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authorRoger Pau Monné <royger@FreeBSD.org>2021-01-27 11:23:32 +0000
committerRoger Pau Monné <royger@FreeBSD.org>2021-02-16 14:26:11 +0000
commitadda2797eb2a29487fe26640a9c990fea7e6585d (patch)
treee3268ac02c268d67c305e8a053c62446863f0bf1 /stand/efi/loader/arch/amd64/multiboot2.c
parent7d3259775cb69f250df3e7fe51d6fff2283c6f20 (diff)
downloadsrc-adda2797eb2a29487fe26640a9c990fea7e6585d.tar.gz
src-adda2797eb2a29487fe26640a9c990fea7e6585d.zip
stand/multiboot2: add support for booting a Xen dom0 in UEFI mode
Add some basic multiboot2 infrastructure to the EFI loader in order to be capable of booting a FreeBSD/Xen dom0 when booted from UEFI. Only a very limited subset of the multiboot2 protocol is implemented in order to support enough to boot into Xen, the implementation doesn't intend to be a full multiboot2 capable implementation. Such multiboot2 functionality is hooked up into the amd64 EFI loader, which is the only architecture that supports Xen dom0 on FreeBSD. The options to boot a FreeBSD/Xen dom0 system are exactly the same as on BIOS, and requires setting the xen_kernel and xen_cmdline options in loader.conf. Sponsored by: Citrix Systems R&D Reviewed by: tsoome, imp Differential revision: https://reviews.freebsd.org/D28497
Diffstat (limited to 'stand/efi/loader/arch/amd64/multiboot2.c')
-rw-r--r--stand/efi/loader/arch/amd64/multiboot2.c567
1 files changed, 567 insertions, 0 deletions
diff --git a/stand/efi/loader/arch/amd64/multiboot2.c b/stand/efi/loader/arch/amd64/multiboot2.c
new file mode 100644
index 000000000000..e4589bc8b0bb
--- /dev/null
+++ b/stand/efi/loader/arch/amd64/multiboot2.c
@@ -0,0 +1,567 @@
+/*-
+ * Copyright (c) 2021 Roger Pau Monné <royger@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.
+ */
+
+/*
+ * This multiboot2 implementation only implements a subset of the full
+ * multiboot2 specification in order to be able to boot Xen and a
+ * FreeBSD Dom0. Trying to use it to boot other multiboot2 compliant
+ * kernels will most surely fail.
+ *
+ * The full multiboot specification can be found here:
+ * https://www.gnu.org/software/grub/manual/multiboot2/multiboot.html
+ */
+
+#include <sys/cdefs.h>
+
+#include <sys/param.h>
+#include <sys/exec.h>
+#include <sys/linker.h>
+#include <sys/module.h>
+#include <sys/stdint.h>
+#define _MACHINE_ELF_WANT_32BIT
+#include <machine/elf.h>
+#include <machine/metadata.h>
+#include <string.h>
+#include <stand.h>
+
+#include <efi.h>
+#include <efilib.h>
+
+#include "bootstrap.h"
+#include "multiboot2.h"
+#include "loader_efi.h"
+
+extern int elf32_loadfile_raw(char *filename, uint64_t dest,
+ struct preloaded_file **result, int multiboot);
+extern int elf64_load_modmetadata(struct preloaded_file *fp, uint64_t dest);
+extern int elf64_obj_loadfile(char *filename, uint64_t dest,
+ struct preloaded_file **result);
+extern int bi_load(char *args, vm_offset_t *modulep, vm_offset_t *kernendp,
+ bool exit_bs);
+
+extern void multiboot2_exec(void *entry, uint64_t multiboot_info,
+ uint64_t stack);
+
+/*
+ * Multiboot2 header information to pass between the loading and the exec
+ * functions.
+ */
+struct mb2hdr {
+ uint32_t efi64_entry;
+};
+
+static int
+loadfile(char *filename, uint64_t dest, struct preloaded_file **result)
+{
+ unsigned int i;
+ int error, fd;
+ void *header_search = NULL;
+ void *multiboot = NULL;
+ ssize_t search_size;
+ struct multiboot_header *header;
+ char *cmdline;
+ struct mb2hdr hdr;
+ bool keep_bs = false;
+
+ /*
+ * Read MULTIBOOT_SEARCH size in order to search for the
+ * multiboot magic header.
+ */
+ if (filename == NULL)
+ return (EFTYPE);
+ if ((fd = open(filename, O_RDONLY)) == -1)
+ return (errno);
+ header_search = malloc(MULTIBOOT_SEARCH);
+ if (header_search == NULL) {
+ error = ENOMEM;
+ goto out;
+ }
+ search_size = read(fd, header_search, MULTIBOOT_SEARCH);
+
+ for (i = 0; i < search_size; i += MULTIBOOT_HEADER_ALIGN) {
+ header = header_search + i;
+ if (header->magic == MULTIBOOT2_HEADER_MAGIC)
+ break;
+ }
+
+ if (i >= MULTIBOOT_SEARCH) {
+ error = EFTYPE;
+ goto out;
+ }
+
+ /* Valid multiboot header has been found, validate checksum */
+ if (header->magic + header->architecture + header->header_length +
+ header->checksum != 0) {
+ printf("Multiboot checksum failed, magic: %#x architecture: %#x"
+ "header_length %#x checksum: %#x\n",
+ header->magic, header->architecture, header->header_length,
+ header->checksum);
+ error = EFTYPE;
+ goto out;
+ }
+
+ if (header->architecture != MULTIBOOT2_ARCHITECTURE_I386) {
+ printf("Unsupported architecture: %#x\n",
+ header->architecture);
+ error = EFTYPE;
+ goto out;
+ }
+
+ multiboot = malloc(header->header_length - sizeof(*header));
+ error = lseek(fd, i + sizeof(*header), SEEK_SET);
+ if (error != i + sizeof(*header)) {
+ printf("Unable to set file pointer to header location: %d\n",
+ error);
+ goto out;
+ }
+ search_size = read(fd, multiboot,
+ header->header_length - sizeof(*header));
+
+ bzero(&hdr, sizeof(hdr));
+ for (i = 0; i < search_size; ) {
+ struct multiboot_header_tag *tag;
+ struct multiboot_header_tag_entry_address *entry;
+ struct multiboot_header_tag_information_request *req;
+ unsigned int j;
+
+ tag = multiboot + i;
+
+ switch(tag->type) {
+ case MULTIBOOT_HEADER_TAG_INFORMATION_REQUEST:
+ req = (void *)tag;
+ for (j = 0;
+ j < (tag->size - sizeof(*tag)) / sizeof(uint32_t);
+ j++) {
+ switch (req->requests[j]) {
+ case MULTIBOOT_TAG_TYPE_MMAP:
+ case MULTIBOOT_TAG_TYPE_BASIC_MEMINFO:
+ /* Only applicable to BIOS. */
+ break;
+
+ case MULTIBOOT_TAG_TYPE_EFI_BS:
+ case MULTIBOOT_TAG_TYPE_EFI64:
+ case MULTIBOOT_TAG_TYPE_EFI64_IH:
+ /* Tags unconditionally added. */
+ break;
+
+ default:
+ if (req->flags &
+ MULTIBOOT_HEADER_TAG_OPTIONAL)
+ break;
+
+ printf(
+ "Unknown non-optional information request %u\n",
+ req->requests[j]);
+ error = EINVAL;
+ goto out;
+ }
+ }
+ break;
+
+ case MULTIBOOT_HEADER_TAG_EFI_BS:
+ /* Never shut down BS. */
+ keep_bs = true;
+ break;
+
+ case MULTIBOOT_HEADER_TAG_MODULE_ALIGN:
+ /* We will align modules by default already. */
+ case MULTIBOOT_HEADER_TAG_END:
+ break;
+
+ case MULTIBOOT_HEADER_TAG_ENTRY_ADDRESS_EFI64:
+ entry = (void *)tag;
+ hdr.efi64_entry = entry->entry_addr;
+ break;
+
+ default:
+ if (tag->flags & MULTIBOOT_HEADER_TAG_OPTIONAL)
+ break;
+ printf("Unknown header tag %#x not optional\n",
+ tag->type);
+ error = EINVAL;
+ goto out;
+ }
+
+ i += roundup2(tag->size, MULTIBOOT_TAG_ALIGN);
+ if (tag->type == MULTIBOOT_HEADER_TAG_END)
+ break;
+ }
+
+ if (hdr.efi64_entry == 0) {
+ printf("No EFI64 entry address provided\n");
+ error = EINVAL;
+ goto out;
+ }
+ if (!keep_bs) {
+ printf("Unable to boot MB2 with BS exited\n");
+ error = EINVAL;
+ goto out;
+ }
+
+ error = elf32_loadfile_raw(filename, dest, result, 1);
+ if (error != 0) {
+ printf(
+ "elf32_loadfile_raw failed: %d unable to load multiboot kernel\n",
+ error);
+ goto out;
+ }
+
+ file_addmetadata(*result, MODINFOMD_NOCOPY | MODINFOMD_MB2HDR,
+ sizeof(hdr), &hdr);
+
+ /*
+ * f_addr is already aligned to PAGE_SIZE, make sure
+ * f_size it's also aligned so when the modules are loaded
+ * they are aligned to PAGE_SIZE.
+ */
+ (*result)->f_size = roundup((*result)->f_size, PAGE_SIZE);
+
+out:
+ if (header_search != NULL)
+ free(header_search);
+ if (multiboot != NULL)
+ free(multiboot);
+ close(fd);
+ return (error);
+}
+
+static unsigned int add_string(void *buf, unsigned int type, const char *str)
+{
+ struct multiboot_tag *tag;
+
+ tag = buf;
+ tag->type = type;
+ tag->size = sizeof(*tag) + strlen(str) + 1;
+ strcpy(buf + sizeof(*tag), str);
+ return (roundup2(tag->size, MULTIBOOT_TAG_ALIGN));
+}
+
+static unsigned int add_efi(void *buf)
+{
+ struct multiboot_tag *bs;
+ struct multiboot_tag_efi64 *efi64;
+ struct multiboot_tag_efi64_ih *ih;
+ unsigned int len;
+
+ len = 0;
+ bs = buf;
+ bs->type = MULTIBOOT_TAG_TYPE_EFI_BS;
+ bs->size = sizeof(*bs);
+ len += roundup2(bs->size, MULTIBOOT_TAG_ALIGN);
+
+ efi64 = buf + len;
+ efi64->type = MULTIBOOT_TAG_TYPE_EFI64;
+ efi64->size = sizeof(*efi64);
+ efi64->pointer = (uintptr_t)ST;
+ len += roundup2(efi64->size, MULTIBOOT_TAG_ALIGN);
+
+ ih = buf + len;
+ ih->type = MULTIBOOT_TAG_TYPE_EFI64_IH;
+ ih->size = sizeof(*ih);
+ ih->pointer = (uintptr_t)IH;
+
+ return (len + roundup2(ih->size, MULTIBOOT_TAG_ALIGN));
+}
+
+static unsigned int add_module(void *buf, vm_offset_t start, vm_offset_t end,
+ const char *cmdline)
+{
+ struct multiboot_tag_module *mod;
+
+ mod = buf;
+ mod->type = MULTIBOOT_TAG_TYPE_MODULE;
+ mod->size = sizeof(*mod);
+ mod->mod_start = start;
+ mod->mod_end = end;
+ if (cmdline != NULL)
+ {
+ strcpy(buf + sizeof(*mod), cmdline);
+ mod->size += strlen(cmdline) + 1;
+ }
+
+ return (roundup2(mod->size, MULTIBOOT_TAG_ALIGN));
+}
+
+static unsigned int add_end(void *buf)
+{
+ struct multiboot_tag *tag;
+
+ tag = buf;
+ tag->type = MULTIBOOT_TAG_TYPE_END;
+ tag->size = sizeof(*tag);
+
+ return (roundup2(tag->size, MULTIBOOT_TAG_ALIGN));
+}
+
+static int
+exec(struct preloaded_file *fp)
+{
+ EFI_PHYSICAL_ADDRESS addr = 0;
+ EFI_PHYSICAL_ADDRESS stack = 0;
+ EFI_STATUS status;
+ void *multiboot_space;
+ vm_offset_t modulep, kernend, kern_base,
+ payload_base;
+ char *cmdline = NULL;
+ size_t len;
+ int error;
+ uint32_t *total_size;
+ struct file_metadata *md;
+ struct xen_header header;
+ struct mb2hdr *hdr;
+
+
+ CTASSERT(sizeof(header) <= PAGE_SIZE);
+
+ if ((md = file_findmetadata(fp,
+ MODINFOMD_NOCOPY | MODINFOMD_MB2HDR)) == NULL) {
+ printf("Missing Multiboot2 EFI64 entry point\n");
+ return(EFTYPE);
+ }
+ hdr = (void *)&md->md_data;
+
+ status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData,
+ EFI_SIZE_TO_PAGES(PAGE_SIZE), &addr);
+ if (EFI_ERROR(status)) {
+ printf("Failed to allocate pages for multiboot2 header: %lu\n",
+ EFI_ERROR_CODE(status));
+ error = ENOMEM;
+ goto error;
+ }
+ status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData,
+ EFI_SIZE_TO_PAGES(128 * 1024), &stack);
+ if (EFI_ERROR(status)) {
+ printf("Failed to allocate pages for Xen stack: %lu\n",
+ EFI_ERROR_CODE(status));
+ error = ENOMEM;
+ goto error;
+ }
+
+ /*
+ * Scratch space to build the multiboot2 header. Reserve the start of
+ * the space to place the header with the size, which we don't know
+ * yet.
+ */
+ multiboot_space = (void *)(uintptr_t)(addr + sizeof(uint32_t) * 2);
+
+ /*
+ * Don't pass the memory size found by the bootloader, the memory
+ * available to Dom0 will be lower than that.
+ */
+ unsetenv("smbios.memory.enabled");
+
+ /* Set the Xen command line. */
+ if (fp->f_args == NULL) {
+ /* Add the Xen command line if it is set. */
+ cmdline = getenv("xen_cmdline");
+ if (cmdline != NULL) {
+ fp->f_args = strdup(cmdline);
+ if (fp->f_args == NULL) {
+ error = ENOMEM;
+ goto error;
+ }
+ }
+ }
+ if (fp->f_args != NULL) {
+ len = strlen(fp->f_name) + 1 + strlen(fp->f_args) + 1;
+ cmdline = malloc(len);
+ if (cmdline == NULL) {
+ error = ENOMEM;
+ goto error;
+ }
+ snprintf(cmdline, len, "%s %s", fp->f_name, fp->f_args);
+ multiboot_space += add_string(multiboot_space,
+ MULTIBOOT_TAG_TYPE_CMDLINE, cmdline);
+ free(cmdline);
+ }
+
+ multiboot_space += add_string(multiboot_space,
+ MULTIBOOT_TAG_TYPE_BOOT_LOADER_NAME, "FreeBSD Loader");
+ multiboot_space += add_efi(multiboot_space);
+
+ /*
+ * Prepare the multiboot module list, Xen assumes the first
+ * module is the Dom0 kernel, and the second one is the initramfs.
+ * This is not optimal for FreeBSD, that doesn't have a initramfs
+ * but instead loads modules dynamically and creates the metadata
+ * info on-the-fly.
+ *
+ * As expected, the first multiboot module is going to be the
+ * FreeBSD kernel loaded as a raw file. The second module is going
+ * to contain the metadata info and the loaded modules.
+ *
+ * There's a small header prefixed in the second module that contains
+ * some information required to calculate the relocated address of
+ * modulep based on the original offset of modulep from the start of
+ * the module address. Note other fields might be added to this header
+ * if required.
+ *
+ * Native layout:
+ * fp->f_addr + fp->f_size
+ * +---------+----------------+------------+
+ * | | | |
+ * | Kernel | Modules | Metadata |
+ * | | | |
+ * +---------+----------------+------------+
+ * fp->f_addr modulep kernend
+ *
+ * Xen dom0 layout:
+ * fp->f_addr fp->f_addr + fp->f_size
+ * +---------+------------+----------------+------------+
+ * | | | | |
+ * | Kernel | xen_header | Modules | Metadata |
+ * | | | | |
+ * +---------+------------+----------------+------------+
+ * modulep kernend
+ * \________/\__________________________________________/
+ * module 0 module 1
+ */
+
+ fp = file_findfile(NULL, "elf kernel");
+ if (fp == NULL) {
+ printf("No FreeBSD kernel provided, aborting\n");
+ error = EINVAL;
+ goto error;
+ }
+
+ error = bi_load(fp->f_args, &modulep, &kernend, false);
+ if (error != 0)
+ goto error;
+
+ /*
+ * Note that the Xen kernel requires to be started with BootServices
+ * enabled, and hence we cannot use efi_copy_finish to relocate the
+ * loaded data from the staging area to the expected loaded addresses.
+ * This is fine because the Xen kernel is relocatable, so it can boot
+ * fine straight from the staging area. We use efi_translate to get the
+ * staging addresses where the kernels and metadata are currently
+ * loaded.
+ */
+ kern_base = (uintptr_t)efi_translate(fp->f_addr);
+ payload_base = kern_base + fp->f_size - PAGE_SIZE;
+ multiboot_space += add_module(multiboot_space, kern_base, payload_base,
+ NULL);
+ multiboot_space += add_module(multiboot_space, payload_base,
+ (uintptr_t)efi_translate(kernend), "header");
+
+ header.flags = XENHEADER_HAS_MODULEP_OFFSET;
+ header.modulep_offset = modulep - (fp->f_addr + fp->f_size - PAGE_SIZE);
+ archsw.arch_copyin(&header, fp->f_addr + fp->f_size - PAGE_SIZE,
+ sizeof(header));
+
+ multiboot_space += add_end(multiboot_space);
+ total_size = (uint32_t *)(uintptr_t)(addr);
+ *total_size = (uintptr_t)multiboot_space - addr;
+
+ if (*total_size > PAGE_SIZE)
+ panic("Multiboot header exceeds fixed size");
+
+ efi_time_fini();
+ dev_cleanup();
+ multiboot2_exec(efi_translate(hdr->efi64_entry), addr,
+ stack + 128 * 1024);
+
+ panic("exec returned");
+
+error:
+ if (addr)
+ BS->FreePages(addr, EFI_SIZE_TO_PAGES(PAGE_SIZE));
+ if (stack)
+ BS->FreePages(stack, EFI_SIZE_TO_PAGES(128 * 1024));
+ return (error);
+}
+
+static int
+obj_loadfile(char *filename, uint64_t dest, struct preloaded_file **result)
+{
+ struct preloaded_file *mfp, *kfp, *rfp;
+ struct kernel_module *kmp;
+ int error;
+
+ /* See if there's a multiboot kernel loaded */
+ mfp = file_findfile(NULL, "elf multiboot kernel");
+ if (mfp == NULL)
+ return (EFTYPE);
+
+ /*
+ * We have a multiboot kernel loaded, see if there's a FreeBSD
+ * kernel loaded also.
+ */
+ kfp = file_findfile(NULL, "elf kernel");
+ if (kfp == NULL) {
+ /*
+ * No kernel loaded, this must be it. The kernel has to
+ * be loaded as a raw file, it will be processed by
+ * Xen and correctly loaded as an ELF file.
+ */
+ rfp = file_loadraw(filename, "elf kernel", 0);
+ if (rfp == NULL) {
+ printf(
+ "Unable to load %s as a multiboot payload kernel\n",
+ filename);
+ return (EINVAL);
+ }
+
+ /* Load kernel metadata... */
+ setenv("kernelname", filename, 1);
+ error = elf64_load_modmetadata(rfp, rfp->f_addr + rfp->f_size);
+ if (error) {
+ printf("Unable to load kernel %s metadata error: %d\n",
+ rfp->f_name, error);
+ return (EINVAL);
+ }
+
+
+ /*
+ * Reserve one page at the end of the kernel to place some
+ * metadata in order to cope for Xen relocating the modules and
+ * the metadata information.
+ */
+ rfp->f_size = roundup(rfp->f_size, PAGE_SIZE);
+ rfp->f_size += PAGE_SIZE;
+ *result = rfp;
+ } else {
+ /* The rest should be loaded as regular modules */
+ error = elf64_obj_loadfile(filename, dest, result);
+ if (error != 0) {
+ printf("Unable to load %s as an object file, error: %d",
+ filename, error);
+ return (error);
+ }
+ }
+
+ return (0);
+}
+
+static int
+obj_exec(struct preloaded_file *fp)
+{
+
+ return (EFTYPE);
+}
+
+struct file_format multiboot2 = { loadfile, exec };
+struct file_format multiboot2_obj = { obj_loadfile, obj_exec };