signal.c

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/*
 *  linux/arch/alpha/kernel/signal.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 *
 *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
 */

#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/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>

#include <asm/bitops.h>
#include <asm/uaccess.h>
#include <asm/sigcontext.h>
#include <asm/ucontext.h>

#include "proto.h"


#define DEBUG_SIG 0

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

asmlinkage int sys_wait4(int, int *, int, struct rusage *);
asmlinkage void ret_from_sys_call(void);
asmlinkage int do_signal(sigset_t *, struct pt_regs *,
			 struct switch_stack *, unsigned long, unsigned long);


int copy_siginfo_to_user(siginfo_t *to, siginfo_t *from)
{
	if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
		return -EFAULT;
	if (from->si_code < 0)
		return __copy_to_user(to, from, sizeof(siginfo_t));
	else {
		int err;

		/* If you change siginfo_t structure, please be sure
		   this code is fixed accordingly.
		   It should never copy any pad contained in the structure
		   to avoid security leaks, but must copy the generic
		   3 ints plus the relevant union member.  */
		err = __put_user(*(long *)&from->si_signo, (long *)&to->si_signo);
		err |= __put_user((short)from->si_code, &to->si_code);
		switch (from->si_code >> 16) {
		case __SI_CHLD >> 16:
			err |= __put_user(from->si_utime, &to->si_utime);
			err |= __put_user(from->si_stime, &to->si_stime);
			err |= __put_user(from->si_status, &to->si_status);
		default:
			err |= __put_user(from->si_addr, &to->si_addr);
			break;
		/* case __SI_RT: This is not generated by the kernel as of now.  */
		}
		return err;
	}
}

/*
 * The OSF/1 sigprocmask calling sequence is different from the
 * C sigprocmask() sequence..
 *
 * how:
 * 1 - SIG_BLOCK
 * 2 - SIG_UNBLOCK
 * 3 - SIG_SETMASK
 *
 * We change the range to -1 .. 1 in order to let gcc easily
 * use the conditional move instructions.
 *
 * Note that we don't need to acquire the kernel lock for SMP
 * operation, as all of this is local to this thread.
 */
asmlinkage unsigned long
osf_sigprocmask(int how, unsigned long newmask, long a2, long a3,
		long a4, long a5, struct pt_regs regs)
{
	unsigned long oldmask = -EINVAL;

	if ((unsigned long)how-1 <= 2) {
		long sign = how-2;		/* -1 .. 1 */
		unsigned long block, unblock;

		newmask &= _BLOCKABLE;
		spin_lock_irq(&current->sigmask_lock);
		oldmask = current->blocked.sig[0];

		unblock = oldmask & ~newmask;
		block = oldmask | newmask;
		if (!sign)
			block = unblock;
		if (sign <= 0)
			newmask = block;
		if (_NSIG_WORDS > 1 && sign > 0)
			sigemptyset(&current->blocked);
		current->blocked.sig[0] = newmask;
		recalc_sigpending(current);
		spin_unlock_irq(&current->sigmask_lock);

		(&regs)->r0 = 0;		/* special no error return */
	}
	return oldmask;
}

asmlinkage int 
osf_sigaction(int sig, const struct osf_sigaction *act,
	      struct osf_sigaction *oact)
{
	struct k_sigaction new_ka, old_ka;
	int ret;

	if (act) {
		old_sigset_t mask;
		if (verify_area(VERIFY_READ, act, sizeof(*act)) ||
		    __get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
		    __get_user(new_ka.sa.sa_flags, &act->sa_flags))
			return -EFAULT;
		__get_user(mask, &act->sa_mask);
		siginitset(&new_ka.sa.sa_mask, mask);
		new_ka.ka_restorer = NULL;
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);

	if (!ret && oact) {
		if (verify_area(VERIFY_WRITE, oact, sizeof(*oact)) ||
		    __put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
		    __put_user(old_ka.sa.sa_flags, &oact->sa_flags))
			return -EFAULT;
		__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
	}

	return ret;
}

asmlinkage int 
sys_rt_sigaction(int sig, const struct sigaction *act, struct sigaction *oact,
		 size_t sigsetsize, void *restorer)
{
	struct k_sigaction new_ka, old_ka;
	int ret;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;

	if (act) {
		new_ka.ka_restorer = restorer;
		if (copy_from_user(&new_ka.sa, act, sizeof(*act)))
			return -EFAULT;
	}

	ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);

	if (!ret && oact) {
		if (copy_to_user(oact, &old_ka.sa, sizeof(*oact)))
			return -EFAULT;
	}

	return ret;
}

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */
asmlinkage int
do_sigsuspend(old_sigset_t mask, struct pt_regs *reg, struct switch_stack *sw)
{
	sigset_t oldset;

	mask &= _BLOCKABLE;
	spin_lock_irq(&current->sigmask_lock);
	oldset = current->blocked;
	siginitset(&current->blocked, mask);
	recalc_sigpending(current);
	spin_unlock_irq(&current->sigmask_lock);

	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(&oldset, reg, sw, 0, 0))
			return -EINTR;
	}
}

asmlinkage int
do_rt_sigsuspend(sigset_t *uset, size_t sigsetsize,
		 struct pt_regs *reg, struct switch_stack *sw)
{
	sigset_t oldset, set;

	/* XXX: Don't preclude handling different sized sigset_t's.  */
	if (sigsetsize != sizeof(sigset_t))
		return -EINVAL;
	if (copy_from_user(&set, uset, sizeof(set)))
		return -EFAULT;

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

	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(&oldset, reg, sw, 0, 0))
			return -EINTR;
	}
}

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

/*
 * Do a signal return; undo the signal stack.
 */

struct sigframe
{
	struct sigcontext sc;
	unsigned long extramask[_NSIG_WORDS-1];
	unsigned int retcode[3];
};

struct rt_sigframe
{
	struct siginfo info;
	struct ucontext uc;
	unsigned int retcode[3];
};

#define INSN_MOV_R30_R16	0x47fe0410
#define INSN_LDI_R0		0x201f0000
#define INSN_CALLSYS		0x00000083

static long
restore_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
		   struct switch_stack *sw)
{
	unsigned long usp;
	long i, err = 0;

	err |= __get_user(regs->pc, &sc->sc_pc);
	sw->r26 = (unsigned long) ret_from_sys_call;

	err |= __get_user(regs->r0, sc->sc_regs+0);
	err |= __get_user(regs->r1, sc->sc_regs+1);
	err |= __get_user(regs->r2, sc->sc_regs+2);
	err |= __get_user(regs->r3, sc->sc_regs+3);
	err |= __get_user(regs->r4, sc->sc_regs+4);
	err |= __get_user(regs->r5, sc->sc_regs+5);
	err |= __get_user(regs->r6, sc->sc_regs+6);
	err |= __get_user(regs->r7, sc->sc_regs+7);
	err |= __get_user(regs->r8, sc->sc_regs+8);
	err |= __get_user(sw->r9, sc->sc_regs+9);
	err |= __get_user(sw->r10, sc->sc_regs+10);
	err |= __get_user(sw->r11, sc->sc_regs+11);
	err |= __get_user(sw->r12, sc->sc_regs+12);
	err |= __get_user(sw->r13, sc->sc_regs+13);
	err |= __get_user(sw->r14, sc->sc_regs+14);
	err |= __get_user(sw->r15, sc->sc_regs+15);
	err |= __get_user(regs->r16, sc->sc_regs+16);
	err |= __get_user(regs->r17, sc->sc_regs+17);
	err |= __get_user(regs->r18, sc->sc_regs+18);
	err |= __get_user(regs->r19, sc->sc_regs+19);
	err |= __get_user(regs->r20, sc->sc_regs+20);
	err |= __get_user(regs->r21, sc->sc_regs+21);
	err |= __get_user(regs->r22, sc->sc_regs+22);
	err |= __get_user(regs->r23, sc->sc_regs+23);
	err |= __get_user(regs->r24, sc->sc_regs+24);
	err |= __get_user(regs->r25, sc->sc_regs+25);
	err |= __get_user(regs->r26, sc->sc_regs+26);
	err |= __get_user(regs->r27, sc->sc_regs+27);
	err |= __get_user(regs->r28, sc->sc_regs+28);
	err |= __get_user(regs->gp, sc->sc_regs+29);
	err |= __get_user(usp, sc->sc_regs+30);
	wrusp(usp);

	for (i = 0; i < 31; i++)
		err |= __get_user(sw->fp[i], sc->sc_fpregs+i);
	err |= __get_user(sw->fp[31], &sc->sc_fpcr);

	return err;
}

asmlinkage void
do_sigreturn(struct sigframe *frame, struct pt_regs *regs,
	     struct switch_stack *sw)
{
	sigset_t set;

	/* Verify that it's a good sigcontext before using it */
	if (verify_area(VERIFY_READ, frame, sizeof(*frame)))
		goto give_sigsegv;
	if (__get_user(set.sig[0], &frame->sc.sc_mask)
	    || (_NSIG_WORDS > 1
		&& __copy_from_user(&set.sig[1], &frame->extramask,
				    sizeof(frame->extramask))))
		goto give_sigsegv;

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

	if (restore_sigcontext(&frame->sc, regs, sw))
		goto give_sigsegv;

	/* Send SIGTRAP if we're single-stepping: */
	if (ptrace_cancel_bpt (current))
		send_sig(SIGTRAP, current, 1);
	return;

give_sigsegv:
	force_sig(SIGSEGV, current);
}

asmlinkage void
do_rt_sigreturn(struct rt_sigframe *frame, struct pt_regs *regs,
		struct switch_stack *sw)
{
	sigset_t set;
	stack_t st;

	/* Verify that it's a good sigcontext before using it */
	if (verify_area(VERIFY_READ, frame, sizeof(*frame)))
		goto give_sigsegv;
	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
		goto give_sigsegv;

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

	if (restore_sigcontext(&frame->uc.uc_mcontext, regs, sw))
		goto give_sigsegv;

	if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))
		goto give_sigsegv;
	/* It is more difficult to avoid calling this function than to
	   call it and ignore errors.  */
	do_sigaltstack(&st, NULL, rdusp());

	/* Send SIGTRAP if we're single-stepping: */
	if (ptrace_cancel_bpt (current))
		send_sig(SIGTRAP, current, 1);
	return;

give_sigsegv:
	force_sig(SIGSEGV, current);
}


/*
 * Set up a signal frame.
 */