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         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  */
 165 static long
 166 setup_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  */
 220 static inline int
 221 rbs_on_sig_stack (unsigned long bsp)
 222 {
 223         return (bsp - current->sas_ss_sp < current->sas_ss_size);
 224 }
 225
 226 static long
 227 setup_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
 317 static long
 318 handle_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  */
 332 void
 333 ia64_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 }