release/src-rt-6.x/linux/linux-2.6/arch/powerpc/kernel/signal_64.c

   1 /*
   2  *  PowerPC version
   3  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   4  *
   5  *  Derived from "arch/i386/kernel/signal.c"
   6  *    Copyright (C) 1991, 1992 Linus Torvalds
   7  *    1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   8  *
   9  *  This program is free software; you can redistribute it and/or
  10  *  modify it under the terms of the GNU General Public License
  11  *  as published by the Free Software Foundation; either version
  12  *  2 of the License, or (at your option) any later version.
  13  */
  14
  15 #include <linux/sched.h>
  16 #include <linux/mm.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/unistd.h>
  23 #include <linux/stddef.h>
  24 #include <linux/elf.h>
  25 #include <linux/ptrace.h>
  26 #include <linux/module.h>
  27
  28 #include <asm/sigcontext.h>
  29 #include <asm/ucontext.h>
  30 #include <asm/uaccess.h>
  31 #include <asm/pgtable.h>
  32 #include <asm/unistd.h>
  33 #include <asm/cacheflush.h>
  34 #include <asm/syscalls.h>
  35 #include <asm/vdso.h>
  36
  37 #define DEBUG_SIG 0
  38
  39 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  40
  41 #define GP_REGS_SIZE    min(sizeof(elf_gregset_t), sizeof(struct pt_regs))
  42 #define FP_REGS_SIZE    sizeof(elf_fpregset_t)
  43
  44 #define TRAMP_TRACEBACK 3
  45 #define TRAMP_SIZE      6
  46
  47 /*
  48  * When we have signals to deliver, we set up on the user stack,
  49  * going down from the original stack pointer:
  50  *      1) a rt_sigframe struct which contains the ucontext
  51  *      2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller
  52  *         frame for the signal handler.
  53  */
  54
  55 struct rt_sigframe {
  56         /* sys_rt_sigreturn requires the ucontext be the first field */
  57         struct ucontext uc;
  58         unsigned long _unused[2];
  59         unsigned int tramp[TRAMP_SIZE];
  60         struct siginfo __user *pinfo;
  61         void __user *puc;
  62         struct siginfo info;
  63         /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */
  64         char abigap[288];
  65 } __attribute__ ((aligned (16)));
  66
  67 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, unsigned long r5,
  68                      unsigned long r6, unsigned long r7, unsigned long r8,
  69                      struct pt_regs *regs)
  70 {
  71         return do_sigaltstack(uss, uoss, regs->gpr[1]);
  72 }
  73
  74
  75 /*
  76  * Set up the sigcontext for the signal frame.
  77  */
  78
  79 static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
  80                  int signr, sigset_t *set, unsigned long handler)
  81 {
  82         /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
  83          * process never used altivec yet (MSR_VEC is zero in pt_regs of
  84          * the context). This is very important because we must ensure we
  85          * don't lose the VRSAVE content that may have been set prior to
  86          * the process doing its first vector operation
  87          * Userland shall check AT_HWCAP to know wether it can rely on the
  88          * v_regs pointer or not
  89          */
  90 #ifdef CONFIG_ALTIVEC
  91         elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful);
  92 #endif
  93         long err = 0;
  94
  95         flush_fp_to_thread(current);
  96
  97 #ifdef CONFIG_ALTIVEC
  98         err |= __put_user(v_regs, &sc->v_regs);
  99
 100         /* save altivec registers */
 101         if (current->thread.used_vr) {
 102                 flush_altivec_to_thread(current);
 103                 /* Copy 33 vec registers (vr0..31 and vscr) to the stack */
 104                 err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128));
 105                 /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg)
 106                  * contains valid data.
 107                  */
 108                 regs->msr |= MSR_VEC;
 109         }
 110         /* We always copy to/from vrsave, it's 0 if we don't have or don't
 111          * use altivec.
 112          */
 113         err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
 114 #else /* CONFIG_ALTIVEC */
 115         err |= __put_user(0, &sc->v_regs);
 116 #endif /* CONFIG_ALTIVEC */
 117         err |= __put_user(&sc->gp_regs, &sc->regs);
 118         WARN_ON(!FULL_REGS(regs));
 119         err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE);
 120         err |= __copy_to_user(&sc->fp_regs, &current->thread.fpr, FP_REGS_SIZE);
 121         err |= __put_user(signr, &sc->signal);
 122         err |= __put_user(handler, &sc->handler);
 123         if (set != NULL)
 124                 err |=  __put_user(set->sig[0], &sc->oldmask);
 125
 126         return err;
 127 }
 128
 129 /*
 130  * Restore the sigcontext from the signal frame.
 131  */
 132
 133 static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
 134                               struct sigcontext __user *sc)
 135 {
 136 #ifdef CONFIG_ALTIVEC
 137         elf_vrreg_t __user *v_regs;
 138 #endif
 139         unsigned long err = 0;
 140         unsigned long save_r13 = 0;
 141         elf_greg_t *gregs = (elf_greg_t *)regs;
 142         unsigned long msr;
 143         int i;
 144
 145         /* If this is not a signal return, we preserve the TLS in r13 */
 146         if (!sig)
 147                 save_r13 = regs->gpr[13];
 148
 149         /* copy everything before MSR */
 150         err |= __copy_from_user(regs, &sc->gp_regs,
 151                                 PT_MSR*sizeof(unsigned long));
 152
 153         /* get MSR separately, transfer the LE bit if doing signal return */
 154         err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
 155         if (sig)
 156                 regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE);
 157
 158         /* skip SOFTE */
 159         for (i = PT_MSR+1; i <= PT_RESULT; i++) {
 160                 if (i == PT_SOFTE)
 161                         continue;
 162                 err |= __get_user(gregs[i], &sc->gp_regs[i]);
 163         }
 164
 165         if (!sig)
 166                 regs->gpr[13] = save_r13;
 167         if (set != NULL)
 168                 err |=  __get_user(set->sig[0], &sc->oldmask);
 169
 170         /*
 171          * Do this before updating the thread state in
 172          * current->thread.fpr/vr.  That way, if we get preempted
 173          * and another task grabs the FPU/Altivec, it won't be
 174          * tempted to save the current CPU state into the thread_struct
 175          * and corrupt what we are writing there.
 176          */
 177         discard_lazy_cpu_state();
 178
 179         /*
 180          * Force reload of FP/VEC.
 181          * This has to be done before copying stuff into current->thread.fpr/vr
 182          * for the reasons explained in the previous comment.
 183          */
 184         regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC);
 185
 186         err |= __copy_from_user(&current->thread.fpr, &sc->fp_regs, FP_REGS_SIZE);
 187
 188 #ifdef CONFIG_ALTIVEC
 189         err |= __get_user(v_regs, &sc->v_regs);
 190         if (err)
 191                 return err;
 192         if (v_regs && !access_ok(VERIFY_READ, v_regs, 34 * sizeof(vector128)))
 193                 return -EFAULT;
 194         /* Copy 33 vec registers (vr0..31 and vscr) from the stack */
 195         if (v_regs != 0 && (msr & MSR_VEC) != 0)
 196                 err |= __copy_from_user(current->thread.vr, v_regs,
 197                                         33 * sizeof(vector128));
 198         else if (current->thread.used_vr)
 199                 memset(current->thread.vr, 0, 33 * sizeof(vector128));
 200         /* Always get VRSAVE back */
 201         if (v_regs != 0)
 202                 err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
 203         else
 204                 current->thread.vrsave = 0;
 205 #endif /* CONFIG_ALTIVEC */
 206
 207         return err;
 208 }
 209
 210 /*
 211  * Allocate space for the signal frame
 212  */
 213 static inline void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 214                                   size_t frame_size)
 215 {
 216         unsigned long newsp;
 217
 218         /* Default to using normal stack */
 219         newsp = regs->gpr[1];
 220
 221         if ((ka->sa.sa_flags & SA_ONSTACK) && current->sas_ss_size) {
 222                 if (! on_sig_stack(regs->gpr[1]))
 223                         newsp = (current->sas_ss_sp + current->sas_ss_size);
 224         }
 225
 226         return (void __user *)((newsp - frame_size) & -16ul);
 227 }
 228
 229 /*
 230  * Setup the trampoline code on the stack
 231  */
 232 static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
 233 {
 234         int i;
 235         long err = 0;
 236
 237         /* addi r1, r1, __SIGNAL_FRAMESIZE  # Pop the dummy stackframe */
 238         err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]);
 239         /* li r0, __NR_[rt_]sigreturn| */
 240         err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]);
 241         /* sc */
 242         err |= __put_user(0x44000002UL, &tramp[2]);
 243
 244         /* Minimal traceback info */
 245         for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++)
 246                 err |= __put_user(0, &tramp[i]);
 247
 248         if (!err)
 249                 flush_icache_range((unsigned long) &tramp[0],
 250                            (unsigned long) &tramp[TRAMP_SIZE]);
 251
 252         return err;
 253 }
 254
 255 /*
 256  * Restore the user process's signal mask (also used by signal32.c)
 257  */
 258 void restore_sigmask(sigset_t *set)
 259 {
 260         sigdelsetmask(set, ~_BLOCKABLE);
 261         spin_lock_irq(&current->sighand->siglock);
 262         current->blocked = *set;
 263         recalc_sigpending();
 264         spin_unlock_irq(&current->sighand->siglock);
 265 }
 266
 267
 268 /*
 269  * Handle {get,set,swap}_context operations
 270  */
 271 int sys_swapcontext(struct ucontext __user *old_ctx,
 272                     struct ucontext __user *new_ctx,
 273                     long ctx_size, long r6, long r7, long r8, struct pt_regs *regs)
 274 {
 275         unsigned char tmp;
 276         sigset_t set;
 277
 278         /* Context size is for future use. Right now, we only make sure
 279          * we are passed something we understand
 280          */
 281         if (ctx_size < sizeof(struct ucontext))
 282                 return -EINVAL;
 283
 284         if (old_ctx != NULL) {
 285                 if (!access_ok(VERIFY_WRITE, old_ctx, sizeof(*old_ctx))
 286                     || setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0)
 287                     || __copy_to_user(&old_ctx->uc_sigmask,
 288                                       &current->blocked, sizeof(sigset_t)))
 289                         return -EFAULT;
 290         }
 291         if (new_ctx == NULL)
 292                 return 0;
 293         if (!access_ok(VERIFY_READ, new_ctx, sizeof(*new_ctx))
 294             || __get_user(tmp, (u8 __user *) new_ctx)
 295             || __get_user(tmp, (u8 __user *) (new_ctx + 1) - 1))
 296                 return -EFAULT;
 297
 298         /*
 299          * If we get a fault copying the context into the kernel's
 300          * image of the user's registers, we can't just return -EFAULT
 301          * because the user's registers will be corrupted.  For instance
 302          * the NIP value may have been updated but not some of the
 303          * other registers.  Given that we have done the access_ok
 304          * and successfully read the first and last bytes of the region
 305          * above, this should only happen in an out-of-memory situation
 306          * or if another thread unmaps the region containing the context.
 307          * We kill the task with a SIGSEGV in this situation.
 308          */
 309
 310         if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set)))
 311                 do_exit(SIGSEGV);
 312         restore_sigmask(&set);
 313         if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext))
 314                 do_exit(SIGSEGV);
 315
 316         /* This returns like rt_sigreturn */
 317         set_thread_flag(TIF_RESTOREALL);
 318         return 0;
 319 }
 320
 321
 322 /*
 323  * Do a signal return; undo the signal stack.
 324  */
 325
 326 int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
 327                      unsigned long r6, unsigned long r7, unsigned long r8,
 328                      struct pt_regs *regs)
 329 {
 330         struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1];
 331         sigset_t set;
 332
 333         /* Always make any pending restarted system calls return -EINTR */
 334         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 335
 336         if (!access_ok(VERIFY_READ, uc, sizeof(*uc)))
 337                 goto badframe;
 338
 339         if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
 340                 goto badframe;
 341         restore_sigmask(&set);
 342         if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext))
 343                 goto badframe;
 344
 345         /* do_sigaltstack expects a __user pointer and won't modify
 346          * what's in there anyway
 347          */
 348         do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]);
 349
 350         set_thread_flag(TIF_RESTOREALL);
 351         return 0;
 352
 353 badframe:
 354 #if DEBUG_SIG
 355         printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n",
 356                regs, uc, &uc->uc_mcontext);
 357 #endif
 358         force_sig(SIGSEGV, current);
 359         return 0;
 360 }
 361
 362 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
 363                 sigset_t *set, struct pt_regs *regs)
 364 {
 365         /* Handler is *really* a pointer to the function descriptor for
 366          * the signal routine.  The first entry in the function
 367          * descriptor is the entry address of signal and the second
 368          * entry is the TOC value we need to use.
 369          */
 370         func_descr_t __user *funct_desc_ptr;
 371         struct rt_sigframe __user *frame;
 372         unsigned long newsp = 0;
 373         long err = 0;
 374
 375         frame = get_sigframe(ka, regs, sizeof(*frame));
 376
 377         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 378                 goto badframe;
 379
 380         err |= __put_user(&frame->info, &frame->pinfo);
 381         err |= __put_user(&frame->uc, &frame->puc);
 382         err |= copy_siginfo_to_user(&frame->info, info);
 383         if (err)
 384                 goto badframe;
 385
 386         /* Create the ucontext.  */
 387         err |= __put_user(0, &frame->uc.uc_flags);
 388         err |= __put_user(0, &frame->uc.uc_link);
 389         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 390         err |= __put_user(sas_ss_flags(regs->gpr[1]),
 391                           &frame->uc.uc_stack.ss_flags);
 392         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 393         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL,
 394                                 (unsigned long)ka->sa.sa_handler);
 395         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 396         if (err)
 397                 goto badframe;
 398
 399         /* Make sure signal handler doesn't get spurious FP exceptions */
 400         current->thread.fpscr.val = 0;
 401
 402         /* Set up to return from userspace. */
 403         if (vdso64_rt_sigtramp && current->mm->context.vdso_base) {
 404                 regs->link = current->mm->context.vdso_base + vdso64_rt_sigtramp;
 405         } else {
 406                 err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
 407                 if (err)
 408                         goto badframe;
 409                 regs->link = (unsigned long) &frame->tramp[0];
 410         }
 411         funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler;
 412
 413         /* Allocate a dummy caller frame for the signal handler. */
 414         newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE;
 415         err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);
 416
 417         /* Set up "regs" so we "return" to the signal handler. */
 418         err |= get_user(regs->nip, &funct_desc_ptr->entry);
 419         /* enter the signal handler in big-endian mode */
 420         regs->msr &= ~MSR_LE;
 421         regs->gpr[1] = newsp;
 422         err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
 423         regs->gpr[3] = signr;
 424         regs->result = 0;
 425         if (ka->sa.sa_flags & SA_SIGINFO) {
 426                 err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo);
 427                 err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc);
 428                 regs->gpr[6] = (unsigned long) frame;
 429         } else {
 430                 regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext;
 431         }
 432         if (err)
 433                 goto badframe;
 434
 435         return 1;
 436
 437 badframe:
 438 #if DEBUG_SIG
 439         printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n",
 440                regs, frame, newsp);
 441 #endif
 442         force_sigsegv(signr, current);
 443         return 0;
 444 }
 445
 446
 447 /*
 448  * OK, we're invoking a handler
 449  */
 450 static int handle_signal(unsigned long sig, struct k_sigaction *ka,
 451                          siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
 452 {
 453         int ret;
 454
 455         /* Set up Signal Frame */
 456         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 457
 458         if (ret) {
 459                 spin_lock_irq(&current->sighand->siglock);
 460                 sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 461                 if (!(ka->sa.sa_flags & SA_NODEFER))
 462                         sigaddset(&current->blocked,sig);
 463                 recalc_sigpending();
 464                 spin_unlock_irq(&current->sighand->siglock);
 465         }
 466
 467         return ret;
 468 }
 469
 470 static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
 471 {
 472         switch ((int)regs->result) {
 473         case -ERESTART_RESTARTBLOCK:
 474         case -ERESTARTNOHAND:
 475                 /* ERESTARTNOHAND means that the syscall should only be
 476                  * restarted if there was no handler for the signal, and since
 477                  * we only get here if there is a handler, we dont restart.
 478                  */
 479                 regs->result = -EINTR;
 480                 regs->gpr[3] = EINTR;
 481                 regs->ccr |= 0x10000000;
 482                 break;
 483         case -ERESTARTSYS:
 484                 /* ERESTARTSYS means to restart the syscall if there is no
 485                  * handler or the handler was registered with SA_RESTART
 486                  */
 487                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 488                         regs->result = -EINTR;
 489                         regs->gpr[3] = EINTR;
 490                         regs->ccr |= 0x10000000;
 491                         break;
 492                 }
 493                 /* fallthrough */
 494         case -ERESTARTNOINTR:
 495                 /* ERESTARTNOINTR means that the syscall should be
 496                  * called again after the signal handler returns.
 497                  */
 498                 regs->gpr[3] = regs->orig_gpr3;
 499                 regs->nip -= 4;
 500                 regs->result = 0;
 501                 break;
 502         }
 503 }
 504
 505 /*
 506  * Note that 'init' is a special process: it doesn't get signals it doesn't
 507  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 508  * mistake.
 509  */
 510 int do_signal(sigset_t *oldset, struct pt_regs *regs)
 511 {
 512         siginfo_t info;
 513         int signr;
 514         struct k_sigaction ka;
 515
 516         /*
 517          * If the current thread is 32 bit - invoke the
 518          * 32 bit signal handling code
 519          */
 520         if (test_thread_flag(TIF_32BIT))
 521                 return do_signal32(oldset, regs);
 522
 523         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 524                 oldset = &current->saved_sigmask;
 525         else if (!oldset)
 526                 oldset = &current->blocked;
 527
 528         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 529         if (signr > 0) {
 530                 int ret;
 531
 532                 /* Whee!  Actually deliver the signal.  */
 533                 if (TRAP(regs) == 0x0C00)
 534                         syscall_restart(regs, &ka);
 535
 536                 /*
 537                  * Reenable the DABR before delivering the signal to
 538                  * user space. The DABR will have been cleared if it
 539                  * triggered inside the kernel.
 540                  */
 541                 if (current->thread.dabr)
 542                         set_dabr(current->thread.dabr);
 543
 544                 ret = handle_signal(signr, &ka, &info, oldset, regs);
 545
 546                 /* If a signal was successfully delivered, the saved sigmask is in
 547                    its frame, and we can clear the TIF_RESTORE_SIGMASK flag */
 548                 if (ret && test_thread_flag(TIF_RESTORE_SIGMASK))
 549                         clear_thread_flag(TIF_RESTORE_SIGMASK);
 550
 551                 return ret;
 552         }
 553
 554         if (TRAP(regs) == 0x0C00) {     /* System Call! */
 555                 if ((int)regs->result == -ERESTARTNOHAND ||
 556                     (int)regs->result == -ERESTARTSYS ||
 557                     (int)regs->result == -ERESTARTNOINTR) {
 558                         regs->gpr[3] = regs->orig_gpr3;
 559                         regs->nip -= 4; /* Back up & retry system call */
 560                         regs->result = 0;
 561                 } else if ((int)regs->result == -ERESTART_RESTARTBLOCK) {
 562                         regs->gpr[0] = __NR_restart_syscall;
 563                         regs->nip -= 4;
 564                         regs->result = 0;
 565                 }
 566         }
 567         /* No signal to deliver -- put the saved sigmask back */
 568         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 569                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 570                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 571         }
 572
 573         return 0;
 574 }
 575 EXPORT_SYMBOL(do_signal);