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signal.c

/*
 * File:         arch/blackfin/kernel/signal.c
 * Based on:
 * Author:
 *
 * Created:
 * Description:
 *
 * Modified:
 *               Copyright 2004-2006 Analog Devices Inc.
 *
 * Bugs:         Enter bugs at http://blackfin.uclinux.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see the file COPYING, or write
 * to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/signal.h>
#include <linux/syscalls.h>
#include <linux/ptrace.h>
#include <linux/tty.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <linux/freezer.h>
#include <linux/uaccess.h>

#include <asm/cacheflush.h>
#include <asm/ucontext.h>
#include <asm/fixed_code.h>

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

/* Location of the trace bit in SYSCFG. */
#define TRACE_BITS 0x0001

00048 struct fdpic_func_descriptor {
      unsigned long     text;
      unsigned long     GOT;
};

struct rt_sigframe {
      int sig;
      struct siginfo *pinfo;
      void *puc;
      /* This is no longer needed by the kernel, but unfortunately userspace
       * code expects it to be there.  */
      char retcode[8];
      struct siginfo info;
      struct ucontext uc;
};

asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
{
      return do_sigaltstack(uss, uoss, rdusp());
}

static inline int
rt_restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *pr0)
{
      unsigned long usp = 0;
      int err = 0;

#define RESTORE(x) err |= __get_user(regs->x, &sc->sc_##x)

      /* restore passed registers */
      RESTORE(r0); RESTORE(r1); RESTORE(r2); RESTORE(r3);
      RESTORE(r4); RESTORE(r5); RESTORE(r6); RESTORE(r7);
      RESTORE(p0); RESTORE(p1); RESTORE(p2); RESTORE(p3);
      RESTORE(p4); RESTORE(p5);
      err |= __get_user(usp, &sc->sc_usp);
      wrusp(usp);
      RESTORE(a0w); RESTORE(a1w);
      RESTORE(a0x); RESTORE(a1x);
      RESTORE(astat);
      RESTORE(rets);
      RESTORE(pc);
      RESTORE(retx);
      RESTORE(fp);
      RESTORE(i0); RESTORE(i1); RESTORE(i2); RESTORE(i3);
      RESTORE(m0); RESTORE(m1); RESTORE(m2); RESTORE(m3);
      RESTORE(l0); RESTORE(l1); RESTORE(l2); RESTORE(l3);
      RESTORE(b0); RESTORE(b1); RESTORE(b2); RESTORE(b3);
      RESTORE(lc0); RESTORE(lc1);
      RESTORE(lt0); RESTORE(lt1);
      RESTORE(lb0); RESTORE(lb1);
      RESTORE(seqstat);

      regs->orig_p0 = -1;     /* disable syscall checks */

      *pr0 = regs->r0;
      return err;
}

asmlinkage int do_rt_sigreturn(unsigned long __unused)
{
      struct pt_regs *regs = (struct pt_regs *)__unused;
      unsigned long usp = rdusp();
      struct rt_sigframe *frame = (struct rt_sigframe *)(usp);
      sigset_t set;
      int r0;

      if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
            goto badframe;
      if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
            goto badframe;

      sigdelsetmask(&set, ~_BLOCKABLE);
      spin_lock_irq(&current->sighand->siglock);
      current->blocked = set;
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);

      if (rt_restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
            goto badframe;

      if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->usp) == -EFAULT)
            goto badframe;

      return r0;

 badframe:
      force_sig(SIGSEGV, current);
      return 0;
}

static inline int rt_setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs)
{
      int err = 0;

#define SETUP(x) err |= __put_user(regs->x, &sc->sc_##x)

      SETUP(r0); SETUP(r1); SETUP(r2); SETUP(r3);
      SETUP(r4); SETUP(r5); SETUP(r6); SETUP(r7);
      SETUP(p0); SETUP(p1); SETUP(p2); SETUP(p3);
      SETUP(p4); SETUP(p5);
      err |= __put_user(rdusp(), &sc->sc_usp);
      SETUP(a0w); SETUP(a1w);
      SETUP(a0x); SETUP(a1x);
      SETUP(astat);
      SETUP(rets);
      SETUP(pc);
      SETUP(retx);
      SETUP(fp);
      SETUP(i0); SETUP(i1); SETUP(i2); SETUP(i3);
      SETUP(m0); SETUP(m1); SETUP(m2); SETUP(m3);
      SETUP(l0); SETUP(l1); SETUP(l2); SETUP(l3);
      SETUP(b0); SETUP(b1); SETUP(b2); SETUP(b3);
      SETUP(lc0); SETUP(lc1);
      SETUP(lt0); SETUP(lt1);
      SETUP(lb0); SETUP(lb1);
      SETUP(seqstat);

      return err;
}

static inline void *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
                         size_t frame_size)
{
      unsigned long usp;

      /* Default to using normal stack.  */
      usp = rdusp();

      /* This is the X/Open sanctioned signal stack switching.  */
      if (ka->sa.sa_flags & SA_ONSTACK) {
            if (!on_sig_stack(usp))
                  usp = current->sas_ss_sp + current->sas_ss_size;
      }
      return (void *)((usp - frame_size) & -8UL);
}

static int
setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t * info,
             sigset_t * set, struct pt_regs *regs)
{
      struct rt_sigframe *frame;
      int err = 0;

      frame = get_sigframe(ka, regs, sizeof(*frame));

      err |= __put_user((current_thread_info()->exec_domain
                     && current_thread_info()->exec_domain->signal_invmap
                     && sig < 32
                     ? current_thread_info()->exec_domain->
                     signal_invmap[sig] : sig), &frame->sig);

      err |= __put_user(&frame->info, &frame->pinfo);
      err |= __put_user(&frame->uc, &frame->puc);
      err |= copy_siginfo_to_user(&frame->info, info);

      /* Create the ucontext.  */
      err |= __put_user(0, &frame->uc.uc_flags);
      err |= __put_user(0, &frame->uc.uc_link);
      err |=
          __put_user((void *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
      err |= __put_user(sas_ss_flags(rdusp()), &frame->uc.uc_stack.ss_flags);
      err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
      err |= rt_setup_sigcontext(&frame->uc.uc_mcontext, regs);
      err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

      if (err)
            goto give_sigsegv;

      /* Set up registers for signal handler */
      wrusp((unsigned long)frame);
      if (current->personality & FDPIC_FUNCPTRS) {
            struct fdpic_func_descriptor __user *funcptr =
                  (struct fdpic_func_descriptor *) ka->sa.sa_handler;
            __get_user(regs->pc, &funcptr->text);
            __get_user(regs->p3, &funcptr->GOT);
      } else
            regs->pc = (unsigned long)ka->sa.sa_handler;
      regs->rets = SIGRETURN_STUB;

      regs->r0 = frame->sig;
      regs->r1 = (unsigned long)(&frame->info);
      regs->r2 = (unsigned long)(&frame->uc);

      /*
       * Clear the trace flag when entering the signal handler, but
       * notify any tracer that was single-stepping it. The tracer
       * may want to single-step inside the handler too.
       */
      if (regs->syscfg & TRACE_BITS) {
            regs->syscfg &= ~TRACE_BITS;
            ptrace_notify(SIGTRAP);
      }

      return 0;

 give_sigsegv:
      if (sig == SIGSEGV)
            ka->sa.sa_handler = SIG_DFL;
      force_sig(SIGSEGV, current);
      return -EFAULT;
}

static inline void
handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
{
      switch (regs->r0) {
      case -ERESTARTNOHAND:
            if (!has_handler)
                  goto do_restart;
            regs->r0 = -EINTR;
            break;

      case -ERESTARTSYS:
            if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
                  regs->r0 = -EINTR;
                  break;
            }
            /* fallthrough */
      case -ERESTARTNOINTR:
 do_restart:
            regs->p0 = regs->orig_p0;
            regs->r0 = regs->orig_r0;
            regs->pc -= 2;
            break;
      }
}

/*
 * OK, we're invoking a handler
 */
static int
handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
            sigset_t *oldset, struct pt_regs *regs)
{
      int ret;

      /* are we from a system call? to see pt_regs->orig_p0 */
      if (regs->orig_p0 >= 0)
            /* If so, check system call restarting.. */
            handle_restart(regs, ka, 1);

      /* set up the stack frame */
      ret = setup_rt_frame(sig, ka, info, oldset, regs);

      if (ret == 0) {
            spin_lock_irq(&current->sighand->siglock);
            sigorsets(&current->blocked, &current->blocked,
                    &ka->sa.sa_mask);
            if (!(ka->sa.sa_flags & SA_NODEFER))
                  sigaddset(&current->blocked, sig);
            recalc_sigpending();
            spin_unlock_irq(&current->sighand->siglock);
      }
      return ret;
}

/*
 * Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 *
 * Note that we go through the signals twice: once to check the signals
 * that the kernel can handle, and then we build all the user-level signal
 * handling stack-frames in one go after that.
 */
asmlinkage void do_signal(struct pt_regs *regs)
{
      siginfo_t info;
      int signr;
      struct k_sigaction ka;
      sigset_t *oldset;

      current->thread.esp0 = (unsigned long)regs;

      if (try_to_freeze())
            goto no_signal;

      if (test_thread_flag(TIF_RESTORE_SIGMASK))
            oldset = &current->saved_sigmask;
      else
            oldset = &current->blocked;

      signr = get_signal_to_deliver(&info, &ka, regs, NULL);
      if (signr > 0) {
            /* Whee!  Actually deliver the signal.  */
            if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
                  /* a signal was successfully delivered; the saved
                   * sigmask will have been stored in the signal frame,
                   * and will be restored by sigreturn, so we can simply
                   * clear the TIF_RESTORE_SIGMASK flag */
                  if (test_thread_flag(TIF_RESTORE_SIGMASK))
                        clear_thread_flag(TIF_RESTORE_SIGMASK);
            }

            return;
      }

 no_signal:
      /* Did we come from a system call? */
      if (regs->orig_p0 >= 0)
            /* Restart the system call - no handlers present */
            handle_restart(regs, NULL, 0);

      /* if there's no signal to deliver, we just put the saved sigmask
       * back */
      if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
            clear_thread_flag(TIF_RESTORE_SIGMASK);
            sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
      }
}

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