/*
 * Copyright 2020, Data61, CSIRO (ABN 41 687 119 230)
 *
 * SPDX-License-Identifier: GPL-2.0-only
 */

#include <arch/kernel/elf.h>
#include <linker.h>

/* minimal ELF functionality for loading GRUB boot module */

BOOT_CODE bool_t elf_checkFile(Elf32_Header_t *elfFile)
{
    return (
               elfFile->e_ident[0] == '\177' &&
               elfFile->e_ident[1] == 'E'    &&
               elfFile->e_ident[2] == 'L'    &&
               elfFile->e_ident[3] == 'F'    &&
               elfFile->e_ident[4] == 1
           );
}

BOOT_CODE v_region_t elf_getMemoryBounds(Elf32_Header_t *elfFile)
{
    Elf32_Phdr_t *phdr = (Elf32_Phdr_t *)((paddr_t)elfFile + elfFile->e_phoff);
    v_region_t elf_reg;
    vptr_t     sect_start;
    vptr_t     sect_end;
    uint32_t   i;

    elf_reg.start = 0xffffffff;
    elf_reg.end = 0;

    /* loop through all program headers (segments) and record start/end address */
    for (i = 0; i < elfFile->e_phnum; i++) {
        if (phdr[i].p_memsz > 0) {
            sect_start = phdr[i].p_vaddr;
            sect_end = sect_start + phdr[i].p_memsz;
            if (sect_start < elf_reg.start) {
                elf_reg.start = sect_start;
            }
            if (sect_end > elf_reg.end) {
                elf_reg.end = sect_end;
            }
        }
    }

    return elf_reg;
}

BOOT_CODE void elf_load(Elf32_Header_t *elfFile, seL4_Word offset)
{
    Elf32_Phdr_t *phdr = (Elf32_Phdr_t *)((paddr_t)elfFile + elfFile->e_phoff);
    paddr_t       src;
    paddr_t       dst;
    uint32_t      len;
    uint32_t      i;

    /* loop through all program headers (segments) and load them */
    for (i = 0; i < elfFile->e_phnum; i++) {
        src = (paddr_t)elfFile + phdr[i].p_offset;
        dst = phdr[i].p_vaddr + offset;
        len = phdr[i].p_filesz;
        memcpy((void *)dst, (char *)src, len);
        dst += len;
        memset((void *)dst, 0, phdr[i].p_memsz - len);
    }
}