ca49b3342d
Implement a subset of the multiboot specification in order to boot Xen and a FreeBSD Dom0 from the FreeBSD bootloader. This multiboot implementation is tailored to boot Xen and FreeBSD Dom0, and it will most surely fail to boot any other multiboot compilant kernel. In order to detect and boot the Xen microkernel, two new file formats are added to the bootloader, multiboot and multiboot_obj. Multiboot support must be tested before regular ELF support, since Xen is a multiboot kernel that also uses ELF. After a multiboot kernel is detected, all the other loaded kernels/modules are parsed by the multiboot_obj format. The layout of the loaded objects in memory is the following; first the Xen kernel is loaded as a 32bit ELF into memory (Xen will switch to long mode by itself), after that the FreeBSD kernel is loaded as a RAW file (Xen will parse and load it using it's internal ELF loader), and finally the metadata and the modules are loaded using the native FreeBSD way. After everything is loaded we jump into Xen's entry point using a small trampoline. The order of the multiboot modules passed to Xen is the following, the first module is the RAW FreeBSD kernel, and the second module is the metadata and the FreeBSD modules. Since Xen will relocate the memory position of the second multiboot module (the one that contains the metadata and native FreeBSD modules), we need to stash the original modulep address inside of the metadata itself in order to recalculate its position once booted. This also means the metadata must come before the loaded modules, so after loading the FreeBSD kernel a portion of memory is reserved in order to place the metadata before booting. In order to tell the loader to boot Xen and then the FreeBSD kernel the following has to be added to the /boot/loader.conf file: xen_cmdline="dom0_mem=1024M dom0_max_vcpus=2 dom0pvh=1 console=com1,vga" xen_kernel="/boot/xen" The first argument contains the command line that will be passed to the Xen kernel, while the second argument is the path to the Xen kernel itself. This can also be done manually from the loader command line, by for example typing the following set of commands: OK unload OK load /boot/xen dom0_mem=1024M dom0_max_vcpus=2 dom0pvh=1 console=com1,vga OK load kernel OK load zfs OK load if_tap OK load ... OK boot Sponsored by: Citrix Systems R&D Reviewed by: jhb Differential Revision: https://reviews.freebsd.org/D517 For the Forth bits: Submitted by: Julien Grall <julien.grall AT citrix.com>
127 lines
3.8 KiB
C
127 lines
3.8 KiB
C
/*-
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* Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#define __ELF_WORD_SIZE 64
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#include <sys/param.h>
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#include <sys/exec.h>
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#include <sys/linker.h>
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#include <string.h>
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#include <machine/bootinfo.h>
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#include <machine/elf.h>
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#include <stand.h>
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#include "bootstrap.h"
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#include "libi386.h"
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#include "btxv86.h"
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static int elf64_exec(struct preloaded_file *amp);
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static int elf64_obj_exec(struct preloaded_file *amp);
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struct file_format amd64_elf = { elf64_loadfile, elf64_exec };
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struct file_format amd64_elf_obj = { elf64_obj_loadfile, elf64_obj_exec };
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#define PG_V 0x001
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#define PG_RW 0x002
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#define PG_U 0x004
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#define PG_PS 0x080
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typedef u_int64_t p4_entry_t;
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typedef u_int64_t p3_entry_t;
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typedef u_int64_t p2_entry_t;
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extern p4_entry_t PT4[];
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extern p3_entry_t PT3[];
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extern p2_entry_t PT2[];
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u_int32_t entry_hi;
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u_int32_t entry_lo;
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extern void amd64_tramp();
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/*
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* There is an ELF kernel and one or more ELF modules loaded.
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* We wish to start executing the kernel image, so make such
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* preparations as are required, and do so.
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*/
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static int
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elf64_exec(struct preloaded_file *fp)
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{
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struct file_metadata *md;
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Elf_Ehdr *ehdr;
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vm_offset_t modulep, kernend;
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int err;
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int i;
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if ((md = file_findmetadata(fp, MODINFOMD_ELFHDR)) == NULL)
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return(EFTYPE);
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ehdr = (Elf_Ehdr *)&(md->md_data);
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err = bi_load64(fp->f_args, 0, &modulep, &kernend, 1);
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if (err != 0)
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return(err);
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bzero(PT4, PAGE_SIZE);
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bzero(PT3, PAGE_SIZE);
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bzero(PT2, PAGE_SIZE);
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/*
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* This is kinda brutal, but every single 1GB VM memory segment points to
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* the same first 1GB of physical memory. But it is more than adequate.
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*/
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for (i = 0; i < 512; i++) {
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/* Each slot of the level 4 pages points to the same level 3 page */
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PT4[i] = (p4_entry_t)VTOP((uintptr_t)&PT3[0]);
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PT4[i] |= PG_V | PG_RW | PG_U;
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/* Each slot of the level 3 pages points to the same level 2 page */
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PT3[i] = (p3_entry_t)VTOP((uintptr_t)&PT2[0]);
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PT3[i] |= PG_V | PG_RW | PG_U;
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/* The level 2 page slots are mapped with 2MB pages for 1GB. */
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PT2[i] = i * (2 * 1024 * 1024);
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PT2[i] |= PG_V | PG_RW | PG_PS | PG_U;
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}
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entry_lo = ehdr->e_entry & 0xffffffff;
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entry_hi = (ehdr->e_entry >> 32) & 0xffffffff;
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#ifdef DEBUG
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printf("Start @ %#llx ...\n", ehdr->e_entry);
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#endif
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dev_cleanup();
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__exec((void *)VTOP(amd64_tramp), modulep, kernend);
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panic("exec returned");
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}
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static int
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elf64_obj_exec(struct preloaded_file *fp)
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{
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return (EFTYPE);
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}
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