linux/arch/ia64/kernel/signal.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Architecture-specific signal handling support.
   4 *
   5 * Copyright (C) 1999-2004 Hewlett-Packard Co
   6 *      David Mosberger-Tang <davidm@hpl.hp.com>
   7 *
   8 * Derived from i386 and Alpha versions.
   9 */
  10
  11#include <linux/errno.h>
  12#include <linux/kernel.h>
  13#include <linux/mm.h>
  14#include <linux/ptrace.h>
  15#include <linux/tracehook.h>
  16#include <linux/sched.h>
  17#include <linux/signal.h>
  18#include <linux/smp.h>
  19#include <linux/stddef.h>
  20#include <linux/tty.h>
  21#include <linux/binfmts.h>
  22#include <linux/unistd.h>
  23#include <linux/wait.h>
  24
  25#include <asm/intrinsics.h>
  26#include <linux/uaccess.h>
  27#include <asm/rse.h>
  28#include <asm/sigcontext.h>
  29
  30#include "sigframe.h"
  31
  32#define DEBUG_SIG       0
  33#define STACK_ALIGN     16              /* minimal alignment for stack pointer */
  34
  35#if _NSIG_WORDS > 1
  36# define PUT_SIGSET(k,u)        __copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t))
  37# define GET_SIGSET(k,u)        __copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t))
  38#else
  39# define PUT_SIGSET(k,u)        __put_user((k)->sig[0], &(u)->sig[0])
  40# define GET_SIGSET(k,u)        __get_user((k)->sig[0], &(u)->sig[0])
  41#endif
  42
  43static long
  44restore_sigcontext (struct sigcontext __user *sc, struct sigscratch *scr)
  45{
  46        unsigned long ip, flags, nat, um, cfm, rsc;
  47        long err;
  48
  49        /* Always make any pending restarted system calls return -EINTR */
  50        current->restart_block.fn = do_no_restart_syscall;
  51
  52        /* restore scratch that always needs gets updated during signal delivery: */
  53        err  = __get_user(flags, &sc->sc_flags);
  54        err |= __get_user(nat, &sc->sc_nat);
  55        err |= __get_user(ip, &sc->sc_ip);                      /* instruction pointer */
  56        err |= __get_user(cfm, &sc->sc_cfm);
  57        err |= __get_user(um, &sc->sc_um);                      /* user mask */
  58        err |= __get_user(rsc, &sc->sc_ar_rsc);
  59        err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat);
  60        err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);
  61        err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
  62        err |= __get_user(scr->pt.pr, &sc->sc_pr);              /* predicates */
  63        err |= __get_user(scr->pt.b0, &sc->sc_br[0]);           /* b0 (rp) */
  64        err |= __get_user(scr->pt.b6, &sc->sc_br[6]);           /* b6 */
  65        err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 8); /* r1 */
  66        err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8);       /* r8-r11 */
  67        err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 2*8);     /* r12-r13 */
  68        err |= __copy_from_user(&scr->pt.r15, &sc->sc_gr[15], 8);       /* r15 */
  69
  70        scr->pt.cr_ifs = cfm | (1UL << 63);
  71        scr->pt.ar_rsc = rsc | (3 << 2); /* force PL3 */
  72
  73        /* establish new instruction pointer: */
  74        scr->pt.cr_iip = ip & ~0x3UL;
  75        ia64_psr(&scr->pt)->ri = ip & 0x3;
  76        scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM);
  77
  78        scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat);
  79
  80        if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
  81                /* Restore most scratch-state only when not in syscall. */
  82                err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);              /* ar.ccv */
  83                err |= __get_user(scr->pt.b7, &sc->sc_br[7]);                   /* b7 */
  84                err |= __get_user(scr->pt.r14, &sc->sc_gr[14]);                 /* r14 */
  85                err |= __copy_from_user(&scr->pt.ar_csd, &sc->sc_ar25, 2*8); /* ar.csd & ar.ssd */
  86                err |= __copy_from_user(&scr->pt.r2, &sc->sc_gr[2], 2*8);       /* r2-r3 */
  87                err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8);    /* r16-r31 */
  88        }
  89
  90        if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) {
  91                struct ia64_psr *psr = ia64_psr(&scr->pt);
  92
  93                err |= __copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16);
  94                psr->mfh = 0;   /* drop signal handler's fph contents... */
  95                preempt_disable();
  96                if (psr->dfh)
  97                        ia64_drop_fpu(current);
  98                else {
  99                        /* We already own the local fph, otherwise psr->dfh wouldn't be 0.  */
 100                        __ia64_load_fpu(current->thread.fph);
 101                        ia64_set_local_fpu_owner(current);
 102                }
 103                preempt_enable();
 104        }
 105        return err;
 106}
 107
 108long
 109ia64_rt_sigreturn (struct sigscratch *scr)
 110{
 111        extern char ia64_strace_leave_kernel, ia64_leave_kernel;
 112        struct sigcontext __user *sc;
 113        sigset_t set;
 114        long retval;
 115
 116        sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc;
 117
 118        /*
 119         * When we return to the previously executing context, r8 and r10 have already
 120         * been setup the way we want them.  Indeed, if the signal wasn't delivered while
 121         * in a system call, we must not touch r8 or r10 as otherwise user-level state
 122         * could be corrupted.
 123         */
 124        retval = (long) &ia64_leave_kernel;
 125        if (test_thread_flag(TIF_SYSCALL_TRACE)
 126            || test_thread_flag(TIF_SYSCALL_AUDIT))
 127                /*
 128                 * strace expects to be notified after sigreturn returns even though the
 129                 * context to which we return may not be in the middle of a syscall.
 130                 * Thus, the return-value that strace displays for sigreturn is
 131                 * meaningless.
 132                 */
 133                retval = (long) &ia64_strace_leave_kernel;
 134
 135        if (!access_ok(sc, sizeof(*sc)))
 136                goto give_sigsegv;
 137
 138        if (GET_SIGSET(&set, &sc->sc_mask))
 139                goto give_sigsegv;
 140
 141        set_current_blocked(&set);
 142
 143        if (restore_sigcontext(sc, scr))
 144                goto give_sigsegv;
 145
 146#if DEBUG_SIG
 147        printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
 148               current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
 149#endif
 150        if (restore_altstack(&sc->sc_stack))
 151                goto give_sigsegv;
 152        return retval;
 153
 154  give_sigsegv:
 155        force_sig(SIGSEGV);
 156        return retval;
 157}
 158
 159/*
 160 * This does just the minimum required setup of sigcontext.
 161 * Specifically, it only installs data that is either not knowable at
 162 * the user-level or that gets modified before execution in the
 163 * trampoline starts.  Everything else is done at the user-level.
 164 */
 165static long
 166setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr)
 167{
 168        unsigned long flags = 0, ifs, cfm, nat;
 169        long err = 0;
 170
 171        ifs = scr->pt.cr_ifs;
 172
 173        if (on_sig_stack((unsigned long) sc))
 174                flags |= IA64_SC_FLAG_ONSTACK;
 175        if ((ifs & (1UL << 63)) == 0)
 176                /* if cr_ifs doesn't have the valid bit set, we got here through a syscall */
 177                flags |= IA64_SC_FLAG_IN_SYSCALL;
 178        cfm = ifs & ((1UL << 38) - 1);
 179        ia64_flush_fph(current);
 180        if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
 181                flags |= IA64_SC_FLAG_FPH_VALID;
 182                err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
 183        }
 184
 185        nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);
 186
 187        err |= __put_user(flags, &sc->sc_flags);
 188        err |= __put_user(nat, &sc->sc_nat);
 189        err |= PUT_SIGSET(mask, &sc->sc_mask);
 190        err |= __put_user(cfm, &sc->sc_cfm);
 191        err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
 192        err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
 193        err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat);            /* ar.unat */
 194        err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);            /* ar.fpsr */
 195        err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
 196        err |= __put_user(scr->pt.pr, &sc->sc_pr);                      /* predicates */
 197        err |= __put_user(scr->pt.b0, &sc->sc_br[0]);                   /* b0 (rp) */
 198        err |= __put_user(scr->pt.b6, &sc->sc_br[6]);                   /* b6 */
 199        err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8);           /* r1 */
 200        err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8);         /* r8-r11 */
 201        err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8);       /* r12-r13 */
 202        err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8);         /* r15 */
 203        err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);
 204
 205        if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
 206                /* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
 207                err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);              /* ar.ccv */
 208                err |= __put_user(scr->pt.b7, &sc->sc_br[7]);                   /* b7 */
 209                err |= __put_user(scr->pt.r14, &sc->sc_gr[14]);                 /* r14 */
 210                err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */
 211                err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8);         /* r2-r3 */
 212                err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8);      /* r16-r31 */
 213        }
 214        return err;
 215}
 216
 217/*
 218 * Check whether the register-backing store is already on the signal stack.
 219 */
 220static inline int
 221rbs_on_sig_stack (unsigned long bsp)
 222{
 223        return (bsp - current->sas_ss_sp < current->sas_ss_size);
 224}
 225
 226static long
 227setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
 228{
 229        extern char __kernel_sigtramp[];
 230        unsigned long tramp_addr, new_rbs = 0, new_sp;
 231        struct sigframe __user *frame;
 232        long err;
 233
 234        new_sp = scr->pt.r12;
 235        tramp_addr = (unsigned long) __kernel_sigtramp;
 236        if (ksig->ka.sa.sa_flags & SA_ONSTACK) {
 237                int onstack = sas_ss_flags(new_sp);
 238
 239                if (onstack == 0) {
 240                        new_sp = current->sas_ss_sp + current->sas_ss_size;
 241                        /*
 242                         * We need to check for the register stack being on the
 243                         * signal stack separately, because it's switched
 244                         * separately (memory stack is switched in the kernel,
 245                         * register stack is switched in the signal trampoline).
 246                         */
 247                        if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
 248                                new_rbs = ALIGN(current->sas_ss_sp,
 249                                                sizeof(long));
 250                } else if (onstack == SS_ONSTACK) {
 251                        unsigned long check_sp;
 252
 253                        /*
 254                         * If we are on the alternate signal stack and would
 255                         * overflow it, don't. Return an always-bogus address
 256                         * instead so we will die with SIGSEGV.
 257                         */
 258                        check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
 259                        if (!likely(on_sig_stack(check_sp))) {
 260                                force_sigsegv(ksig->sig);
 261                                return 1;
 262                        }
 263                }
 264        }
 265        frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
 266
 267        if (!access_ok(frame, sizeof(*frame))) {
 268                force_sigsegv(ksig->sig);
 269                return 1;
 270        }
 271
 272        err  = __put_user(ksig->sig, &frame->arg0);
 273        err |= __put_user(&frame->info, &frame->arg1);
 274        err |= __put_user(&frame->sc, &frame->arg2);
 275        err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
 276        err |= __put_user(0, &frame->sc.sc_loadrs);     /* initialize to zero */
 277        err |= __put_user(ksig->ka.sa.sa_handler, &frame->handler);
 278
 279        err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 280
 281        err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12);
 282        err |= setup_sigcontext(&frame->sc, set, scr);
 283
 284        if (unlikely(err)) {
 285                force_sigsegv(ksig->sig);
 286                return 1;
 287        }
 288
 289        scr->pt.r12 = (unsigned long) frame - 16;       /* new stack pointer */
 290        scr->pt.ar_fpsr = FPSR_DEFAULT;                 /* reset fpsr for signal handler */
 291        scr->pt.cr_iip = tramp_addr;
 292        ia64_psr(&scr->pt)->ri = 0;                     /* start executing in first slot */
 293        ia64_psr(&scr->pt)->be = 0;                     /* force little-endian byte-order */
 294        /*
 295         * Force the interruption function mask to zero.  This has no effect when a
 296         * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
 297         * ignored), but it has the desirable effect of making it possible to deliver a
 298         * signal with an incomplete register frame (which happens when a mandatory RSE
 299         * load faults).  Furthermore, it has no negative effect on the getting the user's
 300         * dirty partition preserved, because that's governed by scr->pt.loadrs.
 301         */
 302        scr->pt.cr_ifs = (1UL << 63);
 303
 304        /*
 305         * Note: this affects only the NaT bits of the scratch regs (the ones saved in
 306         * pt_regs), which is exactly what we want.
 307         */
 308        scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */
 309
 310#if DEBUG_SIG
 311        printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
 312               current->comm, current->pid, ksig->sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
 313#endif
 314        return 0;
 315}
 316
 317static long
 318handle_signal (struct ksignal *ksig, struct sigscratch *scr)
 319{
 320        int ret = setup_frame(ksig, sigmask_to_save(), scr);
 321
 322        if (!ret)
 323                signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 324
 325        return ret;
 326}
 327
 328/*
 329 * Note that `init' is a special process: it doesn't get signals it doesn't want to
 330 * handle.  Thus you cannot kill init even with a SIGKILL even by mistake.
 331 */
 332void
 333ia64_do_signal (struct sigscratch *scr, long in_syscall)
 334{
 335        long restart = in_syscall;
 336        long errno = scr->pt.r8;
 337        struct ksignal ksig;
 338
 339        /*
 340         * This only loops in the rare cases of handle_signal() failing, in which case we
 341         * need to push through a forced SIGSEGV.
 342         */
 343        while (1) {
 344                get_signal(&ksig);
 345
 346                /*
 347                 * get_signal() may have run a debugger (via notify_parent())
 348                 * and the debugger may have modified the state (e.g., to arrange for an
 349                 * inferior call), thus it's important to check for restarting _after_
 350                 * get_signal().
 351                 */
 352                if ((long) scr->pt.r10 != -1)
 353                        /*
 354                         * A system calls has to be restarted only if one of the error codes
 355                         * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned.  If r10
 356                         * isn't -1 then r8 doesn't hold an error code and we don't need to
 357                         * restart the syscall, so we can clear the "restart" flag here.
 358                         */
 359                        restart = 0;
 360
 361                if (ksig.sig <= 0)
 362                        break;
 363
 364                if (unlikely(restart)) {
 365                        switch (errno) {
 366                        case ERESTART_RESTARTBLOCK:
 367                        case ERESTARTNOHAND:
 368                                scr->pt.r8 = EINTR;
 369                                /* note: scr->pt.r10 is already -1 */
 370                                break;
 371                        case ERESTARTSYS:
 372                                if ((ksig.ka.sa.sa_flags & SA_RESTART) == 0) {
 373                                        scr->pt.r8 = EINTR;
 374                                        /* note: scr->pt.r10 is already -1 */
 375                                        break;
 376                                }
 377                                fallthrough;
 378                        case ERESTARTNOINTR:
 379                                ia64_decrement_ip(&scr->pt);
 380                                restart = 0; /* don't restart twice if handle_signal() fails... */
 381                        }
 382                }
 383
 384                /*
 385                 * Whee!  Actually deliver the signal.  If the delivery failed, we need to
 386                 * continue to iterate in this loop so we can deliver the SIGSEGV...
 387                 */
 388                if (handle_signal(&ksig, scr))
 389                        return;
 390        }
 391
 392        /* Did we come from a system call? */
 393        if (restart) {
 394                /* Restart the system call - no handlers present */
 395                if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
 396                    || errno == ERESTART_RESTARTBLOCK)
 397                {
 398                        /*
 399                         * Note: the syscall number is in r15 which is saved in
 400                         * pt_regs so all we need to do here is adjust ip so that
 401                         * the "break" instruction gets re-executed.
 402                         */
 403                        ia64_decrement_ip(&scr->pt);
 404                        if (errno == ERESTART_RESTARTBLOCK)
 405                                scr->pt.r15 = __NR_restart_syscall;
 406                }
 407        }
 408
 409        /* if there's no signal to deliver, we just put the saved sigmask
 410         * back */
 411        restore_saved_sigmask();
 412}
 413