ld_sysdep.h

它通过提供glibc兼容使得应用程序移植到较小的c 库时相当得容易. 它能够应用到带虚拟存储的Linux和uClinux上.在大多数带MMU部件的平台上为使它更加紧凑,它也能够编译成共享库.uClib

/*
 * Various assmbly language/system dependent  hacks that are required
 * so that we can minimize the amount of platform specific code.
 */

/*
 * Define this if the system uses RELOCA.
 */
#undef ELF_USES_RELOCA

/*
 * Get a pointer to the argv array.  On many platforms this can be just
 * the address if the first argument, on other platforms we need to
 * do something a little more subtle here.
 */
#define GET_ARGV(ARGVP, ARGS) ARGVP = ((unsigned long*) & ARGS)

/*
 * Initialization sequence for a GOT.
 */
#define INIT_GOT(GOT_BASE,MODULE) \
{				\
  GOT_BASE[2] = (unsigned long) _dl_linux_resolve; \
  GOT_BASE[1] = (unsigned long) MODULE; \
}

/*
 * Here is a macro to perform a relocation.  This is only used when
 * bootstrapping the dynamic loader.  RELP is the relocation that we
 * are performing, REL is the pointer to the address we are relocating.
 * SYMBOL is the symbol involved in the relocation, and LOAD is the
 * load address.
 */
#define PERFORM_BOOTSTRAP_RELOC(RELP,REL,SYMBOL,LOAD) \
	switch(ELF32_R_TYPE((RELP)->r_info)){		\
	case R_386_32:		\
	  *REL += SYMBOL;		\
	  break;		\
	case R_386_PC32:		\
	  *REL += SYMBOL - (unsigned long) REL;		\
	  break;		\
	case R_386_GLOB_DAT:		\
	case R_386_JMP_SLOT:		\
	  *REL = SYMBOL;		\
	  break;		\
	case R_386_RELATIVE:		\
	  *REL += (unsigned long) LOAD;		\
	  break;		\
	default:		\
	  _dl_exit(1);		\
	}


/*
 * Transfer control to the user's application, once the dynamic loader
 * is done.  This routine has to exit the current function, then 
 * call the _dl_elf_main function.
 */
#define START()		\
	__asm__ volatile ("leave\n\t" \
		    "jmp *%%eax\n\t"	\
		    : "=a" (status) :	"a" (_dl_elf_main))



/* Here we define the magic numbers that this dynamic loader should accept */

#define MAGIC1 EM_386
#undef  MAGIC2
/* Used for error messages */
#define ELF_TARGET "386"

struct elf_resolve;
extern unsigned long _dl_linux_resolver(struct elf_resolve * tpnt, int reloc_entry);

#define do_rem(result, n, base)  result = (n % base)

/* 4096 bytes alignment */
#define PAGE_ALIGN 0xfffff000
#define ADDR_ALIGN 0xfff
#define OFFS_ALIGN 0x7ffff000