LXR linux/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
  38asmlinkage void ret_from_sys_call(void);
  39
  40/*
  41 * The OSF/1 sigprocmask calling sequence is different from the
  42 * C sigprocmask() sequence..
  43 */
  44SYSCALL_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
  59SYSCALL_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(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(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
  90SYSCALL_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
 125struct sigframe
 126{
 127        struct sigcontext sc;
 128        unsigned int retcode[3];
 129};
 130
 131struct 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.  */
 141extern 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
 148static long
 149restore_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
 203asmlinkage void
 204do_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(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                send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
 223                               current);
 224        }
 225        return;
 226
 227give_sigsegv:
 228        force_sig(SIGSEGV, current);
 229}
 230
 231asmlinkage void
 232do_rt_sigreturn(struct rt_sigframe __user *frame)
 233{
 234        struct pt_regs *regs = current_pt_regs();
 235        sigset_t set;
 236
 237        /* Verify that it's a good ucontext_t before using it */
 238        if (!access_ok(&frame->uc, sizeof(frame->uc)))
 239                goto give_sigsegv;
 240        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 241                goto give_sigsegv;
 242
 243        set_current_blocked(&set);
 244
 245        if (restore_sigcontext(&frame->uc.uc_mcontext, regs))
 246                goto give_sigsegv;
 247
 248        /* Send SIGTRAP if we're single-stepping: */
 249        if (ptrace_cancel_bpt (current)) {
 250                send_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *) regs->pc, 0,
 251                               current);
 252        }
 253        return;
 254
 255give_sigsegv:
 256        force_sig(SIGSEGV, current);
 257}
 258
 259
 260/*
 261 * Set up a signal frame.
 262 */
 263
 264static inline void __user *
 265get_sigframe(struct ksignal *ksig, unsigned long sp, size_t frame_size)
 266{
 267        return (void __user *)((sigsp(sp, ksig) - frame_size) & -32ul);
 268}
 269
 270static long
 271setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, 
 272                 unsigned long mask, unsigned long sp)
 273{
 274        struct switch_stack *sw = (struct switch_stack *)regs - 1;
 275        long i, err = 0;
 276
 277        err |= __put_user(on_sig_stack((unsigned long)sc), &sc->sc_onstack);
 278        err |= __put_user(mask, &sc->sc_mask);
 279        err |= __put_user(regs->pc, &sc->sc_pc);
 280        err |= __put_user(8, &sc->sc_ps);
 281
 282        err |= __put_user(regs->r0 , sc->sc_regs+0);
 283        err |= __put_user(regs->r1 , sc->sc_regs+1);
 284        err |= __put_user(regs->r2 , sc->sc_regs+2);
 285        err |= __put_user(regs->r3 , sc->sc_regs+3);
 286        err |= __put_user(regs->r4 , sc->sc_regs+4);
 287        err |= __put_user(regs->r5 , sc->sc_regs+5);
 288        err |= __put_user(regs->r6 , sc->sc_regs+6);
 289        err |= __put_user(regs->r7 , sc->sc_regs+7);
 290        err |= __put_user(regs->r8 , sc->sc_regs+8);
 291        err |= __put_user(sw->r9   , sc->sc_regs+9);
 292        err |= __put_user(sw->r10  , sc->sc_regs+10);
 293        err |= __put_user(sw->r11  , sc->sc_regs+11);
 294        err |= __put_user(sw->r12  , sc->sc_regs+12);
 295        err |= __put_user(sw->r13  , sc->sc_regs+13);
 296        err |= __put_user(sw->r14  , sc->sc_regs+14);
 297        err |= __put_user(sw->r15  , sc->sc_regs+15);
 298        err |= __put_user(regs->r16, sc->sc_regs+16);
 299        err |= __put_user(regs->r17, sc->sc_regs+17);
 300        err |= __put_user(regs->r18, sc->sc_regs+18);
 301        err |= __put_user(regs->r19, sc->sc_regs+19);
 302        err |= __put_user(regs->r20, sc->sc_regs+20);
 303        err |= __put_user(regs->r21, sc->sc_regs+21);
 304        err |= __put_user(regs->r22, sc->sc_regs+22);
 305        err |= __put_user(regs->r23, sc->sc_regs+23);
 306        err |= __put_user(regs->r24, sc->sc_regs+24);
 307        err |= __put_user(regs->r25, sc->sc_regs+25);
 308        err |= __put_user(regs->r26, sc->sc_regs+26);
 309        err |= __put_user(regs->r27, sc->sc_regs+27);
 310        err |= __put_user(regs->r28, sc->sc_regs+28);
 311        err |= __put_user(regs->gp , sc->sc_regs+29);
 312        err |= __put_user(sp, sc->sc_regs+30);
 313        err |= __put_user(0, sc->sc_regs+31);
 314
 315        for (i = 0; i < 31; i++)
 316                err |= __put_user(sw->fp[i], sc->sc_fpregs+i);
 317        err |= __put_user(0, sc->sc_fpregs+31);
 318        err |= __put_user(sw->fp[31], &sc->sc_fpcr);
 319
 320        err |= __put_user(regs->trap_a0, &sc->sc_traparg_a0);
 321        err |= __put_user(regs->trap_a1, &sc->sc_traparg_a1);
 322        err |= __put_user(regs->trap_a2, &sc->sc_traparg_a2);
 323
 324        return err;
 325}
 326
 327static int
 328setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 329{
 330        unsigned long oldsp, r26, err = 0;
 331        struct sigframe __user *frame;
 332
 333        oldsp = rdusp();
 334        frame = get_sigframe(ksig, oldsp, sizeof(*frame));
 335        if (!access_ok(frame, sizeof(*frame)))
 336                return -EFAULT;
 337
 338        err |= setup_sigcontext(&frame->sc, regs, set->sig[0], oldsp);
 339        if (err)
 340                return -EFAULT;
 341
 342        /* Set up to return from userspace.  If provided, use a stub
 343           already in userspace.  */
 344        r26 = (unsigned long) ksig->ka.ka_restorer;
 345        if (!r26) {
 346                err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
 347                err |= __put_user(INSN_LDI_R0+__NR_sigreturn, frame->retcode+1);
 348                err |= __put_user(INSN_CALLSYS, frame->retcode+2);
 349                imb();
 350                r26 = (unsigned long) frame->retcode;
 351        }
 352
 353        /* Check that everything was written properly.  */
 354        if (err)
 355                return err;
 356
 357        /* "Return" to the handler */
 358        regs->r26 = r26;
 359        regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 360        regs->r16 = ksig->sig;                  /* a0: signal number */
 361        regs->r17 = 0;                          /* a1: exception code */
 362        regs->r18 = (unsigned long) &frame->sc; /* a2: sigcontext pointer */
 363        wrusp((unsigned long) frame);
 364        
 365#if DEBUG_SIG
 366        printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 367                current->comm, current->pid, frame, regs->pc, regs->r26);
 368#endif
 369        return 0;
 370}
 371
 372static int
 373setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
 374{
 375        unsigned long oldsp, r26, err = 0;
 376        struct rt_sigframe __user *frame;
 377
 378        oldsp = rdusp();
 379        frame = get_sigframe(ksig, oldsp, sizeof(*frame));
 380        if (!access_ok(frame, sizeof(*frame)))
 381                return -EFAULT;
 382
 383        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 384
 385        /* Create the ucontext.  */
 386        err |= __put_user(0, &frame->uc.uc_flags);
 387        err |= __put_user(0, &frame->uc.uc_link);
 388        err |= __put_user(set->sig[0], &frame->uc.uc_osf_sigmask);
 389        err |= __save_altstack(&frame->uc.uc_stack, oldsp);
 390        err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, 
 391                                set->sig[0], oldsp);
 392        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 393        if (err)
 394                return -EFAULT;
 395
 396        /* Set up to return from userspace.  If provided, use a stub
 397           already in userspace.  */
 398        r26 = (unsigned long) ksig->ka.ka_restorer;
 399        if (!r26) {
 400                err |= __put_user(INSN_MOV_R30_R16, frame->retcode+0);
 401                err |= __put_user(INSN_LDI_R0+__NR_rt_sigreturn,
 402                                  frame->retcode+1);
 403                err |= __put_user(INSN_CALLSYS, frame->retcode+2);
 404                imb();
 405                r26 = (unsigned long) frame->retcode;
 406        }
 407
 408        if (err)
 409                return -EFAULT;
 410
 411        /* "Return" to the handler */
 412        regs->r26 = r26;
 413        regs->r27 = regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 414        regs->r16 = ksig->sig;                    /* a0: signal number */
 415        regs->r17 = (unsigned long) &frame->info; /* a1: siginfo pointer */
 416        regs->r18 = (unsigned long) &frame->uc;   /* a2: ucontext pointer */
 417        wrusp((unsigned long) frame);
 418
 419#if DEBUG_SIG
 420        printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
 421                current->comm, current->pid, frame, regs->pc, regs->r26);
 422#endif
 423
 424        return 0;
 425}
 426
 427
 428/*
 429 * OK, we're invoking a handler.
 430 */
 431static inline void
 432handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 433{
 434        sigset_t *oldset = sigmask_to_save();
 435        int ret;
 436
 437        if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 438                ret = setup_rt_frame(ksig, oldset, regs);
 439        else
 440                ret = setup_frame(ksig, oldset, regs);
 441
 442        signal_setup_done(ret, ksig, 0);
 443}
 444
 445static inline void
 446syscall_restart(unsigned long r0, unsigned long r19,
 447                struct pt_regs *regs, struct k_sigaction *ka)
 448{
 449        switch (regs->r0) {
 450        case ERESTARTSYS:
 451                if (!(ka->sa.sa_flags & SA_RESTART)) {
 452                case ERESTARTNOHAND:
 453                        regs->r0 = EINTR;
 454                        break;
 455                }
 456                /* fallthrough */
 457        case ERESTARTNOINTR:
 458                regs->r0 = r0;  /* reset v0 and a3 and replay syscall */
 459                regs->r19 = r19;
 460                regs->pc -= 4;
 461                break;
 462        case ERESTART_RESTARTBLOCK:
 463                regs->r0 = EINTR;
 464                break;
 465        }
 466}
 467
 468
 469/*
 470 * Note that 'init' is a special process: it doesn't get signals it doesn't
 471 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 472 * mistake.
 473 *
 474 * Note that we go through the signals twice: once to check the signals that
 475 * the kernel can handle, and then we build all the user-level signal handling
 476 * stack-frames in one go after that.
 477 *
 478 * "r0" and "r19" are the registers we need to restore for system call
 479 * restart. "r0" is also used as an indicator whether we can restart at
 480 * all (if we get here from anything but a syscall return, it will be 0)
 481 */
 482static void
 483do_signal(struct pt_regs *regs, unsigned long r0, unsigned long r19)
 484{
 485        unsigned long single_stepping = ptrace_cancel_bpt(current);
 486        struct ksignal ksig;
 487
 488        /* This lets the debugger run, ... */
 489        if (get_signal(&ksig)) {
 490                /* ... so re-check the single stepping. */
 491                single_stepping |= ptrace_cancel_bpt(current);
 492                /* Whee!  Actually deliver the signal.  */
 493                if (r0)
 494                        syscall_restart(r0, r19, regs, &ksig.ka);
 495                handle_signal(&ksig, regs);
 496        } else {
 497                single_stepping |= ptrace_cancel_bpt(current);
 498                if (r0) {
 499                        switch (regs->r0) {
 500                        case ERESTARTNOHAND:
 501                        case ERESTARTSYS:
 502                        case ERESTARTNOINTR:
 503                                /* Reset v0 and a3 and replay syscall.  */
 504                                regs->r0 = r0;
 505                                regs->r19 = r19;
 506                                regs->pc -= 4;
 507                                break;
 508                        case ERESTART_RESTARTBLOCK:
 509                                /* Set v0 to the restart_syscall and replay */
 510                                regs->r0 = __NR_restart_syscall;
 511                                regs->pc -= 4;
 512                                break;
 513                        }
 514                }
 515                restore_saved_sigmask();
 516        }
 517        if (single_stepping)
 518                ptrace_set_bpt(current);        /* re-set breakpoint */
 519}
 520
 521void
 522do_work_pending(struct pt_regs *regs, unsigned long thread_flags,
 523                 unsigned long r0, unsigned long r19)
 524{
 525        do {
 526                if (thread_flags & _TIF_NEED_RESCHED) {
 527                        schedule();
 528                } else {
 529                        local_irq_enable();
 530                        if (thread_flags & _TIF_SIGPENDING) {
 531                                do_signal(regs, r0, r19);
 532                                r0 = 0;
 533                        } else {
 534                                clear_thread_flag(TIF_NOTIFY_RESUME);
 535                                tracehook_notify_resume(regs);
 536                        }
 537                }
 538                local_irq_disable();
 539                thread_flags = current_thread_info()->flags;
 540        } while (thread_flags & _TIF_WORK_MASK);
 541}
 542