/*
 * 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;
}