elfload.c

qemu虚拟机代码

/* This is the Linux kernel elf-loading code, ported into user space */

#include <stdio.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <errno.h>
#include <unistd.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <string.h>

#include "qemu.h"
#include "disas.h"

/* this flag is uneffective under linux too, should be deleted */
#ifndef MAP_DENYWRITE
#define MAP_DENYWRITE 0
#endif

/* should probably go in elf.h */
#ifndef ELIBBAD
#define ELIBBAD 80
#endif

#ifdef TARGET_I386

#define ELF_PLATFORM get_elf_platform()

static const char *get_elf_platform(void)
{
    static char elf_platform[] = "i386";
    int family = (global_env->cpuid_version >> 8) & 0xff;
    if (family > 6)
        family = 6;
    if (family >= 3)
        elf_platform[1] = '0' + family;
    return elf_platform;
}

#define ELF_HWCAP get_elf_hwcap()

static uint32_t get_elf_hwcap(void)
{
  return global_env->cpuid_features;
}

#define ELF_START_MMAP 0x80000000

/*
 * This is used to ensure we don't load something for the wrong architecture.
 */
#define elf_check_arch(x) ( ((x) == EM_386) || ((x) == EM_486) )

/*
 * These are used to set parameters in the core dumps.
 */
#define ELF_CLASS	ELFCLASS32
#define ELF_DATA	ELFDATA2LSB
#define ELF_ARCH	EM_386

	/* SVR4/i386 ABI (pages 3-31, 3-32) says that when the program
	   starts %edx contains a pointer to a function which might be
	   registered using `atexit'.  This provides a mean for the
	   dynamic linker to call DT_FINI functions for shared libraries
	   that have been loaded before the code runs.

	   A value of 0 tells we have no such handler.  */
#define ELF_PLAT_INIT(_r)	_r->edx = 0

static inline void init_thread(struct target_pt_regs *regs, struct image_info *infop)
{
    regs->esp = infop->start_stack;
    regs->eip = infop->entry;
}

#define USE_ELF_CORE_DUMP
#define ELF_EXEC_PAGESIZE	4096

#endif

#ifdef TARGET_ARM

#define ELF_START_MMAP 0x80000000

#define elf_check_arch(x) ( (x) == EM_ARM )

#define ELF_CLASS	ELFCLASS32
#ifdef TARGET_WORDS_BIGENDIAN
#define ELF_DATA	ELFDATA2MSB
#else
#define ELF_DATA	ELFDATA2LSB
#endif
#define ELF_ARCH	EM_ARM

#define ELF_PLAT_INIT(_r)	_r->ARM_r0 = 0

static inline void init_thread(struct target_pt_regs *regs, struct image_info *infop)
{
    target_long stack = infop->start_stack;
    memset(regs, 0, sizeof(*regs));
    regs->ARM_cpsr = 0x10;
    if (infop->entry & 1)
      regs->ARM_cpsr |= CPSR_T;
    regs->ARM_pc = infop->entry & 0xfffffffe;
    regs->ARM_sp = infop->start_stack;
    regs->ARM_r2 = tgetl(stack + 8); /* envp */
    regs->ARM_r1 = tgetl(stack + 4); /* envp */
    /* XXX: it seems that r0 is zeroed after ! */
    //    regs->ARM_r0 = tgetl(stack); /* argc */
}

#define USE_ELF_CORE_DUMP
#define ELF_EXEC_PAGESIZE	4096

enum
{
  ARM_HWCAP_ARM_SWP       = 1 << 0,
  ARM_HWCAP_ARM_HALF      = 1 << 1,
  ARM_HWCAP_ARM_THUMB     = 1 << 2,
  ARM_HWCAP_ARM_26BIT     = 1 << 3,
  ARM_HWCAP_ARM_FAST_MULT = 1 << 4,
  ARM_HWCAP_ARM_FPA       = 1 << 5,
  ARM_HWCAP_ARM_VFP       = 1 << 6,
  ARM_HWCAP_ARM_EDSP      = 1 << 7,
};

#define ELF_HWCAP (ARM_HWCAP_ARM_SWP | ARM_HWCAP_ARM_HALF              \
                    | ARM_HWCAP_ARM_THUMB | ARM_HWCAP_ARM_FAST_MULT     \
                    | ARM_HWCAP_ARM_FPA | ARM_HWCAP_ARM_VFP)

#endif

#ifdef TARGET_SPARC
#ifdef TARGET_SPARC64

#define ELF_START_MMAP 0x80000000

#define elf_check_arch(x) ( (x) == EM_SPARC )

#define ELF_CLASS   ELFCLASS64
#define ELF_DATA    ELFDATA2MSB
#define ELF_ARCH    EM_SPARC

/*XXX*/
#define ELF_PLAT_INIT(_r)

static inline void init_thread(struct target_pt_regs *regs, struct image_info *infop)
{
    regs->tstate = 0;
    regs->pc = infop->entry;
    regs->npc = regs->pc + 4;
    regs->y = 0;
    regs->u_regs[14] = infop->start_stack - 16 * 4;
}

#else
#define ELF_START_MMAP 0x80000000

#define elf_check_arch(x) ( (x) == EM_SPARC )

#define ELF_CLASS   ELFCLASS32
#define ELF_DATA    ELFDATA2MSB
#define ELF_ARCH    EM_SPARC

/*XXX*/
#define ELF_PLAT_INIT(_r)

static inline void init_thread(struct target_pt_regs *regs, struct image_info *infop)
{
    regs->psr = 0;
    regs->pc = infop->entry;
    regs->npc = regs->pc + 4;
    regs->y = 0;
    regs->u_regs[14] = infop->start_stack - 16 * 4;
}

#endif
#endif

#ifdef TARGET_PPC

#define ELF_START_MMAP 0x80000000

#define elf_check_arch(x) ( (x) == EM_PPC )

#define ELF_CLASS	ELFCLASS32
#ifdef TARGET_WORDS_BIGENDIAN
#define ELF_DATA	ELFDATA2MSB
#else
#define ELF_DATA	ELFDATA2LSB
#endif
#define ELF_ARCH	EM_PPC

/* Note that isn't exactly what regular kernel does
 * but this is what the ABI wants and is needed to allow
 * execution of PPC BSD programs.
 */
#define ELF_PLAT_INIT(_r)                                  \
do {                                                       \
    target_ulong *pos = (target_ulong *)bprm->p, tmp = 1;  \
    _r->gpr[3] = bprm->argc;                               \
    _r->gpr[4] = (unsigned long)++pos;                     \
    for (; tmp != 0; pos++)                                \
        tmp = ldl(pos);                                    \
    _r->gpr[5] = (unsigned long)pos;                       \
} while (0)

/*
 * We need to put in some extra aux table entries to tell glibc what
 * the cache block size is, so it can use the dcbz instruction safely.
 */
#define AT_DCACHEBSIZE          19
#define AT_ICACHEBSIZE          20
#define AT_UCACHEBSIZE          21
/* A special ignored type value for PPC, for glibc compatibility.  */
#define AT_IGNOREPPC            22
/*
 * The requirements here are:
 * - keep the final alignment of sp (sp & 0xf)
 * - make sure the 32-bit value at the first 16 byte aligned position of
 *   AUXV is greater than 16 for glibc compatibility.
 *   AT_IGNOREPPC is used for that.
 * - for compatibility with glibc ARCH_DLINFO must always be defined on PPC,
 *   even if DLINFO_ARCH_ITEMS goes to zero or is undefined.
 */
#define DLINFO_ARCH_ITEMS       5
#define ARCH_DLINFO                                                     \
do {                                                                    \
        NEW_AUX_ENT(AT_DCACHEBSIZE, 0x20);                              \
        NEW_AUX_ENT(AT_ICACHEBSIZE, 0x20);                              \
        NEW_AUX_ENT(AT_UCACHEBSIZE, 0);                                 \
        /*                                                              \
         * Now handle glibc compatibility.                              \
         */                                                             \
	NEW_AUX_ENT(AT_IGNOREPPC, AT_IGNOREPPC);			\
	NEW_AUX_ENT(AT_IGNOREPPC, AT_IGNOREPPC);			\
 } while (0)

static inline void init_thread(struct target_pt_regs *_regs, struct image_info *infop)
{
    _regs->msr = 1 << MSR_PR; /* Set user mode */
    _regs->gpr[1] = infop->start_stack;
    _regs->nip = infop->entry;
}

#define USE_ELF_CORE_DUMP
#define ELF_EXEC_PAGESIZE	4096

#endif

#ifdef TARGET_MIPS

#define ELF_START_MMAP 0x80000000

#define elf_check_arch(x) ( (x) == EM_MIPS )

#define ELF_CLASS   ELFCLASS32
#ifdef TARGET_WORDS_BIGENDIAN
#define ELF_DATA	ELFDATA2MSB
#else
#define ELF_DATA	ELFDATA2LSB
#endif
#define ELF_ARCH    EM_MIPS

#define ELF_PLAT_INIT(_r) 

static inline void init_thread(struct target_pt_regs *regs, struct image_info *infop)
{
    regs->cp0_status = CP0St_UM;
    regs->cp0_epc = infop->entry;
    regs->regs[29] = infop->start_stack;
}

#endif /* TARGET_MIPS */

#ifdef TARGET_SH4

#define ELF_START_MMAP 0x80000000

#define elf_check_arch(x) ( (x) == EM_SH )

#define ELF_CLASS ELFCLASS32
#define ELF_DATA  ELFDATA2LSB
#define ELF_ARCH  EM_SH

#define ELF_PLAT_INIT(_r) /* XXXXX */

static inline void init_thread(struct target_pt_regs *regs, struct image_info *infop)
{
  /* Check other registers XXXXX */
  regs->pc = infop->entry;
  regs->regs[15] = infop->start_stack - 16 * 4;
}

#define USE_ELF_CORE_DUMP
#define ELF_EXEC_PAGESIZE        4096

#endif

#ifndef ELF_PLATFORM
#define ELF_PLATFORM (NULL)
#endif

#ifndef ELF_HWCAP
#define ELF_HWCAP 0
#endif

#include "elf.h"

/*
 * MAX_ARG_PAGES defines the number of pages allocated for arguments
 * and envelope for the new program. 32 should suffice, this gives
 * a maximum env+arg of 128kB w/4KB pages!
 */
#define MAX_ARG_PAGES 32

/*
 * This structure is used to hold the arguments that are 
 * used when loading binaries.
 */
struct linux_binprm {
        char buf[128];
        void *page[MAX_ARG_PAGES];
        unsigned long p;
        int sh_bang;
	int fd;
        int e_uid, e_gid;
        int argc, envc;
        char * filename;        /* Name of binary */
        unsigned long loader, exec;
        int dont_iput;          /* binfmt handler has put inode */
};

struct exec
{
  unsigned int a_info;   /* Use macros N_MAGIC, etc for access */
  unsigned int a_text;   /* length of text, in bytes */
  unsigned int a_data;   /* length of data, in bytes */
  unsigned int a_bss;    /* length of uninitialized data area, in bytes */
  unsigned int a_syms;   /* length of symbol table data in file, in bytes */
  unsigned int a_entry;  /* start address */
  unsigned int a_trsize; /* length of relocation info for text, in bytes */
  unsigned int a_drsize; /* length of relocation info for data, in bytes */
};


#define N_MAGIC(exec) ((exec).a_info & 0xffff)
#define OMAGIC 0407
#define NMAGIC 0410
#define ZMAGIC 0413
#define QMAGIC 0314

/* max code+data+bss space allocated to elf interpreter */
#define INTERP_MAP_SIZE (32 * 1024 * 1024)

/* max code+data+bss+brk space allocated to ET_DYN executables */
#define ET_DYN_MAP_SIZE (128 * 1024 * 1024)

/* from personality.h */

/* Flags for bug emulation. These occupy the top three bytes. */
#define STICKY_TIMEOUTS		0x4000000
#define WHOLE_SECONDS		0x2000000

/* Personality types. These go in the low byte. Avoid using the top bit,
 * it will conflict with error returns.
 */
#define PER_MASK		(0x00ff)
#define PER_LINUX		(0x0000)
#define PER_SVR4		(0x0001 | STICKY_TIMEOUTS)
#define PER_SVR3		(0x0002 | STICKY_TIMEOUTS)
#define PER_SCOSVR3		(0x0003 | STICKY_TIMEOUTS | WHOLE_SECONDS)
#define PER_WYSEV386		(0x0004 | STICKY_TIMEOUTS)
#define PER_ISCR4		(0x0005 | STICKY_TIMEOUTS)
#define PER_BSD			(0x0006)
#define PER_XENIX		(0x0007 | STICKY_TIMEOUTS)

/* Necessary parameters */
#define NGROUPS 32

#define TARGET_ELF_EXEC_PAGESIZE TARGET_PAGE_SIZE
#define TARGET_ELF_PAGESTART(_v) ((_v) & ~(unsigned long)(TARGET_ELF_EXEC_PAGESIZE-1))
#define TARGET_ELF_PAGEOFFSET(_v) ((_v) & (TARGET_ELF_EXEC_PAGESIZE-1))

#define INTERPRETER_NONE 0
#define INTERPRETER_AOUT 1
#define INTERPRETER_ELF 2

#define DLINFO_ITEMS 12

static inline void memcpy_fromfs(void * to, const void * from, unsigned long n)
{
	memcpy(to, from, n);
}

extern unsigned long x86_stack_size;

static int load_aout_interp(void * exptr, int interp_fd);

#ifdef BSWAP_NEEDED
static void bswap_ehdr(struct elfhdr *ehdr)
{
    bswap16s(&ehdr->e_type);			/* Object file type */
    bswap16s(&ehdr->e_machine);		/* Architecture */
    bswap32s(&ehdr->e_version);		/* Object file version */
    bswaptls(&ehdr->e_entry);		/* Entry point virtual address */
    bswaptls(&ehdr->e_phoff);		/* Program header table file offset */
    bswaptls(&ehdr->e_shoff);		/* Section header table file offset */
    bswap32s(&ehdr->e_flags);		/* Processor-specific flags */
    bswap16s(&ehdr->e_ehsize);		/* ELF header size in bytes */
    bswap16s(&ehdr->e_phentsize);		/* Program header table entry size */
    bswap16s(&ehdr->e_phnum);		/* Program header table entry count */
    bswap16s(&ehdr->e_shentsize);		/* Section header table entry size */
    bswap16s(&ehdr->e_shnum);		/* Section header table entry count */
    bswap16s(&ehdr->e_shstrndx);		/* Section header string table index */
}

static void bswap_phdr(struct elf_phdr *phdr)
{
    bswap32s(&phdr->p_type);			/* Segment type */
    bswaptls(&phdr->p_offset);		/* Segment file offset */
    bswaptls(&phdr->p_vaddr);		/* Segment virtual address */
    bswaptls(&phdr->p_paddr);		/* Segment physical address */
    bswaptls(&phdr->p_filesz);		/* Segment size in file */
    bswaptls(&phdr->p_memsz);		/* Segment size in memory */
    bswap32s(&phdr->p_flags);		/* Segment flags */
    bswaptls(&phdr->p_align);		/* Segment alignment */
}

static void bswap_shdr(struct elf_shdr *shdr)
{
    bswap32s(&shdr->sh_name);
    bswap32s(&shdr->sh_type);
    bswaptls(&shdr->sh_flags);
    bswaptls(&shdr->sh_addr);
    bswaptls(&shdr->sh_offset);
    bswaptls(&shdr->sh_size);
    bswap32s(&shdr->sh_link);
    bswap32s(&shdr->sh_info);
    bswaptls(&shdr->sh_addralign);
    bswaptls(&shdr->sh_entsize);
}

static void bswap_sym(Elf32_Sym *sym)
{
    bswap32s(&sym->st_name);
    bswap32s(&sym->st_value);
    bswap32s(&sym->st_size);
    bswap16s(&sym->st_shndx);
}
#endif

/*
 * 'copy_string()' copies argument/envelope strings from user
 * memory to free pages in kernel mem. These are in a format ready
 * to be put directly into the top of new user memory.
 *
 */
static unsigned long copy_strings(int argc,char ** argv, void **page,
                unsigned long p)
{
    char *tmp, *tmp1, *pag = NULL;
    int len, offset = 0;

    if (!p) {
	return 0;       /* bullet-proofing */
    }
    while (argc-- > 0) {
        tmp = argv[argc];
        if (!tmp) {
	    fprintf(stderr, "VFS: argc is wrong");
	    exit(-1);
	}
        tmp1 = tmp;
	while (*tmp++);
	len = tmp - tmp1;
	if (p < len) {  /* this shouldn't happen - 128kB */
		return 0;
	}
	while (len) {
	    --p; --tmp; --len;
	    if (--offset < 0) {
		offset = p % TARGET_PAGE_SIZE;
                pag = (char *)page[p/TARGET_PAGE_SIZE];
                if (!pag) {
                    pag = (char *)malloc(TARGET_PAGE_SIZE);