stepping: */
 221         if (ptrace_cancel_bpt (current)) {
 222                 siginfo_t info;
 223
 224                 info.si_signo = SIGTRAP;
 225                 info.si_errno = 0;
 226                 info.si_code = TRAP_BRKPT;
 227                 info.si_addr = (void __user *) regs->pc;
 228                 info.si_trapno = 0;
 229                 send_sig_info(SIGTRAP, &info, current);
 230         }
 231         return;
 232
 233 give_sigsegv:
 234         force_sig(SIGSEGV, current);
 235 }
 236
 237 asmlinkage void
 238 do_rt_sigreturn(struct rt_sigframe __user *frame)
 239 {
 240         struct pt_regs *regs = current_pt_regs();
 241         sigset_t set;
 242
 243         /* Verify that it's a good ucontext_t before using it */
 244         if (!access_ok(VERIFY_READ, &frame->uc, sizeof(frame->uc)))
 245                 goto give_sigsegv;
 246         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 247                 goto give_sigsegv;
 248
 249         set_current_blocked(&set);
 250
 251         if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
 252                 goto give_sigsegv;
 253
 254         /* Send SIGTRAP if we're single-stepping: */
 255         if (ptrace_cancel_bpt (current)) {
 256                 siginfo_t info;
 257
 258                 info.si_signo = SIGTRAP;
 259                 info.si_errno = 0;
 260                 info.si_code = TRAP_BRKPT;
 261                 info.si_addr = (void __user *) regs->pc;
 262                 info.si_trapno = 0;
 263                 send_sig_info(SIGTRAP, &info, current);
 264         }
 265         return;
 266
 267 give_sigsegv:
 268         force_sig(SIGSEGV, current);
 269 }
 270
 271
 272 /*
 273  * Set up a signal frame.
 274  */
 275
 276 static inline void __user *
 277 get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size)
 278 {
 279         return (void __user *)((sigsp(sp, ksig) - frame_size) & -32ul);
 280 }
 281
 282 static long
 283 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 284                  unsigned long mask, unsigned long sp)
 285 {
 286         struct switch_stack *sw = (struct switch_stack *)regs - 1;
 287         long i, err = 0;
 288
 289         err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
 290         err |= __put_user(mask, &sc->sc_mask);
 291         err |= __put_user(regs->pc, &sc->sc_pc);
 292         err |= __put_user(8, &sc->sc_ps);
 293
 294         err |= __put_user(regs->r0 , sc->sc_regs+0);
 295         err |= __put_user(regs->r1 , sc->sc_regs+1);
 296         err |= __put_user(regs->r2 , sc->sc_regs+2);
 297         err |= __put_user(regs->r3 , sc->sc_regs+3);
 298         err |= __put_user(regs->r4 , sc->sc_regs+4);
 299         err |= __put_user(regs->r5 , sc->sc_regs+5);
 300         err |= __put_user(regs->r6 , sc->sc_regs+6);
 301         err |= __put_user(regs->r7 , sc->sc_regs+7);
 302         err |= __put_user(regs->r8 , sc->sc_regs+8);
 303         err |= __put_user(sw->r9   , sc->sc_regs+9);
 304         err |= __put_user(sw->r10  , sc->sc_regs+10);
 305         err |= __put_user(sw->r11  , sc->sc_regs+11);
 306         err |= __put_user(sw->r12  , sc->sc_regs+12);
 307         err |= __put_user(sw->r13  , sc->sc_regs+13);
 308         err |= __put_user(sw->r14  , sc->sc_regs+14);
 309         err |= __put_user(sw->r15  , sc->sc_regs+15);
 310         err |= __put_user(regs->r16, sc->sc_regs+16);
 311         err |= __put_user(regs->r17, sc->sc_regs+17);
 312         err |= __put_user(regs->r18, sc->sc_regs+18);
 313         err |= __put_user(regs->r19, sc->sc_regs+19);
 314         err |= __put_user(regs->r20, sc->sc_regs+20);
 315         err |= __put_user(regs->r21, sc->sc_regs+21);
 316         err |= __put_user(regs->r22, sc->sc_regs+22);
 317         err |= __put_user(regs->r23, sc->sc_regs+23);
 318         err |= __put_user(regs->r24, sc->sc_regs+24);
 319         err |= __put_user(regs->r25, sc->sc_regs+25);
 320         err |= __put_user(regs->r26, sc->sc_regs+26);
 321         err |= __put_user(regs->r27, sc->sc_regs+27);
 322         err |= __put_user(regs->r28, sc->sc_regs+28);
 323         err |= __put_user(regs->gp , sc->sc_regs+29);
 324         err |= __put_user(sp, sc->sc_regs+30);
 325         err |= __put_user(0, sc->sc_regs+31);
 326
 327         for (i = 0; i < 31; i++)
 328                 err |= __put_user(sw->fp[i], sc->sc_fpregs+i);
 329         err |= __put_user(0, sc->sc_fpregs+31);
 330         err |= __put_user(sw->fp[31], &sc->sc_fpcr);
 331
 332         err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0);
 333         err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1);
 334         err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2);
 335
 336         return err;
 337 }
 338
 339 static int
 340 setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 341 {
 342         unsigned long oldsp, r26, err = 0;
 343         struct sigframe __user *frame;
 344
 345         oldsp = rdusp();
 346         frame = get_sigframe(ksig, oldsp, sizeof(*frame));
 347         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 348                 return -EFAULT;
 349
 350         err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp);
 351         if (err)
 352                 return -EFAULT;
 353
 354         /* Set up to return from userspace.  If provided, use a stub
 355            already in userspace.  */
 356         r26 = (unsigned long) ksig->ka.ka_restorer;
 357         if (!r26) {
 358                 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
 359                 err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1);
 360                 err |= __put_user(INSN_CALLSYS, frame->retcode+2);
 361                 imb();
 362                 r26 = (unsigned long) frame->retcode;
 363         }
 364
 365         /* Check that everything was written properly.  */
 366         if (err)
 367                 return err;
 368
 369         /* "Return" to the handler */
 370         regs->r26 = r26;
 371         regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 372         regs->r16 = ksig->sig;                  /* a0: signal number */
 373         regs->r17 = 0;                          /* a1: exception code */
 374         regs->r18 = (unsigned long) &frame->sc; /* a2: sigcontext pointer */
 375         wrusp((unsigned long) frame);
 376
 377 #if DEBUG_SIG
 378         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 379                 current->comm, current->pid, frame, regs->pc, regs->r26);
 380 #endif
 381         return 0;
 382 }
 383
 384 static int
 385 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 386 {
 387         unsigned long oldsp, r26, err = 0;
 388         struct rt_sigframe __user *frame;
 389
 390         oldsp = rdusp();
 391         frame = get_sigframe(ksig, oldsp, sizeof(*frame));
 392         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 393                 return -EFAULT;
 394
 395         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 396
 397         /* Create the ucontext.  */
 398         err |= __put_user(0, &frame->uc.uc_flags);
 399         err |= __put_user(0, &frame->uc.uc_link);
 400         err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask);
 401         err |= __save_altstack(&frame->uc.uc_stack, oldsp);
 402         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs,
 403                                 set->sig[0], oldsp);
 404         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 405         if (err)
 406                 return -EFAULT;
 407
 408         /* Set up to return from userspace.  If provided, use a stub
 409            already in userspace.  */
 410         r26 = (unsigned long) ksig->ka.ka_restorer;
 411         if (!r26) {
 412                 err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
 413                 err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn,
 414                                   frame->retcode+1);
 415                 err |= __put_user(INSN_CALLSYS, frame->retcode+2);
 416                 imb();
 417                 r26 = (unsigned long) frame->retcode;
 418         }
 419
 420         if (err)
 421                 return -EFAULT;
 422
 423         /* "Return" to the handler */
 424         regs->r26 = r26;
 425         regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 426         regs->r16 = ksig->sig;                    /* a0: signal number */
 427         regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */
 428         regs->r18 = (unsigned long) &frame->uc;   /* a2: ucontext pointer */
 429         wrusp((unsigned long) frame);
 430
 431 #if DEBUG_SIG
 432         printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 433                 current->comm, current->pid, frame, regs->pc, regs->r26);
 434 #endif
 435
 436         return 0;
 437 }
 438
 439
 440 /*
 441  * OK, we're invoking a handler.
 442  */
 443 static inline void
 444 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 445 {
 446         sigset_t *oldset = sigmask_to_save();
 447         int ret;
 448
 449         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 450                 ret = setup_rt_frame(ksig, oldset, regs);
 451         else
 452                 ret = setup_frame(ksig, oldset, regs);
 453
 454         signal_setup_done(ret, ksig, 0);
 455 }
 456
 457 static inline void
 458 syscall_restart(unsigned long r0, unsigned long r19,
 459                 struct pt_regs *regs, struct k_sigaction *ka)
 460 {
 461         switch (regs->r0) {
 462         case ERESTARTSYS:
 463                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 464                 case ERESTARTNOHAND:
 465                         regs->r0 = EINTR;
 466                         break;
 467                 }
 468                 /* fallthrough */
 469         case ERESTARTNOINTR:
 470                 regs->r0 = r0;  /* reset v0 and a3 and replay syscall */
 471                 regs->r19 = r19;
 472                 regs->pc -= 4;
 473                 break;
 474         case ERESTART_RESTARTBLOCK:
 475                 regs->r0 = EINTR;
 476                 break;
 477         }
 478 }
 479
 480
 481 /*
 482  * Note that 'init' is a special process: it doesn't get signals it doesn't
 483  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 484  * mistake.
 485  *
 486  * Note that we go through the signals twice: once to check the signals that
 487  * the kernel can handle, and then we build all the user-level signal handling
 488  * stack-frames in one go after that.
 489  *
 490  * "r0" and "r19" are the registers we need to restore for system call
 491  * restart. "r0" is also used as an indicator whether we can restart at
 492  * all (if we get here from anything but a syscall return, it will be 0)
 493  */
 494 static void
 495 do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
 496 {
 497         unsigned long single_stepping = ptrace_cancel_bpt(current);
 498         struct ksignal ksig;
 499
 500         /* This lets the debugger run, ... */
 501         if (get_signal(&ksig)) {
 502                 /* ... so re-check the single stepping. */
 503                 single_stepping |= ptrace_cancel_bpt(current);
 504                 /* Whee!  Actually deliver the signal.  */
 505                 if (r0)
 506                         syscall_restart(r0, r19, regs, &ksig.ka);
 507                 handle_signal(&ksig, regs);
 508         } else {
 509                 single_stepping |= ptrace_cancel_bpt(current);
 510                 if (r0) {
 511                         switch (regs->r0) {
 512                         case ERESTARTNOHAND:
 513                         case ERESTARTSYS:
 514                         case ERESTARTNOINTR:
 515                                 /* Reset v0 and a3 and replay syscall.  */
 516                                 regs->r0 = r0;
 517                                 regs->r19 = r19;
 518                                 regs->pc -= 4;
 519                                 break;
 520                         case ERESTART_RESTARTBLOCK:
 521                                 /* Set v0 to the restart_syscall and replay */
 522                                 regs->r0 = __NR_restart_syscall;
 523                                 regs->pc -= 4;
 524                                 break;
 525                         }
 526                 }
 527                 restore_saved_sigmask();
 528         }
 529         if (single_stepping)
 530                 ptrace_set_bpt(current);        /* re-set breakpoint */
 531 }
 532
 533 void
 534 do_work_pending(struct pt_regs *regs, unsigned long thread_flags,
 535                  unsigned long r0, unsigned long r19)
 536 {
 537         do {
 538                 if (thread_flags & _TIF_NEED_RESCHED) {
 539                         schedule();
 540                 } else {
 541                         local_irq_enable();
 542                         if (thread_flags & _TIF_SIGPENDING) {
 543                                 do_signal(regs, r0, r19);
 544                                 r0 = 0;
 545                         } else {
 546                                 clear_thread_flag(TIF_NOTIFY_RESUME);
 547                                 tracehook_notify_resume(regs);
 548                         }
 549                 }
 550                 local_irq_disable();
 551                 thread_flags = current_thread_info()->flags;
 552         } while (thread_flags & _TIF_WORK_MASK);
 553 }