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1e9d6b0f98
This patch changes the flash device image of OvmfXen to make it look like it's an ELF. For this, we replace the empty embedded variable store by a binary array, which is a ELF file header. The ELF header explain to a loader to load the binary at the address 1MB, then jump to the PVH entry point which will be created in a later patch. The header also includes a Xen ELF note that is part of the PVH ABI. That patch include OvmfXenElfHeaderGenerator.c which can be use to regenerate the ELF header, but this will be a manual step. Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689 Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> Acked-by: Laszlo Ersek <lersek@redhat.com> Message-Id: <20190813113119.14804-6-anthony.perard@citrix.com>
141 lines
3.6 KiB
C
141 lines
3.6 KiB
C
/** @file
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This program generates a hex array to be manually coppied into
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OvmfXen.fdf.
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The purpose is for the flash device image to be recognize as an ELF.
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Copyright (c) 2019, Citrix Systems, Inc.
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include "elf.h"
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#include "stdio.h"
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#include "stddef.h"
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void print_hdr(void *s, size_t size)
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{
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char *c = s;
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while (size--) {
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printf("0x%02hhx, ", *(c++));
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}
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}
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/* Format for the XEN_ELFNOTE_PHYS32_ENTRY program segment */
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#define XEN_ELFNOTE_PHYS32_ENTRY 18
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typedef struct {
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uint32_t name_size;
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uint32_t desc_size;
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uint32_t type;
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char name[4];
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uint32_t desc;
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} xen_elfnote_phys32_entry;
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int main(void)
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{
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/* FW_SIZE */
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size_t ovmf_blob_size = 0x00200000;
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/* Load OVMF at 1MB when running as PVH guest */
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uint32_t ovmf_base_address = 0x00100000;
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/* Xen PVH entry point */
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uint32_t ovmfxen_pvh_entry_point = ovmf_base_address + ovmf_blob_size - 0x30;
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size_t offset_into_file = 0;
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/* ELF file header */
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Elf32_Ehdr hdr = {
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.e_ident = ELFMAG,
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.e_type = ET_EXEC,
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.e_machine = EM_386,
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.e_version = EV_CURRENT,
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.e_entry = ovmfxen_pvh_entry_point,
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.e_flags = R_386_NONE,
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.e_ehsize = sizeof (hdr),
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.e_phentsize = sizeof (Elf32_Phdr),
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};
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offset_into_file += sizeof (hdr);
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hdr.e_ident[EI_CLASS] = ELFCLASS32;
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hdr.e_ident[EI_DATA] = ELFDATA2LSB;
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hdr.e_ident[EI_VERSION] = EV_CURRENT;
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hdr.e_ident[EI_OSABI] = ELFOSABI_LINUX;
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/* Placing program headers just after hdr */
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hdr.e_phoff = sizeof (hdr);
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/* program header */
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Elf32_Phdr phdr_load = {
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.p_type = PT_LOAD,
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.p_offset = 0, /* load everything */
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.p_paddr = ovmf_base_address,
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.p_filesz = ovmf_blob_size,
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.p_memsz = ovmf_blob_size,
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.p_flags = PF_X | PF_W | PF_R,
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.p_align = 0,
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};
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phdr_load.p_vaddr = phdr_load.p_paddr;
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hdr.e_phnum += 1;
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offset_into_file += sizeof (phdr_load);
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/* Xen ELF Note. */
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xen_elfnote_phys32_entry xen_elf_note = {
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.type = XEN_ELFNOTE_PHYS32_ENTRY,
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.name = "Xen",
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.desc = ovmfxen_pvh_entry_point,
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.name_size =
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offsetof (xen_elfnote_phys32_entry, desc) -
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offsetof (xen_elfnote_phys32_entry, name),
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.desc_size =
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sizeof (xen_elfnote_phys32_entry) -
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offsetof (xen_elfnote_phys32_entry, desc),
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};
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Elf32_Phdr phdr_note = {
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.p_type = PT_NOTE,
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.p_filesz = sizeof (xen_elf_note),
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.p_memsz = sizeof (xen_elf_note),
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.p_flags = PF_R,
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.p_align = 0,
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};
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hdr.e_phnum += 1;
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offset_into_file += sizeof (phdr_note);
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phdr_note.p_offset = offset_into_file;
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phdr_note.p_paddr = ovmf_base_address + phdr_note.p_offset;
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phdr_note.p_vaddr = phdr_note.p_paddr;
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/*
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* print elf header
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*/
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size_t i;
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size_t hdr_size = sizeof (hdr);
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size_t entry_off = offsetof(typeof(hdr), e_entry);
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printf("# ELF file header\n");
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print_hdr(&hdr, entry_off);
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printf("\n");
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print_hdr(&hdr.e_entry, sizeof (hdr.e_entry));
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printf(" # hdr.e_entry\n");
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print_hdr(&hdr.e_entry + 1, hdr_size - entry_off - sizeof (hdr.e_entry));
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printf("\n\n# ELF Program segment headers\n");
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printf("# - Load segment\n");
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for (i = 0; i < sizeof (phdr_load); i += 4) {
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print_hdr(((char*)&phdr_load) + i, 4);
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printf("\n");
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}
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printf("# - ELFNOTE segment\n");
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for (i = 0; i < sizeof (phdr_note); i += 4) {
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print_hdr(((char*)&phdr_note) + i, 4);
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printf("\n");
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}
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printf("\n# XEN_ELFNOTE_PHYS32_ENTRY\n");
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for (i = 0; i < sizeof (xen_elf_note); i += 4) {
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print_hdr(((char*)&xen_elf_note) + i, 4);
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printf("\n");
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}
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return 0;
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}
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