xref: /dflybsd-src/test/nvmm/demo/toyvirt/elf.c (revision db3748d66cd4118cb8a910da198671ba63c8117f)

/*
 * Copyright (c) 2018-2021 Maxime Villard, m00nbsd.net
 * All rights reserved.
 *
 * This code is part of the NVMM hypervisor.
 *
 * 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 ``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 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/types.h>
#include <sys/stat.h>

#include <err.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "common.h"

#ifdef __NetBSD__
#define ELFSIZE		64
#include <sys/exec_elf.h>
#else /* DragonFly */
#include <sys/elf64.h>
#define Elf_Ehdr	Elf64_Ehdr
#define Elf_Phdr	Elf64_Phdr
#endif /* __NetBSD__ */

#define ELF_MAXPHNUM	128
#define ELF_MAXSHNUM	32768

static int
elf_check_header(Elf_Ehdr *eh)
{
	if (eh->e_shnum > ELF_MAXSHNUM || eh->e_phnum > ELF_MAXPHNUM)
		return -1;
	return 0;
}

static uint64_t
elf_parse(struct nvmm_machine *mach, char *base)
{
	Elf_Ehdr *ehdr = (Elf_Ehdr *)base;
	Elf_Phdr *phdr;
	uintptr_t hva;
	gpaddr_t lastgpa;
	size_t i;

	if (elf_check_header(ehdr) == -1)
		errx(EXIT_FAILURE, "wrong ELF header");
	phdr = (Elf_Phdr *)((char *)ehdr + ehdr->e_phoff);

	for (i = 0; i < ehdr->e_phnum; i++) {
		if (phdr[i].p_type != PT_LOAD) {
			if (phdr[i].p_filesz == 0) {
				/* Ignore zero-sized GNU_STACK segment
				 * (found on DragonFly) */
				continue;
			} else {
				errx(EXIT_FAILURE, "unsupported ELF");
			}
		}

		hva = toyvirt_mem_add(mach, phdr[i].p_vaddr,
		    roundup(phdr[i].p_filesz, PAGE_SIZE));
		memcpy((void *)hva, base + phdr[i].p_offset, phdr[i].p_filesz);

		lastgpa = phdr[i].p_vaddr +
		    roundup(phdr[i].p_filesz, PAGE_SIZE);
	}

	/* Add 128 pages after the kernel image. */
	toyvirt_mem_add(mach, lastgpa, 128 * PAGE_SIZE);

	return ehdr->e_entry;
}

int
elf_map(struct nvmm_machine *mach, const char *path, uint64_t *rip)
{
	struct stat st;
	char *base = NULL;
	int fd, ret = -1;

	fd = open(path, O_RDONLY);
	if (fstat(fd, &st) == -1)
		goto out;
	if ((size_t)st.st_size < sizeof(Elf_Ehdr))
		goto out;
	base = malloc(st.st_size);
	pread(fd, base, st.st_size, 0);

	*rip = elf_parse(mach, base);
	ret = 0;

out:
	close(fd);
	free(base);
	return ret;
}