LXR linux/arch/sparc/kernel/signal

   1/*
   2 *  arch/sparc64/kernel/signal.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 *  Copyright (C) 1995, 2008 David S. Miller (davem@davemloft.net)
   6 *  Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
   7 *  Copyright (C) 1997 Eddie C. Dost   (ecd@skynet.be)
   8 *  Copyright (C) 1997,1998 Jakub Jelinek   (jj@sunsite.mff.cuni.cz)
   9 */
  10
  11#ifdef CONFIG_COMPAT
  12#include <linux/compat.h>       /* for compat_old_sigset_t */
  13#endif
  14#include <linux/sched.h>
  15#include <linux/kernel.h>
  16#include <linux/signal.h>
  17#include <linux/errno.h>
  18#include <linux/wait.h>
  19#include <linux/ptrace.h>
  20#include <linux/tracehook.h>
  21#include <linux/unistd.h>
  22#include <linux/mm.h>
  23#include <linux/tty.h>
  24#include <linux/binfmts.h>
  25#include <linux/bitops.h>
  26
  27#include <asm/uaccess.h>
  28#include <asm/ptrace.h>
  29#include <asm/pgtable.h>
  30#include <asm/fpumacro.h>
  31#include <asm/uctx.h>
  32#include <asm/siginfo.h>
  33#include <asm/visasm.h>
  34
  35#include "entry.h"
  36#include "systbls.h"
  37
  38#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  39
  40/* {set, get}context() needed for 64-bit SparcLinux userland. */
  41asmlinkage void sparc64_set_context(struct pt_regs *regs)
  42{
  43        struct ucontext __user *ucp = (struct ucontext __user *)
  44                regs->u_regs[UREG_I0];
  45        mc_gregset_t __user *grp;
  46        unsigned long pc, npc, tstate;
  47        unsigned long fp, i7;
  48        unsigned char fenab;
  49        int err;
  50
  51        flush_user_windows();
  52        if (get_thread_wsaved()                                 ||
  53            (((unsigned long)ucp) & (sizeof(unsigned long)-1))  ||
  54            (!__access_ok(ucp, sizeof(*ucp))))
  55                goto do_sigsegv;
  56        grp  = &ucp->uc_mcontext.mc_gregs;
  57        err  = __get_user(pc, &((*grp)[MC_PC]));
  58        err |= __get_user(npc, &((*grp)[MC_NPC]));
  59        if (err || ((pc | npc) & 3))
  60                goto do_sigsegv;
  61        if (regs->u_regs[UREG_I1]) {
  62                sigset_t set;
  63
  64                if (_NSIG_WORDS == 1) {
  65                        if (__get_user(set.sig[0], &ucp->uc_sigmask.sig[0]))
  66                                goto do_sigsegv;
  67                } else {
  68                        if (__copy_from_user(&set, &ucp->uc_sigmask, sizeof(sigset_t)))
  69                                goto do_sigsegv;
  70                }
  71                sigdelsetmask(&set, ~_BLOCKABLE);
  72                spin_lock_irq(&current->sighand->siglock);
  73                current->blocked = set;
  74                recalc_sigpending();
  75                spin_unlock_irq(&current->sighand->siglock);
  76        }
  77        if (test_thread_flag(TIF_32BIT)) {
  78                pc &= 0xffffffff;
  79                npc &= 0xffffffff;
  80        }
  81        regs->tpc = pc;
  82        regs->tnpc = npc;
  83        err |= __get_user(regs->y, &((*grp)[MC_Y]));
  84        err |= __get_user(tstate, &((*grp)[MC_TSTATE]));
  85        regs->tstate &= ~(TSTATE_ASI | TSTATE_ICC | TSTATE_XCC);
  86        regs->tstate |= (tstate & (TSTATE_ASI | TSTATE_ICC | TSTATE_XCC));
  87        err |= __get_user(regs->u_regs[UREG_G1], (&(*grp)[MC_G1]));
  88        err |= __get_user(regs->u_regs[UREG_G2], (&(*grp)[MC_G2]));
  89        err |= __get_user(regs->u_regs[UREG_G3], (&(*grp)[MC_G3]));
  90        err |= __get_user(regs->u_regs[UREG_G4], (&(*grp)[MC_G4]));
  91        err |= __get_user(regs->u_regs[UREG_G5], (&(*grp)[MC_G5]));
  92        err |= __get_user(regs->u_regs[UREG_G6], (&(*grp)[MC_G6]));
  93
  94        /* Skip %g7 as that's the thread register in userspace.  */
  95
  96        err |= __get_user(regs->u_regs[UREG_I0], (&(*grp)[MC_O0]));
  97        err |= __get_user(regs->u_regs[UREG_I1], (&(*grp)[MC_O1]));
  98        err |= __get_user(regs->u_regs[UREG_I2], (&(*grp)[MC_O2]));
  99        err |= __get_user(regs->u_regs[UREG_I3], (&(*grp)[MC_O3]));
 100        err |= __get_user(regs->u_regs[UREG_I4], (&(*grp)[MC_O4]));
 101        err |= __get_user(regs->u_regs[UREG_I5], (&(*grp)[MC_O5]));
 102        err |= __get_user(regs->u_regs[UREG_I6], (&(*grp)[MC_O6]));
 103        err |= __get_user(regs->u_regs[UREG_I7], (&(*grp)[MC_O7]));
 104
 105        err |= __get_user(fp, &(ucp->uc_mcontext.mc_fp));
 106        err |= __get_user(i7, &(ucp->uc_mcontext.mc_i7));
 107        err |= __put_user(fp,
 108              (&(((struct reg_window __user *)(STACK_BIAS+regs->u_regs[UREG_I6]))->ins[6])));
 109        err |= __put_user(i7,
 110              (&(((struct reg_window __user *)(STACK_BIAS+regs->u_regs[UREG_I6]))->ins[7])));
 111
 112        err |= __get_user(fenab, &(ucp->uc_mcontext.mc_fpregs.mcfpu_enab));
 113        if (fenab) {
 114                unsigned long *fpregs = current_thread_info()->fpregs;
 115                unsigned long fprs;
 116                
 117                fprs_write(0);
 118                err |= __get_user(fprs, &(ucp->uc_mcontext.mc_fpregs.mcfpu_fprs));
 119                if (fprs & FPRS_DL)
 120                        err |= copy_from_user(fpregs,
 121                                              &(ucp->uc_mcontext.mc_fpregs.mcfpu_fregs),
 122                                              (sizeof(unsigned int) * 32));
 123                if (fprs & FPRS_DU)
 124                        err |= copy_from_user(fpregs+16,
 125                         ((unsigned long __user *)&(ucp->uc_mcontext.mc_fpregs.mcfpu_fregs))+16,
 126                         (sizeof(unsigned int) * 32));
 127                err |= __get_user(current_thread_info()->xfsr[0],
 128                                  &(ucp->uc_mcontext.mc_fpregs.mcfpu_fsr));
 129                err |= __get_user(current_thread_info()->gsr[0],
 130                                  &(ucp->uc_mcontext.mc_fpregs.mcfpu_gsr));
 131                regs->tstate &= ~TSTATE_PEF;
 132        }
 133        if (err)
 134                goto do_sigsegv;
 135
 136        return;
 137do_sigsegv:
 138        force_sig(SIGSEGV, current);
 139}
 140
 141asmlinkage void sparc64_get_context(struct pt_regs *regs)
 142{
 143        struct ucontext __user *ucp = (struct ucontext __user *)
 144                regs->u_regs[UREG_I0];
 145        mc_gregset_t __user *grp;
 146        mcontext_t __user *mcp;
 147        unsigned long fp, i7;
 148        unsigned char fenab;
 149        int err;
 150
 151        synchronize_user_stack();
 152        if (get_thread_wsaved() || clear_user(ucp, sizeof(*ucp)))
 153                goto do_sigsegv;
 154
 155#if 1
 156        fenab = 0; /* IMO get_context is like any other system call, thus modifies FPU state -jj */
 157#else
 158        fenab = (current_thread_info()->fpsaved[0] & FPRS_FEF);
 159#endif
 160                
 161        mcp = &ucp->uc_mcontext;
 162        grp = &mcp->mc_gregs;
 163
 164        /* Skip over the trap instruction, first. */
 165        if (test_thread_flag(TIF_32BIT)) {
 166                regs->tpc   = (regs->tnpc & 0xffffffff);
 167                regs->tnpc  = (regs->tnpc + 4) & 0xffffffff;
 168        } else {
 169                regs->tpc   = regs->tnpc;
 170                regs->tnpc += 4;
 171        }
 172        err = 0;
 173        if (_NSIG_WORDS == 1)
 174                err |= __put_user(current->blocked.sig[0],
 175                                  (unsigned long __user *)&ucp->uc_sigmask);
 176        else
 177                err |= __copy_to_user(&ucp->uc_sigmask, &current->blocked,
 178                                      sizeof(sigset_t));
 179
 180        err |= __put_user(regs->tstate, &((*grp)[MC_TSTATE]));
 181        err |= __put_user(regs->tpc, &((*grp)[MC_PC]));
 182        err |= __put_user(regs->tnpc, &((*grp)[MC_NPC]));
 183        err |= __put_user(regs->y, &((*grp)[MC_Y]));
 184        err |= __put_user(regs->u_regs[UREG_G1], &((*grp)[MC_G1]));
 185        err |= __put_user(regs->u_regs[UREG_G2], &((*grp)[MC_G2]));
 186        err |= __put_user(regs->u_regs[UREG_G3], &((*grp)[MC_G3]));
 187        err |= __put_user(regs->u_regs[UREG_G4], &((*grp)[MC_G4]));
 188        err |= __put_user(regs->u_regs[UREG_G5], &((*grp)[MC_G5]));
 189        err |= __put_user(regs->u_regs[UREG_G6], &((*grp)[MC_G6]));
 190        err |= __put_user(regs->u_regs[UREG_G7], &((*grp)[MC_G7]));
 191        err |= __put_user(regs->u_regs[UREG_I0], &((*grp)[MC_O0]));
 192        err |= __put_user(regs->u_regs[UREG_I1], &((*grp)[MC_O1]));
 193        err |= __put_user(regs->u_regs[UREG_I2], &((*grp)[MC_O2]));
 194        err |= __put_user(regs->u_regs[UREG_I3], &((*grp)[MC_O3]));
 195        err |= __put_user(regs->u_regs[UREG_I4], &((*grp)[MC_O4]));
 196        err |= __put_user(regs->u_regs[UREG_I5], &((*grp)[MC_O5]));
 197        err |= __put_user(regs->u_regs[UREG_I6], &((*grp)[MC_O6]));
 198        err |= __put_user(regs->u_regs[UREG_I7], &((*grp)[MC_O7]));
 199
 200        err |= __get_user(fp,
 201                 (&(((struct reg_window __user *)(STACK_BIAS+regs->u_regs[UREG_I6]))->ins[6])));
 202        err |= __get_user(i7,
 203                 (&(((struct reg_window __user *)(STACK_BIAS+regs->u_regs[UREG_I6]))->ins[7])));
 204        err |= __put_user(fp, &(mcp->mc_fp));
 205        err |= __put_user(i7, &(mcp->mc_i7));
 206
 207        err |= __put_user(fenab, &(mcp->mc_fpregs.mcfpu_enab));
 208        if (fenab) {
 209                unsigned long *fpregs = current_thread_info()->fpregs;
 210                unsigned long fprs;
 211                
 212                fprs = current_thread_info()->fpsaved[0];
 213                if (fprs & FPRS_DL)
 214                        err |= copy_to_user(&(mcp->mc_fpregs.mcfpu_fregs), fpregs,
 215                                            (sizeof(unsigned int) * 32));
 216                if (fprs & FPRS_DU)
 217                        err |= copy_to_user(
 218                          ((unsigned long __user *)&(mcp->mc_fpregs.mcfpu_fregs))+16, fpregs+16,
 219                          (sizeof(unsigned int) * 32));
 220                err |= __put_user(current_thread_info()->xfsr[0], &(mcp->mc_fpregs.mcfpu_fsr));
 221                err |= __put_user(current_thread_info()->gsr[0], &(mcp->mc_fpregs.mcfpu_gsr));
 222                err |= __put_user(fprs, &(mcp->mc_fpregs.mcfpu_fprs));
 223        }
 224        if (err)
 225                goto do_sigsegv;
 226
 227        return;
 228do_sigsegv:
 229        force_sig(SIGSEGV, current);
 230}
 231
 232struct rt_signal_frame {
 233        struct sparc_stackf     ss;
 234        siginfo_t               info;
 235        struct pt_regs          regs;
 236        __siginfo_fpu_t __user  *fpu_save;
 237        stack_t                 stack;
 238        sigset_t                mask;
 239        __siginfo_fpu_t         fpu_state;
 240};
 241
 242static long _sigpause_common(old_sigset_t set)
 243{
 244        set &= _BLOCKABLE;
 245        spin_lock_irq(&current->sighand->siglock);
 246        current->saved_sigmask = current->blocked;
 247        siginitset(&current->blocked, set);
 248        recalc_sigpending();
 249        spin_unlock_irq(&current->sighand->siglock);
 250
 251        current->state = TASK_INTERRUPTIBLE;
 252        schedule();
 253
 254        set_restore_sigmask();
 255
 256        return -ERESTARTNOHAND;
 257}
 258
 259asmlinkage long sys_sigpause(unsigned int set)
 260{
 261        return _sigpause_common(set);
 262}
 263
 264asmlinkage long sys_sigsuspend(old_sigset_t set)
 265{
 266        return _sigpause_common(set);
 267}
 268
 269static inline int
 270restore_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
 271{
 272        unsigned long *fpregs = current_thread_info()->fpregs;
 273        unsigned long fprs;
 274        int err;
 275
 276        err = __get_user(fprs, &fpu->si_fprs);
 277        fprs_write(0);
 278        regs->tstate &= ~TSTATE_PEF;
 279        if (fprs & FPRS_DL)
 280                err |= copy_from_user(fpregs, &fpu->si_float_regs[0],
 281                               (sizeof(unsigned int) * 32));
 282        if (fprs & FPRS_DU)
 283                err |= copy_from_user(fpregs+16, &fpu->si_float_regs[32],
 284                               (sizeof(unsigned int) * 32));
 285        err |= __get_user(current_thread_info()->xfsr[0], &fpu->si_fsr);
 286        err |= __get_user(current_thread_info()->gsr[0], &fpu->si_gsr);
 287        current_thread_info()->fpsaved[0] |= fprs;
 288        return err;
 289}
 290
 291void do_rt_sigreturn(struct pt_regs *regs)
 292{
 293        struct rt_signal_frame __user *sf;
 294        unsigned long tpc, tnpc, tstate;
 295        __siginfo_fpu_t __user *fpu_save;
 296        sigset_t set;
 297        int err;
 298
 299        /* Always make any pending restarted system calls return -EINTR */
 300        current_thread_info()->restart_block.fn = do_no_restart_syscall;
 301
 302        synchronize_user_stack ();
 303        sf = (struct rt_signal_frame __user *)
 304                (regs->u_regs [UREG_FP] + STACK_BIAS);
 305
 306        /* 1. Make sure we are not getting garbage from the user */
 307        if (((unsigned long) sf) & 3)
 308                goto segv;
 309
 310        err = get_user(tpc, &sf->regs.tpc);
 311        err |= __get_user(tnpc, &sf->regs.tnpc);
 312        if (test_thread_flag(TIF_32BIT)) {
 313                tpc &= 0xffffffff;
 314                tnpc &= 0xffffffff;
 315        }
 316        err |= ((tpc | tnpc) & 3);
 317
 318        /* 2. Restore the state */
 319        err |= __get_user(regs->y, &sf->regs.y);
 320        err |= __get_user(tstate, &sf->regs.tstate);
 321        err |= copy_from_user(regs->u_regs, sf->regs.u_regs, sizeof(regs->u_regs));
 322
 323        /* User can only change condition codes and %asi in %tstate. */
 324        regs->tstate &= ~(TSTATE_ASI | TSTATE_ICC | TSTATE_XCC);
 325        regs->tstate |= (tstate & (TSTATE_ASI | TSTATE_ICC | TSTATE_XCC));
 326
 327        err |= __get_user(fpu_save, &sf->fpu_save);
 328        if (fpu_save)
 329                err |= restore_fpu_state(regs, &sf->fpu_state);
 330
 331        err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
 332        err |= do_sigaltstack(&sf->stack, NULL, (unsigned long)sf);
 333
 334        if (err)
 335                goto segv;
 336
 337        regs->tpc = tpc;
 338        regs->tnpc = tnpc;
 339
 340        /* Prevent syscall restart.  */
 341        pt_regs_clear_syscall(regs);
 342
 343        sigdelsetmask(&set, ~_BLOCKABLE);
 344        spin_lock_irq(&current->sighand->siglock);
 345        current->blocked = set;
 346        recalc_sigpending();
 347        spin_unlock_irq(&current->sighand->siglock);
 348        return;
 349segv:
 350        force_sig(SIGSEGV, current);
 351}
 352
 353/* Checks if the fp is valid */
 354static int invalid_frame_pointer(void __user *fp, int fplen)
 355{
 356        if (((unsigned long) fp) & 7)
 357                return 1;
 358        return 0;
 359}
 360
 361static inline int
 362save_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
 363{
 364        unsigned long *fpregs = current_thread_info()->fpregs;
 365        unsigned long fprs;
 366        int err = 0;
 367        
 368        fprs = current_thread_info()->fpsaved[0];
 369        if (fprs & FPRS_DL)
 370                err |= copy_to_user(&fpu->si_float_regs[0], fpregs,
 371                                    (sizeof(unsigned int) * 32));
 372        if (fprs & FPRS_DU)
 373                err |= copy_to_user(&fpu->si_float_regs[32], fpregs+16,
 374                                    (sizeof(unsigned int) * 32));
 375        err |= __put_user(current_thread_info()->xfsr[0], &fpu->si_fsr);
 376        err |= __put_user(current_thread_info()->gsr[0], &fpu->si_gsr);
 377        err |= __put_user(fprs, &fpu->si_fprs);
 378
 379        return err;
 380}
 381
 382static inline void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, unsigned long framesize)
 383{
 384        unsigned long sp = regs->u_regs[UREG_FP] + STACK_BIAS;
 385
 386        /*
 387         * If we are on the alternate signal stack and would overflow it, don't.
 388         * Return an always-bogus address instead so we will die with SIGSEGV.
 389         */
 390        if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
 391                return (void __user *) -1L;
 392
 393        /* This is the X/Open sanctioned signal stack switching.  */
 394        if (ka->sa.sa_flags & SA_ONSTACK) {
 395                if (sas_ss_flags(sp) == 0)
 396                        sp = current->sas_ss_sp + current->sas_ss_size;
 397        }
 398
 399        /* Always align the stack frame.  This handles two cases.  First,
 400         * sigaltstack need not be mindful of platform specific stack
 401         * alignment.  Second, if we took this signal because the stack
 402         * is not aligned properly, we'd like to take the signal cleanly
 403         * and report that.
 404         */
 405        sp &= ~7UL;
 406
 407        return (void __user *)(sp - framesize);
 408}
 409
 410static inline void
 411setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
 412               int signo, sigset_t *oldset, siginfo_t *info)
 413{
 414        struct rt_signal_frame __user *sf;
 415        int sigframe_size, err;
 416
 417        /* 1. Make sure everything is clean */
 418        synchronize_user_stack();
 419        save_and_clear_fpu();
 420        
 421        sigframe_size = sizeof(struct rt_signal_frame);
 422        if (!(current_thread_info()->fpsaved[0] & FPRS_FEF))
 423                sigframe_size -= sizeof(__siginfo_fpu_t);
 424
 425        sf = (struct rt_signal_frame __user *)
 426                get_sigframe(ka, regs, sigframe_size);
 427        
 428        if (invalid_frame_pointer (sf, sigframe_size))
 429                goto sigill;
 430
 431        if (get_thread_wsaved() != 0)
 432                goto sigill;
 433
 434        /* 2. Save the current process state */
 435        err = copy_to_user(&sf->regs, regs, sizeof (*regs));
 436
 437        if (current_thread_info()->fpsaved[0] & FPRS_FEF) {
 438                err |= save_fpu_state(regs, &sf->fpu_state);
 439                err |= __put_user((u64)&sf->fpu_state, &sf->fpu_save);
 440        } else {
 441                err |= __put_user(0, &sf->fpu_save);
 442        }
 443        
 444        /* Setup sigaltstack */
 445        err |= __put_user(current->sas_ss_sp, &sf->stack.ss_sp);
 446        err |= __put_user(sas_ss_flags(regs->u_regs[UREG_FP]), &sf->stack.ss_flags);
 447        err |= __put_user(current->sas_ss_size, &sf->stack.ss_size);
 448
 449        err |= copy_to_user(&sf->mask, oldset, sizeof(sigset_t));
 450
 451        err |= copy_in_user((u64 __user *)sf,
 452                            (u64 __user *)(regs->u_regs[UREG_FP]+STACK_BIAS),
 453                            sizeof(struct reg_window));
 454
 455        if (info)
 456                err |= copy_siginfo_to_user(&sf->info, info);
 457        else {
 458                err |= __put_user(signo, &sf->info.si_signo);
 459                err |= __put_user(SI_NOINFO, &sf->info.si_code);
 460        }
 461        if (err)
 462                goto sigsegv;
 463        
 464        /* 3. signal handler back-trampoline and parameters */
 465        regs->u_regs[UREG_FP] = ((unsigned long) sf) - STACK_BIAS;
 466        regs->u_regs[UREG_I0] = signo;
 467        regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
 468
 469        /* The sigcontext is passed in this way because of how it
 470         * is defined in GLIBC's /usr/include/bits/sigcontext.h
 471         * for sparc64.  It includes the 128 bytes of siginfo_t.
 472         */
 473        regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
 474
 475        /* 5. signal handler */
 476        regs->tpc = (unsigned long) ka->sa.sa_handler;
 477        regs->tnpc = (regs->tpc + 4);
 478        if (test_thread_flag(TIF_32BIT)) {
 479                regs->tpc &= 0xffffffff;
 480                regs->tnpc &= 0xffffffff;
 481        }
 482        /* 4. return to kernel instructions */
 483        regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
 484        return;
 485
 486sigill:
 487        do_exit(SIGILL);
 488sigsegv:
 489        force_sigsegv(signo, current);
 490}
 491
 492static inline void handle_signal(unsigned long signr, struct k_sigaction *ka,
 493                                 siginfo_t *info,
 494                                 sigset_t *oldset, struct pt_regs *regs)
 495{
 496        setup_rt_frame(ka, regs, signr, oldset,
 497                       (ka->sa.sa_flags & SA_SIGINFO) ? info : NULL);
 498        spin_lock_irq(&current->sighand->siglock);
 499        sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
 500        if (!(ka->sa.sa_flags & SA_NOMASK))
 501                sigaddset(&current->blocked,signr);
 502        recalc_sigpending();
 503        spin_unlock_irq(&current->sighand->siglock);
 504}
 505
 506static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
 507                                   struct sigaction *sa)
 508{
 509        switch (regs->u_regs[UREG_I0]) {
 510        case ERESTART_RESTARTBLOCK:
 511        case ERESTARTNOHAND:
 512        no_system_call_restart:
 513                regs->u_regs[UREG_I0] = EINTR;
 514                regs->tstate |= (TSTATE_ICARRY|TSTATE_XCARRY);
 515                break;
 516        case ERESTARTSYS:
 517                if (!(sa->sa_flags & SA_RESTART))
 518                        goto no_system_call_restart;
 519                /* fallthrough */
 520        case ERESTARTNOINTR:
 521                regs->u_regs[UREG_I0] = orig_i0;
 522                regs->tpc -= 4;
 523                regs->tnpc -= 4;
 524        }
 525}
 526
 527/* Note that 'init' is a special process: it doesn't get signals it doesn't
 528 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 529 * mistake.
 530 */
 531static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
 532{
 533        struct k_sigaction ka;
 534        int restart_syscall;
 535        sigset_t *oldset;
 536        siginfo_t info;
 537        int signr;
 538        
 539        if (pt_regs_is_syscall(regs) &&
 540            (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY))) {
 541                restart_syscall = 1;
 542        } else
 543                restart_syscall = 0;
 544
 545        if (current_thread_info()->status & TS_RESTORE_SIGMASK)
 546                oldset = &current->saved_sigmask;
 547        else
 548                oldset = &current->blocked;
 549
 550#ifdef CONFIG_COMPAT
 551        if (test_thread_flag(TIF_32BIT)) {
 552                extern void do_signal32(sigset_t *, struct pt_regs *,
 553                                        int restart_syscall,
 554                                        unsigned long orig_i0);
 555                do_signal32(oldset, regs, restart_syscall, orig_i0);
 556                return;
 557        }
 558#endif  
 559
 560        signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 561
 562        /* If the debugger messes with the program counter, it clears
 563         * the software "in syscall" bit, directing us to not perform
 564         * a syscall restart.
 565         */
 566        if (restart_syscall && !pt_regs_is_syscall(regs))
 567                restart_syscall = 0;
 568
 569        if (signr > 0) {
 570                if (restart_syscall)
 571                        syscall_restart(orig_i0, regs, &ka.sa);
 572                handle_signal(signr, &ka, &info, oldset, regs);
 573
 574                /* A signal was successfully delivered; the saved
 575                 * sigmask will have been stored in the signal frame,
 576                 * and will be restored by sigreturn, so we can simply
 577                 * clear the TS_RESTORE_SIGMASK flag.
 578                 */
 579                current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 580
 581                tracehook_signal_handler(signr, &info, &ka, regs, 0);
 582                return;
 583        }
 584        if (restart_syscall &&
 585            (regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
 586             regs->u_regs[UREG_I0] == ERESTARTSYS ||
 587             regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
 588                /* replay the system call when we are done */
 589                regs->u_regs[UREG_I0] = orig_i0;
 590                regs->tpc -= 4;
 591                regs->tnpc -= 4;
 592        }
 593        if (restart_syscall &&
 594            regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
 595                regs->u_regs[UREG_G1] = __NR_restart_syscall;
 596                regs->tpc -= 4;
 597                regs->tnpc -= 4;
 598        }
 599
 600        /* If there's no signal to deliver, we just put the saved sigmask
 601         * back
 602         */
 603        if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
 604                current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
 605                sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 606        }
 607}
 608
 609void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, unsigned long thread_info_flags)
 610{
 611        if (thread_info_flags & _TIF_SIGPENDING)
 612                do_signal(regs, orig_i0);
 613        if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 614                clear_thread_flag(TIF_NOTIFY_RESUME);
 615                tracehook_notify_resume(regs);
 616                if (current->replacement_session_keyring)
 617                        key_replace_session_keyring();
 618        }
 619}
 620
 621