arch/ppc64/kernel/signal.c

   1 /*
   2  *  linux/arch/ppc64/kernel/signal.c
   3  *
   4  *  PowerPC version
   5  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   6  *
   7  *  Derived from "arch/i386/kernel/signal.c"
   8  *    Copyright (C) 1991, 1992 Linus Torvalds
   9  *    1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  10  *
  11  *  This program is free software; you can redistribute it and/or
  12  *  modify it under the terms of the GNU General Public License
  13  *  as published by the Free Software Foundation; either version
  14  *  2 of the License, or (at your option) any later version.
  15  */
  16
  17 #include <linux/config.h>
  18 #include <linux/sched.h>
  19 #include <linux/mm.h>
  20 #include <linux/smp.h>
  21 #include <linux/smp_lock.h>
  22 #include <linux/kernel.h>
  23 #include <linux/signal.h>
  24 #include <linux/errno.h>
  25 #include <linux/wait.h>
  26 #include <linux/unistd.h>
  27 #include <linux/stddef.h>
  28 #include <linux/elf.h>
  29 #include <linux/ptrace.h>
  30 #include <linux/module.h>
  31
  32 #include <asm/sigcontext.h>
  33 #include <asm/ucontext.h>
  34 #include <asm/uaccess.h>
  35 #include <asm/pgtable.h>
  36 #include <asm/ppcdebug.h>
  37 #include <asm/unistd.h>
  38 #include <asm/cacheflush.h>
  39 #include <asm/vdso.h>
  40
  41 #define DEBUG_SIG 0
  42
  43 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  44
  45 #define GP_REGS_SIZE    min(sizeof(elf_gregset_t), sizeof(struct pt_regs))
  46 #define FP_REGS_SIZE    sizeof(elf_fpregset_t)
  47
  48 #define TRAMP_TRACEBACK 3
  49 #define TRAMP_SIZE      6
  50
  51 /*
  52  * When we have signals to deliver, we set up on the user stack,
  53  * going down from the original stack pointer:
  54  *      1) a rt_sigframe struct which contains the ucontext
  55  *      2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller
  56  *         frame for the signal handler.
  57  */
  58
  59 struct rt_sigframe {
  60         /* sys_rt_sigreturn requires the ucontext be the first field */
  61         struct ucontext uc;
  62         unsigned long _unused[2];
  63         unsigned int tramp[TRAMP_SIZE];
  64         struct siginfo *pinfo;
  65         void *puc;
  66         struct siginfo info;
  67         /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */
  68         char abigap[288];
  69 } __attribute__ ((aligned (16)));
  70
  71
  72 /*
  73  * Atomically swap in the new signal mask, and wait for a signal.
  74  */
  75 long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, int p3, int p4,
  76                        int p6, int p7, struct pt_regs *regs)
  77 {
  78         sigset_t saveset, newset;
  79
  80         /* XXX: Don't preclude handling different sized sigset_t's.  */
  81         if (sigsetsize != sizeof(sigset_t))
  82                 return -EINVAL;
  83
  84         if (copy_from_user(&newset, unewset, sizeof(newset)))
  85                 return -EFAULT;
  86         sigdelsetmask(&newset, ~_BLOCKABLE);
  87
  88         spin_lock_irq(&current->sighand->siglock);
  89         saveset = current->blocked;
  90         current->blocked = newset;
  91         recalc_sigpending();
  92         spin_unlock_irq(&current->sighand->siglock);
  93
  94         regs->result = -EINTR;
  95         regs->gpr[3] = EINTR;
  96         regs->ccr |= 0x10000000;
  97         while (1) {
  98                 current->state = TASK_INTERRUPTIBLE;
  99                 schedule();
 100                 if (do_signal(&saveset, regs))
 101                         return 0;
 102         }
 103 }
 104
 105 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, unsigned long r5,
 106                      unsigned long r6, unsigned long r7, unsigned long r8,
 107                      struct pt_regs *regs)
 108 {
 109         return do_sigaltstack(uss, uoss, regs->gpr[1]);
 110 }
 111
 112
 113 /*
 114  * Set up the sigcontext for the signal frame.
 115  */
 116
 117 static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 118                  int signr, sigset_t *set, unsigned long handler)
 119 {
 120         /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
 121          * process never used altivec yet (MSR_VEC is zero in pt_regs of
 122          * the context). This is very important because we must ensure we
 123          * don't lose the VRSAVE content that may have been set prior to
 124          * the process doing its first vector operation
 125          * Userland shall check AT_HWCAP to know wether it can rely on the
 126          * v_regs pointer or not
 127          */
 128 #ifdef CONFIG_ALTIVEC
 129         elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful);
 130 #endif
 131         long err = 0;
 132
 133         flush_fp_to_thread(current);
 134
 135         /* Make sure signal doesn't get spurrious FP exceptions */
 136         current->thread.fpscr = 0;
 137
 138 #ifdef CONFIG_ALTIVEC
 139         err |= __put_user(v_regs, &sc->v_regs);
 140
 141         /* save altivec registers */
 142         if (current->thread.used_vr) {
 143                 flush_altivec_to_thread(current);
 144                 /* Copy 33 vec registers (vr0..31 and vscr) to the stack */
 145                 err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128));
 146                 /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg)
 147                  * contains valid data.
 148                  */
 149                 regs->msr |= MSR_VEC;
 150         }
 151         /* We always copy to/from vrsave, it's 0 if we don't have or don't
 152          * use altivec.
 153          */
 154         err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
 155 #else /* CONFIG_ALTIVEC */
 156         err |= __put_user(0, &sc->v_regs);
 157 #endif /* CONFIG_ALTIVEC */
 158         err |= __put_user(&sc->gp_regs, &sc->regs);
 159         err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE);
 160         err |= __copy_to_user(&sc->fp_regs, &current->thread.fpr, FP_REGS_SIZE);
 161         err |= __put_user(signr, &sc->signal);
 162         err |= __put_user(handler, &sc->handler);
 163         if (set != NULL)
 164                 err |=  __put_user(set->sig[0], &sc->oldmask);
 165
 166         return err;
 167 }
 168
 169 /*
 170  * Restore the sigcontext from the signal frame.
 171  */
 172
 173 static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
 174                               struct sigcontext __user *sc)
 175 {
 176 #ifdef CONFIG_ALTIVEC
 177         elf_vrreg_t __user *v_regs;
 178 #endif
 179         unsigned long err = 0;
 180         unsigned long save_r13 = 0;
 181         elf_greg_t *gregs = (elf_greg_t *)regs;
 182 #ifdef CONFIG_ALTIVEC
 183         unsigned long msr;
 184 #endif
 185         int i;
 186
 187         /* If this is not a signal return, we preserve the TLS in r13 */
 188         if (!sig)
 189                 save_r13 = regs->gpr[13];
 190
 191         /* copy everything before MSR */
 192         err |= __copy_from_user(regs, &sc->gp_regs,
 193                                 PT_MSR*sizeof(unsigned long));
 194
 195         /* skip MSR and SOFTE */
 196         for (i = PT_MSR+1; i <= PT_RESULT; i++) {
 197                 if (i == PT_SOFTE)
 198                         continue;
 199                 err |= __get_user(gregs[i], &sc->gp_regs[i]);
 200         }
 201
 202         if (!sig)
 203                 regs->gpr[13] = save_r13;
 204         err |= __copy_from_user(&current->thread.fpr, &sc->fp_regs, FP_REGS_SIZE);
 205         if (set != NULL)
 206                 err |=  __get_user(set->sig[0], &sc->oldmask);
 207
 208 #ifdef CONFIG_ALTIVEC
 209         err |= __get_user(v_regs, &sc->v_regs);
 210         err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
 211         if (err)
 212                 return err;
 213         /* Copy 33 vec registers (vr0..31 and vscr) from the stack */
 214         if (v_regs != 0 && (msr & MSR_VEC) != 0)
 215                 err |= __copy_from_user(current->thread.vr, v_regs,
 216                                         33 * sizeof(vector128));
 217         else if (current->thread.used_vr)
 218                 memset(current->thread.vr, 0, 33 * sizeof(vector128));
 219         /* Always get VRSAVE back */
 220         if (v_regs != 0)
 221                 err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
 222         else
 223                 current->thread.vrsave = 0;
 224 #endif /* CONFIG_ALTIVEC */
 225
 226 #ifndef CONFIG_SMP
 227         preempt_disable();
 228         if (last_task_used_math == current)
 229                 last_task_used_math = NULL;
 230         if (last_task_used_altivec == current)
 231                 last_task_used_altivec = NULL;
 232         preempt_enable();
 233 #endif
 234         /* Force reload of FP/VEC */
 235         regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC);
 236
 237         return err;
 238 }
 239
 240 /*
 241  * Allocate space for the signal frame
 242  */
 243 static inline void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 244                                   size_t frame_size)
 245 {
 246         unsigned long newsp;
 247
 248         /* Default to using normal stack */
 249         newsp = regs->gpr[1];
 250
 251         if (ka->sa.sa_flags & SA_ONSTACK) {
 252                 if (! on_sig_stack(regs->gpr[1]))
 253                         newsp = (current->sas_ss_sp + current->sas_ss_size);
 254         }
 255
 256         return (void __user *)((newsp - frame_size) & -16ul);
 257 }
 258
 259 /*
 260  * Setup the trampoline code on the stack
 261  */
 262 static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
 263 {
 264         int i;
 265         long err = 0;
 266
 267         /* addi r1, r1, __SIGNAL_FRAMESIZE  # Pop the dummy stackframe */
 268         err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]);
 269         /* li r0, __NR_[rt_]sigreturn| */
 270         err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]);
 271         /* sc */
 272         err |= __put_user(0x44000002UL, &tramp[2]);
 273
 274         /* Minimal traceback info */
 275         for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++)
 276                 err |= __put_user(0, &tramp[i]);
 277
 278         if (!err)
 279                 flush_icache_range((unsigned long) &tramp[0],
 280                            (unsigned long) &tramp[TRAMP_SIZE]);
 281
 282         return err;
 283 }
 284
 285 /*
 286  * Restore the user process's signal mask (also used by signal32.c)
 287  */
 288 void restore_sigmask(sigset_t *set)
 289 {
 290         sigdelsetmask(set, ~_BLOCKABLE);
 291         spin_lock_irq(&current->sighand->siglock);
 292         current->blocked = *set;
 293         recalc_sigpending();
 294         spin_unlock_irq(&current->sighand->siglock);
 295 }
 296
 297
 298 /*
 299  * Handle {get,set,swap}_context operations
 300  */
 301 int sys_swapcontext(struct ucontext __user *old_ctx,
 302                     struct ucontext __user *new_ctx,
 303                     long ctx_size, long r6, long r7, long r8, struct pt_regs *regs)
 304 {
 305         unsigned char tmp;
 306         sigset_t set;
 307
 308         /* Context size is for future use. Right now, we only make sure
 309          * we are passed something we understand
 310          */
 311         if (ctx_size < sizeof(struct ucontext))
 312                 return -EINVAL;
 313
 314         if (old_ctx != NULL) {
 315                 if (!access_ok(VERIFY_WRITE, old_ctx, sizeof(*old_ctx))
 316                     || setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0)
 317                     || __copy_to_user(&old_ctx->uc_sigmask,
 318                                       &current->blocked, sizeof(sigset_t)))
 319                         return -EFAULT;
 320         }
 321         if (new_ctx == NULL)
 322                 return 0;
 323         if (!access_ok(VERIFY_READ, new_ctx, sizeof(*new_ctx))
 324             || __get_user(tmp, (u8 __user *) new_ctx)
 325             || __get_user(tmp, (u8 __user *) (new_ctx + 1) - 1))
 326                 return -EFAULT;
 327
 328         /*
 329          * If we get a fault copying the context into the kernel's
 330          * image of the user's registers, we can't just return -EFAULT
 331          * because the user's registers will be corrupted.  For instance
 332          * the NIP value may have been updated but not some of the
 333          * other registers.  Given that we have done the access_ok
 334          * and successfully read the first and last bytes of the region
 335          * above, this should only happen in an out-of-memory situation
 336          * or if another thread unmaps the region containing the context.
 337          * We kill the task with a SIGSEGV in this situation.
 338          */
 339
 340         if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set)))
 341                 do_exit(SIGSEGV);
 342         restore_sigmask(&set);
 343         if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext))
 344                 do_exit(SIGSEGV);
 345
 346         /* This returns like rt_sigreturn */
 347         return 0;
 348 }
 349
 350
 351 /*
 352  * Do a signal return; undo the signal stack.
 353  */
 354
 355 int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
 356                      unsigned long r6, unsigned long r7, unsigned long r8,
 357                      struct pt_regs *regs)
 358 {
 359         struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1];
 360         sigset_t set;
 361
 362         /* Always make any pending restarted system calls return -EINTR */
 363         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 364
 365         if (!access_ok(VERIFY_READ, uc, sizeof(*uc)))
 366                 goto badframe;
 367
 368         if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
 369                 goto badframe;
 370         restore_sigmask(&set);
 371         if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext))
 372                 goto badframe;
 373
 374         /* do_sigaltstack expects a __user pointer and won't modify
 375          * what's in there anyway
 376          */
 377         do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]);
 378
 379         return regs->result;
 380
 381 badframe:
 382 #if DEBUG_SIG
 383         printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n",
 384                regs, uc, &uc->uc_mcontext);
 385 #endif
 386         force_sig(SIGSEGV, current);
 387         return 0;
 388 }
 389
 390 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
 391                 sigset_t *set, struct pt_regs *regs)
 392 {
 393         /* Handler is *really* a pointer to the function descriptor for
 394          * the signal routine.  The first entry in the function
 395          * descriptor is the entry address of signal and the second
 396          * entry is the TOC value we need to use.
 397          */
 398         func_descr_t __user *funct_desc_ptr;
 399         struct rt_sigframe __user *frame;
 400         unsigned long newsp = 0;
 401         long err = 0;
 402
 403         frame = get_sigframe(ka, regs, sizeof(*frame));
 404
 405         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 406                 goto badframe;
 407
 408         err |= __put_user(&frame->info, &frame->pinfo);
 409         err |= __put_user(&frame->uc, &frame->puc);
 410         err |= copy_siginfo_to_user(&frame->info, info);
 411         if (err)
 412                 goto badframe;
 413
 414         /* Create the ucontext.  */
 415         err |= __put_user(0, &frame->uc.uc_flags);
 416         err |= __put_user(0, &frame->uc.uc_link);
 417         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 418         err |= __put_user(sas_ss_flags(regs->gpr[1]),
 419                           &frame->uc.uc_stack.ss_flags);
 420         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 421         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL,
 422                                 (unsigned long)ka->sa.sa_handler);
 423         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 424         if (err)
 425                 goto badframe;
 426
 427         /* Set up to return from userspace. */
 428         if (vdso64_rt_sigtramp && current->thread.vdso_base) {
 429                 regs->link = current->thread.vdso_base + vdso64_rt_sigtramp;
 430         } else {
 431                 err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
 432                 if (err)
 433                         goto badframe;
 434                 regs->link = (unsigned long) &frame->tramp[0];
 435         }
 436         funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler;
 437
 438         /* Allocate a dummy caller frame for the signal handler. */
 439         newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE;
 440         err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);
 441
 442         /* Set up "regs" so we "return" to the signal handler. */
 443         err |= get_user(regs->nip, &funct_desc_ptr->entry);
 444         regs->gpr[1] = newsp;
 445         err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
 446         regs->gpr[3] = signr;
 447         regs->result = 0;
 448         if (ka->sa.sa_flags & SA_SIGINFO) {
 449                 err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo);
 450                 err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc);
 451                 regs->gpr[6] = (unsigned long) frame;
 452         } else {
 453                 regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext;
 454         }
 455         if (err)
 456                 goto badframe;
 457
 458         if (test_thread_flag(TIF_SINGLESTEP))
 459                 ptrace_notify(SIGTRAP);
 460
 461         return 1;
 462
 463 badframe:
 464 #if DEBUG_SIG
 465         printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n",
 466                regs, frame, newsp);
 467 #endif
 468         force_sigsegv(signr, current);
 469         return 0;
 470 }
 471
 472
 473 /*
 474  * OK, we're invoking a handler
 475  */
 476 static int handle_signal(unsigned long sig, struct k_sigaction *ka,
 477                          siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
 478 {
 479         int ret;
 480
 481         /* Set up Signal Frame */
 482         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 483
 484         if (ret) {
 485                 spin_lock_irq(&current->sighand->siglock);
 486                 sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 487                 if (!(ka->sa.sa_flags & SA_NODEFER))
 488                         sigaddset(&current->blocked,sig);
 489                 recalc_sigpending();
 490                 spin_unlock_irq(&current->sighand->siglock);
 491         }
 492
 493         return ret;
 494 }
 495
 496 static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
 497 {
 498         switch ((int)regs->result) {
 499         case -ERESTART_RESTARTBLOCK:
 500         case -ERESTARTNOHAND:
 501                 /* ERESTARTNOHAND means that the syscall should only be
 502                  * restarted if there was no handler for the signal, and since
 503                  * we only get here if there is a handler, we dont restart.
 504                  */
 505                 regs->result = -EINTR;
 506                 break;
 507         case -ERESTARTSYS:
 508                 /* ERESTARTSYS means to restart the syscall if there is no
 509                  * handler or the handler was registered with SA_RESTART
 510                  */
 511                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 512                         regs->result = -EINTR;
 513                         break;
 514                 }
 515                 /* fallthrough */
 516         case -ERESTARTNOINTR:
 517                 /* ERESTARTNOINTR means that the syscall should be
 518                  * called again after the signal handler returns.
 519                  */
 520                 regs->gpr[3] = regs->orig_gpr3;
 521                 regs->nip -= 4;
 522                 regs->result = 0;
 523                 break;
 524         }
 525 }
 526
 527 /*
 528  * Note that 'init' is a special process: it doesn't get signals it doesn't
 529  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 530  * mistake.
 531  */
 532 int do_signal(sigset_t *oldset, struct pt_regs *regs)
 533 {
 534         siginfo_t info;
 535         int signr;
 536         struct k_sigaction ka;
 537
 538         /*
 539          * If the current thread is 32 bit - invoke the
 540          * 32 bit signal handling code
 541          */
 542         if (test_thread_flag(TIF_32BIT))
 543                 return do_signal32(oldset, regs);
 544
 545         if (!oldset)
 546                 oldset = &current->blocked;
 547
 548         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 549         if (signr > 0) {
 550                 /* Whee!  Actually deliver the signal.  */
 551                 if (TRAP(regs) == 0x0C00)
 552                         syscall_restart(regs, &ka);
 553
 554                 /*
 555                  * Reenable the DABR before delivering the signal to
 556                  * user space. The DABR will have been cleared if it
 557                  * triggered inside the kernel.
 558                  */
 559                 if (current->thread.dabr)
 560                         set_dabr(current->thread.dabr);
 561
 562                 return handle_signal(signr, &ka, &info, oldset, regs);
 563         }
 564
 565         if (TRAP(regs) == 0x0C00) {     /* System Call! */
 566                 if ((int)regs->result == -ERESTARTNOHAND ||
 567                     (int)regs->result == -ERESTARTSYS ||
 568                     (int)regs->result == -ERESTARTNOINTR) {
 569                         regs->gpr[3] = regs->orig_gpr3;
 570                         regs->nip -= 4; /* Back up & retry system call */
 571                         regs->result = 0;
 572                 } else if ((int)regs->result == -ERESTART_RESTARTBLOCK) {
 573                         regs->gpr[0] = __NR_restart_syscall;
 574                         regs->nip -= 4;
 575                         regs->result = 0;
 576                 }
 577         }
 578
 579         return 0;
 580 }
 581 EXPORT_SYMBOL(do_signal);