arch/ia64/kernel/signal.c

   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
  43 static long
  44 restore_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
 108 long
 109 ia64_rt_sigreturn (struct sigscratch *scr)
 110 {
 111         extern char ia64_strace_leave_kernel, ia64_leave_kernel;
 112         struct sigcontext __user *sc;
 113         struct siginfo si;
 114         sigset_t set;
 115         long retval;
 116
 117         sc = &((struct sigframe __user *) (scr->pt.r12 + 16))->sc;
 118
 119         /*
 120          * When we return to the previously executing context, r8 and r10 have already
 121          * been setup the way we want them.  Indeed, if the signal wasn't delivered while
 122          * in a system call, we must not touch r8 or r10 as otherwise user-level state
 123          * could be corrupted.
 124          */
 125         retval = (long) &ia64_leave_kernel;
 126         if (test_thread_flag(TIF_SYSCALL_TRACE)
 127             || test_thread_flag(TIF_SYSCALL_AUDIT))
 128                 /*
 129                  * strace expects to be notified after sigreturn returns even though the
 130                  * context to which we return may not be in the middle of a syscall.
 131                  * Thus, the return-value that strace displays for sigreturn is
 132                  * meaningless.
 133                  */
 134                 retval = (long) &ia64_strace_leave_kernel;
 135
 136         if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
 137                 goto give_sigsegv;
 138
 139         if (GET_SIGSET(&set, &sc->sc_mask))
 140                 goto give_sigsegv;
 141
 142         set_current_blocked(&set);
 143
 144         if (restore_sigcontext(sc, scr))
 145                 goto give_sigsegv;
 146
 147 #if DEBUG_SIG
 148         printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
 149                current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
 150 #endif
 151         if (restore_altstack(&sc->sc_stack))
 152                 goto give_sigsegv;
 153         return retval;
 154
 155   give_sigsegv:
 156         si.si_signo = SIGSEGV;
 157         si.si_errno = 0;
 158         si.si_code = SI_KERNEL;
 159         si.si_pid = task_pid_vnr(current);
 160         si.si_uid = from_kuid_munged(current_user_ns(), current_uid());
 161         si.si_addr = sc;
 162         force_sig_info(SIGSEGV, &si, current);
 163         return retval;
 164 }
 165
 166 /*
 167  * This does just the minimum required setup of sigcontext.
 168  * Specifically, it only installs data that is either not knowable at
 169  * the user-level or that gets modified before execution in the
 170  * trampoline starts.  Everything else is done at the user-level.
 171  */
 172 static long
 173 setup_sigcontext (struct sigcontext __user *sc, sigset_t *mask, struct sigscratch *scr)
 174 {
 175         unsigned long flags = 0, ifs, cfm, nat;
 176         long err = 0;
 177
 178         ifs = scr->pt.cr_ifs;
 179
 180         if (on_sig_stack((unsigned long) sc))
 181                 flags |= IA64_SC_FLAG_ONSTACK;
 182         if ((ifs & (1UL << 63)) == 0)
 183                 /* if cr_ifs doesn't have the valid bit set, we got here through a syscall */
 184                 flags |= IA64_SC_FLAG_IN_SYSCALL;
 185         cfm = ifs & ((1UL << 38) - 1);
 186         ia64_flush_fph(current);
 187         if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
 188                 flags |= IA64_SC_FLAG_FPH_VALID;
 189                 err = __copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
 190         }
 191
 192         nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);
 193
 194         err |= __put_user(flags, &sc->sc_flags);
 195         err |= __put_user(nat, &sc->sc_nat);
 196         err |= PUT_SIGSET(mask, &sc->sc_mask);
 197         err |= __put_user(cfm, &sc->sc_cfm);
 198         err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
 199         err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
 200         err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat);            /* ar.unat */
 201         err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);            /* ar.fpsr */
 202         err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
 203         err |= __put_user(scr->pt.pr, &sc->sc_pr);                      /* predicates */
 204         err |= __put_user(scr->pt.b0, &sc->sc_br[0]);                   /* b0 (rp) */
 205         err |= __put_user(scr->pt.b6, &sc->sc_br[6]);                   /* b6 */
 206         err |= __copy_to_user(&sc->sc_gr[1], &scr->pt.r1, 8);           /* r1 */
 207         err |= __copy_to_user(&sc->sc_gr[8], &scr->pt.r8, 4*8);         /* r8-r11 */
 208         err |= __copy_to_user(&sc->sc_gr[12], &scr->pt.r12, 2*8);       /* r12-r13 */
 209         err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8);         /* r15 */
 210         err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);
 211
 212         if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
 213                 /* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
 214                 err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);              /* ar.ccv */
 215                 err |= __put_user(scr->pt.b7, &sc->sc_br[7]);                   /* b7 */
 216                 err |= __put_user(scr->pt.r14, &sc->sc_gr[14]);                 /* r14 */
 217                 err |= __copy_to_user(&sc->sc_ar25, &scr->pt.ar_csd, 2*8); /* ar.csd & ar.ssd */
 218                 err |= __copy_to_user(&sc->sc_gr[2], &scr->pt.r2, 2*8);         /* r2-r3 */
 219                 err |= __copy_to_user(&sc->sc_gr[16], &scr->pt.r16, 16*8);      /* r16-r31 */
 220         }
 221         return err;
 222 }
 223
 224 /*
 225  * Check whether the register-backing store is already on the signal stack.
 226  */
 227 static inline int
 228 rbs_on_sig_stack (unsigned long bsp)
 229 {
 230         return (bsp - current->sas_ss_sp < current->sas_ss_size);
 231 }
 232
 233 static long
 234 force_sigsegv_info (int sig, void __user *addr)
 235 {
 236         unsigned long flags;
 237         struct siginfo si;
 238
 239         if (sig == SIGSEGV) {
 240                 /*
 241                  * Acquiring siglock around the sa_handler-update is almost
 242                  * certainly overkill, but this isn't a
 243                  * performance-critical path and I'd rather play it safe
 244                  * here than having to debug a nasty race if and when
 245                  * something changes in kernel/signal.c that would make it
 246                  * no longer safe to modify sa_handler without holding the
 247                  * lock.
 248                  */
 249                 spin_lock_irqsave(&current->sighand->siglock, flags);
 250                 current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
 251                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 252         }
 253         si.si_signo = SIGSEGV;
 254         si.si_errno = 0;
 255         si.si_code = SI_KERNEL;
 256         si.si_pid = task_pid_vnr(current);
 257         si.si_uid = from_kuid_munged(current_user_ns(), current_uid());
 258         si.si_addr = addr;
 259         force_sig_info(SIGSEGV, &si, current);
 260         return 1;
 261 }
 262
 263 static long
 264 setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
 265 {
 266         extern char __kernel_sigtramp[];
 267         unsigned long tramp_addr, new_rbs = 0, new_sp;
 268         struct sigframe __user *frame;
 269         long err;
 270
 271         new_sp = scr->pt.r12;
 272         tramp_addr = (unsigned long) __kernel_sigtramp;
 273         if (ksig->ka.sa.sa_flags & SA_ONSTACK) {
 274                 int onstack = sas_ss_flags(new_sp);
 275
 276                 if (onstack == 0) {
 277                         new_sp = current->sas_ss_sp + current->sas_ss_size;
 278                         /*
 279                          * We need to check for the register stack being on the
 280                          * signal stack separately, because it's switched
 281                          * separately (memory stack is switched in the kernel,
 282                          * register stack is switched in the signal trampoline).
 283                          */
 284                         if (!rbs_on_sig_stack(scr->pt.ar_bspstore))
 285                                 new_rbs = ALIGN(current->sas_ss_sp,
 286                                                 sizeof(long));
 287                 } else if (onstack == SS_ONSTACK) {
 288                         unsigned long check_sp;
 289
 290                         /*
 291                          * If we are on the alternate signal stack and would
 292                          * overflow it, don't. Return an always-bogus address
 293                          * instead so we will die with SIGSEGV.
 294                          */
 295                         check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
 296                         if (!likely(on_sig_stack(check_sp)))
 297                                 return force_sigsegv_info(ksig->sig, (void __user *)
 298                                                           check_sp);
 299                 }
 300         }
 301         frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
 302
 303         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 304                 return force_sigsegv_info(ksig->sig, frame);
 305
 306         err  = __put_user(ksig->sig, &frame->arg0);
 307         err |= __put_user(&frame->info, &frame->arg1);
 308         err |= __put_user(&frame->sc, &frame->arg2);
 309         err |= __put_user(new_rbs, &frame->sc.sc_rbs_base);
 310         err |= __put_user(0, &frame->sc.sc_loadrs);     /* initialize to zero */
 311         err |= __put_user(ksig->ka.sa.sa_handler, &frame->handler);
 312
 313         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 314
 315         err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12);
 316         err |= setup_sigcontext(&frame->sc, set, scr);
 317
 318         if (unlikely(err))
 319                 return force_sigsegv_info(ksig->sig, frame);
 320
 321         scr->pt.r12 = (unsigned long) frame - 16;       /* new stack pointer */
 322         scr->pt.ar_fpsr = FPSR_DEFAULT;                 /* reset fpsr for signal handler */
 323         scr->pt.cr_iip = tramp_addr;
 324         ia64_psr(&scr->pt)->ri = 0;                     /* start executing in first slot */
 325         ia64_psr(&scr->pt)->be = 0;                     /* force little-endian byte-order */
 326         /*
 327          * Force the interruption function mask to zero.  This has no effect when a
 328          * system-call got interrupted by a signal (since, in that case, scr->pt_cr_ifs is
 329          * ignored), but it has the desirable effect of making it possible to deliver a
 330          * signal with an incomplete register frame (which happens when a mandatory RSE
 331          * load faults).  Furthermore, it has no negative effect on the getting the user's
 332          * dirty partition preserved, because that's governed by scr->pt.loadrs.
 333          */
 334         scr->pt.cr_ifs = (1UL << 63);
 335
 336         /*
 337          * Note: this affects only the NaT bits of the scratch regs (the ones saved in
 338          * pt_regs), which is exactly what we want.
 339          */
 340         scr->scratch_unat = 0; /* ensure NaT bits of r12 is clear */
 341
 342 #if DEBUG_SIG
 343         printk("SIG deliver (%s:%d): sig=%d sp=%lx ip=%lx handler=%p\n",
 344                current->comm, current->pid, ksig->sig, scr->pt.r12, frame->sc.sc_ip, frame->handler);
 345 #endif
 346         return 0;
 347 }
 348
 349 static long
 350 handle_signal (struct ksignal *ksig, struct sigscratch *scr)
 351 {
 352         int ret = setup_frame(ksig, sigmask_to_save(), scr);
 353
 354         if (!ret)
 355                 signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 356
 357         return ret;
 358 }
 359
 360 /*
 361  * Note that `init' is a special process: it doesn't get signals it doesn't want to
 362  * handle.  Thus you cannot kill init even with a SIGKILL even by mistake.
 363  */
 364 void
 365 ia64_do_signal (struct sigscratch *scr, long in_syscall)
 366 {
 367         long restart = in_syscall;
 368         long errno = scr->pt.r8;
 369         struct ksignal ksig;
 370
 371         /*
 372          * This only loops in the rare cases of handle_signal() failing, in which case we
 373          * need to push through a forced SIGSEGV.
 374          */
 375         while (1) {
 376                 get_signal(&ksig);
 377
 378                 /*
 379                  * get_signal_to_deliver() may have run a debugger (via notify_parent())
 380                  * and the debugger may have modified the state (e.g., to arrange for an
 381                  * inferior call), thus it's important to check for restarting _after_
 382                  * get_signal_to_deliver().
 383                  */
 384                 if ((long) scr->pt.r10 != -1)
 385                         /*
 386                          * A system calls has to be restarted only if one of the error codes
 387                          * ERESTARTNOHAND, ERESTARTSYS, or ERESTARTNOINTR is returned.  If r10
 388                          * isn't -1 then r8 doesn't hold an error code and we don't need to
 389                          * restart the syscall, so we can clear the "restart" flag here.
 390                          */
 391                         restart = 0;
 392
 393                 if (ksig.sig <= 0)
 394                         break;
 395
 396                 if (unlikely(restart)) {
 397                         switch (errno) {
 398                               case ERESTART_RESTARTBLOCK:
 399                               case ERESTARTNOHAND:
 400                                 scr->pt.r8 = EINTR;
 401                                 /* note: scr->pt.r10 is already -1 */
 402                                 break;
 403
 404                               case ERESTARTSYS:
 405                                 if ((ksig.ka.sa.sa_flags & SA_RESTART) == 0) {
 406                                         scr->pt.r8 = EINTR;
 407                                         /* note: scr->pt.r10 is already -1 */
 408                                         break;
 409                                 }
 410                               case ERESTARTNOINTR:
 411                                 ia64_decrement_ip(&scr->pt);
 412                                 restart = 0; /* don't restart twice if handle_signal() fails... */
 413                         }
 414                 }
 415
 416                 /*
 417                  * Whee!  Actually deliver the signal.  If the delivery failed, we need to
 418                  * continue to iterate in this loop so we can deliver the SIGSEGV...
 419                  */
 420                 if (handle_signal(&ksig, scr))
 421                         return;
 422         }
 423
 424         /* Did we come from a system call? */
 425         if (restart) {
 426                 /* Restart the system call - no handlers present */
 427                 if (errno == ERESTARTNOHAND || errno == ERESTARTSYS || errno == ERESTARTNOINTR
 428                     || errno == ERESTART_RESTARTBLOCK)
 429                 {
 430                         /*
 431                          * Note: the syscall number is in r15 which is saved in
 432                          * pt_regs so all we need to do here is adjust ip so that
 433                          * the "break" instruction gets re-executed.
 434                          */
 435                         ia64_decrement_ip(&scr->pt);
 436                         if (errno == ERESTART_RESTARTBLOCK)
 437                                 scr->pt.r15 = __NR_restart_syscall;
 438                 }
 439         }
 440
 441         /* if there's no signal to deliver, we just put the saved sigmask
 442          * back */
 443         restore_saved_sigmask();
 444 }