dl-machine.h

glibc 2.9,最新版的C语言库函数

/* Machine-dependent ELF dynamic relocation inline functions.  SPARC version.
   Copyright (C) 1996-2003, 2004, 2005, 2006, 2007
   Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#ifndef dl_machine_h
#define dl_machine_h

#define ELF_MACHINE_NAME "sparc"

#include <string.h>
#include <sys/param.h>
#include <ldsodefs.h>
#include <tls.h>

#ifndef VALIDX
# define VALIDX(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM \
		      + DT_EXTRANUM + DT_VALTAGIDX (tag))
#endif

/* Some SPARC opcodes we need to use for self-modifying code.  */
#define OPCODE_NOP	0x01000000 /* nop */
#define OPCODE_CALL	0x40000000 /* call ?; add PC-rel word address */
#define OPCODE_SETHI_G1	0x03000000 /* sethi ?, %g1; add value>>10 */
#define OPCODE_JMP_G1	0x81c06000 /* jmp %g1+?; add lo 10 bits of value */
#define OPCODE_SAVE_SP	0x9de3bfa8 /* save %sp, -(16+6)*4, %sp */
#define OPCODE_BA	0x30800000 /* b,a ?; add PC-rel word address */

/* Return nonzero iff ELF header is compatible with the running host.  */
static inline int
elf_machine_matches_host (const Elf32_Ehdr *ehdr)
{
  if (ehdr->e_machine == EM_SPARC)
    return 1;
  else if (ehdr->e_machine == EM_SPARC32PLUS)
    {
      /* XXX The following is wrong!  Dave Miller rejected to implement it
	 correctly.  If this causes problems shoot *him*!  */
#ifdef SHARED
      return GLRO(dl_hwcap) & GLRO(dl_hwcap_mask) & HWCAP_SPARC_V9;
#else
      return GLRO(dl_hwcap) & HWCAP_SPARC_V9;
#endif
    }
  else
    return 0;
}

/* We have to do this because elf_machine_{dynamic,load_address} can be
   invoked from functions that have no GOT references, and thus the compiler
   has no obligation to load the PIC register.  */
#define LOAD_PIC_REG(PIC_REG)	\
do {	register Elf32_Addr pc __asm("o7"); \
	__asm("sethi %%hi(_GLOBAL_OFFSET_TABLE_-4), %1\n\t" \
	      "call 1f\n\t" \
	      "add %1, %%lo(_GLOBAL_OFFSET_TABLE_+4), %1\n" \
	      "1:\tadd %1, %0, %1" \
	      : "=r" (pc), "=r" (PIC_REG)); \
} while (0)

/* Return the link-time address of _DYNAMIC.  Conveniently, this is the
   first element of the GOT.  This must be inlined in a function which
   uses global data.  */
static inline Elf32_Addr
elf_machine_dynamic (void)
{
  register Elf32_Addr *got asm ("%l7");

  LOAD_PIC_REG (got);

  return *got;
}

/* Return the run-time load address of the shared object.  */
static inline Elf32_Addr
elf_machine_load_address (void)
{
  register Elf32_Addr *pc __asm ("%o7"), *got __asm ("%l7");

  __asm ("sethi %%hi(_GLOBAL_OFFSET_TABLE_-4), %1\n\t"
	 "call 1f\n\t"
	 " add %1, %%lo(_GLOBAL_OFFSET_TABLE_+4), %1\n\t"
	 "call _DYNAMIC\n\t"
	 "call _GLOBAL_OFFSET_TABLE_\n"
	 "1:\tadd %1, %0, %1\n\t" : "=r" (pc), "=r" (got));

  /* got is now l_addr + _GLOBAL_OFFSET_TABLE_
     *got is _DYNAMIC
     pc[2]*4 is l_addr + _DYNAMIC - (long)pc - 8
     pc[3]*4 is l_addr + _GLOBAL_OFFSET_TABLE_ - (long)pc - 12  */
  return (Elf32_Addr) got - *got + (pc[2] - pc[3]) * 4 - 4;
}

/* Set up the loaded object described by L so its unrelocated PLT
   entries will jump to the on-demand fixup code in dl-runtime.c.  */

static inline int
elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
{
  Elf32_Addr *plt;
  extern void _dl_runtime_resolve (Elf32_Word);
  extern void _dl_runtime_profile (Elf32_Word);

  if (l->l_info[DT_JMPREL] && lazy)
    {
      Elf32_Addr rfunc;

      /* The entries for functions in the PLT have not yet been filled in.
	 Their initial contents will arrange when called to set the high 22
	 bits of %g1 with an offset into the .rela.plt section and jump to
	 the beginning of the PLT.  */
      plt = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
      if (__builtin_expect(profile, 0))
	{
	  rfunc = (Elf32_Addr) &_dl_runtime_profile;

	  if (GLRO(dl_profile) != NULL
	      && _dl_name_match_p (GLRO(dl_profile), l))
	    GL(dl_profile_map) = l;
	}
      else
	{
	  rfunc = (Elf32_Addr) &_dl_runtime_resolve;
	}

      /* The beginning of the PLT does:

		sethi %hi(_dl_runtime_{resolve,profile}), %g2
	 pltpc:	jmpl %g2 + %lo(_dl_runtime_{resolve,profile}), %g2
		 nop
		.word MAP

         The PC value (pltpc) saved in %g2 by the jmpl points near the
	 location where we store the link_map pointer for this object.  */

      plt[0] = 0x05000000 | ((rfunc >> 10) & 0x003fffff);
      plt[1] = 0x85c0a000 | (rfunc & 0x3ff);
      plt[2] = OPCODE_NOP;	/* Fill call delay slot.  */
      plt[3] = (Elf32_Addr) l;
      if (__builtin_expect (l->l_info[VALIDX(DT_GNU_PRELINKED)] != NULL, 0)
	  || __builtin_expect (l->l_info [VALIDX (DT_GNU_LIBLISTSZ)] != NULL, 0))
	{
	  /* Need to reinitialize .plt to undo prelinking.  */
	  Elf32_Rela *rela = (Elf32_Rela *) D_PTR (l, l_info[DT_JMPREL]);
	  Elf32_Rela *relaend
	    = (Elf32_Rela *) ((char *) rela
			      + l->l_info[DT_PLTRELSZ]->d_un.d_val);
#if !defined RTLD_BOOTSTRAP && !defined __sparc_v9__
	  /* Note that we don't mask the hwcap here, as the flush is
	     essential to functionality on those cpu's that implement it.
	     For sparcv9 we can assume flush is present.  */
	  const int do_flush = GLRO(dl_hwcap) & HWCAP_SPARC_FLUSH;
#else
	  const int do_flush = 1;
#endif

	  /* prelink must ensure there are no R_SPARC_NONE relocs left
	     in .rela.plt.  */
	  while (rela < relaend)
	    {
	      *(unsigned int *) rela->r_offset
		= OPCODE_SETHI_G1 | (rela->r_offset - (Elf32_Addr) plt);
	      *(unsigned int *) (rela->r_offset + 4)
		= OPCODE_BA | ((((Elf32_Addr) plt
				 - rela->r_offset - 4) >> 2) & 0x3fffff);
	      if (do_flush)
		{
		  __asm __volatile ("flush %0" : : "r"(rela->r_offset));
		  __asm __volatile ("flush %0+4" : : "r"(rela->r_offset));
		}
	      ++rela;
	    }
	}
    }

  return lazy;
}

/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
   PLT entries should not be allowed to define the value.
   ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
   of the main executable's symbols, as for a COPY reloc.  */
#if !defined RTLD_BOOTSTRAP || USE___THREAD
# define elf_machine_type_class(type) \
  ((((type) == R_SPARC_JMP_SLOT						      \
     || ((type) >= R_SPARC_TLS_GD_HI22 && (type) <= R_SPARC_TLS_TPOFF64))     \
    * ELF_RTYPE_CLASS_PLT)						      \
   | (((type) == R_SPARC_COPY) * ELF_RTYPE_CLASS_COPY))
#else
# define elf_machine_type_class(type) \
  ((((type) == R_SPARC_JMP_SLOT) * ELF_RTYPE_CLASS_PLT)			      \
   | (((type) == R_SPARC_COPY) * ELF_RTYPE_CLASS_COPY))
#endif

/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
#define ELF_MACHINE_JMP_SLOT	R_SPARC_JMP_SLOT

/* The SPARC never uses Elf32_Rel relocations.  */
#define ELF_MACHINE_NO_REL 1

/* The SPARC overlaps DT_RELA and DT_PLTREL.  */
#define ELF_MACHINE_PLTREL_OVERLAP 1

/* Undo the sub %sp, 6*4, %sp; add %sp, 22*4, %o0 below to get at the
   value we want in __libc_stack_end.  */
#define DL_STACK_END(cookie) \
  ((void *) (((long) (cookie)) - (22 - 6) * 4))

/* Initial entry point code for the dynamic linker.
   The C function `_dl_start' is the real entry point;
   its return value is the user program's entry point.  */

#define RTLD_START __asm__ ("\
	.text\n\
	.globl	_start\n\
	.type	_start, @function\n\
	.align	32\n\
_start:\n\
  /* Allocate space for functions to drop their arguments.  */\n\
	sub	%sp, 6*4, %sp\n\
  /* Pass pointer to argument block to _dl_start.  */\n\
	call	_dl_start\n\
	 add	%sp, 22*4, %o0\n\
	/* FALTHRU */\n\
	.globl	_dl_start_user\n\
	.type	_dl_start_user, @function\n\
_dl_start_user:\n\
  /* Load the PIC register.  */\n\
1:	call	2f\n\
	 sethi	%hi(_GLOBAL_OFFSET_TABLE_-(1b-.)), %l7\n\
2:	or	%l7, %lo(_GLOBAL_OFFSET_TABLE_-(1b-.)), %l7\n\
	add	%l7, %o7, %l7\n\
  /* Save the user entry point address in %l0 */\n\
	mov	%o0, %l0\n\
  /* See if we were run as a command with the executable file name as an\n\
     extra leading argument.  If so, adjust the contents of the stack.  */\n\
	sethi	%hi(_dl_skip_args), %g2\n\
	or	%g2, %lo(_dl_skip_args), %g2\n\
	ld	[%l7+%g2], %i0\n\
	ld	[%i0], %i0\n\
	tst	%i0\n\
	beq	3f\n\
	 ld	[%sp+22*4], %i5		/* load argc */\n\
	/* Find out how far to shift.  */\n\
	sethi	%hi(_dl_argv), %l3\n\
	or	%l3, %lo(_dl_argv), %l3\n\
	ld	[%l7+%l3], %l3\n\
	sub	%i5, %i0, %i5\n\
	ld	[%l3], %l4\n\
	sll	%i0, 2, %i2\n\
	st	%i5, [%sp+22*4]\n\
	sub	%l4, %i2, %l4\n\
	add	%sp, 23*4, %i1\n\
	add	%i1, %i2, %i2\n\
	st	%l4, [%l3]\n\
	/* Copy down argv */\n\
21:	ld	[%i2], %i3\n\
	add	%i2, 4, %i2\n\
	tst	%i3\n\
	st	%i3, [%i1]\n\
	bne	21b\n\
	 add	%i1, 4, %i1\n\
	/* Copy down env */\n\
22:	ld	[%i2], %i3\n\
	add	%i2, 4, %i2\n\
	tst	%i3\n\
	st	%i3, [%i1]\n\
	bne	22b\n\
	 add	%i1, 4, %i1\n\
	/* Copy down auxiliary table.  */\n\
23:	ld	[%i2], %i3\n\
	ld	[%i2+4], %i4\n\
	add	%i2, 8, %i2\n\
	tst	%i3\n\
	st	%i3, [%i1]\n\
	st	%i4, [%i1+4]\n\
	bne	23b\n\
	 add	%i1, 8, %i1\n\
  /* %o0 = _dl_loaded, %o1 = argc, %o2 = argv, %o3 = envp.  */\n\
3:	sethi	%hi(_rtld_local), %o0\n\
	add	%sp, 23*4, %o2\n\
	orcc	%o0, %lo(_rtld_local), %o0\n\