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[];
  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 #ifdef CONFIG_MIPS_FP_SUPPORT
  66
  67 /*
  68  * Thread saved context copy to/from a signal context presumed to be on the
  69  * user stack, and therefore accessed with appropriate macros from uaccess.h.
  70  */
  71 static int copy_fp_to_sigcontext(void __user *sc)
  72 {
  73         struct mips_abi *abi = current->thread.abi;
  74         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
  75         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
  76         int i;
  77         int err = 0;
  78         int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
  79
  80         for (i = 0; i < NUM_FPU_REGS; i += inc) {
  81                 err |=
  82                     __put_user(get_fpr64(&current->thread.fpu.fpr[i], 0),
  83                                &fpregs[i]);
  84         }
  85         err |= __put_user(current->thread.fpu.fcr31, csr);
  86
  87         return err;
  88 }
  89
  90 static int copy_fp_from_sigcontext(void __user *sc)
  91 {
  92         struct mips_abi *abi = current->thread.abi;
  93         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
  94         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
  95         int i;
  96         int err = 0;
  97         int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
  98         u64 fpr_val;
  99
 100         for (i = 0; i < NUM_FPU_REGS; i += inc) {
 101                 err |= __get_user(fpr_val, &fpregs[i]);
 102                 set_fpr64(&current->thread.fpu.fpr[i], 0, fpr_val);
 103         }
 104         err |= __get_user(current->thread.fpu.fcr31, csr);
 105
 106         return err;
 107 }
 108
 109 #else /* !CONFIG_MIPS_FP_SUPPORT */
 110
 111 static int copy_fp_to_sigcontext(void __user *sc)
 112 {
 113         return 0;
 114 }
 115
 116 static int copy_fp_from_sigcontext(void __user *sc)
 117 {
 118         return 0;
 119 }
 120
 121 #endif /* !CONFIG_MIPS_FP_SUPPORT */
 122
 123 /*
 124  * Wrappers for the assembly _{save,restore}_fp_context functions.
 125  */
 126 static int save_hw_fp_context(void __user *sc)
 127 {
 128         struct mips_abi *abi = current->thread.abi;
 129         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
 130         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
 131
 132         return _save_fp_context(fpregs, csr);
 133 }
 134
 135 static int restore_hw_fp_context(void __user *sc)
 136 {
 137         struct mips_abi *abi = current->thread.abi;
 138         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
 139         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
 140
 141         return _restore_fp_context(fpregs, csr);
 142 }
 143
 144 /*
 145  * Extended context handling.
 146  */
 147
 148 static inline void __user *sc_to_extcontext(void __user *sc)
 149 {
 150         struct ucontext __user *uc;
 151
 152         /*
 153          * We can just pretend the sigcontext is always embedded in a struct
 154          * ucontext here, because the offset from sigcontext to extended
 155          * context is the same in the struct sigframe case.
 156          */
 157         uc = container_of(sc, struct ucontext, uc_mcontext);
 158         return &uc->uc_extcontext;
 159 }
 160
 161 #ifdef CONFIG_CPU_HAS_MSA
 162
 163 static int save_msa_extcontext(void __user *buf)
 164 {
 165         struct msa_extcontext __user *msa = buf;
 166         uint64_t val;
 167         int i, err;
 168
 169         if (!thread_msa_context_live())
 170                 return 0;
 171
 172         /*
 173          * Ensure that we can't lose the live MSA context between checking
 174          * for it & writing it to memory.
 175          */
 176         preempt_disable();
 177
 178         if (is_msa_enabled()) {
 179                 /*
 180                  * There are no EVA versions of the vector register load/store
 181                  * instructions, so MSA context has to be saved to kernel memory
 182                  * and then copied to user memory. The save to kernel memory
 183                  * should already have been done when handling scalar FP
 184                  * context.
 185                  */
 186                 BUG_ON(IS_ENABLED(CONFIG_EVA));
 187
 188                 err = __put_user(read_msa_csr(), &msa->csr);
 189                 err |= _save_msa_all_upper(&msa->wr);
 190
 191                 preempt_enable();
 192         } else {
 193                 preempt_enable();
 194
 195                 err = __put_user(current->thread.fpu.msacsr, &msa->csr);
 196
 197                 for (i = 0; i < NUM_FPU_REGS; i++) {
 198                         val = get_fpr64(&current->thread.fpu.fpr[i], 1);
 199                         err |= __put_user(val, &msa->wr[i]);
 200                 }
 201         }
 202
 203         err |= __put_user(MSA_EXTCONTEXT_MAGIC, &msa->ext.magic);
 204         err |= __put_user(sizeof(*msa), &msa->ext.size);
 205
 206         return err ? -EFAULT : sizeof(*msa);
 207 }
 208
 209 static int restore_msa_extcontext(void __user *buf, unsigned int size)
 210 {
 211         struct msa_extcontext __user *msa = buf;
 212         unsigned long long val;
 213         unsigned int csr;
 214         int i, err;
 215
 216         if (size != sizeof(*msa))
 217                 return -EINVAL;
 218
 219         err = get_user(csr, &msa->csr);
 220         if (err)
 221                 return err;
 222
 223         preempt_disable();
 224
 225         if (is_msa_enabled()) {
 226                 /*
 227                  * There are no EVA versions of the vector register load/store
 228                  * instructions, so MSA context has to be copied to kernel
 229                  * memory and later loaded to registers. The same is true of
 230                  * scalar FP context, so FPU & MSA should have already been
 231                  * disabled whilst handling scalar FP context.
 232                  */
 233                 BUG_ON(IS_ENABLED(CONFIG_EVA));
 234
 235                 write_msa_csr(csr);
 236                 err |= _restore_msa_all_upper(&msa->wr);
 237                 preempt_enable();
 238         } else {
 239                 preempt_enable();
 240
 241                 current->thread.fpu.msacsr = csr;
 242
 243                 for (i = 0; i < NUM_FPU_REGS; i++) {
 244                         err |= __get_user(val, &msa->wr[i]);
 245                         set_fpr64(&current->thread.fpu.fpr[i], 1, val);
 246                 }
 247         }
 248
 249         return err;
 250 }
 251
 252 #else /* !CONFIG_CPU_HAS_MSA */
 253
 254 static int save_msa_extcontext(void __user *buf)
 255 {
 256         return 0;
 257 }
 258
 259 static int restore_msa_extcontext(void __user *buf, unsigned int size)
 260 {
 261         return SIGSYS;
 262 }
 263
 264 #endif /* !CONFIG_CPU_HAS_MSA */
 265
 266 static int save_extcontext(void __user *buf)
 267 {
 268         int sz;
 269
 270         sz = save_msa_extcontext(buf);
 271         if (sz < 0)
 272                 return sz;
 273         buf += sz;
 274
 275         /* If no context was saved then trivially return */
 276         if (!sz)
 277                 return 0;
 278
 279         /* Write the end marker */
 280         if (__put_user(END_EXTCONTEXT_MAGIC, (u32 *)buf))
 281                 return -EFAULT;
 282
 283         sz += sizeof(((struct extcontext *)NULL)->magic);
 284         return sz;
 285 }
 286
 287 static int restore_extcontext(void __user *buf)
 288 {
 289         struct extcontext ext;
 290         int err;
 291
 292         while (1) {
 293                 err = __get_user(ext.magic, (unsigned int *)buf);
 294                 if (err)
 295                         return err;
 296
 297                 if (ext.magic == END_EXTCONTEXT_MAGIC)
 298                         return 0;
 299
 300                 err = __get_user(ext.size, (unsigned int *)(buf
 301                         + offsetof(struct extcontext, size)));
 302                 if (err)
 303                         return err;
 304
 305                 switch (ext.magic) {
 306                 case MSA_EXTCONTEXT_MAGIC:
 307                         err = restore_msa_extcontext(buf, ext.size);
 308                         break;
 309
 310                 default:
 311                         err = -EINVAL;
 312                         break;
 313                 }
 314
 315                 if (err)
 316                         return err;
 317
 318                 buf += ext.size;
 319         }
 320 }
 321
 322 /*
 323  * Helper routines
 324  */
 325 int protected_save_fp_context(void __user *sc)
 326 {
 327         struct mips_abi *abi = current->thread.abi;
 328         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
 329         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
 330         uint32_t __user *used_math = sc + abi->off_sc_used_math;
 331         unsigned int used, ext_sz;
 332         int err;
 333
 334         used = used_math() ? USED_FP : 0;
 335         if (!used)
 336                 goto fp_done;
 337
 338         if (!test_thread_flag(TIF_32BIT_FPREGS))
 339                 used |= USED_FR1;
 340         if (test_thread_flag(TIF_HYBRID_FPREGS))
 341                 used |= USED_HYBRID_FPRS;
 342
 343         /*
 344          * EVA does not have userland equivalents of ldc1 or sdc1, so
 345          * save to the kernel FP context & copy that to userland below.
 346          */
 347         if (IS_ENABLED(CONFIG_EVA))
 348                 lose_fpu(1);
 349
 350         while (1) {
 351                 lock_fpu_owner();
 352                 if (is_fpu_owner()) {
 353                         err = save_fp_context(sc);
 354                         unlock_fpu_owner();
 355                 } else {
 356                         unlock_fpu_owner();
 357                         err = copy_fp_to_sigcontext(sc);
 358                 }
 359                 if (likely(!err))
 360                         break;
 361                 /* touch the sigcontext and try again */
 362                 err = __put_user(0, &fpregs[0]) |
 363                         __put_user(0, &fpregs[31]) |
 364                         __put_user(0, csr);
 365                 if (err)
 366                         return err;     /* really bad sigcontext */
 367         }
 368
 369 fp_done:
 370         ext_sz = err = save_extcontext(sc_to_extcontext(sc));
 371         if (err < 0)
 372                 return err;
 373         used |= ext_sz ? USED_EXTCONTEXT : 0;
 374
 375         return __put_user(used, used_math);
 376 }
 377
 378 int protected_restore_fp_context(void __user *sc)
 379 {
 380         struct mips_abi *abi = current->thread.abi;
 381         uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
 382         uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
 383         uint32_t __user *used_math = sc + abi->off_sc_used_math;
 384         unsigned int used;
 385         int err, sig = 0, tmp __maybe_unused;
 386
 387         err = __get_user(used, used_math);
 388         conditional_used_math(used & USED_FP);
 389
 390         /*
 391          * The signal handler may have used FPU; give it up if the program
 392          * doesn't want it following sigreturn.
 393          */
 394         if (err || !(used & USED_FP))
 395                 lose_fpu(0);
 396         if (err)
 397                 return err;
 398         if (!(used & USED_FP))
 399                 goto fp_done;
 400
 401         err = sig = fpcsr_pending(csr);
 402         if (err < 0)
 403                 return err;
 404
 405         /*
 406          * EVA does not have userland equivalents of ldc1 or sdc1, so we
 407          * disable the FPU here such that the code below simply copies to
 408          * the kernel FP context.
 409          */
 410         if (IS_ENABLED(CONFIG_EVA))
 411                 lose_fpu(0);
 412
 413         while (1) {
 414                 lock_fpu_owner();
 415                 if (is_fpu_owner()) {
 416                         err = restore_fp_context(sc);
 417                         unlock_fpu_owner();
 418                 } else {
 419                         unlock_fpu_owner();
 420                         err = copy_fp_from_sigcontext(sc);
 421                 }
 422                 if (likely(!err))
 423                         break;
 424                 /* touch the sigcontext and try again */
 425                 err = __get_user(tmp, &fpregs[0]) |
 426                         __get_user(tmp, &fpregs[31]) |
 427                         __get_user(tmp, csr);
 428                 if (err)
 429                         break;  /* really bad sigcontext */
 430         }
 431
 432 fp_done:
 433         if (!err && (used & USED_EXTCONTEXT))
 434                 err = restore_extcontext(sc_to_extcontext(sc));
 435
 436         return err ?: sig;
 437 }
 438
 439 int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 440 {
 441         int err = 0;
 442         int i;
 443
 444         err |= __put_user(regs->cp0_epc, &sc->sc_pc);
 445
 446         err |= __put_user(0, &sc->sc_regs[0]);
 447         for (i = 1; i < 32; i++)
 448                 err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
 449
 450 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 451         err |= __put_user(regs->acx, &sc->sc_acx);
 452 #endif
 453         err |= __put_user(regs->hi, &sc->sc_mdhi);
 454         err |= __put_user(regs->lo, &sc->sc_mdlo);
 455         if (cpu_has_dsp) {
 456                 err |= __put_user(mfhi1(), &sc->sc_hi1);
 457                 err |= __put_user(mflo1(), &sc->sc_lo1);
 458                 err |= __put_user(mfhi2(), &sc->sc_hi2);
 459                 err |= __put_user(mflo2(), &sc->sc_lo2);
 460                 err |= __put_user(mfhi3(), &sc->sc_hi3);
 461                 err |= __put_user(mflo3(), &sc->sc_lo3);
 462                 err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
 463         }
 464
 465
 466         /*
 467          * Save FPU state to signal context. Signal handler
 468          * will "inherit" current FPU state.
 469          */
 470         err |= protected_save_fp_context(sc);
 471
 472         return err;
 473 }
 474
 475 static size_t extcontext_max_size(void)
 476 {
 477         size_t sz = 0;
 478
 479         /*
 480          * The assumption here is that between this point & the point at which
 481          * the extended context is saved the size of the context should only
 482          * ever be able to shrink (if the task is preempted), but never grow.
 483          * That is, what this function returns is an upper bound on the size of
 484          * the extended context for the current task at the current time.
 485          */
 486
 487         if (thread_msa_context_live())
 488                 sz += sizeof(struct msa_extcontext);
 489
 490         /* If any context is saved then we'll append the end marker */
 491         if (sz)
 492                 sz += sizeof(((struct extcontext *)NULL)->magic);
 493
 494         return sz;
 495 }
 496
 497 int fpcsr_pending(unsigned int __user *fpcsr)
 498 {
 499         int err, sig = 0;
 500         unsigned int csr, enabled;
 501
 502         err = __get_user(csr, fpcsr);
 503         enabled = FPU_CSR_UNI_X | ((csr & FPU_CSR_ALL_E) << 5);
 504         /*
 505          * If the signal handler set some FPU exceptions, clear it and
 506          * send SIGFPE.
 507          */
 508         if (csr & enabled) {
 509                 csr &= ~enabled;
 510                 err |= __put_user(csr, fpcsr);
 511                 sig = SIGFPE;
 512         }
 513         return err ?: sig;
 514 }
 515
 516 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
 517 {
 518         unsigned long treg;
 519         int err = 0;
 520         int i;
 521
 522         /* Always make any pending restarted system calls return -EINTR */
 523         current->restart_block.fn = do_no_restart_syscall;
 524
 525         err |= __get_user(regs->cp0_epc, &sc->sc_pc);
 526
 527 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 528         err |= __get_user(regs->acx, &sc->sc_acx);
 529 #endif
 530         err |= __get_user(regs->hi, &sc->sc_mdhi);
 531         err |= __get_user(regs->lo, &sc->sc_mdlo);
 532         if (cpu_has_dsp) {
 533                 err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
 534                 err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
 535                 err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
 536                 err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
 537                 err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
 538                 err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
 539                 err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
 540         }
 541
 542         for (i = 1; i < 32; i++)
 543                 err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
 544
 545         return err ?: protected_restore_fp_context(sc);
 546 }
 547
 548 #ifdef CONFIG_WAR_ICACHE_REFILLS
 549 #define SIGMASK         ~(cpu_icache_line_size()-1)
 550 #else
 551 #define SIGMASK         ALMASK
 552 #endif
 553
 554 void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
 555                           size_t frame_size)
 556 {
 557         unsigned long sp;
 558
 559         /* Leave space for potential extended context */
 560         frame_size += extcontext_max_size();
 561
 562         /* Default to using normal stack */
 563         sp = regs->regs[29];
 564
 565         /*
 566          * FPU emulator may have it's own trampoline active just
 567          * above the user stack, 16-bytes before the next lowest
 568          * 16 byte boundary.  Try to avoid trashing it.
 569          */
 570         sp -= 32;
 571
 572         sp = sigsp(sp, ksig);
 573
 574         return (void __user *)((sp - frame_size) & SIGMASK);
 575 }
 576
 577 /*
 578  * Atomically swap in the new signal mask, and wait for a signal.
 579  */
 580
 581 #ifdef CONFIG_TRAD_SIGNALS
 582 SYSCALL_DEFINE1(sigsuspend, sigset_t __user *, uset)
 583 {
 584         return sys_rt_sigsuspend(uset, sizeof(sigset_t));
 585 }
 586 #endif
 587
 588 #ifdef CONFIG_TRAD_SIGNALS
 589 SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
 590         struct sigaction __user *, oact)
 591 {
 592         struct k_sigaction new_ka, old_ka;
 593         int ret;
 594         int err = 0;
 595
 596         if (act) {
 597                 old_sigset_t mask;
 598
 599                 if (!access_ok(act, sizeof(*act)))
 600                         return -EFAULT;
 601                 err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
 602                 err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
 603                 err |= __get_user(mask, &act->sa_mask.sig[0]);
 604                 if (err)
 605                         return -EFAULT;
 606
 607                 siginitset(&new_ka.sa.sa_mask, mask);
 608         }
 609
 610         ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
 611
 612         if (!ret && oact) {
 613                 if (!access_ok(oact, sizeof(*oact)))
 614                         return -EFAULT;
 615                 err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
 616                 err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
 617                 err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
 618                 err |= __put_user(0, &oact->sa_mask.sig[1]);
 619                 err |= __put_user(0, &oact->sa_mask.sig[2]);
 620                 err |= __put_user(0, &oact->sa_mask.sig[3]);
 621                 if (err)
 622                         return -EFAULT;
 623         }
 624
 625         return ret;
 626 }
 627 #endif
 628
 629 #ifdef CONFIG_TRAD_SIGNALS
 630 asmlinkage void sys_sigreturn(void)
 631 {
 632         struct sigframe __user *frame;
 633         struct pt_regs *regs;
 634         sigset_t blocked;
 635         int sig;
 636
 637         regs = current_pt_regs();
 638         frame = (struct sigframe __user *)regs->regs[29];
 639         if (!access_ok(frame, sizeof(*frame)))
 640                 goto badframe;
 641         if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
 642                 goto badframe;
 643
 644         set_current_blocked(&blocked);
 645
 646         sig = restore_sigcontext(regs, &frame->sf_sc);
 647         if (sig < 0)
 648                 goto badframe;
 649         else if (sig)
 650                 force_sig(sig);
 651
 652         /*
 653          * Don't let your children do this ...
 654          */
 655         __asm__ __volatile__(
 656                 "move\t$29, %0\n\t"
 657                 "j\tsyscall_exit"
 658                 : /* no outputs */
 659                 : "r" (regs));
 660         /* Unreached */
 661
 662 badframe:
 663         force_sig(SIGSEGV);
 664 }
 665 #endif /* CONFIG_TRAD_SIGNALS */
 666
 667 asmlinkage void sys_rt_sigreturn(void)
 668 {
 669         struct rt_sigframe __user *frame;
 670         struct pt_regs *regs;
 671         sigset_t set;
 672         int sig;
 673
 674         regs = current_pt_regs();
 675         frame = (struct rt_sigframe __user *)regs->regs[29];
 676         if (!access_ok(frame, sizeof(*frame)))
 677                 goto badframe;
 678         if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
 679                 goto badframe;
 680
 681         set_current_blocked(&set);
 682
 683         sig = restore_sigcontext(regs, &frame->rs_uc.uc_mcontext);
 684         if (sig < 0)
 685                 goto badframe;
 686         else if (sig)
 687                 force_sig(sig);
 688
 689         if (restore_altstack(&frame->rs_uc.uc_stack))
 690                 goto badframe;
 691
 692         /*
 693          * Don't let your children do this ...
 694          */
 695         __asm__ __volatile__(
 696                 "move\t$29, %0\n\t"
 697                 "j\tsyscall_exit"
 698                 : /* no outputs */
 699                 : "r" (regs));
 700         /* Unreached */
 701
 702 badframe:
 703         force_sig(SIGSEGV);
 704 }
 705
 706 #ifdef CONFIG_TRAD_SIGNALS
 707 static int setup_frame(void *sig_return, struct ksignal *ksig,
 708                        struct pt_regs *regs, sigset_t *set)
 709 {
 710         struct sigframe __user *frame;
 711         int err = 0;
 712
 713         frame = get_sigframe(ksig, regs, sizeof(*frame));
 714         if (!access_ok(frame, sizeof (*frame)))
 715                 return -EFAULT;
 716
 717         err |= setup_sigcontext(regs, &frame->sf_sc);
 718         err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
 719         if (err)
 720                 return -EFAULT;
 721
 722         /*
 723          * Arguments to signal handler:
 724          *
 725          *   a0 = signal number
 726          *   a1 = 0 (should be cause)
 727          *   a2 = pointer to struct sigcontext
 728          *
 729          * $25 and c0_epc point to the signal handler, $29 points to the
 730          * struct sigframe.
 731          */
 732         regs->regs[ 4] = ksig->sig;
 733         regs->regs[ 5] = 0;
 734         regs->regs[ 6] = (unsigned long) &frame->sf_sc;
 735         regs->regs[29] = (unsigned long) frame;
 736         regs->regs[31] = (unsigned long) sig_return;
 737         regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;
 738
 739         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 740                current->comm, current->pid,
 741                frame, regs->cp0_epc, regs->regs[31]);
 742         return 0;
 743 }
 744 #endif
 745
 746 static int setup_rt_frame(void *sig_return, struct ksignal *ksig,
 747                           struct pt_regs *regs, sigset_t *set)
 748 {
 749         struct rt_sigframe __user *frame;
 750         int err = 0;
 751
 752         frame = get_sigframe(ksig, regs, sizeof(*frame));
 753         if (!access_ok(frame, sizeof (*frame)))
 754                 return -EFAULT;
 755
 756         /* Create siginfo.  */
 757         err |= copy_siginfo_to_user(&frame->rs_info, &ksig->info);
 758
 759         /* Create the ucontext.  */
 760         err |= __put_user(0, &frame->rs_uc.uc_flags);
 761         err |= __put_user(NULL, &frame->rs_uc.uc_link);
 762         err |= __save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]);
 763         err |= setup_sigcontext(regs, &frame->rs_uc.uc_mcontext);
 764         err |= __copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set));
 765
 766         if (err)
 767                 return -EFAULT;
 768
 769         /*
 770          * Arguments to signal handler:
 771          *
 772          *   a0 = signal number
 773          *   a1 = 0 (should be cause)
 774          *   a2 = pointer to ucontext
 775          *
 776          * $25 and c0_epc point to the signal handler, $29 points to
 777          * the struct rt_sigframe.
 778          */
 779         regs->regs[ 4] = ksig->sig;
 780         regs->regs[ 5] = (unsigned long) &frame->rs_info;
 781         regs->regs[ 6] = (unsigned long) &frame->rs_uc;
 782         regs->regs[29] = (unsigned long) frame;
 783         regs->regs[31] = (unsigned long) sig_return;
 784         regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;
 785
 786         DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
 787                current->comm, current->pid,
 788                frame, regs->cp0_epc, regs->regs[31]);
 789
 790         return 0;
 791 }
 792
 793 struct mips_abi mips_abi = {
 794 #ifdef CONFIG_TRAD_SIGNALS
 795         .setup_frame    = setup_frame,
 796 #endif
 797         .setup_rt_frame = setup_rt_frame,
 798         .restart        = __NR_restart_syscall,
 799
 800         .off_sc_fpregs = offsetof(struct sigcontext, sc_fpregs),
 801         .off_sc_fpc_csr = offsetof(struct sigcontext, sc_fpc_csr),
 802         .off_sc_used_math = offsetof(struct sigcontext, sc_used_math),
 803
 804         .vdso           = &vdso_image,
 805 };
 806
 807 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 808 {
 809         sigset_t *oldset = sigmask_to_save();
 810         int ret;
 811         struct mips_abi *abi = current->thread.abi;
 812         void *vdso = current->mm->context.vdso;
 813
 814         /*
 815          * If we were emulating a delay slot instruction, exit that frame such
 816          * that addresses in the sigframe are as expected for userland and we
 817          * don't have a problem if we reuse the thread's frame for an
 818          * instruction within the signal handler.
 819          */
 820         dsemul_thread_rollback(regs);
 821
 822         if (regs->regs[0]) {
 823                 switch(regs->regs[2]) {
 824                 case ERESTART_RESTARTBLOCK:
 825                 case ERESTARTNOHAND:
 826                         regs->regs[2] = EINTR;
 827                         break;
 828                 case ERESTARTSYS:
 829                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 830                                 regs->regs[2] = EINTR;
 831                                 break;
 832                         }
 833                         fallthrough;
 834                 case ERESTARTNOINTR:
 835                         regs->regs[7] = regs->regs[26];
 836                         regs->regs[2] = regs->regs[0];
 837                         regs->cp0_epc -= 4;
 838                 }
 839
 840                 regs->regs[0] = 0;              /* Don't deal with this again.  */
 841         }
 842
 843         rseq_signal_deliver(ksig, regs);
 844
 845         if (sig_uses_siginfo(&ksig->ka, abi))
 846                 ret = abi->setup_rt_frame(vdso + abi->vdso->off_rt_sigreturn,
 847                                           ksig, regs, oldset);
 848         else
 849                 ret = abi->setup_frame(vdso + abi->vdso->off_sigreturn,
 850                                        ksig, regs, oldset);
 851
 852         signal_setup_done(ret, ksig, 0);
 853 }
 854
 855 static void do_signal(struct pt_regs *regs)
 856 {
 857         struct ksignal ksig;
 858
 859         if (get_signal(&ksig)) {
 860                 /* Whee!  Actually deliver the signal.  */
 861                 handle_signal(&ksig, regs);
 862                 return;
 863         }
 864
 865         if (regs->regs[0]) {
 866                 switch (regs->regs[2]) {
 867                 case ERESTARTNOHAND:
 868                 case ERESTARTSYS:
 869                 case ERESTARTNOINTR:
 870                         regs->regs[2] = regs->regs[0];
 871                         regs->regs[7] = regs->regs[26];
 872                         regs->cp0_epc -= 4;
 873                         break;
 874
 875                 case ERESTART_RESTARTBLOCK:
 876                         regs->regs[2] = current->thread.abi->restart;
 877                         regs->regs[7] = regs->regs[26];
 878                         regs->cp0_epc -= 4;
 879                         break;
 880                 }
 881                 regs->regs[0] = 0;      /* Don't deal with this again.  */
 882         }
 883
 884         /*
 885          * If there's no signal to deliver, we just put the saved sigmask
 886          * back
 887          */
 888         restore_saved_sigmask();
 889 }
 890
 891 /*
 892  * notification of userspace execution resumption
 893  * - triggered by the TIF_WORK_MASK flags
 894  */
 895 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 896         __u32 thread_info_flags)
 897 {
 898         local_irq_enable();
 899
 900         user_exit();
 901
 902         if (thread_info_flags & _TIF_UPROBE)
 903                 uprobe_notify_resume(regs);
 904
 905         /* deal with pending signal delivery */
 906         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
 907                 do_signal(regs);
 908
 909         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 910                 tracehook_notify_resume(regs);
 911                 rseq_handle_notify_resume(NULL, regs);
 912         }
 913
 914         user_enter();
 915 }
 916
 917 #if defined(CONFIG_SMP) && defined(CONFIG_MIPS_FP_SUPPORT)
 918 static int smp_save_fp_context(void __user *sc)
 919 {
 920         return raw_cpu_has_fpu
 921                ? save_hw_fp_context(sc)
 922                : copy_fp_to_sigcontext(sc);
 923 }
 924
 925 static int smp_restore_fp_context(void __user *sc)
 926 {
 927         return raw_cpu_has_fpu
 928                ? restore_hw_fp_context(sc)
 929                : copy_fp_from_sigcontext(sc);
 930 }
 931 #endif
 932
 933 static int signal_setup(void)
 934 {
 935         /*
 936          * The offset from sigcontext to extended context should be the same
 937          * regardless of the type of signal, such that userland can always know
 938          * where to look if it wishes to find the extended context structures.
 939          */
 940         BUILD_BUG_ON((offsetof(struct sigframe, sf_extcontext) -
 941                       offsetof(struct sigframe, sf_sc)) !=
 942                      (offsetof(struct rt_sigframe, rs_uc.uc_extcontext) -
 943                       offsetof(struct rt_sigframe, rs_uc.uc_mcontext)));
 944
 945 #if defined(CONFIG_SMP) && defined(CONFIG_MIPS_FP_SUPPORT)
 946         /* For now just do the cpu_has_fpu check when the functions are invoked */
 947         save_fp_context = smp_save_fp_context;
 948         restore_fp_context = smp_restore_fp_context;
 949 #else
 950         if (cpu_has_fpu) {
 951                 save_fp_context = save_hw_fp_context;
 952                 restore_fp_context = restore_hw_fp_context;
 953         } else {
 954                 save_fp_context = copy_fp_to_sigcontext;
 955                 restore_fp_context = copy_fp_from_sigcontext;
 956         }
 957 #endif /* CONFIG_SMP */
 958
 959         return 0;
 960 }
 961
 962 arch_initcall(signal_setup);