arch/powerpc/kernel/signal_64.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/unistd.h>
  37 #include <asm/cacheflush.h>
  38 #include <asm/vdso.h>
  39
  40 #define DEBUG_SIG 0
  41
  42 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  43
  44 #define GP_REGS_SIZE    min(sizeof(elf_gregset_t), sizeof(struct pt_regs))
  45 #define FP_REGS_SIZE    sizeof(elf_fpregset_t)
  46
  47 #define TRAMP_TRACEBACK 3
  48 #define TRAMP_SIZE      6
  49
  50 /*
  51  * When we have signals to deliver, we set up on the user stack,
  52  * going down from the original stack pointer:
  53  *      1) a rt_sigframe struct which contains the ucontext
  54  *      2) a gap of __SIGNAL_FRAMESIZE bytes which acts as a dummy caller
  55  *         frame for the signal handler.
  56  */
  57
  58 struct rt_sigframe {
  59         /* sys_rt_sigreturn requires the ucontext be the first field */
  60         struct ucontext uc;
  61         unsigned long _unused[2];
  62         unsigned int tramp[TRAMP_SIZE];
  63         struct siginfo *pinfo;
  64         void *puc;
  65         struct siginfo info;
  66         /* 64 bit ABI allows for 288 bytes below sp before decrementing it. */
  67         char abigap[288];
  68 } __attribute__ ((aligned (16)));
  69
  70
  71 /*
  72  * Atomically swap in the new signal mask, and wait for a signal.
  73  */
  74 long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, int p3, int p4,
  75                        int p6, int p7, struct pt_regs *regs)
  76 {
  77         sigset_t saveset, newset;
  78
  79         /* XXX: Don't preclude handling different sized sigset_t's.  */
  80         if (sigsetsize != sizeof(sigset_t))
  81                 return -EINVAL;
  82
  83         if (copy_from_user(&newset, unewset, sizeof(newset)))
  84                 return -EFAULT;
  85         sigdelsetmask(&newset, ~_BLOCKABLE);
  86
  87         spin_lock_irq(&current->sighand->siglock);
  88         saveset = current->blocked;
  89         current->blocked = newset;
  90         recalc_sigpending();
  91         spin_unlock_irq(&current->sighand->siglock);
  92
  93         regs->result = -EINTR;
  94         regs->gpr[3] = EINTR;
  95         regs->ccr |= 0x10000000;
  96         while (1) {
  97                 current->state = TASK_INTERRUPTIBLE;
  98                 schedule();
  99                 if (do_signal(&saveset, regs)) {
 100                         set_thread_flag(TIF_RESTOREALL);
 101                         return 0;
 102                 }
 103         }
 104 }
 105
 106 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, unsigned long r5,
 107                      unsigned long r6, unsigned long r7, unsigned long r8,
 108                      struct pt_regs *regs)
 109 {
 110         return do_sigaltstack(uss, uoss, regs->gpr[1]);
 111 }
 112
 113
 114 /*
 115  * Set up the sigcontext for the signal frame.
 116  */
 117
 118 static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 119                  int signr, sigset_t *set, unsigned long handler)
 120 {
 121         /* When CONFIG_ALTIVEC is set, we _always_ setup v_regs even if the
 122          * process never used altivec yet (MSR_VEC is zero in pt_regs of
 123          * the context). This is very important because we must ensure we
 124          * don't lose the VRSAVE content that may have been set prior to
 125          * the process doing its first vector operation
 126          * Userland shall check AT_HWCAP to know wether it can rely on the
 127          * v_regs pointer or not
 128          */
 129 #ifdef CONFIG_ALTIVEC
 130         elf_vrreg_t __user *v_regs = (elf_vrreg_t __user *)(((unsigned long)sc->vmx_reserve + 15) & ~0xful);
 131 #endif
 132         long err = 0;
 133
 134         flush_fp_to_thread(current);
 135
 136 #ifdef CONFIG_ALTIVEC
 137         err |= __put_user(v_regs, &sc->v_regs);
 138
 139         /* save altivec registers */
 140         if (current->thread.used_vr) {
 141                 flush_altivec_to_thread(current);
 142                 /* Copy 33 vec registers (vr0..31 and vscr) to the stack */
 143                 err |= __copy_to_user(v_regs, current->thread.vr, 33 * sizeof(vector128));
 144                 /* set MSR_VEC in the MSR value in the frame to indicate that sc->v_reg)
 145                  * contains valid data.
 146                  */
 147                 regs->msr |= MSR_VEC;
 148         }
 149         /* We always copy to/from vrsave, it's 0 if we don't have or don't
 150          * use altivec.
 151          */
 152         err |= __put_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
 153 #else /* CONFIG_ALTIVEC */
 154         err |= __put_user(0, &sc->v_regs);
 155 #endif /* CONFIG_ALTIVEC */
 156         err |= __put_user(&sc->gp_regs, &sc->regs);
 157         if (!FULL_REGS(regs)) {
 158                 /* Zero out the unsaved GPRs to avoid information
 159                    leak, and set TIF_SAVE_NVGPRS to ensure that the
 160                    registers do actually get saved later. */
 161                 memset(&regs->gpr[14], 0, 18 * sizeof(unsigned long));
 162                 set_thread_flag(TIF_SAVE_NVGPRS);
 163                 current_thread_info()->nvgprs_frame = &sc->gp_regs;
 164         }
 165         err |= __copy_to_user(&sc->gp_regs, regs, GP_REGS_SIZE);
 166         err |= __copy_to_user(&sc->fp_regs, &current->thread.fpr, FP_REGS_SIZE);
 167         err |= __put_user(signr, &sc->signal);
 168         err |= __put_user(handler, &sc->handler);
 169         if (set != NULL)
 170                 err |=  __put_user(set->sig[0], &sc->oldmask);
 171
 172         return err;
 173 }
 174
 175 /*
 176  * Restore the sigcontext from the signal frame.
 177  */
 178
 179 static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
 180                               struct sigcontext __user *sc)
 181 {
 182 #ifdef CONFIG_ALTIVEC
 183         elf_vrreg_t __user *v_regs;
 184 #endif
 185         unsigned long err = 0;
 186         unsigned long save_r13 = 0;
 187         elf_greg_t *gregs = (elf_greg_t *)regs;
 188 #ifdef CONFIG_ALTIVEC
 189         unsigned long msr;
 190 #endif
 191         int i;
 192
 193         /* If this is not a signal return, we preserve the TLS in r13 */
 194         if (!sig)
 195                 save_r13 = regs->gpr[13];
 196
 197         /* copy everything before MSR */
 198         err |= __copy_from_user(regs, &sc->gp_regs,
 199                                 PT_MSR*sizeof(unsigned long));
 200
 201         /* skip MSR and SOFTE */
 202         for (i = PT_MSR+1; i <= PT_RESULT; i++) {
 203                 if (i == PT_SOFTE)
 204                         continue;
 205                 err |= __get_user(gregs[i], &sc->gp_regs[i]);
 206         }
 207
 208         if (!sig)
 209                 regs->gpr[13] = save_r13;
 210         err |= __copy_from_user(&current->thread.fpr, &sc->fp_regs, FP_REGS_SIZE);
 211         if (set != NULL)
 212                 err |=  __get_user(set->sig[0], &sc->oldmask);
 213
 214 #ifdef CONFIG_ALTIVEC
 215         err |= __get_user(v_regs, &sc->v_regs);
 216         err |= __get_user(msr, &sc->gp_regs[PT_MSR]);
 217         if (err)
 218                 return err;
 219         /* Copy 33 vec registers (vr0..31 and vscr) from the stack */
 220         if (v_regs != 0 && (msr & MSR_VEC) != 0)
 221                 err |= __copy_from_user(current->thread.vr, v_regs,
 222                                         33 * sizeof(vector128));
 223         else if (current->thread.used_vr)
 224                 memset(current->thread.vr, 0, 33 * sizeof(vector128));
 225         /* Always get VRSAVE back */
 226         if (v_regs != 0)
 227                 err |= __get_user(current->thread.vrsave, (u32 __user *)&v_regs[33]);
 228         else
 229                 current->thread.vrsave = 0;
 230 #endif /* CONFIG_ALTIVEC */
 231
 232 #ifndef CONFIG_SMP
 233         preempt_disable();
 234         if (last_task_used_math == current)
 235                 last_task_used_math = NULL;
 236         if (last_task_used_altivec == current)
 237                 last_task_used_altivec = NULL;
 238         preempt_enable();
 239 #endif
 240         /* Force reload of FP/VEC */
 241         regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC);
 242
 243         return err;
 244 }
 245
 246 /*
 247  * Allocate space for the signal frame
 248  */
 249 static inline void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 250                                   size_t frame_size)
 251 {
 252         unsigned long newsp;
 253
 254         /* Default to using normal stack */
 255         newsp = regs->gpr[1];
 256
 257         if (ka->sa.sa_flags & SA_ONSTACK) {
 258                 if (! on_sig_stack(regs->gpr[1]))
 259                         newsp = (current->sas_ss_sp + current->sas_ss_size);
 260         }
 261
 262         return (void __user *)((newsp - frame_size) & -16ul);
 263 }
 264
 265 /*
 266  * Setup the trampoline code on the stack
 267  */
 268 static long setup_trampoline(unsigned int syscall, unsigned int __user *tramp)
 269 {
 270         int i;
 271         long err = 0;
 272
 273         /* addi r1, r1, __SIGNAL_FRAMESIZE  # Pop the dummy stackframe */
 274         err |= __put_user(0x38210000UL | (__SIGNAL_FRAMESIZE & 0xffff), &tramp[0]);
 275         /* li r0, __NR_[rt_]sigreturn| */
 276         err |= __put_user(0x38000000UL | (syscall & 0xffff), &tramp[1]);
 277         /* sc */
 278         err |= __put_user(0x44000002UL, &tramp[2]);
 279
 280         /* Minimal traceback info */
 281         for (i=TRAMP_TRACEBACK; i < TRAMP_SIZE ;i++)
 282                 err |= __put_user(0, &tramp[i]);
 283
 284         if (!err)
 285                 flush_icache_range((unsigned long) &tramp[0],
 286                            (unsigned long) &tramp[TRAMP_SIZE]);
 287
 288         return err;
 289 }
 290
 291 /*
 292  * Restore the user process's signal mask (also used by signal32.c)
 293  */
 294 void restore_sigmask(sigset_t *set)
 295 {
 296         sigdelsetmask(set, ~_BLOCKABLE);
 297         spin_lock_irq(&current->sighand->siglock);
 298         current->blocked = *set;
 299         recalc_sigpending();
 300         spin_unlock_irq(&current->sighand->siglock);
 301 }
 302
 303
 304 /*
 305  * Handle {get,set,swap}_context operations
 306  */
 307 int sys_swapcontext(struct ucontext __user *old_ctx,
 308                     struct ucontext __user *new_ctx,
 309                     long ctx_size, long r6, long r7, long r8, struct pt_regs *regs)
 310 {
 311         unsigned char tmp;
 312         sigset_t set;
 313
 314         /* Context size is for future use. Right now, we only make sure
 315          * we are passed something we understand
 316          */
 317         if (ctx_size < sizeof(struct ucontext))
 318                 return -EINVAL;
 319
 320         if (old_ctx != NULL) {
 321                 if (!access_ok(VERIFY_WRITE, old_ctx, sizeof(*old_ctx))
 322                     || setup_sigcontext(&old_ctx->uc_mcontext, regs, 0, NULL, 0)
 323                     || __copy_to_user(&old_ctx->uc_sigmask,
 324                                       &current->blocked, sizeof(sigset_t)))
 325                         return -EFAULT;
 326         }
 327         if (new_ctx == NULL)
 328                 return 0;
 329         if (!access_ok(VERIFY_READ, new_ctx, sizeof(*new_ctx))
 330             || __get_user(tmp, (u8 __user *) new_ctx)
 331             || __get_user(tmp, (u8 __user *) (new_ctx + 1) - 1))
 332                 return -EFAULT;
 333
 334         /*
 335          * If we get a fault copying the context into the kernel's
 336          * image of the user's registers, we can't just return -EFAULT
 337          * because the user's registers will be corrupted.  For instance
 338          * the NIP value may have been updated but not some of the
 339          * other registers.  Given that we have done the access_ok
 340          * and successfully read the first and last bytes of the region
 341          * above, this should only happen in an out-of-memory situation
 342          * or if another thread unmaps the region containing the context.
 343          * We kill the task with a SIGSEGV in this situation.
 344          */
 345
 346         if (__copy_from_user(&set, &new_ctx->uc_sigmask, sizeof(set)))
 347                 do_exit(SIGSEGV);
 348         restore_sigmask(&set);
 349         if (restore_sigcontext(regs, NULL, 0, &new_ctx->uc_mcontext))
 350                 do_exit(SIGSEGV);
 351
 352         /* This returns like rt_sigreturn */
 353         set_thread_flag(TIF_RESTOREALL);
 354         return 0;
 355 }
 356
 357
 358 /*
 359  * Do a signal return; undo the signal stack.
 360  */
 361
 362 int sys_rt_sigreturn(unsigned long r3, unsigned long r4, unsigned long r5,
 363                      unsigned long r6, unsigned long r7, unsigned long r8,
 364                      struct pt_regs *regs)
 365 {
 366         struct ucontext __user *uc = (struct ucontext __user *)regs->gpr[1];
 367         sigset_t set;
 368
 369         /* Always make any pending restarted system calls return -EINTR */
 370         current_thread_info()->restart_block.fn = do_no_restart_syscall;
 371
 372         if (!access_ok(VERIFY_READ, uc, sizeof(*uc)))
 373                 goto badframe;
 374
 375         if (__copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
 376                 goto badframe;
 377         restore_sigmask(&set);
 378         if (restore_sigcontext(regs, NULL, 1, &uc->uc_mcontext))
 379                 goto badframe;
 380
 381         /* do_sigaltstack expects a __user pointer and won't modify
 382          * what's in there anyway
 383          */
 384         do_sigaltstack(&uc->uc_stack, NULL, regs->gpr[1]);
 385
 386         set_thread_flag(TIF_RESTOREALL);
 387         return 0;
 388
 389 badframe:
 390 #if DEBUG_SIG
 391         printk("badframe in sys_rt_sigreturn, regs=%p uc=%p &uc->uc_mcontext=%p\n",
 392                regs, uc, &uc->uc_mcontext);
 393 #endif
 394         force_sig(SIGSEGV, current);
 395         return 0;
 396 }
 397
 398 static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
 399                 sigset_t *set, struct pt_regs *regs)
 400 {
 401         /* Handler is *really* a pointer to the function descriptor for
 402          * the signal routine.  The first entry in the function
 403          * descriptor is the entry address of signal and the second
 404          * entry is the TOC value we need to use.
 405          */
 406         func_descr_t __user *funct_desc_ptr;
 407         struct rt_sigframe __user *frame;
 408         unsigned long newsp = 0;
 409         long err = 0;
 410
 411         frame = get_sigframe(ka, regs, sizeof(*frame));
 412
 413         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 414                 goto badframe;
 415
 416         err |= __put_user(&frame->info, &frame->pinfo);
 417         err |= __put_user(&frame->uc, &frame->puc);
 418         err |= copy_siginfo_to_user(&frame->info, info);
 419         if (err)
 420                 goto badframe;
 421
 422         /* Create the ucontext.  */
 423         err |= __put_user(0, &frame->uc.uc_flags);
 424         err |= __put_user(0, &frame->uc.uc_link);
 425         err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 426         err |= __put_user(sas_ss_flags(regs->gpr[1]),
 427                           &frame->uc.uc_stack.ss_flags);
 428         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 429         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, signr, NULL,
 430                                 (unsigned long)ka->sa.sa_handler);
 431         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 432         if (err)
 433                 goto badframe;
 434
 435         /* Make sure signal handler doesn't get spurious FP exceptions */
 436         current->thread.fpscr.val = 0;
 437
 438         /* Set up to return from userspace. */
 439         if (vdso64_rt_sigtramp && current->thread.vdso_base) {
 440                 regs->link = current->thread.vdso_base + vdso64_rt_sigtramp;
 441         } else {
 442                 err |= setup_trampoline(__NR_rt_sigreturn, &frame->tramp[0]);
 443                 if (err)
 444                         goto badframe;
 445                 regs->link = (unsigned long) &frame->tramp[0];
 446         }
 447         funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler;
 448
 449         /* Allocate a dummy caller frame for the signal handler. */
 450         newsp = (unsigned long)frame - __SIGNAL_FRAMESIZE;
 451         err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);
 452
 453         /* Set up "regs" so we "return" to the signal handler. */
 454         err |= get_user(regs->nip, &funct_desc_ptr->entry);
 455         regs->gpr[1] = newsp;
 456         err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
 457         regs->gpr[3] = signr;
 458         regs->result = 0;
 459         if (ka->sa.sa_flags & SA_SIGINFO) {
 460                 err |= get_user(regs->gpr[4], (unsigned long __user *)&frame->pinfo);
 461                 err |= get_user(regs->gpr[5], (unsigned long __user *)&frame->puc);
 462                 regs->gpr[6] = (unsigned long) frame;
 463         } else {
 464                 regs->gpr[4] = (unsigned long)&frame->uc.uc_mcontext;
 465         }
 466         if (err)
 467                 goto badframe;
 468
 469         return 1;
 470
 471 badframe:
 472 #if DEBUG_SIG
 473         printk("badframe in setup_rt_frame, regs=%p frame=%p newsp=%lx\n",
 474                regs, frame, newsp);
 475 #endif
 476         force_sigsegv(signr, current);
 477         return 0;
 478 }
 479
 480
 481 /*
 482  * OK, we're invoking a handler
 483  */
 484 static int handle_signal(unsigned long sig, struct k_sigaction *ka,
 485                          siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
 486 {
 487         int ret;
 488
 489         /* Set up Signal Frame */
 490         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 491
 492         if (ret) {
 493                 spin_lock_irq(&current->sighand->siglock);
 494                 sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 495                 if (!(ka->sa.sa_flags & SA_NODEFER))
 496                         sigaddset(&current->blocked,sig);
 497                 recalc_sigpending();
 498                 spin_unlock_irq(&current->sighand->siglock);
 499         }
 500
 501         return ret;
 502 }
 503
 504 static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
 505 {
 506         switch ((int)regs->result) {
 507         case -ERESTART_RESTARTBLOCK:
 508         case -ERESTARTNOHAND:
 509                 /* ERESTARTNOHAND means that the syscall should only be
 510                  * restarted if there was no handler for the signal, and since
 511                  * we only get here if there is a handler, we dont restart.
 512                  */
 513                 regs->result = -EINTR;
 514                 regs->gpr[3] = EINTR;
 515                 regs->ccr |= 0x10000000;
 516                 break;
 517         case -ERESTARTSYS:
 518                 /* ERESTARTSYS means to restart the syscall if there is no
 519                  * handler or the handler was registered with SA_RESTART
 520                  */
 521                 if (!(ka->sa.sa_flags & SA_RESTART)) {
 522                         regs->result = -EINTR;
 523                         regs->gpr[3] = EINTR;
 524                         regs->ccr |= 0x10000000;
 525                         break;
 526                 }
 527                 /* fallthrough */
 528         case -ERESTARTNOINTR:
 529                 /* ERESTARTNOINTR means that the syscall should be
 530                  * called again after the signal handler returns.
 531                  */
 532                 regs->gpr[3] = regs->orig_gpr3;
 533                 regs->nip -= 4;
 534                 regs->result = 0;
 535                 break;
 536         }
 537 }
 538
 539 /*
 540  * Note that 'init' is a special process: it doesn't get signals it doesn't
 541  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 542  * mistake.
 543  */
 544 int do_signal(sigset_t *oldset, struct pt_regs *regs)
 545 {
 546         siginfo_t info;
 547         int signr;
 548         struct k_sigaction ka;
 549
 550         /*
 551          * If the current thread is 32 bit - invoke the
 552          * 32 bit signal handling code
 553          */
 554         if (test_thread_flag(TIF_32BIT))
 555                 return do_signal32(oldset, regs);
 556
 557         if (!oldset)
 558                 oldset = &current->blocked;
 559
 560         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 561         if (signr > 0) {
 562                 /* Whee!  Actually deliver the signal.  */
 563                 if (TRAP(regs) == 0x0C00)
 564                         syscall_restart(regs, &ka);
 565
 566                 /*
 567                  * Reenable the DABR before delivering the signal to
 568                  * user space. The DABR will have been cleared if it
 569                  * triggered inside the kernel.
 570                  */
 571                 if (current->thread.dabr)
 572                         set_dabr(current->thread.dabr);
 573
 574                 return handle_signal(signr, &ka, &info, oldset, regs);
 575         }
 576
 577         if (TRAP(regs) == 0x0C00) {     /* System Call! */
 578                 if ((int)regs->result == -ERESTARTNOHAND ||
 579                     (int)regs->result == -ERESTARTSYS ||
 580                     (int)regs->result == -ERESTARTNOINTR) {
 581                         regs->gpr[3] = regs->orig_gpr3;
 582                         regs->nip -= 4; /* Back up & retry system call */
 583                         regs->result = 0;
 584                 } else if ((int)regs->result == -ERESTART_RESTARTBLOCK) {
 585                         regs->gpr[0] = __NR_restart_syscall;
 586                         regs->nip -= 4;
 587                         regs->result = 0;
 588                 }
 589         }
 590
 591         return 0;
 592 }
 593 EXPORT_SYMBOL(do_signal);