arch/mips/kernel/signal.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1991, 1992  Linus Torvalds
   7  * Copyright (C) 1994 - 2000  Ralf Baechle
   8  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   9  * Copyright (C) 2014, Imagination Technologies Ltd.
  10  */
  11 #include <linux/cache.h>
  12 #include <linux/context_tracking.h>
  13 #include <linux/irqflags.h>
  14 #include <linux/sched.h>
  15 #include <linux/mm.h>
  16 #include <linux/personality.h>
  17 #include <linux/smp.h>
  18 #include <linux/kernel.h>
  19 #include <linux/signal.h>
  20 #include <linux/errno.h>
  21 #include <linux/wait.h>
  22 #include <linux/ptrace.h>
  23 #include <linux/unistd.h>
  24 #include <linux/uprobes.h>
  25 #include <linux/compiler.h>
  26 #include <linux/syscalls.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/tracehook.h>
  29
  30 #include <asm/abi.h>
  31 #include <asm/asm.h>
  32 #include <linux/bitops.h>
  33 #include <asm/cacheflush.h>
  34 #include <asm/fpu.h>
  35 #include <asm/sim.h>
  36 #include <asm/ucontext.h>
  37 #include <asm/cpu-features.h>
  38 #include <asm/war.h>
  39 #include <asm/dsp.h>
  40 #include <asm/inst.h>
  41 #include <asm/msa.h>
  42
  43 #include "signal-common.h"
  44
  45 static int (*save_fp_context)(void __user *sc);
  46 static int (*restore_fp_context)(void __user *sc);
  47
  48 struct sigframe {
  49         u32 sf_ass[4];          /* argument save space for o32 */
  50         u32 sf_pad[2];          /* Was: signal trampoline */
  51
  52         /* Matches struct ucontext from its uc_mcontext field onwards */
  53         struct sigcontext sf_sc;
  54         sigset_t sf_mask;
  55         unsigned long long sf_extcontext[0];
  56 };
  57
  58 struct rt_sigframe {
  59         u32 rs_ass[4];          /* argument save space for o32 */
  60         u32 rs_pad[2];          /* Was: signal trampoline */
  61         struct siginfo rs_info;
  62         struct ucontext rs_uc;
  63 };
  64
  65 /*
  66  * Thread saved context copy to/from a signal context presumed to be on the
  67  * user stack, and therefore accessed with appropriate macros from uaccess.h.
  68  */
  69 static int copy_fp_to_sigcontext(void __user *sc)
  70 {
  71         struct mips_abi *abi = current->thread.abi;
  72         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
  73         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
  74         int i;
  75         int err = 0;
  76         int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
  77
  78         for (i = 0; i < NUM_FPU_REGS; i += inc) {
  79                 err |=
  80                     __put_user(get_fpr64(&current->thread.fpu.fpr[i], 0),
  81                                &fpregs[i]);
  82         }
  83         err |= __put_user(current->thread.fpu.fcr31, csr);
  84
  85         return err;
  86 }
  87
  88 static int copy_fp_from_sigcontext(void __user *sc)
  89 {
  90         struct mips_abi *abi = current->thread.abi;
  91         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
  92         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
  93         int i;
  94         int err = 0;
  95         int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
  96         u64 fpr_val;
  97
  98         for (i = 0; i < NUM_FPU_REGS; i += inc) {
  99                 err |= __get_user(fpr_val, &fpregs[i]);
 100                 set_fpr64(&current->thread.fpu.fpr[i], 0, fpr_val);
 101         }
 102         err |= __get_user(current->thread.fpu.fcr31, csr);
 103
 104         return err;
 105 }
 106
 107 /*
 108  * Wrappers for the assembly _{save,restore}_fp_context functions.
 109  */
 110 static int save_hw_fp_context(void __user *sc)
 111 {
 112         struct mips_abi *abi = current->thread.abi;
 113         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
 114         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
 115
 116         return _save_fp_context(fpregs, csr);
 117 }
 118
 119 static int restore_hw_fp_context(void __user *sc)
 120 {
 121         struct mips_abi *abi = current->thread.abi;
 122         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
 123         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
 124
 125         return _restore_fp_context(fpregs, csr);
 126 }
 127
 128 /*
 129  * Extended context handling.
 130  */
 131
 132 static inline void __user *sc_to_extcontext(void __user *sc)
 133 {
 134         struct ucontext __user *uc;
 135
 136         /*
 137          * We can just pretend the sigcontext is always embedded in a struct
 138          * ucontext here, because the offset from sigcontext to extended
 139          * context is the same in the struct sigframe case.
 140          */
 141         uc = container_of(sc, struct ucontext, uc_mcontext);
 142         return &uc->uc_extcontext;
 143 }
 144
 145 static int save_msa_extcontext(void __user *buf)
 146 {
 147         struct msa_extcontext __user *msa = buf;
 148         uint64_t val;
 149         int i, err;
 150
 151         if (!thread_msa_context_live())
 152                 return 0;
 153
 154         /*
 155          * Ensure that we can't lose the live MSA context between checking
 156          * for it & writing it to memory.
 157          */
 158         preempt_disable();
 159
 160         if (is_msa_enabled()) {
 161                 /*
 162                  * There are no EVA versions of the vector register load/store
 163                  * instructions, so MSA context has to be saved to kernel memory
 164                  * and then copied to user memory. The save to kernel memory
 165                  * should already have been done when handling scalar FP
 166                  * context.
 167                  */
 168                 BUG_ON(IS_ENABLED(CONFIG_EVA));
 169
 170                 err = __put_user(read_msa_csr(), &msa->csr);
 171                 err |= _save_msa_all_upper(&msa->wr);
 172
 173                 preempt_enable();
 174         } else {
 175                 preempt_enable();
 176
 177                 err = __put_user(current->thread.fpu.msacsr, &msa->csr);
 178
 179                 for (i = 0; i < NUM_FPU_REGS; i++) {
 180                         val = get_fpr64(&current->thread.fpu.fpr[i], 1);
 181                         err |= __put_user(val, &msa->wr[i]);
 182                 }
 183         }
 184
 185         err |= __put_user(MSA_EXTCONTEXT_MAGIC, &msa->ext.magic);
 186         err |= __put_user(sizeof(*msa), &msa->ext.size);
 187
 188         return err ? -EFAULT : sizeof(*msa);
 189 }
 190
 191 static int restore_msa_extcontext(void __user *buf, unsigned int size)
 192 {
 193         struct msa_extcontext __user *msa = buf;
 194         unsigned long long val;
 195         unsigned int csr;
 196         int i, err;
 197
 198         if (!IS_ENABLED(CONFIG_CPU_HAS_MSA))
 199                 return SIGSYS;
 200
 201         if (size != sizeof(*msa))
 202                 return -EINVAL;
 203
 204         err = get_user(csr, &msa->csr);
 205         if (err)
 206                 return err;
 207
 208         preempt_disable();
 209
 210         if (is_msa_enabled()) {
 211                 /*
 212                  * There are no EVA versions of the vector register load/store
 213                  * instructions, so MSA context has to be copied to kernel
 214                  * memory and later loaded to registers. The same is true of
 215                  * scalar FP context, so FPU & MSA should have already been
 216                  * disabled whilst handling scalar FP context.
 217                  */
 218                 BUG_ON(IS_ENABLED(CONFIG_EVA));
 219
 220                 write_msa_csr(csr);
 221                 err |= _restore_msa_all_upper(&msa->wr);
 222                 preempt_enable();
 223         } else {
 224                 preempt_enable();
 225
 226                 current->thread.fpu.msacsr = csr;
 227
 228                 for (i = 0; i < NUM_FPU_REGS; i++) {
 229                         err |= __get_user(val, &msa->wr[i]);
 230                         set_fpr64(&current->thread.fpu.fpr[i], 1, val);
 231                 }
 232         }
 233
 234         return err;
 235 }
 236
 237 static int save_extcontext(void __user *buf)
 238 {
 239         int sz;
 240
 241         sz = save_msa_extcontext(buf);
 242         if (sz < 0)
 243                 return sz;
 244         buf += sz;
 245
 246         /* If no context was saved then trivially return */
 247         if (!sz)
 248                 return 0;
 249
 250         /* Write the end marker */
 251         if (__put_user(END_EXTCONTEXT_MAGIC, (u32 *)buf))
 252                 return -EFAULT;
 253
 254         sz += sizeof(((struct extcontext *)NULL)->magic);
 255         return sz;
 256 }
 257
 258 static int restore_extcontext(void __user *buf)
 259 {
 260         struct extcontext ext;
 261         int err;
 262
 263         while (1) {
 264                 err = __get_user(ext.magic, (unsigned int *)buf);
 265                 if (err)
 266                         return err;
 267
 268                 if (ext.magic == END_EXTCONTEXT_MAGIC)
 269                         return 0;
 270
 271                 err = __get_user(ext.size, (unsigned int *)(buf
 272                         + offsetof(struct extcontext, size)));
 273                 if (err)
 274                         return err;
 275
 276                 switch (ext.magic) {
 277                 case MSA_EXTCONTEXT_MAGIC:
 278                         err = restore_msa_extcontext(buf, ext.size);
 279                         break;
 280
 281                 default:
 282                         err = -EINVAL;
 283                         break;
 284                 }
 285
 286                 if (err)
 287                         return err;
 288
 289                 buf += ext.size;
 290         }
 291 }
 292
 293 /*
 294  * Helper routines
 295  */
 296 int protected_save_fp_context(void __user *sc)
 297 {
 298         struct mips_abi *abi = current->thread.abi;
 299         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
 300         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
 301         uint32_t __user *used_math = sc + abi->off_sc_used_math;
 302         unsigned int used, ext_sz;
 303         int err;
 304
 305         used = used_math() ? USED_FP : 0;
 306         if (!used)
 307                 goto fp_done;
 308
 309         if (!test_thread_flag(TIF_32BIT_FPREGS))
 310                 used |= USED_FR1;
 311         if (test_thread_flag(TIF_HYBRID_FPREGS))
 312                 used |= USED_HYBRID_FPRS;
 313
 314         /*
 315          * EVA does not have userland equivalents of ldc1 or sdc1, so
 316          * save to the kernel FP context & copy that to userland below.
 317          */
 318         if (IS_ENABLED(CONFIG_EVA))
 319                 lose_fpu(1);
 320
 321         while (1) {
 322                 lock_fpu_owner();
 323                 if (is_fpu_owner()) {
 324                         err = save_fp_context(sc);
 325                         unlock_fpu_owner();
 326                 } else {
 327                         unlock_fpu_owner();
 328                         err = copy_fp_to_sigcontext(sc);
 329                 }
 330                 if (likely(!err))
 331                         break;
 332                 /* touch the sigcontext and try again */
 333                 err = __put_user(0, &fpregs[0]) |
 334                         __put_user(0, &fpregs[31]) |
 335                         __put_user(0, csr);
 336                 if (err)
 337                         return err;     /* really bad sigcontext */
 338         }
 339
 340 fp_done:
 341         ext_sz = err = save_extcontext(sc_to_extcontext(sc));
 342         if (err < 0)
 343                 return err;
 344         used |= ext_sz ? USED_EXTCONTEXT : 0;
 345
 346         return __put_user(used, used_math);
 347 }
 348
 349 int protected_restore_fp_context(void __user *sc)
 350 {
 351         struct mips_abi *abi = current->thread.abi;
 352         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
 353         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
 354         uint32_t __user *used_math = sc + abi->off_sc_used_math;
 355         unsigned int used;
 356         int err, sig = 0, tmp __maybe_unused;
 357
 358         err = __get_user(used, used_math);
 359         conditional_used_math(used & USED_FP);
 360
 361         /*
 362          * The signal handler may have used FPU; give it up if the program
 363          * doesn't want it following sigreturn.
 364          */
 365         if (err || !(used & USED_FP))
 366                 lose_fpu(0);
 367         if (err)
 368                 return err;
 369         if (!(used & USED_FP))
 370                 goto fp_done;
 371
 372         err = sig = fpcsr_pending(csr);
 373         if (err < 0)
 374                 return err;
 375
 376         /*
 377          * EVA does not have userland equivalents of ldc1 or sdc1, so we
 378          * disable the FPU here such that the code below simply copies to
 379          * the kernel FP context.
 380          */
 381         if (IS_ENABLED(CONFIG_EVA))
 382                 lose_fpu(0);
 383
 384         while (1) {
 385                 lock_fpu_owner();
 386                 if (is_fpu_owner()) {
 387                         err = restore_fp_context(sc);
 388                         unlock_fpu_owner();
 389                 } else {
 390                         unlock_fpu_owner();
 391                         err = copy_fp_from_sigcontext(sc);
 392                 }
 393                 if (likely(!err))
 394                         break;
 395                 /* touch the sigcontext and try again */
 396                 err = __get_user(tmp, &fpregs[0]) |
 397                         __get_user(tmp, &fpregs[31]) |
 398                         __get_user(tmp, csr);
 399                 if (err)
 400                         break;  /* really bad sigcontext */
 401         }
 402
 403 fp_done:
 404         if (!err && (used & USED_EXTCONTEXT))
 405                 err = restore_extcontext(sc_to_extcontext(sc));
 406
 407         return err ?: sig;
 408 }
 409
 410 int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 411 {
 412         int err = 0;
 413         int i;
 414
 415         err |= __put_user(regs->cp0_epc, &sc->sc_pc);
 416
 417         err |= __put_user(0, &sc->sc_regs[0]);
 418         for (i = 1; i < 32; i++)
 419                 err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
 420
 421 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 422         err |= __put_user(regs->acx, &sc->sc_acx);
 423 #endif
 424         err |= __put_user(regs->hi, &sc->sc_mdhi);
 425         err |= __put_user(regs->lo, &sc->sc_mdlo);
 426         if (cpu_has_dsp) {
 427                 err |= __put_user(mfhi1(), &sc->sc_hi1);
 428                 err |= __put_user(mflo1(), &sc->sc_lo1);
 429                 err |= __put_user(mfhi2(), &sc->sc_hi2);
 430                 err |= __put_user(mflo2(), &sc->sc_lo2);
 431                 err |= __put_user(mfhi3(), &sc->sc_hi3);
 432                 err |= __put_user(mflo3(), &sc->sc_lo3);
 433                 err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
 434         }
 435
 436
 437         /*
 438          * Save FPU state to signal context. Signal handler
 439          * will "inherit" current FPU state.
 440          */
 441         err |= protected_save_fp_context(sc);
 442
 443         return err;
 444 }
 445
 446 static size_t extcontext_max_size(void)
 447 {
 448         size_t sz = 0;
 449
 450         /*
 451          * The assumption here is that between this point & the point at which
 452          * the extended context is saved the size of the context should only
 453          * ever be able to shrink (if the task is preempted), but never grow.
 454          * That is, what this function returns is an upper bound on the size of
 455          * the extended context for the current task at the current time.
 456          */
 457
 458         if (thread_msa_context_live())
 459                 sz += sizeof(struct msa_extcontext);
 460
 461         /* If any context is saved then we'll append the end marker */
 462         if (sz)
 463                 sz += sizeof(((struct extcontext *)NULL)->magic);
 464
 465         return sz;
 466 }
 467
 468 int fpcsr_pending(unsigned int __user *fpcsr)
 469 {
 470         int err, sig = 0;
 471         unsigned int csr, enabled;
 472
 473         err = __get_user(csr, fpcsr);
 474         enabled = FPU_CSR_UNI_X | ((csr & FPU_CSR_ALL_E) << 5);
 475         /*
 476          * If the signal handler set some FPU exceptions, clear it and
 477          * send SIGFPE.
 478          */
 479         if (csr & enabled) {
 480                 csr &= ~enabled;
 481                 err |= __put_user(csr, fpcsr);
 482                 sig = SIGFPE;
 483         }
 484         return err ?: sig;
 485 }
 486
 487 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 488 {
 489         unsigned long treg;
 490         int err = 0;
 491         int i;
 492
 493         /* Always make any pending restarted system calls return -EINTR */
 494         current->restart_block.fn = do_no_restart_syscall;
 495
 496         err |= __get_user(regs->cp0_epc, &sc->sc_pc);
 497
 498 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 499         err |= __get_user(regs->acx, &sc->sc_acx);
 500 #endif
 501         err |= __get_user(regs->hi, &sc->sc_mdhi);
 502         err |= __get_user(regs->lo, &sc->sc_mdlo);
 503         if (cpu_has_dsp) {
 504                 err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
 505                 err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
 506                 err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
 507                 err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
 508                 err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
 509                 err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
 510                 err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
 511         }
 512
 513         for (i = 1; i < 32; i++)
 514                 err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
 515
 516         return err ?: protected_restore_fp_context(sc);
 517 }
 518
 519 void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
 520                           size_t frame_size)
 521 {
 522         unsigned long sp;
 523
 524         /* Leave space for potential extended context */
 525         frame_size += extcontext_max_size();
 526
 527         /* Default to using normal stack */
 528         sp = regs->regs[29];
 529
 530         /*
 531          * FPU emulator may have it's own trampoline active just
 532          * above the user stack, 16-bytes before the next lowest
 533          * 16 byte boundary.  Try to avoid trashing it.
 534          */
 535         sp -= 32;
 536
 537         sp = sigsp(sp, ksig);
 538
 539         return (void __user *)((sp - frame_size) & (ICACHE_REFILLS_WORKAROUND_WAR ? ~(cpu_icache_line_size()-1) : ALMASK));
 540 }
 541
 542 /*
 543  * Atomically swap in the new signal mask, and wait for a signal.
 544  */
 545
 546 #ifdef CONFIG_TRAD_SIGNALS
 547 SYSCALL_DEFINE1(sigsuspend, sigset_t __user *, uset)
 548 {
 549         return sys_rt_sigsuspend(uset, sizeof(sigset_t));
 550 }
 551 #endif
 552
 553 #ifdef CONFIG_TRAD_SIGNALS
 554 SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
 555         struct sigaction __user *, oact)
 556 {
 557         struct k_sigaction new_ka, old_ka;
 558         int ret;
 559         int err = 0;
 560
 561         if (act) {
 562                 old_sigset_t mask;
 563
 564                 if (!access_ok(VERIFY_READ, act, sizeof(*act)))
 565                         return -EFAULT;
 566                 err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
 567                 err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 568                 err |= __get_user(mask, &act->sa_mask.sig[0]);
 569                 if (err)
 570                         return -EFAULT;
 571
 572                 siginitset(&new_ka.sa.sa_mask, mask);
 573         }
 574
 575         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 576
 577         if (!ret && oact) {
 578                 if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)))
 579                         return -EFAULT;
 580                 err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 581                 err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
 582                 err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
 583                 err |= __put_user(0, &oact->sa_mask.sig[1]);
 584                 err |= __put_user(0, &oact->sa_mask.sig[2]);
 585                 err |= __put_user(0, &oact->sa_mask.sig[3]);
 586                 if (err)
 587                         return -EFAULT;
 588         }
 589
 590         return ret;
 591 }
 592 #endif
 593
 594 #ifdef CONFIG_TRAD_SIGNALS
 595 asmlinkage void sys_sigreturn(nabi_no_regargs struct pt_regs regs)
 596 {
 597         struct sigframe __user *frame;
 598         sigset_t blocked;
 599         int sig;
 600
 601         frame = (struct sigframe __user *) regs.regs[29];
 602         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 603                 goto badframe;
 604         if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
 605                 goto badframe;
 606
 607         set_current_blocked(&blocked);
 608
 609         sig = restore_sigcontext(&regs, &frame->sf_sc);
 610         if (sig < 0)
 611                 goto badframe;
 612         else if (sig)
 613                 force_sig(sig, current);
 614
 615         /*
 616          * Don't let your children do this ...
 617          */
 618         __asm__ __volatile__(
 619                 "move\t$29, %0\n\t"
 620                 "j\tsyscall_exit"
 621                 :/* no outputs */
 622                 :"r" (&regs));
 623         /* Unreached */
 624
 625 badframe:
 626         force_sig(SIGSEGV, current);
 627 }
 628 #endif /* CONFIG_TRAD_SIGNALS */
 629
 630 asmlinkage void sys_rt_sigreturn(nabi_no_regargs struct pt_regs regs)
 631 {
 632         struct rt_sigframe __user *frame;
 633         sigset_t set;
 634         int sig;
 635
 636         frame = (struct rt_sigframe __user *) regs.regs[29];
 637         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 638                 goto badframe;
 639         if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
 640                 goto badframe;
 641
 642         set_current_blocked(&set);
 643
 644         sig = restore_sigcontext(&regs, &frame->rs_uc.uc_mcontext);
 645         if (sig < 0)
 646                 goto badframe;
 647         else if (sig)
 648                 force_sig(sig, current);
 649
 650         if (restore_altstack(&frame->rs_uc.uc_stack))
 651                 goto badframe;
 652
 653         /*
 654          * Don't let your children do this ...
 655          */
 656         __asm__ __volatile__(
 657                 "move\t$29, %0\n\t"
 658                 "j\tsyscall_exit"
 659                 :/* no outputs */
 660                 :"r" (&regs));
 661         /* Unreached */
 662
 663 badframe:
 664         force_sig(SIGSEGV, current);
 665 }
 666
 667 #ifdef CONFIG_TRAD_SIGNALS
 668 static int setup_frame(void *sig_return, struct ksignal *ksig,
 669                        struct pt_regs *regs, sigset_t *set)
 670 {
 671         struct sigframe __user *frame;
 672         int err = 0;
 673
 674         frame = get_sigframe(ksig, regs, sizeof(*frame));
 675         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 676                 return -EFAULT;
 677
 678         err |= setup_sigcontext(regs, &frame->sf_sc);
 679         err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
 680         if (err)
 681                 return -EFAULT;
 682
 683         /*
 684          * Arguments to signal handler:
 685          *
 686          *   a0 = signal number
 687          *   a1 = 0 (should be cause)
 688          *   a2 = pointer to struct sigcontext
 689          *
 690          * $25 and c0_epc point to the signal handler, $29 points to the
 691          * struct sigframe.
 692          */
 693         regs->regs[ 4] = ksig->sig;
 694         regs->regs[ 5] = 0;
 695         regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 696         regs->regs[29] = (unsigned long) frame;
 697         regs->regs[31] = (unsigned long) sig_return;
 698         regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;
 699
 700         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 701                current->comm, current->pid,
 702                frame, regs->cp0_epc, regs->regs[31]);
 703         return 0;
 704 }
 705 #endif
 706
 707 static int setup_rt_frame(void *sig_return, struct ksignal *ksig,
 708                           struct pt_regs *regs, sigset_t *set)
 709 {
 710         struct rt_sigframe __user *frame;
 711         int err = 0;
 712
 713         frame = get_sigframe(ksig, regs, sizeof(*frame));
 714         if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
 715                 return -EFAULT;
 716
 717         /* Create siginfo.  */
 718         err |= copy_siginfo_to_user(&frame->rs_info, &ksig->info);
 719
 720         /* Create the ucontext.  */
 721         err |= __put_user(0, &frame->rs_uc.uc_flags);
 722         err |= __put_user(NULL, &frame->rs_uc.uc_link);
 723         err |= __save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
 724         err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
 725         err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
 726
 727         if (err)
 728                 return -EFAULT;
 729
 730         /*
 731          * Arguments to signal handler:
 732          *
 733          *   a0 = signal number
 734          *   a1 = 0 (should be cause)
 735          *   a2 = pointer to ucontext
 736          *
 737          * $25 and c0_epc point to the signal handler, $29 points to
 738          * the struct rt_sigframe.
 739          */
 740         regs->regs[ 4] = ksig->sig;
 741         regs->regs[ 5] = (unsigned long) &frame->rs_info;
 742         regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 743         regs->regs[29] = (unsigned long) frame;
 744         regs->regs[31] = (unsigned long) sig_return;
 745         regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;
 746
 747         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 748                current->comm, current->pid,
 749                frame, regs->cp0_epc, regs->regs[31]);
 750
 751         return 0;
 752 }
 753
 754 struct mips_abi mips_abi = {
 755 #ifdef CONFIG_TRAD_SIGNALS
 756         .setup_frame    = setup_frame,
 757 #endif
 758         .setup_rt_frame = setup_rt_frame,
 759         .restart        = __NR_restart_syscall,
 760
 761         .off_sc_fpregs = offsetof(struct sigcontext, sc_fpregs),
 762         .off_sc_fpc_csr = offsetof(struct sigcontext, sc_fpc_csr),
 763         .off_sc_used_math = offsetof(struct sigcontext, sc_used_math),
 764
 765         .vdso           = &vdso_image,
 766 };
 767
 768 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 769 {
 770         sigset_t *oldset = sigmask_to_save();
 771         int ret;
 772         struct mips_abi *abi = current->thread.abi;
 773         void *vdso = current->mm->context.vdso;
 774
 775         /*
 776          * If we were emulating a delay slot instruction, exit that frame such
 777          * that addresses in the sigframe are as expected for userland and we
 778          * don't have a problem if we reuse the thread's frame for an
 779          * instruction within the signal handler.
 780          */
 781         dsemul_thread_rollback(regs);
 782
 783         if (regs->regs[0]) {
 784                 switch(regs->regs[2]) {
 785                 case ERESTART_RESTARTBLOCK:
 786                 case ERESTARTNOHAND:
 787                         regs->regs[2] = EINTR;
 788                         break;
 789                 case ERESTARTSYS:
 790                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 791                                 regs->regs[2] = EINTR;
 792                                 break;
 793                         }
 794                 /* fallthrough */
 795                 case ERESTARTNOINTR:
 796                         regs->regs[7] = regs->regs[26];
 797                         regs->regs[2] = regs->regs[0];
 798                         regs->cp0_epc -= 4;
 799                 }
 800
 801                 regs->regs[0] = 0;              /* Don't deal with this again.  */
 802         }
 803
 804         if (sig_uses_siginfo(&ksig->ka, abi))
 805                 ret = abi->setup_rt_frame(vdso + abi->vdso->off_rt_sigreturn,
 806                                           ksig, regs, oldset);
 807         else
 808                 ret = abi->setup_frame(vdso + abi->vdso->off_sigreturn,
 809                                        ksig, regs, oldset);
 810
 811         signal_setup_done(ret, ksig, 0);
 812 }
 813
 814 static void do_signal(struct pt_regs *regs)
 815 {
 816         struct ksignal ksig;
 817
 818         if (get_signal(&ksig)) {
 819                 /* Whee!  Actually deliver the signal.  */
 820                 handle_signal(&ksig, regs);
 821                 return;
 822         }
 823
 824         if (regs->regs[0]) {
 825                 switch (regs->regs[2]) {
 826                 case ERESTARTNOHAND:
 827                 case ERESTARTSYS:
 828                 case ERESTARTNOINTR:
 829                         regs->regs[2] = regs->regs[0];
 830                         regs->regs[7] = regs->regs[26];
 831                         regs->cp0_epc -= 4;
 832                         break;
 833
 834                 case ERESTART_RESTARTBLOCK:
 835                         regs->regs[2] = current->thread.abi->restart;
 836                         regs->regs[7] = regs->regs[26];
 837                         regs->cp0_epc -= 4;
 838                         break;
 839                 }
 840                 regs->regs[0] = 0;      /* Don't deal with this again.  */
 841         }
 842
 843         /*
 844          * If there's no signal to deliver, we just put the saved sigmask
 845          * back
 846          */
 847         restore_saved_sigmask();
 848 }
 849
 850 /*
 851  * notification of userspace execution resumption
 852  * - triggered by the TIF_WORK_MASK flags
 853  */
 854 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 855         __u32 thread_info_flags)
 856 {
 857         local_irq_enable();
 858
 859         user_exit();
 860
 861         if (thread_info_flags & _TIF_UPROBE)
 862                 uprobe_notify_resume(regs);
 863
 864         /* deal with pending signal delivery */
 865         if (thread_info_flags & _TIF_SIGPENDING)
 866                 do_signal(regs);
 867
 868         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 869                 clear_thread_flag(TIF_NOTIFY_RESUME);
 870                 tracehook_notify_resume(regs);
 871         }
 872
 873         user_enter();
 874 }
 875
 876 #ifdef CONFIG_SMP
 877 static int smp_save_fp_context(void __user *sc)
 878 {
 879         return raw_cpu_has_fpu
 880                ? save_hw_fp_context(sc)
 881                : copy_fp_to_sigcontext(sc);
 882 }
 883
 884 static int smp_restore_fp_context(void __user *sc)
 885 {
 886         return raw_cpu_has_fpu
 887                ? restore_hw_fp_context(sc)
 888                : copy_fp_from_sigcontext(sc);
 889 }
 890 #endif
 891
 892 static int signal_setup(void)
 893 {
 894         /*
 895          * The offset from sigcontext to extended context should be the same
 896          * regardless of the type of signal, such that userland can always know
 897          * where to look if it wishes to find the extended context structures.
 898          */
 899         BUILD_BUG_ON((offsetof(struct sigframe, sf_extcontext) -
 900                       offsetof(struct sigframe, sf_sc)) !=
 901                      (offsetof(struct rt_sigframe, rs_uc.uc_extcontext) -
 902                       offsetof(struct rt_sigframe, rs_uc.uc_mcontext)));
 903
 904 #ifdef CONFIG_SMP
 905         /* For now just do the cpu_has_fpu check when the functions are invoked */
 906         save_fp_context = smp_save_fp_context;
 907         restore_fp_context = smp_restore_fp_context;
 908 #else
 909         if (cpu_has_fpu) {
 910                 save_fp_context = save_hw_fp_context;
 911                 restore_fp_context = restore_hw_fp_context;
 912         } else {
 913                 save_fp_context = copy_fp_to_sigcontext;
 914                 restore_fp_context = copy_fp_from_sigcontext;
 915         }
 916 #endif /* CONFIG_SMP */
 917
 918         return 0;
 919 }
 920
 921 arch_initcall(signal_setup);