/*-
 * Copyright (c) 2014 Andrew Turner
 * All rights reserved.
 *
 * 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 "opt_platform.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/limits.h>
#include <sys/proc.h>
#include <sys/sf_buf.h>
#include <sys/signal.h>
#include <sys/sysent.h>
#include <sys/unistd.h>

#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/uma.h>
#include <vm/uma_int.h>

#include <machine/armreg.h>
#include <machine/cpu.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/frame.h>

#ifdef VFP
#include <machine/vfp.h>
#endif

#include <dev/psci/psci.h>

/*
 * psci.c is "default" in ARM64 kernel config files
 * psci_reset will do nothing until/unless the psci device probes/attaches.
 * Therefore, it is safe to default the cpu_reset_hook to psci_reset.
 */
cpu_reset_hook_t cpu_reset_hook = psci_reset;

/*
 * Finish a fork operation, with process p2 nearly set up.
 * Copy and update the pcb, set up the stack so that the child
 * ready to run and return to user mode.
 */
void
cpu_fork(struct thread *td1, struct proc *p2, struct thread *td2, int flags)
{
        struct pcb *pcb2;
        struct trapframe *tf;

        if ((flags & RFPROC) == 0)
                return;

        if (td1 == curthread) {
                /*
                 * Save the tpidr_el0 and the vfp state, these normally happen
                 * in cpu_switch, but if userland changes these then forks
                 * this may not have happened.
                 */
                td1->td_pcb->pcb_tpidr_el0 = READ_SPECIALREG(tpidr_el0);
                td1->td_pcb->pcb_tpidrro_el0 = READ_SPECIALREG(tpidrro_el0);
#ifdef VFP
                if ((td1->td_pcb->pcb_fpflags & PCB_FP_STARTED) != 0)
                        vfp_save_state(td1, td1->td_pcb);
#endif
        }

        pcb2 = (struct pcb *)(td2->td_kstack +
            td2->td_kstack_pages * PAGE_SIZE) - 1;

        td2->td_pcb = pcb2;
        bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));

        /* Clear the debug register state. */
        bzero(&pcb2->pcb_dbg_regs, sizeof(pcb2->pcb_dbg_regs));

        ptrauth_fork(td2, td1);

        tf = STACKALIGN((struct trapframe *)pcb2 - 1);
        bcopy(td1->td_frame, tf, sizeof(*tf));
        tf->tf_x[0] = 0;
        tf->tf_x[1] = 0;
        tf->tf_spsr = td1->td_frame->tf_spsr & (PSR_M_32 | PSR_DAIF);

        td2->td_frame = tf;

        /* Set the return value registers for fork() */
        td2->td_pcb->pcb_x[PCB_X19] = (uintptr_t)fork_return;
        td2->td_pcb->pcb_x[PCB_X20] = (uintptr_t)td2;
        td2->td_pcb->pcb_x[PCB_LR] = (uintptr_t)fork_trampoline;
        td2->td_pcb->pcb_sp = (uintptr_t)td2->td_frame;

        vfp_new_thread(td2, td1, true);

        /* Setup to release spin count in fork_exit(). */
        td2->td_md.md_spinlock_count = 1;
        td2->td_md.md_saved_daif = PSR_DAIF_DEFAULT;

        /* Copy the TCR_EL1 value */
        td2->td_proc->p_md.md_tcr = td1->td_proc->p_md.md_tcr;

#if defined(PERTHREAD_SSP)
        /* Set the new canary */
        arc4random_buf(&td2->td_md.md_canary, sizeof(td2->td_md.md_canary));
#endif
}

void
cpu_reset(void)
{

        cpu_reset_hook();

        printf("cpu_reset failed");
        while(1)
                __asm volatile("wfi" ::: "memory");
}

void
cpu_set_syscall_retval(struct thread *td, int error)
{
        struct trapframe *frame;

        frame = td->td_frame;

        if (__predict_true(error == 0)) {
                frame->tf_x[0] = td->td_retval[0];
                frame->tf_x[1] = td->td_retval[1];
                frame->tf_spsr &= ~PSR_C;       /* carry bit */
                return;
        }

        switch (error) {
        case ERESTART:
                frame->tf_elr -= 4;
                break;
        case EJUSTRETURN:
                break;
        default:
                frame->tf_spsr |= PSR_C;        /* carry bit */
                frame->tf_x[0] = error;
                break;
        }
}

/*
 * Initialize machine state, mostly pcb and trap frame for a new
 * thread, about to return to userspace.  Put enough state in the new
 * thread's PCB to get it to go back to the fork_return(), which
 * finalizes the thread state and handles peculiarities of the first
 * return to userspace for the new thread.
 */
void
cpu_copy_thread(struct thread *td, struct thread *td0)
{
        bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));
        bcopy(td0->td_pcb, td->td_pcb, sizeof(struct pcb));

        td->td_pcb->pcb_x[PCB_X19] = (uintptr_t)fork_return;
        td->td_pcb->pcb_x[PCB_X20] = (uintptr_t)td;
        td->td_pcb->pcb_x[PCB_LR] = (uintptr_t)fork_trampoline;
        td->td_pcb->pcb_sp = (uintptr_t)td->td_frame;

        /* Update VFP state for the new thread */
        vfp_new_thread(td, td0, false);

        /* Setup to release spin count in fork_exit(). */
        td->td_md.md_spinlock_count = 1;
        td->td_md.md_saved_daif = PSR_DAIF_DEFAULT;

#if defined(PERTHREAD_SSP)
        /* Set the new canary */
        arc4random_buf(&td->td_md.md_canary, sizeof(td->td_md.md_canary));
#endif

        /* Generate new pointer authentication keys. */
        ptrauth_copy_thread(td, td0);
}

/*
 * Set that machine state for performing an upcall that starts
 * the entry function with the given argument.
 */
int
cpu_set_upcall(struct thread *td, void (*entry)(void *), void *arg,
        stack_t *stack)
{
        struct trapframe *tf = td->td_frame;

        /* 32bits processes use r13 for sp */
        if (td->td_frame->tf_spsr & PSR_M_32) {
                tf->tf_x[13] = STACKALIGN((uintptr_t)stack->ss_sp +
                    stack->ss_size);
                if ((register_t)entry & 1)
                        tf->tf_spsr |= PSR_T;
        } else
                tf->tf_sp = STACKALIGN((uintptr_t)stack->ss_sp +
                    stack->ss_size);
        tf->tf_elr = (register_t)entry;
        tf->tf_x[0] = (register_t)arg;
        tf->tf_x[29] = 0;
        tf->tf_lr = 0;
        return (0);
}

int
cpu_set_user_tls(struct thread *td, void *tls_base, int thr_flags __unused)
{
        struct pcb *pcb;

        if ((uintptr_t)tls_base >= VM_MAXUSER_ADDRESS)
                return (EINVAL);

        pcb = td->td_pcb;
        if (td->td_frame->tf_spsr & PSR_M_32) {
                /* 32bits arm stores the user TLS into tpidrro */
                pcb->pcb_tpidrro_el0 = (register_t)tls_base;
                pcb->pcb_tpidr_el0 = (register_t)tls_base;
                if (td == curthread) {
                        WRITE_SPECIALREG(tpidrro_el0, tls_base);
                        WRITE_SPECIALREG(tpidr_el0, tls_base);
                }
        } else {
                pcb->pcb_tpidr_el0 = (register_t)tls_base;
                if (td == curthread)
                        WRITE_SPECIALREG(tpidr_el0, tls_base);
        }

        return (0);
}

void
cpu_thread_exit(struct thread *td)
{
}

void
cpu_thread_alloc(struct thread *td)
{

        td->td_pcb = (struct pcb *)(td->td_kstack +
            td->td_kstack_pages * PAGE_SIZE) - 1;
        td->td_frame = (struct trapframe *)STACKALIGN(
            (struct trapframe *)td->td_pcb - 1);
        ptrauth_thread_alloc(td);
}

void
cpu_thread_free(struct thread *td)
{
}

void
cpu_thread_clean(struct thread *td)
{
}

/*
 * Intercept the return address from a freshly forked process that has NOT
 * been scheduled yet.
 *
 * This is needed to make kernel threads stay in kernel mode.
 */
void
cpu_fork_kthread_handler(struct thread *td, void (*func)(void *), void *arg)
{

        td->td_pcb->pcb_x[PCB_X19] = (uintptr_t)func;
        td->td_pcb->pcb_x[PCB_X20] = (uintptr_t)arg;
}

void
cpu_update_pcb(struct thread *td)
{
        MPASS(td == curthread);
        td->td_pcb->pcb_tpidr_el0 = READ_SPECIALREG(tpidr_el0);
        td->td_pcb->pcb_tpidrro_el0 = READ_SPECIALREG(tpidrro_el0);
}

void
cpu_exit(struct thread *td)
{
}

bool
cpu_exec_vmspace_reuse(struct proc *p __unused, vm_map_t map __unused)
{

        return (true);
}

int
cpu_procctl(struct thread *td __unused, int idtype __unused, id_t id __unused,
    int com __unused, void *data __unused)
{

        return (EINVAL);
}

void
cpu_sync_core(void)
{
        /*
         * Do nothing. According to ARM ARMv8 D1.11 Exception return
         * If FEAT_ExS is not implemented, or if FEAT_ExS is
         * implemented and the SCTLR_ELx.EOS field is set, exception
         * return from ELx is a context synchronization event.
         */
}