userboot/userboot/elf64_freebsd.c

/*-
 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
 * 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#define __ELF_WORD_SIZE 64
#include <sys/param.h>
#include <sys/exec.h>
#include <sys/linker.h>
#include <string.h>
#include <i386/include/bootinfo.h>
#include <machine/elf.h>
#include <stand.h>

#include "bootstrap.h"
#include "libuserboot.h"

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

struct file_format amd64_elf = { elf64_loadfile, elf64_exec };
struct file_format amd64_elf_obj = { elf64_obj_loadfile, elf64_obj_exec };

#define MSR_EFER        0xc0000080
#define EFER_LME        0x00000100
#define EFER_LMA    0x00000400  /* Long mode active (R) */
#define CR4_PAE         0x00000020
#define CR4_VMXE    (1UL << 13)
#define CR4_PSE         0x00000010
#define CR0_PG          0x80000000
#define CR0_PE      0x00000001  /* Protected mode Enable */
#define CR0_NE      0x00000020  /* Numeric Error enable (EX16 vs IRQ13) */

#define PG_V    0x001
#define PG_RW   0x002
#define PG_U    0x004
#define PG_PS   0x080

typedef u_int64_t p4_entry_t;
typedef u_int64_t p3_entry_t;
typedef u_int64_t p2_entry_t;

#define GUEST_NULL_SEL      0
#define GUEST_CODE_SEL      1
#define GUEST_DATA_SEL      2
#define GUEST_GDTR_LIMIT    (3 * 8 - 1)

static void
setup_freebsd_gdt(uint64_t *gdtr)
{
    gdtr[GUEST_NULL_SEL] = 0;
    gdtr[GUEST_CODE_SEL] = 0x0020980000000000;
    gdtr[GUEST_DATA_SEL] = 0x0000900000000000;
}

/*
 * 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)
{
    struct file_metadata    *md;
    Elf_Ehdr        *ehdr;
    vm_offset_t     modulep, kernend;
    int         err;
    int         i;
    uint32_t        stack[1024];
    p4_entry_t      PT4[512];
    p3_entry_t      PT3[512];
    p2_entry_t      PT2[512];
    uint64_t        gdtr[3];

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

    err = bi_load64(fp->f_args, &modulep, &kernend);
    if (err != 0)
        return(err);

    bzero(PT4, PAGE_SIZE);
    bzero(PT3, PAGE_SIZE);
    bzero(PT2, PAGE_SIZE);

    /*
     * Build a scratch stack at physical 0x1000, page tables:
     *  PT4 at 0x2000,
     *  PT3 at 0x3000,
     *  PT2 at 0x4000,
     *      gdtr at 0x5000,
     */

    /*
     * 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 level 4 pages points to the same level 3 page */
        PT4[i] = (p4_entry_t) 0x3000;
        PT4[i] |= PG_V | PG_RW | PG_U;

        /* Each slot of the level 3 pages points to the same level 2 page */
        PT3[i] = (p3_entry_t) 0x4000;
        PT3[i] |= PG_V | PG_RW | PG_U;

        /* The level 2 page slots are mapped with 2MB pages for 1GB. */
        PT2[i] = i * (2 * 1024 * 1024);
        PT2[i] |= PG_V | PG_RW | PG_PS | PG_U;
    }

#ifdef DEBUG
    printf("Start @ %#llx ...\n", ehdr->e_entry);
#endif

    dev_cleanup();

    stack[0] = 0;       /* return address */;
    stack[1] = modulep;
    stack[2] = kernend;
    CALLBACK(copyin, stack, 0x1000, sizeof(stack));
    CALLBACK(copyin, PT4, 0x2000, sizeof(PT4));
    CALLBACK(copyin, PT3, 0x3000, sizeof(PT3));
    CALLBACK(copyin, PT2, 0x4000, sizeof(PT2));
    CALLBACK(setreg, 4, 0x1000);

    CALLBACK(setmsr, MSR_EFER, EFER_LMA | EFER_LME);
    CALLBACK(setcr, 4, CR4_PAE | CR4_VMXE);
    CALLBACK(setcr, 3, 0x2000);
    CALLBACK(setcr, 0, CR0_PG | CR0_PE | CR0_NE);

    setup_freebsd_gdt(gdtr);
    CALLBACK(copyin, gdtr, 0x5000, sizeof(gdtr));
        CALLBACK(setgdt, 0x5000, sizeof(gdtr));

    CALLBACK(exec, ehdr->e_entry);

    panic("exec returned");
}

static int
elf64_obj_exec(struct preloaded_file *fp)
{

    return (EFTYPE);
}