glibc/sysdeps/sparc/sparc64/dl-machine.h

/* Machine-dependent ELF dynamic relocation inline functions.  Sparc64 version.
   Copyright (C) 1997 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 Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

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

#define ELF_MACHINE_NAME "sparc64"

#include <assert.h>
#include <string.h>
#include <link.h>
#include <sys/param.h>
#include <sysdep.h>


/* Translate a processor-specific dynamic tag to the index into l_info.  */
#define DT_SPARC(x)	(DT_SPARC_##x - DT_LOPROC + DT_NUM)

/* Return nonzero iff E_MACHINE is compatible with the running host.  */
static inline int
elf_machine_matches_host (Elf64_Half e_machine)
{
  return e_machine == EM_SPARC64;
}

/* 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 Elf64_Addr
elf_machine_dynamic (void)
{
  register Elf64_Addr elf_pic_register __asm__("%l7");

  return *(Elf64_Addr *)elf_pic_register;
}


/* Return the run-time load address of the shared object.  */
static inline Elf64_Addr
elf_machine_load_address (void)
{
  register Elf64_Addr elf_pic_register __asm__("%l7");
  Elf64_Addr pc, la;

  /* Utilize the fact that a local .got entry will be partially
     initialized at startup awaiting its RELATIVE fixup.  */

  __asm("sethi %%hi(.Load_address), %1\n"
	".Load_address:\n\t"
	"rd %%pc, %0\n\t"
	"or %1, %%lo(.Load_address), %1\n\t"
	: "=r"(pc), "=r"(la));

  return pc - *(Elf64_Addr *)(elf_pic_register + la);
}

#ifdef RESOLVE
/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
   MAP is the object containing the reloc.  */

static inline void
elf_machine_rela (struct link_map *map, const Elf64_Rela *reloc,
		  const Elf64_Sym *sym, const struct r_found_version *version,
		  Elf64_Addr *const reloc_addr)
{
#ifndef RTLD_BOOTSTRAP
  /* This is defined in rtld.c, but nowhere in the static libc.a; make the
     reference weak so static programs can still link.  This declaration
     cannot be done when compiling rtld.c (i.e.  #ifdef RTLD_BOOTSTRAP)
     because rtld.c contains the common defn for _dl_rtld_map, which is
     incompatible with a weak decl in the same file.  */
  weak_extern (_dl_rtld_map);
#endif

  if (ELF64_R_TYPE (reloc->r_info) == R_SPARC_RELATIVE)
    {
#ifndef RTLD_BOOTSTRAP
      if (map != &_dl_rtld_map) /* Already done in rtld itself. */
#endif
	*reloc_addr = map->l_addr + reloc->r_addend;
    }
  else
    {
      const Elf64_Sym *const refsym = sym;
      Elf64_Addr value;
      if (sym->st_shndx != SHN_UNDEF &&
	  ELF64_ST_BIND (sym->st_info) == STB_LOCAL)
	value = map->l_addr;
      else
	{
	  value = RESOLVE (&sym, version, ELF64_R_TYPE (reloc->r_info));
	  if (sym)
	    value += sym->st_value;
	}
      value += reloc->r_addend;	/* Assume copy relocs have zero addend.  */

      switch (ELF64_R_TYPE (reloc->r_info))
	{
	case R_SPARC_COPY:
	  if (sym->st_size > refsym->st_size
	      || (_dl_verbose && sym->st_size < refsym->st_size))
	    {
	      extern char **_dl_argv;
	      const char *strtab;

	      strtab = ((void *) map->l_addr
			+ map->l_info[DT_STRTAB]->d_un.d_ptr);
	      _dl_sysdep_error (_dl_argv[0] ?: "<program name unknown>",
				": Symbol `", strtab + refsym->st_name,
				"' has different size in shared object, "
				"consider re-linking\n", NULL);
	    }
	  memcpy (reloc_addr, (void *) value, MIN (sym->st_size,
						   refsym->st_size));
	  break;

	case R_SPARC_64:
	case R_SPARC_GLOB_DAT:
	  *reloc_addr = value;
	  break;
	case R_SPARC_8:
	  *(char *) reloc_addr = value;
	  break;
	case R_SPARC_16:
	  *(short *) reloc_addr = value;
	  break;
	case R_SPARC_DISP8:
	  *(char *) reloc_addr = (value - (Elf64_Addr) reloc_addr);
	  break;
	case R_SPARC_DISP16:
	  *(short *) reloc_addr = (value - (Elf64_Addr) reloc_addr);
	  break;
	case R_SPARC_DISP32:
	  *(unsigned int *)reloc_addr = (value - (Elf64_Addr) reloc_addr);
	  break;
	case R_SPARC_LO10:
	  *(unsigned *)reloc_addr = (*(unsigned *)reloc_addr & ~0x3ff)
				     | (value & 0x3ff);
	  break;
	case R_SPARC_WDISP30:
	  *(unsigned *)reloc_addr = ((*(unsigned *)reloc_addr & 0xc0000000)
			 | ((value - (Elf64_Addr) reloc_addr) >> 2));
	  break;
	case R_SPARC_HI22:
	  *(unsigned *)reloc_addr = (*(unsigned *)reloc_addr & 0xffc00000)
				     | (value >> 10);
	  break;

	case R_SPARC_JMP_SLOT:
	  {
	    Elf64_Dyn *pltfmt = map->l_info[DT_SPARC(PLTFMT)];
	    switch (pltfmt ? pltfmt->d_un.d_val : 0)
	      {
	      case 1: /* .got.plt with absolute addresses */
		*reloc_addr = value;
	        break;
	      case 2: /* .got.plt with got-relative addresses */
		*reloc_addr = value - (map->l_info[DT_PLTGOT]->d_un.d_ptr
				       + map->l_addr);
		break;
	      default:
		assert (! "unexpected .plt format type");
	      }
	  }
	  break;

	case R_SPARC_NONE:		/* Alright, Wilbur.  */
	  break;
	default:
	  assert (! "unexpected dynamic reloc type");
	  break;
	}
    }
}

static inline void
elf_machine_lazy_rel (struct link_map *map, const Elf64_Rela *reloc)
{
  switch (ELF64_R_TYPE (reloc->r_info))
    {
    case R_SPARC_NONE:
      break;
    case R_SPARC_JMP_SLOT:
      break;
    default:
      assert (! "unexpected PLT reloc type");
      break;
    }
}

#endif	/* RESOLVE */

/* Nonzero iff TYPE should not be allowed to resolve to one of
   the main executable's symbols, as for a COPY reloc.  */
#define elf_machine_lookup_noexec_p(type) ((type) == R_SPARC_COPY)

/* Nonzero iff TYPE describes relocation of a PLT entry, so
   PLT entries should not be allowed to define the value.  */
#define elf_machine_lookup_noplt_p(type) ((type) == R_SPARC_JMP_SLOT)

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

/* The SPARC never uses Elf64_Rel relocations.  */
#define ELF_MACHINE_NO_REL 1

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

/* 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)
{
  Elf64_Addr *got;
  extern void _dl_runtime_resolve (void);

  if (l->l_info[DT_JMPREL] && lazy)
    {
      got = (Elf64_Addr *) (l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr);
      got[1] = (Elf64_Addr) l;  /* Identify this shared object.  */
      /* This function will get called to fix up the GOT entry indicated by
         the offset on the stack, and then jump to the resolved address.  */
      got[2] = (Elf64_Addr) &_dl_runtime_resolve;
    }

  return lazy;
}

/* This code is used in dl-runtime.c to call the `fixup' function
   and then redirect to the address it returns.  */
#define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\
	.globl _dl_runtime_resolve
	.type _dl_runtime_resolve, @function
_dl_runtime_resolve:
	save %sp, -160, %sp
	mov %g5, %o0
	call fixup
	 mov %g6, %o1
	jmp %o0
	 restore
	.size _dl_runtime_resolve, .-_dl_runtime_resolve
");

/* The PLT uses Elf64_Rela relocs.  */
#define elf_machine_relplt elf_machine_rela


/* 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 __S1(x)	#x
#define __S(x)	__S1(x)

#define RTLD_START __asm__ ( "\
	.global _start
	.type _start, @function
_start:
   /* Make room for functions to drop their arguments on the stack.  */
	sub	%sp, 6*8, %sp
   /* Pass pointer to argument block to _dl_start.  */
	call	_dl_start
	 add	 %sp," __S(STACK_BIAS) "+22*8,%o0
	/* FALLTHRU */
	.size _start, .-_start

	.global _dl_start_user
	.type _dl_start_user, @function
_dl_start_user:
   /* Load the GOT register.  */
1:	call	11f
	sethi	%hi(_GLOBAL_OFFSET_TABLE_-(1b-.)),%l7
11:	or	%l7,%lo(_GLOBAL_OFFSET_TABLE_-(1b-.)),%l7
	add	%l7,%o7,%l7
   /* Save the user entry point address in %l0.  */
	mov	%o0,%l0
   /* See if we were run as a command with the executable file name as an
      extra leading argument.  If so, we must shift things around since we
      must keep the stack doubleword aligned.  */
	sethi	%hi(_dl_skip_args), %g2
	or	%g2, %lo(_dl_skip_args), %g2
	ldx	[%l7+%g2], %i0
	ld	[%i0], %i0
	brz,pt	%i0, 2f
	 nop
	/* Find out how far to shift.  */
	ldx	[%sp+" __S(STACK_BIAS) "+22*8], %i1
	sub	%i1, %i0, %i1
	sllx	%i0, 3, %i2
	stx	%i1, [%sp+" __S(STACK_BIAS) "+22*8]
	add	%sp, " __S(STACK_BIAS) "+23*8, %i1
	add	%i1, %i2, %i2
	/* Copy down argv.  */
12:	ldx	[%i2], %i3
	add	%i2, 8, %i2
	stx	%i3, [%i1]
	brnz,pt	%i3, 12b
	 add	%i1, 8, %i1
	/* Copy down envp.  */
13:	ldx	[%i2], %i3
	add	%i2, 8, %i2
	stx	%i3, [%i1]
	brnz,pt	%i3, 13b
	 add	%i1, 8, %i1
	/* Copy down auxiliary table.  */
14:	ldx	[%i2], %i3
	ldx	[%i2+8], %i4
	add	%i2, 16, %i2
	stx	%i3, [%i1]
	stx	%i4, [%i1+8]
	brnz,pt	%i3, 13b
	 add	%i1, 16, %i1
   /* Load _dl_default_scope[2] to pass to _dl_init_next.  */
2:	sethi	%hi(_dl_default_scope), %g2
	or	%g2, %lo(_dl_default_scope), %g2
	ldx	[%l7+%g2], %g2
	ldx	[%g2+2*8], %l1
   /* Call _dl_init_next to return the address of an initializer to run.  */
3:	call	_dl_init_next
	 mov	%l1, %o0
	brz,pn	%o0, 4f
	 nop
	jmpl	%o0, %o7
	 nop
	ba,a	3b
   /* Clear the startup flag.  */
4:	sethi	%hi(_dl_starting_up), %g2
	or	%g2, %lo(_dl_starting_up), %g2
	ldx	[%l7+%g2], %g2
	st	%g0, [%g2]
   /* Pass our finalizer function to the user in %g1.  */
	sethi	%hi(_dl_fini), %g1
	or	%g1, %lo(_dl_fini), %g1
	ldx	[%l7+%g1], %g1
   /* Jump to the user's entry point & undo the allocation of the xtra regs.  */
	jmp	%l0
	 add	%sp, 6*8, %sp
	.size _dl_start_user, .-_dl_start_user");