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Initial revision

/*	$OpenBSD: sig_machdep.c,v 1.18 2006/06/11 20:48:13 miod Exp $	*/
/*	$NetBSD: sig_machdep.c,v 1.3 1997/04/30 23:28:03 gwr Exp $	*/

/*
 * Copyright (c) 1997 Theo de Raadt
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1982, 1986, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	from: Utah Hdr: machdep.c 1.74 92/12/20
 *	from: @(#)machdep.c	8.10 (Berkeley) 4/20/94
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/user.h>
#include <sys/exec.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/signal.h>
#include <sys/signalvar.h>
#include <sys/malloc.h>
#include <sys/buf.h>

#include <uvm/uvm_extern.h>

#include <sys/syscallargs.h>

#include <machine/cpu.h>
#include <machine/reg.h>

extern short exframesize[];

#define SS_RTEFRAME	1
#define SS_FPSTATE	2
#define SS_USERREGS	4

struct sigstate {
	int	ss_flags;		/* which of the following are valid */
	struct	frame ss_frame;		/* original exception frame */
	struct	fpframe ss_fpstate;	/* 68881/68882 state info */
};

/*
 * WARNING: code in locore.s assumes the layout shown for sf_signum
 * thru sf_handler so... don't screw with them!
 */
struct sigframe {
	int	sf_signum;		/* signo for handler */
	siginfo_t *sf_sip;		/* pointer to siginfo_t */
	struct	sigcontext *sf_scp;	/* context ptr for handler */
	sig_t	sf_handler;		/* handler addr for u_sigc */
	struct	sigstate sf_state;	/* state of the hardware */
	struct	sigcontext sf_sc;	/* actual context */
	siginfo_t sf_si;
};

#ifdef DEBUG
int sigdebug = 0;
int sigpid = 0;
#define SDB_FOLLOW	0x01
#define SDB_KSTACK	0x02
#define SDB_FPSTATE	0x04
#endif

/*
 * Send an interrupt to process.
 */
void
sendsig(catcher, sig, mask, code, type, val)
	sig_t catcher;
	int sig, mask;
	u_long code;
	int type;
	union sigval val;
{
	struct proc *p = curproc;
	struct sigframe *fp, *kfp;
	struct frame *frame;
	struct sigacts *psp = p->p_sigacts;
	short ft;
	int oonstack, fsize;

	frame = (struct frame *)p->p_md.md_regs;
	ft = frame->f_format;
	oonstack = psp->ps_sigstk.ss_flags & SS_ONSTACK;

	/*
	 * Allocate and validate space for the signal handler
	 * context. Note that if the stack is in P0 space, the
	 * call to grow() is a nop, and the useracc() check
	 * will fail if the process has not already allocated
	 * the space with a `brk'.
	 */
	fsize = sizeof(struct sigframe);
	if ((psp->ps_flags & SAS_ALTSTACK) && !oonstack &&
	    (psp->ps_sigonstack & sigmask(sig))) {
		fp = (struct sigframe *)(psp->ps_sigstk.ss_sp +
					 psp->ps_sigstk.ss_size - fsize);
		psp->ps_sigstk.ss_flags |= SS_ONSTACK;
	} else
		fp = (struct sigframe *)(frame->f_regs[SP] - fsize);
	if ((unsigned)fp <= USRSTACK - ctob(p->p_vmspace->vm_ssize)) 
		(void)uvm_grow(p, (unsigned)fp);
#ifdef DEBUG
	if ((sigdebug & SDB_KSTACK) && p->p_pid == sigpid)
		printf("sendsig(%d): sig %d ssp %p usp %p scp %p ft %d\n",
		       p->p_pid, sig, &oonstack, fp, &fp->sf_sc, ft);
#endif
	kfp = (struct sigframe *)malloc((u_long)fsize, M_TEMP,
	    M_WAITOK | M_CANFAIL);
	if (kfp == NULL) {
		/* Better halt the process in its track than panicing */
		sigexit(p, SIGILL);
		/* NOTREACHED */
	}

	/* 
	 * Build the argument list for the signal handler.
	 */
	kfp->sf_signum = sig;
	kfp->sf_sip = NULL;
	kfp->sf_scp = &fp->sf_sc;
	kfp->sf_handler = catcher;

	/*
	 * Save necessary hardware state.  Currently this includes:
	 *	- general registers
	 *	- original exception frame (if not a "normal" frame)
	 *	- FP coprocessor state
	 */
	kfp->sf_state.ss_flags = SS_USERREGS;
	bcopy((caddr_t)frame->f_regs,
	      (caddr_t)kfp->sf_state.ss_frame.f_regs, sizeof frame->f_regs);
	if (ft >= FMT7) {
#ifdef DEBUG
		if (ft > 15 || exframesize[ft] < 0)
			panic("sendsig: bogus frame type");
#endif
		kfp->sf_state.ss_flags |= SS_RTEFRAME;
		kfp->sf_state.ss_frame.f_format = frame->f_format;
		kfp->sf_state.ss_frame.f_vector = frame->f_vector;
		bcopy((caddr_t)&frame->F_u,
		      (caddr_t)&kfp->sf_state.ss_frame.F_u, exframesize[ft]);
		/*
		 * Leave an indicator that we need to clean up the kernel
		 * stack.  We do this by setting the "pad word" above the
		 * hardware stack frame to the amount the stack must be
		 * adjusted by.
		 *
		 * N.B. we increment rather than just set f_stackadj in
		 * case we are called from syscall when processing a
		 * sigreturn.  In that case, f_stackadj may be non-zero.
		 */
		frame->f_stackadj += exframesize[ft];
		frame->f_format = frame->f_vector = 0;
#ifdef DEBUG
		if (sigdebug & SDB_FOLLOW)
			printf("sendsig(%d): copy out %d of frame %d\n",
			       p->p_pid, exframesize[ft], ft);
#endif
	}

	if (fputype) {
		kfp->sf_state.ss_flags |= SS_FPSTATE;
		m68881_save(&kfp->sf_state.ss_fpstate);
	}
#ifdef DEBUG
	if ((sigdebug & SDB_FPSTATE) && *(char *)&kfp->sf_state.ss_fpstate)
		printf("sendsig(%d): copy out FP state (%x) to %p\n",
		       p->p_pid, *(u_int *)&kfp->sf_state.ss_fpstate,
		       &kfp->sf_state.ss_fpstate);
#endif
	/*
	 * Build the signal context to be used by sigreturn.
	 */
	kfp->sf_sc.sc_onstack = oonstack;
	kfp->sf_sc.sc_mask = mask;
	kfp->sf_sc.sc_sp = frame->f_regs[SP];
	kfp->sf_sc.sc_fp = frame->f_regs[A6];
	kfp->sf_sc.sc_ap = (int)&fp->sf_state;
	kfp->sf_sc.sc_pc = frame->f_pc;
	kfp->sf_sc.sc_ps = frame->f_sr;

	if (psp->ps_siginfo & sigmask(sig)) {
		kfp->sf_sip = &fp->sf_si;
		initsiginfo(&kfp->sf_si, sig, code, type, val);
	}

	/* XXX do not copy out siginfo if not needed */
	if (copyout((caddr_t)kfp, (caddr_t)fp, fsize) != 0) {
#ifdef DEBUG
		if ((sigdebug & SDB_KSTACK) && p->p_pid == sigpid)
			printf("sendsig(%d): copyout failed on sig %d\n",
			       p->p_pid, sig);
#endif
		/*
		 * Process has trashed its stack; give it an illegal
		 * instruction to halt it in its tracks.
		 */
		free((caddr_t)kfp, M_TEMP);
		sigexit(p, SIGILL);
		/* NOTREACHED */
	}
	frame->f_regs[SP] = (int)fp;
#ifdef DEBUG
	if (sigdebug & SDB_FOLLOW)
		printf("sendsig(%d): sig %d scp %p fp %p sc_sp %x sc_ap %x\n",
		       p->p_pid, sig, kfp->sf_scp, fp,
		       kfp->sf_sc.sc_sp, kfp->sf_sc.sc_ap);
#endif
	/*
	 * Signal trampoline code is at base of user stack.
	 */
	frame->f_pc = p->p_sigcode;
#ifdef DEBUG
	if ((sigdebug & SDB_KSTACK) && p->p_pid == sigpid)
		printf("sendsig(%d): sig %d returns\n",
		       p->p_pid, sig);
#endif
	free((caddr_t)kfp, M_TEMP);
}

/*
 * System call to cleanup state after a signal
 * has been taken.  Reset signal mask and
 * stack state from context left by sendsig (above).
 * Return to previous pc and psl as specified by
 * context left by sendsig. Check carefully to
 * make sure that the user has not modified the
 * psl to gain improper privileges or to cause
 * a machine fault.
 */
int
sys_sigreturn(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_sigreturn_args /* {
		syscallarg(struct sigcontext *) sigcntxp;
	} */ *uap = v;
	register struct sigcontext *scp;
	register struct frame *frame;
	register int rf;
	struct sigcontext tsigc;
	struct sigstate tstate;
	int flags;

	scp = SCARG(uap, sigcntxp);
#ifdef DEBUG
	if (sigdebug & SDB_FOLLOW)
		printf("sigreturn: pid %d, scp %p\n", p->p_pid, scp);
#endif
	if ((int)scp & 1)
		return (EINVAL);

	/*
	 * Test and fetch the context structure.
	 * We grab it all at once for speed.
	 */
	if (copyin((caddr_t)scp, (caddr_t)&tsigc, sizeof tsigc))
		return (EINVAL);
	scp = &tsigc;
	if ((scp->sc_ps & PSL_USERCLR) != 0 ||
	    (scp->sc_ps & PSL_USERSET) != PSL_USERSET)
		return (EINVAL);
	/*
	 * Restore the user supplied information
	 */
	if (scp->sc_onstack & 1)
		p->p_sigacts->ps_sigstk.ss_flags |= SS_ONSTACK;
	else
		p->p_sigacts->ps_sigstk.ss_flags &= ~SS_ONSTACK;
	p->p_sigmask = scp->sc_mask &~ sigcantmask;
	frame = (struct frame *) p->p_md.md_regs;
	frame->f_regs[SP] = scp->sc_sp;
	frame->f_regs[A6] = scp->sc_fp;
	frame->f_pc = scp->sc_pc;
	frame->f_sr = scp->sc_ps;

	/*
	 * Grab pointer to hardware state information.
	 * If zero, the user is probably doing a longjmp.
	 */
	if ((rf = scp->sc_ap) == 0)
		return (EJUSTRETURN);
	/*
	 * See if there is anything to do before we go to the
	 * expense of copying in close to 1/2K of data
	 */
	if (copyin((caddr_t)rf, &flags, sizeof(int)) != 0)
		return (EINVAL);
#ifdef DEBUG
	if (sigdebug & SDB_FOLLOW)
		printf("sigreturn(%d): sc_ap %x flags %x\n",
		       p->p_pid, rf, flags);
#endif
	if (flags == 0 || copyin((caddr_t)rf, (caddr_t)&tstate, sizeof tstate))
		return (EJUSTRETURN);
#ifdef DEBUG
	if ((sigdebug & SDB_KSTACK) && p->p_pid == sigpid)
		printf("sigreturn(%d): ssp %p usp %x scp %p ft %d\n",
		       p->p_pid, &flags, scp->sc_sp, SCARG(uap, sigcntxp),
		       (flags&SS_RTEFRAME) ? tstate.ss_frame.f_format : -1);
#endif
	/*
	 * Restore most of the users registers except for A6 and SP
	 * which were handled above.
	 */
	if (flags & SS_USERREGS)
		bcopy((caddr_t)tstate.ss_frame.f_regs,
		      (caddr_t)frame->f_regs, sizeof(frame->f_regs)-2*NBPW);
	/*
	 * Restore long stack frames.  Note that we do not copy
	 * back the saved SR or PC, they were picked up above from
	 * the sigcontext structure.
	 */
	if (flags & SS_RTEFRAME) {
		register int sz;
		
		/* grab frame type and validate */
		sz = tstate.ss_frame.f_format;
		if (sz > 15 || (sz = exframesize[sz]) < 0)
			return (EINVAL);
		frame->f_stackadj -= sz;
		frame->f_format = tstate.ss_frame.f_format;
		frame->f_vector = tstate.ss_frame.f_vector;
		bcopy((caddr_t)&tstate.ss_frame.F_u, (caddr_t)&frame->F_u, sz);
#ifdef DEBUG
		if (sigdebug & SDB_FOLLOW)
			printf("sigreturn(%d): copy in %d of frame type %d\n",
			       p->p_pid, sz, tstate.ss_frame.f_format);
#endif
	}
	/*
	 * Finally we restore the original FP context
	 */
	if (fputype && (flags & SS_FPSTATE))
		m68881_restore(&tstate.ss_fpstate);
#ifdef DEBUG
	if ((sigdebug & SDB_FPSTATE) && *(char *)&tstate.ss_fpstate)
		printf("sigreturn(%d): copied in FP state (%x) at %p\n",
		       p->p_pid, *(u_int *)&tstate.ss_fpstate,
		       &tstate.ss_fpstate);
	if ((sigdebug & SDB_FOLLOW) ||
	    ((sigdebug & SDB_KSTACK) && p->p_pid == sigpid))
		printf("sigreturn(%d): returns\n", p->p_pid);
#endif
	return (EJUSTRETURN);
}