/*-
 * Copyright (c) 2014 Andrew Turner
 * Copyright (c) 2015-2017 Ruslan Bukin <br@bsdpad.com>
 * All rights reserved.
 *
 * Portions of this software were developed by SRI International and the
 * University of Cambridge Computer Laboratory under DARPA/AFRL contract
 * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
 *
 * Portions of this software were developed by the University of Cambridge
 * Computer Laboratory as part of the CTSRD Project, with support from the
 * UK Higher Education Innovation Fund (HEIF).
 *
 * 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 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 AUTHOR 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.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/ptrace.h>
#include <sys/reg.h>
#include <sys/rwlock.h>
#include <sys/sched.h>
#include <sys/signalvar.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>
#include <sys/ucontext.h>

#include <machine/cpu.h>
#include <machine/fpe.h>
#include <machine/kdb.h>
#include <machine/pcb.h>
#include <machine/pte.h>
#include <machine/riscvreg.h>
#include <machine/sbi.h>
#include <machine/trap.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>

static void get_fpcontext(struct thread *td, mcontext_t *mcp);
static void set_fpcontext(struct thread *td, mcontext_t *mcp);

_Static_assert(sizeof(mcontext_t) == 864, "mcontext_t size incorrect");
_Static_assert(sizeof(ucontext_t) == 936, "ucontext_t size incorrect");
_Static_assert(sizeof(siginfo_t) == 80, "siginfo_t size incorrect");

int
fill_regs(struct thread *td, struct reg *regs)
{
        struct trapframe *frame;

        frame = td->td_frame;
        regs->sepc = frame->tf_sepc;
        regs->sstatus = frame->tf_sstatus;
        regs->ra = frame->tf_ra;
        regs->sp = frame->tf_sp;
        regs->gp = frame->tf_gp;
        regs->tp = frame->tf_tp;

        memcpy(regs->t, frame->tf_t, sizeof(regs->t));
        memcpy(regs->s, frame->tf_s, sizeof(regs->s));
        memcpy(regs->a, frame->tf_a, sizeof(regs->a));

        return (0);
}

int
set_regs(struct thread *td, struct reg *regs)
{
        struct trapframe *frame;

        frame = td->td_frame;
        frame->tf_sepc = regs->sepc;
        frame->tf_ra = regs->ra;
        frame->tf_sp = regs->sp;
        frame->tf_gp = regs->gp;
        frame->tf_tp = regs->tp;

        memcpy(frame->tf_t, regs->t, sizeof(frame->tf_t));
        memcpy(frame->tf_s, regs->s, sizeof(frame->tf_s));
        memcpy(frame->tf_a, regs->a, sizeof(frame->tf_a));

        return (0);
}

int
fill_fpregs(struct thread *td, struct fpreg *regs)
{
        struct pcb *pcb;

        pcb = td->td_pcb;

        if ((pcb->pcb_fpflags & PCB_FP_STARTED) != 0) {
                /*
                 * If we have just been running FPE instructions we will
                 * need to save the state to memcpy it below.
                 */
                if (td == curthread)
                        fpe_state_save(td);

                memcpy(regs->fp_x, pcb->pcb_x, sizeof(regs->fp_x));
                regs->fp_fcsr = pcb->pcb_fcsr;
        } else
                memset(regs, 0, sizeof(*regs));

        return (0);
}

int
set_fpregs(struct thread *td, struct fpreg *regs)
{
        struct trapframe *frame;
        struct pcb *pcb;

        frame = td->td_frame;
        pcb = td->td_pcb;

        memcpy(pcb->pcb_x, regs->fp_x, sizeof(regs->fp_x));
        pcb->pcb_fcsr = regs->fp_fcsr;
        pcb->pcb_fpflags |= PCB_FP_STARTED;
        frame->tf_sstatus &= ~SSTATUS_FS_MASK;
        frame->tf_sstatus |= SSTATUS_FS_CLEAN;

        return (0);
}

int
fill_dbregs(struct thread *td, struct dbreg *regs)
{

        panic("fill_dbregs");
}

int
set_dbregs(struct thread *td, struct dbreg *regs)
{

        panic("set_dbregs");
}

void
exec_setregs(struct thread *td, struct image_params *imgp, uintptr_t stack)
{
        struct trapframe *tf;
        struct pcb *pcb;

        tf = td->td_frame;
        pcb = td->td_pcb;

        memset(tf, 0, sizeof(struct trapframe));

        tf->tf_a[0] = stack;
        tf->tf_sp = STACKALIGN(stack);
        tf->tf_ra = imgp->entry_addr;
        tf->tf_sepc = imgp->entry_addr;

        pcb->pcb_fpflags &= ~PCB_FP_STARTED;
}

/* Sanity check these are the same size, they will be memcpy'd to and from */
CTASSERT(sizeof(((struct trapframe *)0)->tf_a) ==
    sizeof((struct gpregs *)0)->gp_a);
CTASSERT(sizeof(((struct trapframe *)0)->tf_s) ==
    sizeof((struct gpregs *)0)->gp_s);
CTASSERT(sizeof(((struct trapframe *)0)->tf_t) ==
    sizeof((struct gpregs *)0)->gp_t);
CTASSERT(sizeof(((struct trapframe *)0)->tf_a) ==
    sizeof((struct reg *)0)->a);
CTASSERT(sizeof(((struct trapframe *)0)->tf_s) ==
    sizeof((struct reg *)0)->s);
CTASSERT(sizeof(((struct trapframe *)0)->tf_t) ==
    sizeof((struct reg *)0)->t);

int
get_mcontext(struct thread *td, mcontext_t *mcp, int clear_ret)
{
        struct trapframe *tf = td->td_frame;

        memcpy(mcp->mc_gpregs.gp_t, tf->tf_t, sizeof(mcp->mc_gpregs.gp_t));
        memcpy(mcp->mc_gpregs.gp_s, tf->tf_s, sizeof(mcp->mc_gpregs.gp_s));
        memcpy(mcp->mc_gpregs.gp_a, tf->tf_a, sizeof(mcp->mc_gpregs.gp_a));

        if (clear_ret & GET_MC_CLEAR_RET) {
                mcp->mc_gpregs.gp_a[0] = 0;
                mcp->mc_gpregs.gp_t[0] = 0; /* clear syscall error */
        }

        mcp->mc_gpregs.gp_ra = tf->tf_ra;
        mcp->mc_gpregs.gp_sp = tf->tf_sp;
        mcp->mc_gpregs.gp_gp = tf->tf_gp;
        mcp->mc_gpregs.gp_tp = tf->tf_tp;
        mcp->mc_gpregs.gp_sepc = tf->tf_sepc;
        mcp->mc_gpregs.gp_sstatus = tf->tf_sstatus;
        get_fpcontext(td, mcp);

        return (0);
}

int
set_mcontext(struct thread *td, mcontext_t *mcp)
{
        struct trapframe *tf;

        tf = td->td_frame;

        /*
         * Permit changes to the USTATUS bits of SSTATUS.
         *
         * Ignore writes to read-only bits (SD, XS).
         *
         * Ignore writes to the FS field as set_fpcontext() will set
         * it explicitly.
         */
        if (((mcp->mc_gpregs.gp_sstatus ^ tf->tf_sstatus) &
            ~(SSTATUS_SD | SSTATUS_XS_MASK | SSTATUS_FS_MASK | SSTATUS_UPIE |
            SSTATUS_UIE)) != 0)
                return (EINVAL);

        memcpy(tf->tf_t, mcp->mc_gpregs.gp_t, sizeof(tf->tf_t));
        memcpy(tf->tf_s, mcp->mc_gpregs.gp_s, sizeof(tf->tf_s));
        memcpy(tf->tf_a, mcp->mc_gpregs.gp_a, sizeof(tf->tf_a));

        tf->tf_ra = mcp->mc_gpregs.gp_ra;
        tf->tf_sp = mcp->mc_gpregs.gp_sp;
        tf->tf_gp = mcp->mc_gpregs.gp_gp;
        tf->tf_sepc = mcp->mc_gpregs.gp_sepc;
        tf->tf_sstatus = mcp->mc_gpregs.gp_sstatus;
        set_fpcontext(td, mcp);

        return (0);
}

static void
get_fpcontext(struct thread *td, mcontext_t *mcp)
{
        struct pcb *curpcb;

        critical_enter();

        curpcb = curthread->td_pcb;

        KASSERT(td->td_pcb == curpcb, ("Invalid fpe pcb"));

        if ((curpcb->pcb_fpflags & PCB_FP_STARTED) != 0) {
                /*
                 * If we have just been running FPE instructions we will
                 * need to save the state to memcpy it below.
                 */
                fpe_state_save(td);

                KASSERT((curpcb->pcb_fpflags & ~PCB_FP_USERMASK) == 0,
                    ("Non-userspace FPE flags set in get_fpcontext"));
                memcpy(mcp->mc_fpregs.fp_x, curpcb->pcb_x,
                    sizeof(mcp->mc_fpregs.fp_x));
                mcp->mc_fpregs.fp_fcsr = curpcb->pcb_fcsr;
                mcp->mc_fpregs.fp_flags = curpcb->pcb_fpflags;
                mcp->mc_flags |= _MC_FP_VALID;
        }

        critical_exit();
}

static void
set_fpcontext(struct thread *td, mcontext_t *mcp)
{
        struct pcb *curpcb;

        td->td_frame->tf_sstatus &= ~SSTATUS_FS_MASK;
        td->td_frame->tf_sstatus |= SSTATUS_FS_OFF;

        critical_enter();

        if ((mcp->mc_flags & _MC_FP_VALID) != 0) {
                curpcb = curthread->td_pcb;
                /* FPE usage is enabled, override registers. */
                memcpy(curpcb->pcb_x, mcp->mc_fpregs.fp_x,
                    sizeof(mcp->mc_fpregs.fp_x));
                curpcb->pcb_fcsr = mcp->mc_fpregs.fp_fcsr;
                curpcb->pcb_fpflags = mcp->mc_fpregs.fp_flags & PCB_FP_USERMASK;
                td->td_frame->tf_sstatus |= SSTATUS_FS_CLEAN;
        }

        critical_exit();
}

int
sys_sigreturn(struct thread *td, struct sigreturn_args *uap)
{
        ucontext_t uc;
        int error;

        if (copyin(uap->sigcntxp, &uc, sizeof(uc)))
                return (EFAULT);

        error = set_mcontext(td, &uc.uc_mcontext);
        if (error != 0)
                return (error);

        /* Restore signal mask. */
        kern_sigprocmask(td, SIG_SETMASK, &uc.uc_sigmask, NULL, 0);

        return (EJUSTRETURN);
}

void
sendsig(sig_t catcher, ksiginfo_t *ksi, sigset_t *mask)
{
        struct sigframe *fp, frame;
        struct sysentvec *sysent;
        struct trapframe *tf;
        struct sigacts *psp;
        struct thread *td;
        struct proc *p;
        int onstack;
        int sig;

        td = curthread;
        p = td->td_proc;
        PROC_LOCK_ASSERT(p, MA_OWNED);

        sig = ksi->ksi_signo;
        psp = p->p_sigacts;
        mtx_assert(&psp->ps_mtx, MA_OWNED);

        tf = td->td_frame;
        onstack = sigonstack(tf->tf_sp);

        CTR4(KTR_SIG, "sendsig: td=%p (%s) catcher=%p sig=%d", td, p->p_comm,
            catcher, sig);

        /* Allocate and validate space for the signal handler context. */
        if ((td->td_pflags & TDP_ALTSTACK) != 0 && !onstack &&
            SIGISMEMBER(psp->ps_sigonstack, sig)) {
                fp = (struct sigframe *)((uintptr_t)td->td_sigstk.ss_sp +
                    td->td_sigstk.ss_size);
        } else {
                fp = (struct sigframe *)td->td_frame->tf_sp;
        }

        /* Make room, keeping the stack aligned */
        fp--;
        fp = STACKALIGN(fp);

        /* Fill in the frame to copy out */
        bzero(&frame, sizeof(frame));
        get_mcontext(td, &frame.sf_uc.uc_mcontext, 0);
        frame.sf_si = ksi->ksi_info;
        frame.sf_uc.uc_sigmask = *mask;
        frame.sf_uc.uc_stack = td->td_sigstk;
        frame.sf_uc.uc_stack.ss_flags = (td->td_pflags & TDP_ALTSTACK) != 0 ?
            (onstack ? SS_ONSTACK : 0) : SS_DISABLE;
        mtx_unlock(&psp->ps_mtx);
        PROC_UNLOCK(td->td_proc);

        /* Copy the sigframe out to the user's stack. */
        if (copyout(&frame, fp, sizeof(*fp)) != 0) {
                /* Process has trashed its stack. Kill it. */
                CTR2(KTR_SIG, "sendsig: sigexit td=%p fp=%p", td, fp);
                PROC_LOCK(p);
                sigexit(td, SIGILL);
        }

        tf->tf_a[0] = sig;
        tf->tf_a[1] = (register_t)&fp->sf_si;
        tf->tf_a[2] = (register_t)&fp->sf_uc;

        tf->tf_sepc = (register_t)catcher;
        tf->tf_sp = (register_t)fp;

        sysent = p->p_sysent;
        if (PROC_HAS_SHP(p))
                tf->tf_ra = (register_t)PROC_SIGCODE(p);
        else
                tf->tf_ra = (register_t)(PROC_PS_STRINGS(p) -
                    *(sysent->sv_szsigcode));

        CTR3(KTR_SIG, "sendsig: return td=%p pc=%#x sp=%#x", td, tf->tf_sepc,
            tf->tf_sp);

        PROC_LOCK(p);
        mtx_lock(&psp->ps_mtx);
}