/*-
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * Copyright (c) 1982, 1986 The Regents of the University of California.
 * Copyright (c) 1989, 1990 William Jolitz
 * Copyright (c) 1994 John Dyson
 * 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, and William Jolitz.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. 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.
 *      Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
 */

#include <sys/cdefs.h>
#include "opt_isa.h"
#include "opt_npx.h"
#include "opt_reset.h"
#include "opt_cpu.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sysent.h>
#include <sys/sf_buf.h>
#include <sys/smp.h>
#include <sys/sched.h>
#include <sys/sysctl.h>
#include <sys/unistd.h>
#include <sys/vnode.h>
#include <sys/vmmeter.h>

#include <machine/cpu.h>
#include <machine/cputypes.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/pcb_ext.h>
#include <machine/smp.h>
#include <machine/vm86.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_param.h>

_Static_assert(__OFFSETOF_MONITORBUF == offsetof(struct pcpu, pc_monitorbuf),
    "__OFFSETOF_MONITORBUF does not correspond with offset of pc_monitorbuf.");

union savefpu *
get_pcb_user_save_td(struct thread *td)
{
        vm_offset_t p;

        p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE -
            roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN);
        KASSERT(__is_aligned(p, XSAVE_AREA_ALIGN),
            ("Unaligned pcb_user_save area"));
        return ((union savefpu *)p);
}

union savefpu *
get_pcb_user_save_pcb(struct pcb *pcb)
{
        vm_offset_t p;

        p = (vm_offset_t)(pcb + 1);
        return ((union savefpu *)p);
}

struct pcb *
get_pcb_td(struct thread *td)
{
        vm_offset_t p;

        p = td->td_kstack + td->td_kstack_pages * PAGE_SIZE -
            roundup2(cpu_max_ext_state_size, XSAVE_AREA_ALIGN) -
            sizeof(struct pcb);
        return ((struct pcb *)p);
}

void *
alloc_fpusave(int flags)
{
        void *res;
        struct savefpu_ymm *sf;

        res = malloc(cpu_max_ext_state_size, M_DEVBUF, flags);
        if (use_xsave) {
                sf = (struct savefpu_ymm *)res;
                bzero(&sf->sv_xstate.sx_hd, sizeof(sf->sv_xstate.sx_hd));
                sf->sv_xstate.sx_hd.xstate_bv = xsave_mask;
        }
        return (res);
}

/*
 * Common code shared between cpu_fork() and cpu_copy_thread() for
 * initializing a thread.
 */
static void
copy_thread(struct thread *td1, struct thread *td2)
{
        struct pcb *pcb2;

        pcb2 = td2->td_pcb;

        /* Ensure that td1's pcb is up to date for user threads. */
        if ((td2->td_pflags & TDP_KTHREAD) == 0) {
                MPASS(td1 == curthread);
                td1->td_pcb->pcb_gs = rgs();
                critical_enter();
                if (PCPU_GET(fpcurthread) == td1)
                        npxsave(td1->td_pcb->pcb_save);
                critical_exit();
        }

        /* Copy td1's pcb */
        bcopy(td1->td_pcb, pcb2, sizeof(*pcb2));

        /* Properly initialize pcb_save */
        pcb2->pcb_save = get_pcb_user_save_pcb(pcb2);

        /* Kernel threads start with clean NPX and segment bases. */
        if ((td2->td_pflags & TDP_KTHREAD) != 0) {
                pcb2->pcb_gs = _udatasel;
                set_fsbase(td2, 0);
                set_gsbase(td2, 0);
                pcb2->pcb_flags &= ~(PCB_NPXINITDONE | PCB_NPXUSERINITDONE |
                    PCB_KERNNPX | PCB_KERNNPX_THR);
        } else {
                MPASS((pcb2->pcb_flags & (PCB_KERNNPX | PCB_KERNNPX_THR)) == 0);
                bcopy(get_pcb_user_save_td(td1), get_pcb_user_save_pcb(pcb2),
                    cpu_max_ext_state_size);
        }

        /*
         * Set registers for trampoline to user mode.  Leave space for the
         * return address on stack.  These are the kernel mode register values.
         */
        pcb2->pcb_edi = 0;
        pcb2->pcb_esi = (int)fork_return;                   /* trampoline arg */
        pcb2->pcb_ebp = 0;
        pcb2->pcb_esp = (int)td2->td_frame - sizeof(void *); /* trampoline arg */
        pcb2->pcb_ebx = (int)td2;                           /* trampoline arg */
        pcb2->pcb_eip = (int)fork_trampoline + setidt_disp;
        /*
         * If we didn't copy the pcb, we'd need to do the following registers:
         * pcb2->pcb_cr3:       cloned above.
         * pcb2->pcb_dr*:       cloned above.
         * pcb2->pcb_savefpu:   cloned above.
         * pcb2->pcb_flags:     cloned above.
         * pcb2->pcb_onfault:   cloned above (always NULL here?).
         * pcb2->pcb_gs:        cloned above.
         * pcb2->pcb_ext:       cleared below.
         */
        pcb2->pcb_ext = NULL;

        /* Setup to release spin count in fork_exit(). */
        td2->td_md.md_spinlock_count = 1;
        td2->td_md.md_saved_flags = PSL_KERNEL | PSL_I;
}

/*
 * 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 proc *p1;
        struct pcb *pcb2;
        struct mdproc *mdp2;

        p1 = td1->td_proc;
        if ((flags & RFPROC) == 0) {
                if ((flags & RFMEM) == 0) {
                        /* unshare user LDT */
                        struct mdproc *mdp1 = &p1->p_md;
                        struct proc_ldt *pldt, *pldt1;

                        mtx_lock_spin(&dt_lock);
                        if ((pldt1 = mdp1->md_ldt) != NULL &&
                            pldt1->ldt_refcnt > 1) {
                                pldt = user_ldt_alloc(mdp1, pldt1->ldt_len);
                                if (pldt == NULL)
                                        panic("could not copy LDT");
                                mdp1->md_ldt = pldt;
                                set_user_ldt(mdp1);
                                user_ldt_deref(pldt1);
                        } else
                                mtx_unlock_spin(&dt_lock);
                }
                return;
        }

        /* Point the pcb to the top of the stack */
        pcb2 = get_pcb_td(td2);
        td2->td_pcb = pcb2;

        copy_thread(td1, td2);

        /* Reset debug registers in the new process */
        x86_clear_dbregs(pcb2);

        /* Point mdproc and then copy over td1's contents */
        mdp2 = &p2->p_md;
        bcopy(&p1->p_md, mdp2, sizeof(*mdp2));

        /*
         * Copy the trap frame for the return to user mode as if from a
         * syscall.  This copies most of the user mode register values.
         * The -VM86_STACK_SPACE (-16) is so we can expand the trapframe
         * if we go to vm86.
         */
        td2->td_frame = (struct trapframe *)((caddr_t)td2->td_pcb -
            VM86_STACK_SPACE) - 1;
        bcopy(td1->td_frame, td2->td_frame, sizeof(struct trapframe));

        /* Set child return values. */
        p2->p_sysent->sv_set_fork_retval(td2);

        /*
         * If the parent process has the trap bit set (i.e. a debugger
         * had single stepped the process to the system call), we need
         * to clear the trap flag from the new frame.
         */
        td2->td_frame->tf_eflags &= ~PSL_T;

        /* Set cr3 for the new process. */
        pcb2->pcb_cr3 = pmap_get_cr3(vmspace_pmap(p2->p_vmspace));

        /*
         * XXX don't copy the i/o pages.  this should probably be fixed.
         */
        pcb2->pcb_ext = NULL;

        /* Copy the LDT, if necessary. */
        mtx_lock_spin(&dt_lock);
        if (mdp2->md_ldt != NULL) {
                if (flags & RFMEM) {
                        mdp2->md_ldt->ldt_refcnt++;
                } else {
                        mdp2->md_ldt = user_ldt_alloc(mdp2,
                            mdp2->md_ldt->ldt_len);
                        if (mdp2->md_ldt == NULL)
                                panic("could not copy LDT");
                }
        }
        mtx_unlock_spin(&dt_lock);

        /*
         * Now, cpu_switch() can schedule the new process.
         * pcb_esp is loaded pointing to the cpu_switch() stack frame
         * containing the return address when exiting cpu_switch.
         * This will normally be to fork_trampoline(), which will have
         * %ebx loaded with the new proc's pointer.  fork_trampoline()
         * will set up a stack to call fork_return(p, frame); to complete
         * the return to user-mode.
         */
}

void
x86_set_fork_retval(struct thread *td)
{
        struct trapframe * frame = td->td_frame;

        frame->tf_eax = 0;              /* Child returns zero */
        frame->tf_eflags &= ~PSL_C;     /* success */
        frame->tf_edx = 1;              /* System V emulation */
}

/*
 * 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)
{
        /*
         * Note that the trap frame follows the args, so the function
         * is really called like this:  func(arg, frame);
         */
        td->td_pcb->pcb_esi = (int) func;       /* function */
        td->td_pcb->pcb_ebx = (int) arg;        /* first arg */
}

void
cpu_exit(struct thread *td)
{

        /*
         * If this process has a custom LDT, release it.  Reset pc->pcb_gs
         * and %gs before we free it in case they refer to an LDT entry.
         */
        mtx_lock_spin(&dt_lock);
        if (td->td_proc->p_md.md_ldt) {
                td->td_pcb->pcb_gs = _udatasel;
                load_gs(_udatasel);
                user_ldt_free(td);
        } else
                mtx_unlock_spin(&dt_lock);
}

void
cpu_thread_exit(struct thread *td)
{

        critical_enter();
        if (td == PCPU_GET(fpcurthread))
                npxdrop();
        critical_exit();

        /* Disable any hardware breakpoints. */
        if (td->td_pcb->pcb_flags & PCB_DBREGS) {
                reset_dbregs();
                td->td_pcb->pcb_flags &= ~PCB_DBREGS;
        }
}

void
cpu_thread_clean(struct thread *td)
{
        struct pcb *pcb;

        pcb = td->td_pcb; 
        if (pcb->pcb_ext != NULL) {
                /* if (pcb->pcb_ext->ext_refcount-- == 1) ?? */
                /*
                 * XXX do we need to move the TSS off the allocated pages
                 * before freeing them?  (not done here)
                 */
                pmap_trm_free(pcb->pcb_ext, ctob(IOPAGES + 1));
                pcb->pcb_ext = NULL;
        }
}

void
cpu_thread_alloc(struct thread *td)
{
        struct pcb *pcb;
        struct xstate_hdr *xhdr;

        td->td_pcb = pcb = get_pcb_td(td);
        td->td_frame = (struct trapframe *)((caddr_t)pcb -
            VM86_STACK_SPACE) - 1;
        pcb->pcb_ext = NULL; 
        pcb->pcb_save = get_pcb_user_save_pcb(pcb);
        if (use_xsave) {
                xhdr = (struct xstate_hdr *)(pcb->pcb_save + 1);
                bzero(xhdr, sizeof(*xhdr));
                xhdr->xstate_bv = xsave_mask;
        }
}

void
cpu_thread_free(struct thread *td)
{

        cpu_thread_clean(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_set_syscall_retval(struct thread *td, int error)
{

        switch (error) {
        case 0:
                td->td_frame->tf_eax = td->td_retval[0];
                td->td_frame->tf_edx = td->td_retval[1];
                td->td_frame->tf_eflags &= ~PSL_C;
                break;

        case ERESTART:
                /*
                 * Reconstruct pc, assuming lcall $X,y is 7 bytes, int
                 * 0x80 is 2 bytes. We saved this in tf_err.
                 */
                td->td_frame->tf_eip -= td->td_frame->tf_err;
                break;

        case EJUSTRETURN:
                break;

        default:
                td->td_frame->tf_eax = error;
                td->td_frame->tf_eflags |= PSL_C;
                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)
{
        copy_thread(td0, td);

        /*
         * Copy user general-purpose registers.
         *
         * Some of these registers are rewritten by cpu_set_upcall()
         * and linux_set_upcall().
         */
        bcopy(td0->td_frame, td->td_frame, sizeof(struct trapframe));

        /* If the current thread has the trap bit set (i.e. a debugger had
         * single stepped the process to the system call), we need to clear
         * the trap flag from the new frame. Otherwise, the new thread will
         * receive a (likely unexpected) SIGTRAP when it executes the first
         * instruction after returning to userland.
         */
        td->td_frame->tf_eflags &= ~PSL_T;
}

/*
 * 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)
{
        /*
         * Set the trap frame to point at the beginning of the entry
         * function.
         */
        td->td_frame->tf_ebp = 0; 
        td->td_frame->tf_esp =
            (((int)stack->ss_sp + stack->ss_size - 4) & ~0x0f) - 4;
        td->td_frame->tf_eip = (int)entry;

        /* Return address sentinel value to stop stack unwinding. */
        if (suword((void *)td->td_frame->tf_esp, 0) != 0)
                return (EFAULT);

        /* Pass the argument to the entry point. */
        if (suword((void *)(td->td_frame->tf_esp + sizeof(void *)),
            (int)arg) != 0)
                return (EFAULT);
        return (0);
}

int
cpu_set_user_tls(struct thread *td, void *tls_base, int thr_flags __unused)
{
        struct segment_descriptor sd;
        uint32_t base;

        /*
         * Construct a descriptor and store it in the pcb for
         * the next context switch.  Also store it in the gdt
         * so that the load of tf_fs into %fs will activate it
         * at return to userland.
         */
        base = (uint32_t)tls_base;
        sd.sd_lobase = base & 0xffffff;
        sd.sd_hibase = (base >> 24) & 0xff;
        sd.sd_lolimit = 0xffff; /* 4GB limit, wraps around */
        sd.sd_hilimit = 0xf;
        sd.sd_type  = SDT_MEMRWA;
        sd.sd_dpl   = SEL_UPL;
        sd.sd_p     = 1;
        sd.sd_xx    = 0;
        sd.sd_def32 = 1;
        sd.sd_gran  = 1;
        critical_enter();
        /* set %gs */
        td->td_pcb->pcb_gsd = sd;
        if (td == curthread) {
                PCPU_GET(fsgs_gdt)[1] = sd;
                load_gs(GSEL(GUGS_SEL, SEL_UPL));
        }
        critical_exit();
        return (0);
}

void
cpu_update_pcb(struct thread *td)
{
        MPASS(td == curthread);
        td->td_pcb->pcb_gs = rgs();
}

/*
 * Convert kernel VA to physical address
 */
vm_paddr_t
kvtop(void *addr)
{
        vm_paddr_t pa;

        pa = pmap_kextract((vm_offset_t)addr);
        if (pa == 0)
                panic("kvtop: zero page frame");
        return (pa);
}

/*
 * Get an sf_buf from the freelist.  May block if none are available.
 */
void
sf_buf_map(struct sf_buf *sf, int flags)
{

        pmap_sf_buf_map(sf);
#ifdef SMP
        sf_buf_shootdown(sf, flags);
#endif
}

#ifdef SMP
static void
sf_buf_shootdown_curcpu_cb(pmap_t pmap __unused,
    vm_offset_t addr1 __unused, vm_offset_t addr2 __unused)
{
}

void
sf_buf_shootdown(struct sf_buf *sf, int flags)
{
        cpuset_t other_cpus;
        u_int cpuid;

        sched_pin();
        cpuid = PCPU_GET(cpuid);
        if (!CPU_ISSET(cpuid, &sf->cpumask)) {
                CPU_SET(cpuid, &sf->cpumask);
                invlpg(sf->kva);
        }
        if ((flags & SFB_CPUPRIVATE) == 0) {
                other_cpus = all_cpus;
                CPU_CLR(cpuid, &other_cpus);
                CPU_ANDNOT(&other_cpus, &other_cpus, &sf->cpumask);
                if (!CPU_EMPTY(&other_cpus)) {
                        CPU_OR(&sf->cpumask, &sf->cpumask, &other_cpus);
                        smp_masked_invlpg(other_cpus, sf->kva, kernel_pmap,
                            sf_buf_shootdown_curcpu_cb);
                }
        }
        sched_unpin();
}
#endif

/*
 * MD part of sf_buf_free().
 */
int
sf_buf_unmap(struct sf_buf *sf)
{

        return (0);
}

static void
sf_buf_invalidate(struct sf_buf *sf)
{
        vm_page_t m = sf->m;

        /*
         * Use pmap_qenter to update the pte for
         * existing mapping, in particular, the PAT
         * settings are recalculated.
         */
        pmap_qenter(sf->kva, &m, 1);
        pmap_invalidate_cache_range(sf->kva, sf->kva + PAGE_SIZE);
}

/*
 * Invalidate the cache lines that may belong to the page, if
 * (possibly old) mapping of the page by sf buffer exists.  Returns
 * TRUE when mapping was found and cache invalidated.
 */
boolean_t
sf_buf_invalidate_cache(vm_page_t m)
{

        return (sf_buf_process_page(m, sf_buf_invalidate));
}