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signal.c

/*  linux/arch/sparc/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
 *  Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
 *  Copyright (C) 1997 Eddie C. Dost   (ecd@skynet.be)
 */

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/mm.h>
#include <linux/tty.h>
#include <linux/smp.h>
#include <linux/binfmts.h>    /* do_coredum */
#include <linux/bitops.h>
#include <linux/tracehook.h>

#include <asm/uaccess.h>
#include <asm/ptrace.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>   /* flush_sig_insns */

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

extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
               void *fpqueue, unsigned long *fpqdepth);
extern void fpload(unsigned long *fpregs, unsigned long *fsr);

struct signal_frame {
      struct sparc_stackf     ss;
      __siginfo_t       info;
      __siginfo_fpu_t __user  *fpu_save;
      unsigned long           insns[2] __attribute__ ((aligned (8)));
      unsigned int            extramask[_NSIG_WORDS - 1];
      unsigned int            extra_size; /* Should be 0 */
      __siginfo_fpu_t         fpu_state;
};

struct rt_signal_frame {
      struct sparc_stackf     ss;
      siginfo_t         info;
      struct pt_regs          regs;
      sigset_t          mask;
      __siginfo_fpu_t __user  *fpu_save;
      unsigned int            insns[2];
      stack_t                 stack;
      unsigned int            extra_size; /* Should be 0 */
      __siginfo_fpu_t         fpu_state;
};

/* Align macros */
#define SF_ALIGNEDSZ  (((sizeof(struct signal_frame) + 7) & (~7)))
#define RT_ALIGNEDSZ  (((sizeof(struct rt_signal_frame) + 7) & (~7)))

static int _sigpause_common(old_sigset_t set)
{
      set &= _BLOCKABLE;
      spin_lock_irq(&current->sighand->siglock);
      current->saved_sigmask = current->blocked;
      siginitset(&current->blocked, set);
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);

      current->state = TASK_INTERRUPTIBLE;
      schedule();
      set_thread_flag(TIF_RESTORE_SIGMASK);

      return -ERESTARTNOHAND;
}

asmlinkage int sys_sigsuspend(old_sigset_t set)
{
      return _sigpause_common(set);
}

static inline int
restore_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
{
      int err;
#ifdef CONFIG_SMP
      if (test_tsk_thread_flag(current, TIF_USEDFPU))
            regs->psr &= ~PSR_EF;
#else
      if (current == last_task_used_math) {
            last_task_used_math = NULL;
            regs->psr &= ~PSR_EF;
      }
#endif
      set_used_math();
      clear_tsk_thread_flag(current, TIF_USEDFPU);

      if (!access_ok(VERIFY_READ, fpu, sizeof(*fpu)))
            return -EFAULT;

      err = __copy_from_user(&current->thread.float_regs[0], &fpu->si_float_regs[0],
                         (sizeof(unsigned long) * 32));
      err |= __get_user(current->thread.fsr, &fpu->si_fsr);
      err |= __get_user(current->thread.fpqdepth, &fpu->si_fpqdepth);
      if (current->thread.fpqdepth != 0)
            err |= __copy_from_user(&current->thread.fpqueue[0],
                              &fpu->si_fpqueue[0],
                              ((sizeof(unsigned long) +
                              (sizeof(unsigned long *)))*16));
      return err;
}

asmlinkage void do_sigreturn(struct pt_regs *regs)
{
      struct signal_frame __user *sf;
      unsigned long up_psr, pc, npc;
      sigset_t set;
      __siginfo_fpu_t __user *fpu_save;
      int err;

      /* Always make any pending restarted system calls return -EINTR */
      current_thread_info()->restart_block.fn = do_no_restart_syscall;

      synchronize_user_stack();

      sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];

      /* 1. Make sure we are not getting garbage from the user */
      if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
            goto segv_and_exit;

      if (((unsigned long) sf) & 3)
            goto segv_and_exit;

      err = __get_user(pc,  &sf->info.si_regs.pc);
      err |= __get_user(npc, &sf->info.si_regs.npc);

      if ((pc | npc) & 3)
            goto segv_and_exit;

      /* 2. Restore the state */
      up_psr = regs->psr;
      err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));

      /* User can only change condition codes and FPU enabling in %psr. */
      regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
              | (regs->psr & (PSR_ICC | PSR_EF));

      /* Prevent syscall restart.  */
      pt_regs_clear_syscall(regs);

      err |= __get_user(fpu_save, &sf->fpu_save);

      if (fpu_save)
            err |= restore_fpu_state(regs, fpu_save);

      /* This is pretty much atomic, no amount locking would prevent
       * the races which exist anyways.
       */
      err |= __get_user(set.sig[0], &sf->info.si_mask);
      err |= __copy_from_user(&set.sig[1], &sf->extramask,
                          (_NSIG_WORDS-1) * sizeof(unsigned int));
                     
      if (err)
            goto segv_and_exit;

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

segv_and_exit:
      force_sig(SIGSEGV, current);
}

asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
{
      struct rt_signal_frame __user *sf;
      unsigned int psr, pc, npc;
      __siginfo_fpu_t __user *fpu_save;
      mm_segment_t old_fs;
      sigset_t set;
      stack_t st;
      int err;

      synchronize_user_stack();
      sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
      if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) ||
          (((unsigned long) sf) & 0x03))
            goto segv;

      err = __get_user(pc, &sf->regs.pc);
      err |= __get_user(npc, &sf->regs.npc);
      err |= ((pc | npc) & 0x03);

      err |= __get_user(regs->y, &sf->regs.y);
      err |= __get_user(psr, &sf->regs.psr);

      err |= __copy_from_user(&regs->u_regs[UREG_G1],
                        &sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));

      regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);

      /* Prevent syscall restart.  */
      pt_regs_clear_syscall(regs);

      err |= __get_user(fpu_save, &sf->fpu_save);

      if (fpu_save)
            err |= restore_fpu_state(regs, fpu_save);
      err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
      
      err |= __copy_from_user(&st, &sf->stack, sizeof(stack_t));
      
      if (err)
            goto segv;
            
      regs->pc = pc;
      regs->npc = npc;
      
      /* It is more difficult to avoid calling this function than to
       * call it and ignore errors.
       */
      old_fs = get_fs();
      set_fs(KERNEL_DS);
      do_sigaltstack((const stack_t __user *) &st, NULL, (unsigned long)sf);
      set_fs(old_fs);

      sigdelsetmask(&set, ~_BLOCKABLE);
      spin_lock_irq(&current->sighand->siglock);
      current->blocked = set;
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);
      return;
segv:
      force_sig(SIGSEGV, current);
}

/* Checks if the fp is valid */
static inline int invalid_frame_pointer(void __user *fp, int fplen)
{
      if ((((unsigned long) fp) & 7) ||
          !__access_ok((unsigned long)fp, fplen) ||
          ((sparc_cpu_model == sun4 || sparc_cpu_model == sun4c) &&
           ((unsigned long) fp < 0xe0000000 && (unsigned long) fp >= 0x20000000)))
            return 1;
      
      return 0;
}

static inline void __user *get_sigframe(struct sigaction *sa, struct pt_regs *regs, unsigned long framesize)
{
      unsigned long sp = regs->u_regs[UREG_FP];

      /*
       * If we are on the alternate signal stack and would overflow it, don't.
       * Return an always-bogus address instead so we will die with SIGSEGV.
       */
      if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
            return (void __user *) -1L;

      /* This is the X/Open sanctioned signal stack switching.  */
      if (sa->sa_flags & SA_ONSTACK) {
            if (sas_ss_flags(sp) == 0)
                  sp = current->sas_ss_sp + current->sas_ss_size;
      }

      /* Always align the stack frame.  This handles two cases.  First,
       * sigaltstack need not be mindful of platform specific stack
       * alignment.  Second, if we took this signal because the stack
       * is not aligned properly, we'd like to take the signal cleanly
       * and report that.
       */
      sp &= ~7UL;

      return (void __user *)(sp - framesize);
}

static inline int
save_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
{
      int err = 0;
#ifdef CONFIG_SMP
      if (test_tsk_thread_flag(current, TIF_USEDFPU)) {
            put_psr(get_psr() | PSR_EF);
            fpsave(&current->thread.float_regs[0], &current->thread.fsr,
                   &current->thread.fpqueue[0], &current->thread.fpqdepth);
            regs->psr &= ~(PSR_EF);
            clear_tsk_thread_flag(current, TIF_USEDFPU);
      }
#else
      if (current == last_task_used_math) {
            put_psr(get_psr() | PSR_EF);
            fpsave(&current->thread.float_regs[0], &current->thread.fsr,
                   &current->thread.fpqueue[0], &current->thread.fpqdepth);
            last_task_used_math = NULL;
            regs->psr &= ~(PSR_EF);
      }
#endif
      err |= __copy_to_user(&fpu->si_float_regs[0],
                        &current->thread.float_regs[0],
                        (sizeof(unsigned long) * 32));
      err |= __put_user(current->thread.fsr, &fpu->si_fsr);
      err |= __put_user(current->thread.fpqdepth, &fpu->si_fpqdepth);
      if (current->thread.fpqdepth != 0)
            err |= __copy_to_user(&fpu->si_fpqueue[0],
                              &current->thread.fpqueue[0],
                              ((sizeof(unsigned long) +
                              (sizeof(unsigned long *)))*16));
      clear_used_math();
      return err;
}

static void setup_frame(struct k_sigaction *ka, struct pt_regs *regs,
                  int signo, sigset_t *oldset)
{
      struct signal_frame __user *sf;
      int sigframe_size, err;

      /* 1. Make sure everything is clean */
      synchronize_user_stack();

      sigframe_size = SF_ALIGNEDSZ;
      if (!used_math())
            sigframe_size -= sizeof(__siginfo_fpu_t);

      sf = (struct signal_frame __user *)
            get_sigframe(&ka->sa, regs, sigframe_size);

      if (invalid_frame_pointer(sf, sigframe_size))
            goto sigill_and_return;

      if (current_thread_info()->w_saved != 0)
            goto sigill_and_return;

      /* 2. Save the current process state */
      err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
      
      err |= __put_user(0, &sf->extra_size);

      if (used_math()) {
            err |= save_fpu_state(regs, &sf->fpu_state);
            err |= __put_user(&sf->fpu_state, &sf->fpu_save);
      } else {
            err |= __put_user(0, &sf->fpu_save);
      }

      err |= __put_user(oldset->sig[0], &sf->info.si_mask);
      err |= __copy_to_user(sf->extramask, &oldset->sig[1],
                        (_NSIG_WORDS - 1) * sizeof(unsigned int));
      err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
                        sizeof(struct reg_window));
      if (err)
            goto sigsegv;
      
      /* 3. signal handler back-trampoline and parameters */
      regs->u_regs[UREG_FP] = (unsigned long) sf;
      regs->u_regs[UREG_I0] = signo;
      regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
      regs->u_regs[UREG_I2] = (unsigned long) &sf->info;

      /* 4. signal handler */
      regs->pc = (unsigned long) ka->sa.sa_handler;
      regs->npc = (regs->pc + 4);

      /* 5. return to kernel instructions */
      if (ka->ka_restorer)
            regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
      else {
            regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);

            /* mov __NR_sigreturn, %g1 */
            err |= __put_user(0x821020d8, &sf->insns[0]);

            /* t 0x10 */
            err |= __put_user(0x91d02010, &sf->insns[1]);
            if (err)
                  goto sigsegv;

            /* Flush instruction space. */
            flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
      }
      return;

sigill_and_return:
      do_exit(SIGILL);
sigsegv:
      force_sigsegv(signo, current);
}

static void setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
                     int signo, sigset_t *oldset, siginfo_t *info)
{
      struct rt_signal_frame __user *sf;
      int sigframe_size;
      unsigned int psr;
      int err;

      synchronize_user_stack();
      sigframe_size = RT_ALIGNEDSZ;
      if (!used_math())
            sigframe_size -= sizeof(__siginfo_fpu_t);
      sf = (struct rt_signal_frame __user *)
            get_sigframe(&ka->sa, regs, sigframe_size);
      if (invalid_frame_pointer(sf, sigframe_size))
            goto sigill;
      if (current_thread_info()->w_saved != 0)
            goto sigill;

      err  = __put_user(regs->pc, &sf->regs.pc);
      err |= __put_user(regs->npc, &sf->regs.npc);
      err |= __put_user(regs->y, &sf->regs.y);
      psr = regs->psr;
      if (used_math())
            psr |= PSR_EF;
      err |= __put_user(psr, &sf->regs.psr);
      err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
      err |= __put_user(0, &sf->extra_size);

      if (psr & PSR_EF) {
            err |= save_fpu_state(regs, &sf->fpu_state);
            err |= __put_user(&sf->fpu_state, &sf->fpu_save);
      } else {
            err |= __put_user(0, &sf->fpu_save);
      }
      err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
      
      /* Setup sigaltstack */
      err |= __put_user(current->sas_ss_sp, &sf->stack.ss_sp);
      err |= __put_user(sas_ss_flags(regs->u_regs[UREG_FP]), &sf->stack.ss_flags);
      err |= __put_user(current->sas_ss_size, &sf->stack.ss_size);
      
      err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
                        sizeof(struct reg_window));   

      err |= copy_siginfo_to_user(&sf->info, info);

      if (err)
            goto sigsegv;

      regs->u_regs[UREG_FP] = (unsigned long) sf;
      regs->u_regs[UREG_I0] = signo;
      regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
      regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;

      regs->pc = (unsigned long) ka->sa.sa_handler;
      regs->npc = (regs->pc + 4);

      if (ka->ka_restorer)
            regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
      else {
            regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);

            /* mov __NR_sigreturn, %g1 */
            err |= __put_user(0x821020d8, &sf->insns[0]);

            /* t 0x10 */
            err |= __put_user(0x91d02010, &sf->insns[1]);
            if (err)
                  goto sigsegv;

            /* Flush instruction space. */
            flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
      }
      return;

sigill:
      do_exit(SIGILL);
sigsegv:
      force_sigsegv(signo, current);
}

static inline void
handle_signal(unsigned long signr, struct k_sigaction *ka,
            siginfo_t *info, sigset_t *oldset, struct pt_regs *regs)
{
      if (ka->sa.sa_flags & SA_SIGINFO)
            setup_rt_frame(ka, regs, signr, oldset, info);
      else
            setup_frame(ka, regs, signr, oldset);

      spin_lock_irq(&current->sighand->siglock);
      sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
      if (!(ka->sa.sa_flags & SA_NOMASK))
            sigaddset(&current->blocked, signr);
      recalc_sigpending();
      spin_unlock_irq(&current->sighand->siglock);
}

static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
                           struct sigaction *sa)
{
      switch(regs->u_regs[UREG_I0]) {
      case ERESTART_RESTARTBLOCK:
      case ERESTARTNOHAND:
      no_system_call_restart:
            regs->u_regs[UREG_I0] = EINTR;
            regs->psr |= PSR_C;
            break;
      case ERESTARTSYS:
            if (!(sa->sa_flags & SA_RESTART))
                  goto no_system_call_restart;
            /* fallthrough */
      case ERESTARTNOINTR:
            regs->u_regs[UREG_I0] = orig_i0;
            regs->pc -= 4;
            regs->npc -= 4;
      }
}

/* 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.
 */
static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
{
      struct k_sigaction ka;
      int restart_syscall;
      sigset_t *oldset;
      siginfo_t info;
      int signr;

      if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
            restart_syscall = 1;
      else
            restart_syscall = 0;

      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 the debugger messes with the program counter, it clears
       * the software "in syscall" bit, directing us to not perform
       * a syscall restart.
       */
      if (restart_syscall && !pt_regs_is_syscall(regs))
            restart_syscall = 0;

      if (signr > 0) {
            if (restart_syscall)
                  syscall_restart(orig_i0, regs, &ka.sa);
            handle_signal(signr, &ka, &info, oldset, regs);

            /* 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);

            tracehook_signal_handler(signr, &info, &ka, regs, 0);
            return;
      }
      if (restart_syscall &&
          (regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
           regs->u_regs[UREG_I0] == ERESTARTSYS ||
           regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
            /* replay the system call when we are done */
            regs->u_regs[UREG_I0] = orig_i0;
            regs->pc -= 4;
            regs->npc -= 4;
      }
      if (restart_syscall &&
          regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
            regs->u_regs[UREG_G1] = __NR_restart_syscall;
            regs->pc -= 4;
            regs->npc -= 4;
      }

      /* 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);
      }
}

void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
                  unsigned long thread_info_flags)
{
      if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
            do_signal(regs, orig_i0);
      if (thread_info_flags & _TIF_NOTIFY_RESUME) {
            clear_thread_flag(TIF_NOTIFY_RESUME);
            tracehook_notify_resume(regs);
      }
}

asmlinkage int
do_sys_sigstack(struct sigstack __user *ssptr, struct sigstack __user *ossptr,
            unsigned long sp)
{
      int ret = -EFAULT;

      /* First see if old state is wanted. */
      if (ossptr) {
            if (put_user(current->sas_ss_sp + current->sas_ss_size,
                       &ossptr->the_stack) ||
                __put_user(on_sig_stack(sp), &ossptr->cur_status))
                  goto out;
      }

      /* Now see if we want to update the new state. */
      if (ssptr) {
            char *ss_sp;

            if (get_user(ss_sp, &ssptr->the_stack))
                  goto out;
            /* If the current stack was set with sigaltstack, don't
               swap stacks while we are on it.  */
            ret = -EPERM;
            if (current->sas_ss_sp && on_sig_stack(sp))
                  goto out;

            /* Since we don't know the extent of the stack, and we don't
               track onstack-ness, but rather calculate it, we must
               presume a size.  Ho hum this interface is lossy.  */
            current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
            current->sas_ss_size = SIGSTKSZ;
      }
      ret = 0;
out:
      return ret;
}

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