/*-
 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
 * Copyright (c) 2014 The FreeBSD Foundation
 * 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.
 */

#define __ELF_WORD_SIZE 64
#include <sys/param.h>
#include <sys/linker.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <machine/elf.h>
#include <machine/pmap_pae.h>
#include <machine/segments.h>

#include <efi.h>
#include <efilib.h>

#include "bootstrap.h"

#include "loader_efi.h"

static int      elf64_exec(struct preloaded_file *amp);
static int      elf64_obj_exec(struct preloaded_file *amp);

static struct file_format amd64_elf = {
        .l_load = elf64_loadfile,
        .l_exec = elf64_exec
};

static struct file_format amd64_elf_obj = {
        .l_load = elf64_obj_loadfile,
        .l_exec = elf64_obj_exec
};

struct file_format *file_formats[] = {
        &amd64_elf,
        &amd64_elf_obj,
        NULL
};

/*
 * i386's pmap_pae.h doesn't provide this, so
 * just typedef our own.
 */
typedef pdpt_entry_t pml4_entry_t;

static void (*trampoline)(uint32_t stack, void *copy_finish, uint32_t kernend,
    uint32_t modulep, uint64_t *pagetable, void *gdtr, uint64_t entry);

extern void *amd64_tramp;
extern uint32_t amd64_tramp_size;

/*
 * There is an ELF kernel and one or more ELF modules loaded.
 * We wish to start executing the kernel image, so make such
 * preparations as are required, and do so.
 */
static int
elf64_exec(struct preloaded_file *fp)
{
        /*
         * segments.h gives us a 32-bit gdtr, but
         * we want a 64-bit one, so define our own.
         */
        struct {
                uint16_t rd_limit;
                uint64_t rd_base;
        } __packed *gdtr;
        EFI_PHYSICAL_ADDRESS    ptr;
        EFI_ALLOCATE_TYPE       type;
        EFI_STATUS              err;
        struct file_metadata    *md;
        Elf_Ehdr                *ehdr;
        pml4_entry_t            *PT4;
        pdpt_entry_t            *PT3;
        pd_entry_t              *PT2;
        struct user_segment_descriptor *gdt;
        vm_offset_t             modulep, kernend, trampstack;
        int i;

        switch (copy_staging) {
        case COPY_STAGING_ENABLE:
                type = AllocateMaxAddress;
                break;
        case COPY_STAGING_DISABLE:
                type = AllocateAnyPages;
                break;
        case COPY_STAGING_AUTO:
                type = fp->f_kernphys_relocatable ?
                    AllocateAnyPages : AllocateMaxAddress;
                break;
        }

        if ((md = file_findmetadata(fp, MODINFOMD_ELFHDR)) == NULL)
                return (EFTYPE);
        ehdr = (Elf_Ehdr *)&(md->md_data);

        ptr = G(1);
        err = BS->AllocatePages(type, EfiLoaderCode,
            EFI_SIZE_TO_PAGES(amd64_tramp_size), &ptr);
        if (EFI_ERROR(err)) {
                printf("Unable to allocate trampoline\n");
                return (ENOMEM);
        }

        trampoline = (void *)(uintptr_t)ptr;
        bcopy(&amd64_tramp, trampoline, amd64_tramp_size);

        /*
         * Allocate enough space for the GDTR + two GDT segments +
         * our temporary stack (28 bytes).
         */
#define DATASZ (sizeof(*gdtr) + \
            sizeof(struct user_segment_descriptor) * 2 + 28)

        ptr = G(1);
        err = BS->AllocatePages(type, EfiLoaderData,
            EFI_SIZE_TO_PAGES(DATASZ), &ptr);
        if (EFI_ERROR(err)) {
                printf("Unable to allocate GDT and stack\n");
                BS->FreePages((uintptr_t)trampoline, 1);
                return (ENOMEM);
        }

        trampstack = ptr + DATASZ;

#undef DATASZ

        gdt = (void *)(uintptr_t)ptr;
        gdt[0] = (struct user_segment_descriptor) { 0 };
        gdt[1] = (struct user_segment_descriptor) {
            .sd_p = 1, .sd_long = 1, .sd_type = SDT_MEMERC
        };

        gdtr = (void *)(uintptr_t)(ptr +
            sizeof(struct user_segment_descriptor) * 2);
        gdtr->rd_limit = sizeof(struct user_segment_descriptor) * 2 - 1;
        gdtr->rd_base = (uintptr_t)gdt;

        if (type == AllocateMaxAddress) {
                /* Copy staging enabled */

                ptr = G(1);
                err = BS->AllocatePages(AllocateMaxAddress, EfiLoaderData,
                    EFI_SIZE_TO_PAGES(512 * 3 * sizeof(uint64_t)), &ptr);
                if (EFI_ERROR(err)) {
                        printf("Unable to allocate trampoline page table\n");
                        BS->FreePages((uintptr_t)trampoline, 1);
                        BS->FreePages((uintptr_t)gdt, 1);
                        return (ENOMEM);
                }
                PT4 = (pml4_entry_t *)(uintptr_t)ptr;

                PT3 = &PT4[512];
                PT2 = &PT3[512];

                /*
                 * This is kinda brutal, but every single 1GB VM
                 * memory segment points to the same first 1GB of
                 * physical memory.  But it is more than adequate.
                 */
                for (i = 0; i < 512; i++) {
                        /*
                         * Each slot of the L4 pages points to the
                         * same L3 page.
                         */
                        PT4[i] = (uintptr_t)PT3 | PG_V | PG_RW;

                        /*
                         * Each slot of the L3 pages points to the
                         * same L2 page.
                         */
                        PT3[i] = (uintptr_t)PT2 | PG_V | PG_RW;

                        /*
                         * The L2 page slots are mapped with 2MB pages for 1GB.
                         */
                        PT2[i] = (i * M(2)) | PG_V | PG_RW | PG_PS;
                }
        } else {
                pdpt_entry_t    *PT3_l, *PT3_u;
                pd_entry_t      *PT2_l0, *PT2_l1, *PT2_l2, *PT2_l3, *PT2_u0, *PT2_u1;

                err = BS->AllocatePages(AllocateAnyPages, EfiLoaderData,
                    EFI_SIZE_TO_PAGES(512 * 9 * sizeof(uint64_t)), &ptr);
                if (EFI_ERROR(err)) {
                        printf("Unable to allocate trampoline page table\n");
                        BS->FreePages((uintptr_t)trampoline, 1);
                        BS->FreePages((uintptr_t)gdt, 1);
                        return (ENOMEM);
                }
                PT4 = (pml4_entry_t *)(uintptr_t)ptr;

                PT3_l = &PT4[512];
                PT3_u = &PT3_l[512];
                PT2_l0 = &PT3_u[512];
                PT2_l1 = &PT2_l0[512];
                PT2_l2 = &PT2_l1[512];
                PT2_l3 = &PT2_l2[512];
                PT2_u0 = &PT2_l3[512];
                PT2_u1 = &PT2_u0[512];

                /* 1:1 mapping of lower 4G */
                PT4[0] = (uintptr_t)PT3_l | PG_V | PG_RW;
                PT3_l[0] = (uintptr_t)PT2_l0 | PG_V | PG_RW;
                PT3_l[1] = (uintptr_t)PT2_l1 | PG_V | PG_RW;
                PT3_l[2] = (uintptr_t)PT2_l2 | PG_V | PG_RW;
                PT3_l[3] = (uintptr_t)PT2_l3 | PG_V | PG_RW;
                for (i = 0; i < 2048; i++) {
                        PT2_l0[i] = ((pd_entry_t)i * M(2)) | PG_V | PG_RW | PG_PS;
                }

                /* mapping of kernel 2G below top */
                PT4[511] = (uintptr_t)PT3_u | PG_V | PG_RW;
                PT3_u[511] = (uintptr_t)PT2_u1 | PG_V | PG_RW;
                PT3_u[510] = (uintptr_t)PT2_u0 | PG_V | PG_RW;
                /* compat mapping of phys @0 */
                PT2_u0[0] = PG_PS | PG_V | PG_RW;
                /* this maps past staging area */
                for (i = 1; i < 1024; i++) {
                        PT2_u0[i] = (staging + (i - 1) * M(2))
                        | PG_V | PG_RW | PG_PS;
                }
        }

        printf(
            "staging %#llx (%scopying) tramp %p PT4 %p GDT %p\n"
            "Start @ %#llx ...\n", staging,
            type == AllocateMaxAddress ? "" : "not ", trampoline, PT4, gdt,
            ehdr->e_entry
        );


        /*
         * we have to cleanup here because net_cleanup() doesn't work after
         * we call ExitBootServices
         */
        dev_cleanup();

        efi_time_fini();
        err = bi_load(fp->f_args, &modulep, &kernend, true);
        if (err != 0) {
                efi_time_init();
                return (err);
        }

        trampoline(trampstack, type == AllocateMaxAddress ? efi_copy_finish :
            efi_copy_finish_nop, kernend, modulep, PT4, gdtr, ehdr->e_entry);

        panic("exec returned");
}

static int
elf64_obj_exec(struct preloaded_file *fp)
{
        return (EFTYPE);
}