signal.c

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/*
 * Architecture-specific signal handling support.
 *
 * Copyright (C) 1999-2000 Hewlett-Packard Co
 * Copyright (C) 1999-2000 David Mosberger-Tang <[e-mail]>
 *
 * Derived from i386 and Alpha versions.
 */

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/wait.h>

#include <asm/ia32.h>
#include <asm/uaccess.h>
#include <asm/rse.h>
#include <asm/sigcontext.h>

#define DEBUG_SIG	0
#define STACK_ALIGN	16		/* minimal alignment for stack pointer */
#define _BLOCKABLE	(~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

#if _NSIG_WORDS > 1
# define PUT_SIGSET(k,u)	__copy_to_user((u)->sig, (k)->sig, sizeof(sigset_t))
# define GET_SIGSET(k,u)	__copy_from_user((k)->sig, (u)->sig, sizeof(sigset_t))
#else
# define PUT_SIGSET(k,u)	__put_user((k)->sig[0], &(u)->sig[0])
# define GET_SIGSET(k,u)	__get_user((k)->sig[0], &(u)->sig[0])
#endif

struct sigscratch {
#ifdef CONFIG_IA64_NEW_UNWIND
	unsigned long scratch_unat;	/* ar.unat for the general registers saved in pt */
	unsigned long pad;
#else
	struct switch_stack sw;
#endif
	struct pt_regs pt;
};

struct sigframe {
	struct siginfo info;
	struct sigcontext sc;
};

extern long sys_wait4 (int, int *, int, struct rusage *);
extern long ia64_do_signal (sigset_t *, struct sigscratch *, long);	/* forward decl */

long
ia64_rt_sigsuspend (sigset_t *uset, size_t sigsetsize, struct sigscratch *scr)
{
	sigset_t oldset, set;

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

	/*
	 * The return below usually returns to the signal handler.  We need to
	 * pre-set the correct error code here to ensure that the right values
	 * get saved in sigcontext by ia64_do_signal.
	 */
#ifdef CONFIG_IA32_SUPPORT
        if (IS_IA32_PROCESS(&scr->pt)) {
                scr->pt.r8 = -EINTR;
        } else
#endif
	{
		scr->pt.r8 = EINTR;
		scr->pt.r10 = -1;
	}
	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (ia64_do_signal(&oldset, scr, 1))
			return -EINTR;
	}
}

asmlinkage long
sys_sigaltstack (const stack_t *uss, stack_t *uoss, long arg2, long arg3, long arg4,
		 long arg5, long arg6, long arg7, long stack)
{
	struct pt_regs *pt = (struct pt_regs *) &stack;

	return do_sigaltstack(uss, uoss, pt->r12);
}

static long
restore_sigcontext (struct sigcontext *sc, struct sigscratch *scr)
{
	unsigned long ip, flags, nat, um, cfm;
	long err;

	/* restore scratch that always needs gets updated during signal delivery: */
	err = __get_user(flags, &sc->sc_flags);

	err |= __get_user(nat, &sc->sc_nat);
	err |= __get_user(ip, &sc->sc_ip);			/* instruction pointer */
	err |= __get_user(cfm, &sc->sc_cfm);
	err |= __get_user(um, &sc->sc_um);			/* user mask */
	err |= __get_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
	err |= __get_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);
	err |= __get_user(scr->pt.ar_unat, &sc->sc_ar_unat);
	err |= __get_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);
	err |= __get_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);
	err |= __get_user(scr->pt.pr, &sc->sc_pr);		/* predicates */
	err |= __get_user(scr->pt.b0, &sc->sc_br[0]);		/* b0 (rp) */
	err |= __get_user(scr->pt.b6, &sc->sc_br[6]);		/* b6 */
	err |= __get_user(scr->pt.b7, &sc->sc_br[7]);		/* b7 */
	err |= __copy_from_user(&scr->pt.r1, &sc->sc_gr[1], 3*8);	/* r1-r3 */
	err |= __copy_from_user(&scr->pt.r8, &sc->sc_gr[8], 4*8);	/* r8-r11 */
	err |= __copy_from_user(&scr->pt.r12, &sc->sc_gr[12], 4*8);	/* r12-r15 */
	err |= __copy_from_user(&scr->pt.r16, &sc->sc_gr[16], 16*8);	/* r16-r31 */

	scr->pt.cr_ifs = cfm | (1UL << 63);

	/* establish new instruction pointer: */
	scr->pt.cr_iip = ip & ~0x3UL;
	ia64_psr(&scr->pt)->ri = ip & 0x3;
	scr->pt.cr_ipsr = (scr->pt.cr_ipsr & ~IA64_PSR_UM) | (um & IA64_PSR_UM);

#ifdef CONFIG_IA64_NEW_UNWIND
	scr->scratch_unat = ia64_put_scratch_nat_bits(&scr->pt, nat);
#else
	ia64_put_nat_bits(&scr->pt, &scr->sw, nat);	/* restore the original scratch NaT bits */
#endif

	if ((flags & IA64_SC_FLAG_FPH_VALID) != 0) {
		struct ia64_psr *psr = ia64_psr(&scr->pt);

		__copy_from_user(current->thread.fph, &sc->sc_fr[32], 96*16);
		if (!psr->dfh) {
			psr->mfh = 0;
			__ia64_load_fpu(current->thread.fph);
		}
	}
	return err;
}

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(from->si_signo, &to->si_signo);
		err |= __put_user(from->si_errno, &to->si_errno);
		err |= __put_user((short)from->si_code, &to->si_code);
		switch (from->si_code >> 16) {
		      case __SI_FAULT >> 16:
			err |= __put_user(from->si_isr, &to->si_isr);
		      case __SI_POLL >> 16:
			err |= __put_user(from->si_addr, &to->si_addr);
			err |= __put_user(from->si_imm, &to->si_imm);
			break;
		      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_uid, &to->si_uid);
			err |= __put_user(from->si_pid, &to->si_pid);
			break;
		      /* case __SI_RT: This is not generated by the kernel as of now.  */
		}
		return err;
	}
}

long
ia64_rt_sigreturn (struct sigscratch *scr)
{
	extern char ia64_strace_leave_kernel, ia64_leave_kernel;
	struct sigcontext *sc;
	struct siginfo si;
	sigset_t set;
	long retval;

	sc = &((struct sigframe *) (scr->pt.r12 + 16))->sc;

	/*
	 * When we return to the previously executing context, r8 and
	 * r10 have already been setup the way we want them.  Indeed,
	 * if the signal wasn't delivered while in a system call, we
	 * must not touch r8 or r10 as otherwise user-level stat could
	 * be corrupted.
	 */
	retval = (long) &ia64_leave_kernel;
	if (current->ptrace & PT_TRACESYS)
		/*
		 * strace expects to be notified after sigreturn
		 * returns even though the context to which we return
		 * may not be in the middle of a syscall.  Thus, the
		 * return-value that strace displays for sigreturn is
		 * meaningless.
		 */
		retval = (long) &ia64_strace_leave_kernel;

	if (!access_ok(VERIFY_READ, sc, sizeof(*sc)))
		goto give_sigsegv;

	if (GET_SIGSET(&set, &sc->sc_mask))
		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(sc, scr))
		goto give_sigsegv;

#if DEBUG_SIG
	printk("SIG return (%s:%d): sp=%lx ip=%lx\n",
	       current->comm, current->pid, scr->pt.r12, scr->pt.cr_iip);
#endif
	/*
	 * It is more difficult to avoid calling this function than to
	 * call it and ignore errors.
	 */
	do_sigaltstack(&sc->sc_stack, 0, scr->pt.r12);
	return retval;

  give_sigsegv:
	si.si_signo = SIGSEGV;
	si.si_errno = 0;
	si.si_code = SI_KERNEL;
	si.si_pid = current->pid;
	si.si_uid = current->uid;
	si.si_addr = sc;
	force_sig_info(SIGSEGV, &si, current);
	return retval;
}

/*
 * This does just the minimum required setup of sigcontext.
 * Specifically, it only installs data that is either not knowable at
 * the user-level or that gets modified before execution in the
 * trampoline starts.  Everything else is done at the user-level.
 */
static long
setup_sigcontext (struct sigcontext *sc, sigset_t *mask, struct sigscratch *scr)
{
	unsigned long flags = 0, ifs, nat;
	long err;

	ifs = scr->pt.cr_ifs;

	if (on_sig_stack((unsigned long) sc))
		flags |= IA64_SC_FLAG_ONSTACK;
	if ((ifs & (1UL << 63)) == 0) {
		/* if cr_ifs isn't valid, we got here through a syscall */
		flags |= IA64_SC_FLAG_IN_SYSCALL;
	}
	ia64_flush_fph(current);
	if ((current->thread.flags & IA64_THREAD_FPH_VALID)) {
		flags |= IA64_SC_FLAG_FPH_VALID;
		__copy_to_user(&sc->sc_fr[32], current->thread.fph, 96*16);
	}

	/*
	 * Note: sw->ar_unat is UNDEFINED unless the process is being
	 * PTRACED.  However, this is OK because the NaT bits of the
	 * preserved registers (r4-r7) are never being looked at by
	 * the signal handler (registers r4-r7 are used instead).
	 */
#ifdef CONFIG_IA64_NEW_UNWIND
	nat = ia64_get_scratch_nat_bits(&scr->pt, scr->scratch_unat);
#else
	nat = ia64_get_nat_bits(&scr->pt, &scr->sw);
#endif

	err  = __put_user(flags, &sc->sc_flags);

	err |= __put_user(nat, &sc->sc_nat);
	err |= PUT_SIGSET(mask, &sc->sc_mask);
	err |= __put_user(scr->pt.cr_ipsr & IA64_PSR_UM, &sc->sc_um);
	err |= __put_user(scr->pt.ar_rsc, &sc->sc_ar_rsc);
	err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);
	err |= __put_user(scr->pt.ar_unat, &sc->sc_ar_unat);		/* ar.unat */
	err |= __put_user(scr->pt.ar_fpsr, &sc->sc_ar_fpsr);		/* ar.fpsr */
	err |= __put_user(scr->pt.ar_pfs, &sc->sc_ar_pfs);