Orange‘s chapter10缺少的elf.h文件定义

Orange’s操作系统源码chapter 10,缺少的elf.h文件以及get_kernel_map()函数

  1. elf.h只用到elf_header和section_header,以及魔数 (写出部分定义就可以,剩下的没用)

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    #ifndef _ORANGES_ELF_H_
    #define _ORANGES_ELF_H_

    typedef u32 Elf32_Word,Elf32_Addr,Elf32_Off;
    typedef u16 Elf32_Half;

    /* ELF header */
    typedef struct
    {
        unsigned char e_ident[16];
        Elf32_Half      e_type;
        Elf32_Half      e_machine;
        Elf32_Word      e_version;
        Elf32_Addr      e_entry;
        Elf32_Off       e_phoff;
        Elf32_Off       e_shoff;
        Elf32_Word      e_flags;
        Elf32_Half      e_ehsize;
        Elf32_Half      e_phentsize;
        Elf32_Half      e_phnum;
        Elf32_Half      e_shentsize;
        Elf32_Half      e_shnum;
        Elf32_Half      e_shstrndx;
    }Elf32_Ehdr; 

    /* program header程序表头 (段描述头) */
    typedef struct
    {
        Elf32_Word      p_type;
        Elf32_Off       p_offset;
        Elf32_Addr      p_vaddr;
        Elf32_Addr      p_paddr;
        Elf32_Word      p_filesz;
        Elf32_Word      p_memsz;
        Elf32_Word      p_flags;
    }Elf32_Phdr;

    /* section header节表头 */
    typedef struct 
    {
        Elf32_Word      sh_name;
        Elf32_Word      sh_type;
        Elf32_Word      sh_flags;
        Elf32_Addr      sh_addr;
        Elf32_Off       sh_offset;
        Elf32_Word      sh_size;
        Elf32_Word      sh_link;
        Elf32_Word      sh_info;
        Elf32_Word      sh_addralign;
        Elf32_Word      sh_entsize;
    }Elf32_Shdr;

    /* 定义elf魔数 */
    // #define ELFMAG  0x464c457f
    #define ELFMAG  1179403647
    /* 定义elf mag长度 */
    #define SELFMAG 4

    /* sh_type字段定义 */
    #define SHT_NULL        0
    #define SHT_PROGBITS    1
    #define SHT_SYMTAB      2
    #define SHT_STRTAB      3
    #define SHT_RELA        4
    #define SHT_HASH        5
    #define SHT_DYNAMIC     6
    #define SHT_NOTE        7
    #define SHT_NOBITS      8
    #define SHT_REL         9
    #define SHT_SHLIB       10
    #define SHt_DYNSYM      11

    /* sh_falgs字段定义 */
    #define SHF_WRITE       0x1
    #define SHF_ALLOC       0x2
    #define SHF_EXECINSTR   0x4
    #define SHF_MASKPROC    0xF0000000

    #endif

    参考ELF文件格式

    ​ Xbook2 elf.h

  2. 自定义的memcmp(,,)第2个参数是void*,所以把宏改一下

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    /* 解析内核文件,获取内核镜像的内存范围 */
    int get_kernel_map(unsigned int *b,unsigned int *l)
    {
        struct boot_params bp;
        get_boot_params(&bp);

        /* ELF header */
        Elf32_Ehdr *elf_header = (Elf32_Ehdr*)(bp.kernel_file);
        
        unsigned int temp = ELFMAG;
        /* 确保kernel file应该是ELF格式 */
        if (memcmp(elf_header->e_ident,(void*)&temp,SELFMAG) != 0)
            return -1;

        *b = ~0;
        unsigned int t = 0;
        int i;
        for (i=0; i<elf_header->e_shnum; i++)
        {
            /* 拿到每一个section header项 */
            Elf32_Shdr* section_header = 
                (Elf32_Shdr*)(bp.kernel_file + 
                                elf_header->e_shoff + 
                                i * elf_header->e_shentsize);
            
            /* 判断此段是否需要载入内存 */
            if (section_header->sh_flags & SHF_ALLOC)
            {
                int bottom  = section_header->sh_addr;
                int top     = section_header->sh_addr+section_header->sh_size;

                if (*b > bottom)
                    *b = bottom;
                if (t < top)
                    t = top; 
            }
        }
        assert(*b < t);
        *l = t - *b - 1;

        return 0;
    }

    因为给出的源代码并没有elf.h的定义但是又使用了,也不知道为什么,所以自己改了改

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