[thirdparty/glibc.git] / sysdeps / m68k / dl-machine.h

/* Machine-dependent ELF dynamic relocation inline functions.  m68k version.
Copyright (C) 1996 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., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#define ELF_MACHINE_NAME "m68k"

#include <assert.h>
#include <string.h>
#include <link.h>


/* Return nonzero iff E_MACHINE is compatible with the running host.  */
static inline int
elf_machine_matches_host (Elf32_Half e_machine)
{
  switch (e_machine)
    {
    case EM_68K:
      return 1;
    default:
      return 0;
    }
}


/* Return the run-time address of the _GLOBAL_OFFSET_TABLE_.
   Must be inlined in a function which uses global data.  */
static inline Elf32_Addr *
elf_machine_got (void)
{
  register Elf32_Addr *got asm ("%a5");
  return got;
}


/* Return the run-time load address of the shared object.  */
static inline Elf32_Addr
elf_machine_load_address (void)
{
  Elf32_Addr addr;
  asm ("here:	lea here(%%pc), %0\n"
       "	sub.l %#here, %0"
       : "=a" (addr));
  return addr;
}

/* The `subl' insn above will contain an R_68K_RELATIVE relocation
   entry intended to insert the run-time address of the label `here'.
   This will be the first relocation in the text of the dynamic
   linker; we skip it to avoid trying to modify read-only text in this
   early stage.  */
#define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) \
  ((dynamic_info)[DT_RELA]->d_un.d_ptr += sizeof (Elf32_Rela), \
   (dynamic_info)[DT_RELASZ]->d_un.d_val -= sizeof (Elf32_Rela))

/* 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 Elf32_Rela *reloc, const Elf32_Sym *sym,
		  Elf32_Addr (*resolve) (const Elf32_Sym **ref,
					 Elf32_Addr reloc_addr,
					 int noplt))
{
  Elf32_Addr *const reloc_addr = (void *) (map->l_addr + reloc->r_offset);
  Elf32_Addr loadbase;

  switch (ELF32_R_TYPE (reloc->r_info))
    {
    case R_68K_COPY:
      loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
      memcpy (reloc_addr, (void *) (loadbase + sym->st_value), sym->st_size);
      break;
    case R_68K_GLOB_DAT:
      loadbase = (resolve ? (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0) :
		  /* RESOLVE is null during bootstrap relocation.  */
		  map->l_addr);
      *reloc_addr = sym ? (loadbase + sym->st_value) : 0;
      break;
    case R_68K_JMP_SLOT:
      loadbase = (resolve ? (*resolve) (&sym, (Elf32_Addr) reloc_addr, 1) :
		  /* RESOLVE is null during bootstrap relocation.  */
		  map->l_addr);
      *reloc_addr = sym ? (loadbase + sym->st_value) : 0;
      break;
    case R_68K_8:
      loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
      *(char *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
			      + reloc->r_addend);
      break;
    case R_68K_16:
      loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
      *(short *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
			       + reloc->r_addend);
      break;
    case R_68K_32:
      loadbase = (resolve ? (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0) :
		  /* RESOLVE is null during bootstrap relocation.  */
		  map->l_addr);
      *reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
		     + reloc->r_addend);
      break;
    case R_68K_RELATIVE:
      *reloc_addr = map->l_addr + reloc->r_addend;
      break;
    case R_68K_PC8:
      loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
      *(char *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
			      + reloc->r_addend
			      - (Elf32_Addr) reloc_addr);
      break;
    case R_68K_PC16:
      loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
      *(short *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
			       + reloc->r_addend
			       - (Elf32_Addr) reloc_addr);
      break;
    case R_68K_PC32:
      loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
      *reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
		     + reloc->r_addend
		     - (Elf32_Addr) reloc_addr);
      break;
    case R_68K_NONE:		/* Alright, Wilbur.  */
      break;
    default:
      assert (! "unexpected dynamic reloc type");
      break;
    }
}

static inline void
elf_machine_lazy_rel (struct link_map *map, const Elf32_Rela *reloc)
{
  Elf32_Addr *const reloc_addr = (void *) (map->l_addr + reloc->r_offset);
  switch (ELF32_R_TYPE (reloc->r_info))
    {
    case R_68K_NONE:
      break;
    case R_68K_JMP_SLOT:
      *reloc_addr += map->l_addr;
      break;
    default:
      assert (! "unexpected PLT reloc type");
      break;
    }
}

/* Nonzero iff TYPE describes relocation of a PLT entry, so
   PLT entries should not be allowed to define the value.  */
#define elf_machine_pltrel_p(type) ((type) == R_68K_JMP_SLOT)

/* The m68k never uses Elf32_Rel relocations.  */
#define ELF_MACHINE_NO_REL 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 void
elf_machine_runtime_setup (struct link_map *l, int lazy)
{
  Elf32_Addr *got;
  extern void _dl_runtime_resolve (Elf32_Word);

  if (l->l_info[DT_JMPREL] && lazy)
    {
      /* The GOT entries for functions in the PLT have not yet been
	 filled in.  Their initial contents will arrange when called
	 to push an offset into the .rela.plt section, push
	 _GLOBAL_OFFSET_TABLE_[1], and then jump to
	 _GLOBAL_OFFSET_TABLE_[2].  */
      got = (Elf32_Addr *) (l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr);
      got[1] = (Elf32_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] = (Elf32_Addr) &_dl_runtime_resolve;
    }

  /* 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 ("\
| Trampoline for _dl_runtime_resolver
	.globl _dl_runtime_resolve
	.type _dl_runtime_resolve, @function
_dl_runtime_resolve:
	| Save %a0 (struct return address) and %a1.
	move.l %a0, -(%sp)
	move.l %a1, -(%sp)
	| Call the real address resolver.
	jbsr fixup
	| Restore register %a0 and %a1.
	move.l (%sp)+, %a1
	move.l (%sp)+, %a0
	| Pop parameters
	addq.l #8, %sp
	| Call real function.
	jmp (%d0)
	.size _dl_runtime_resolve, . - _dl_runtime_resolve
");
#define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
/* The PLT uses Elf32_Rela relocs.  */
#define elf_machine_relplt elf_machine_rela
}


/* Mask identifying addresses reserved for the user program,
   where the dynamic linker should not map anything.  */
#define ELF_MACHINE_USER_ADDRESS_MASK	0x80000000UL

/* 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
.globl _start
.globl _dl_start_user
_start:
	move.l %sp, -(%sp)
	jbsr _dl_start
	addq.l #4, %sp
_dl_start_user:
	| Save the user entry point address in %a4.
	move.l %d0, %a4
	| Point %a5 at the GOT.
	lea _GLOBAL_OFFSET_TABLE_@GOTPC(%pc), %a5
	| See if we were run as a command with the executable file
	| name as an extra leading argument.
	move.l ([_dl_skip_args@GOT, %a5]), %d0
	jeq 0f
	| Pop the original argument count
	move.l (%sp)+, %d1
	| Subtract _dl_skip_args from it.
	sub.l %d0, %d1
	| Adjust the stack pointer to skip _dl_skip_args words.
	lea (%sp, %d0*4), %sp
	| Push back the modified argument count.
	move.l %d1, -(%sp)
0:	| Push _dl_default_scope[2] as argument in _dl_init_next call below.
	move.l ([_dl_default_scope@GOT, %a5]), %d2
0:	move.l (%d2, 8), -(%sp)
	| Call _dl_init_next to return the address of an initializer
	| function to run.
	bsr.l _dl_init_next@PLTPC
	add.l #4, %sp | Pop argument.
	| Check for zero return, when out of initializers.
	tst.l %d0
	jeq 1f
	| Call the shared object initializer function.
	| NOTE: We depend only on the registers (%d2, %a4 and %a5)
	| and the return address pushed by this call;
	| the initializer is called with the stack just
	| as it appears on entry, and it is free to move
	| the stack around, as long as it winds up jumping to
	| the return address on the top of the stack.
	move.l %d0, %a0
	jsr (%a0)
	| Loop to call _dl_init_next for the next initializer.
	jra 0b
1:	| Pass our finalizer function to the user in %a1.
	move.l _dl_fini@GOT(%a5), %a1
	| Initialize %fp with the stack pointer.
	move.l %sp, %fp
	| Jump to the user's entry point.
	jmp (%a4)");
Commit	Line	Data
01f3e03b RM	1	/* Machine-dependent ELF dynamic relocation inline functions. m68k version.
	2	Copyright (C) 1996 Free Software Foundation, Inc.
	3	This file is part of the GNU C Library.
	4
	5	The GNU C Library is free software; you can redistribute it and/or
	6	modify it under the terms of the GNU Library General Public License as
	7	published by the Free Software Foundation; either version 2 of the
	8	License, or (at your option) any later version.
	9
	10	The GNU C Library is distributed in the hope that it will be useful,
	11	but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	13	Library General Public License for more details.
	14
	15	You should have received a copy of the GNU Library General Public
	16	License along with the GNU C Library; see the file COPYING.LIB. If
	17	not, write to the Free Software Foundation, Inc., 675 Mass Ave,
	18	Cambridge, MA 02139, USA. */
	19
	20	#define ELF_MACHINE_NAME "m68k"
	21
	22	#include <assert.h>
	23	#include <string.h>
	24	#include <link.h>
	25
	26
	27	/* Return nonzero iff E_MACHINE is compatible with the running host. */
	28	static inline int
	29	elf_machine_matches_host (Elf32_Half e_machine)
	30	{
	31	switch (e_machine)
	32	{
	33	case EM_68K:
	34	return 1;
	35	default:
	36	return 0;
	37	}
	38	}
	39
	40
	41	/* Return the run-time address of the _GLOBAL_OFFSET_TABLE_.
	42	Must be inlined in a function which uses global data. */
	43	static inline Elf32_Addr *
	44	elf_machine_got (void)
	45	{
	46	register Elf32_Addr *got asm ("%a5");
	47	return got;
	48	}
	49
	50
	51	/* Return the run-time load address of the shared object. */
	52	static inline Elf32_Addr
	53	elf_machine_load_address (void)
	54	{
be10a868 RM	55	Elf32_Addr addr;
	56	asm ("here: lea here(%%pc), %0\n"
	57	" sub.l %#here, %0"
	58	: "=a" (addr));
	59	return addr;
01f3e03b RM	60	}
01f3e03b RM	61
be10a868 RM	62	/* The `subl' insn above will contain an R_68K_RELATIVE relocation
	63	entry intended to insert the run-time address of the label `here'.
	64	This will be the first relocation in the text of the dynamic
	65	linker; we skip it to avoid trying to modify read-only text in this
	66	early stage. */
	67	#define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) \
	68	((dynamic_info)[DT_RELA]->d_un.d_ptr += sizeof (Elf32_Rela), \
	69	(dynamic_info)[DT_RELASZ]->d_un.d_val -= sizeof (Elf32_Rela))
	70
01f3e03b RM	71	/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
	72	MAP is the object containing the reloc. */
	73
	74	static inline void
	75	elf_machine_rela (struct link_map *map,
1c2f546b	76	const Elf32_Rela reloc, const Elf32_Sym sym,
710f7bab RM	77	Elf32_Addr (resolve) (const Elf32_Sym *ref,
	78	Elf32_Addr reloc_addr,
	79	int noplt))
01f3e03b RM	80	{
01f3e03b RM	81	Elf32_Addr const reloc_addr = (void ) (map->l_addr + reloc->r_offset);
710f7bab	82	Elf32_Addr loadbase;
01f3e03b RM	83
	84	switch (ELF32_R_TYPE (reloc->r_info))
	85	{
	86	case R_68K_COPY:
710f7bab RM	87	loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
710f7bab RM	88	memcpy (reloc_addr, (void *) (loadbase + sym->st_value), sym->st_size);
01f3e03b RM	89	break;
01f3e03b RM	90	case R_68K_GLOB_DAT:
710f7bab RM	91	loadbase = (resolve ? (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0) :
	92	/* RESOLVE is null during bootstrap relocation. */
	93	map->l_addr);
	94	*reloc_addr = sym ? (loadbase + sym->st_value) : 0;
	95	break;
01f3e03b	96	case R_68K_JMP_SLOT:
710f7bab RM	97	loadbase = (resolve ? (*resolve) (&sym, (Elf32_Addr) reloc_addr, 1) :
	98	/* RESOLVE is null during bootstrap relocation. */
	99	map->l_addr);
	100	*reloc_addr = sym ? (loadbase + sym->st_value) : 0;
01f3e03b RM	101	break;
01f3e03b RM	102	case R_68K_8:
710f7bab RM	103	loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
	104	(char ) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
	105	+ reloc->r_addend);
01f3e03b RM	106	break;
01f3e03b RM	107	case R_68K_16:
710f7bab RM	108	loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
	109	(short ) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
	110	+ reloc->r_addend);
01f3e03b RM	111	break;
01f3e03b RM	112	case R_68K_32:
1c2f546b RM	113	loadbase = (resolve ? (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0) :
	114	/* RESOLVE is null during bootstrap relocation. */
	115	map->l_addr);
710f7bab RM	116	*reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
710f7bab RM	117	+ reloc->r_addend);
01f3e03b RM	118	break;
	119	case R_68K_RELATIVE:
	120	*reloc_addr = map->l_addr + reloc->r_addend;
	121	break;
	122	case R_68K_PC8:
710f7bab RM	123	loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
	124	(char ) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
	125	+ reloc->r_addend
01f3e03b RM	126	- (Elf32_Addr) reloc_addr);
	127	break;
	128	case R_68K_PC16:
710f7bab RM	129	loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
	130	(short ) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
	131	+ reloc->r_addend
01f3e03b RM	132	- (Elf32_Addr) reloc_addr);
	133	break;
	134	case R_68K_PC32:
710f7bab RM	135	loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
	136	*reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
	137	+ reloc->r_addend
	138	- (Elf32_Addr) reloc_addr);
01f3e03b RM	139	break;
	140	case R_68K_NONE: /* Alright, Wilbur. */
	141	break;
	142	default:
	143	assert (! "unexpected dynamic reloc type");
	144	break;
	145	}
	146	}
	147
	148	static inline void
	149	elf_machine_lazy_rel (struct link_map map, const Elf32_Rela reloc)
	150	{
	151	Elf32_Addr const reloc_addr = (void ) (map->l_addr + reloc->r_offset);
	152	switch (ELF32_R_TYPE (reloc->r_info))
	153	{
	154	case R_68K_NONE:
	155	break;
	156	case R_68K_JMP_SLOT:
	157	*reloc_addr += map->l_addr;
	158	break;
	159	default:
	160	assert (! "unexpected PLT reloc type");
	161	break;
	162	}
	163	}
	164
6c03c2cf RM	165	/* Nonzero iff TYPE describes relocation of a PLT entry, so
	166	PLT entries should not be allowed to define the value. */
	167	#define elf_machine_pltrel_p(type) ((type) == R_68K_JMP_SLOT)
	168
01f3e03b RM	169	/* The m68k never uses Elf32_Rel relocations. */
	170	#define ELF_MACHINE_NO_REL 1
	171
	172
	173	/* Set up the loaded object described by L so its unrelocated PLT
	174	entries will jump to the on-demand fixup code in dl-runtime.c. */
	175
	176	static inline void
	177	elf_machine_runtime_setup (struct link_map *l, int lazy)
	178	{
	179	Elf32_Addr *got;
	180	extern void _dl_runtime_resolve (Elf32_Word);
	181
	182	if (l->l_info[DT_JMPREL] && lazy)
	183	{
	184	/* The GOT entries for functions in the PLT have not yet been
	185	filled in. Their initial contents will arrange when called
	186	to push an offset into the .rela.plt section, push
	187	_GLOBAL_OFFSET_TABLE_[1], and then jump to
	188	_GLOBAL_OFFSET_TABLE_[2]. */
	189	got = (Elf32_Addr *) (l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr);
	190	got[1] = (Elf32_Addr) l; /* Identify this shared object. */
	191	/* This function will get called to fix up the GOT entry
	192	indicated by the offset on the stack, and then jump to the
	193	resolved address. */
	194	got[2] = (Elf32_Addr) &_dl_runtime_resolve;
	195	}
	196
	197	/* This code is used in dl-runtime.c to call the `fixup' function
	198	and then redirect to the address it returns. */
	199	#define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\
	200	\| Trampoline for _dl_runtime_resolver
	201	.globl _dl_runtime_resolve
	202	.type _dl_runtime_resolve, @function
	203	_dl_runtime_resolve:
be10a868	204	\| Save %a0 (struct return address) and %a1.
01f3e03b	205	move.l %a0, -(%sp)
be10a868	206	move.l %a1, -(%sp)
01f3e03b	207	\| Call the real address resolver.
be10a868 RM	208	jbsr fixup
	209	\| Restore register %a0 and %a1.
	210	move.l (%sp)+, %a1
01f3e03b RM	211	move.l (%sp)+, %a0
	212	\| Pop parameters
	213	addq.l #8, %sp
	214	\| Call real function.
	215	jmp (%d0)
	216	.size _dl_runtime_resolve, . - _dl_runtime_resolve
	217	");
be10a868 RM	218	#define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
	219	/* The PLT uses Elf32_Rela relocs. */
	220	#define elf_machine_relplt elf_machine_rela
01f3e03b RM	221	}
	222
	223
	224	/* Mask identifying addresses reserved for the user program,
	225	where the dynamic linker should not map anything. */
	226	#define ELF_MACHINE_USER_ADDRESS_MASK 0x80000000UL
	227
	228	/* Initial entry point code for the dynamic linker.
	229	The C function `_dl_start' is the real entry point;
	230	its return value is the user program's entry point. */
	231
	232	#define RTLD_START asm ("\
	233	.text
	234	.globl _start
	235	.globl _dl_start_user
	236	_start:
8d6468d0	237	move.l %sp, -(%sp)
01f3e03b	238	jbsr _dl_start
8d6468d0	239	addq.l #4, %sp
01f3e03b RM	240	_dl_start_user:
	241	\| Save the user entry point address in %a4.
	242	move.l %d0, %a4
	243	\| Point %a5 at the GOT.
	244	lea _GLOBAL_OFFSET_TABLE_@GOTPC(%pc), %a5
	245	\| See if we were run as a command with the executable file
	246	\| name as an extra leading argument.
	247	move.l ([_dl_skip_args@GOT, %a5]), %d0
	248	jeq 0f
	249	\| Pop the original argument count
	250	move.l (%sp)+, %d1
	251	\| Subtract _dl_skip_args from it.
	252	sub.l %d0, %d1
	253	\| Adjust the stack pointer to skip _dl_skip_args words.
	254	lea (%sp, %d0*4), %sp
	255	\| Push back the modified argument count.
	256	move.l %d1, -(%sp)
ba79d61b RM	257	0: \| Push _dl_default_scope[2] as argument in _dl_init_next call below.
	258	move.l ([_dl_default_scope@GOT, %a5]), %d2
	259	0: move.l (%d2, 8), -(%sp)
01f3e03b RM	260	\| Call _dl_init_next to return the address of an initializer
01f3e03b RM	261	\| function to run.
f68b86cc RM	262	bsr.l _dl_init_next@PLTPC
f68b86cc RM	263	add.l #4, %sp \| Pop argument.
01f3e03b RM	264	\| Check for zero return, when out of initializers.
	265	tst.l %d0
	266	jeq 1f
	267	\| Call the shared object initializer function.
f68b86cc	268	\| NOTE: We depend only on the registers (%d2, %a4 and %a5)
01f3e03b RM	269	\| and the return address pushed by this call;
	270	\| the initializer is called with the stack just
	271	\| as it appears on entry, and it is free to move
	272	\| the stack around, as long as it winds up jumping to
	273	\| the return address on the top of the stack.
	274	move.l %d0, %a0
	275	jsr (%a0)
	276	\| Loop to call _dl_init_next for the next initializer.
	277	jra 0b
	278	1: \| Pass our finalizer function to the user in %a1.
	279	move.l _dl_fini@GOT(%a5), %a1
	280	\| Initialize %fp with the stack pointer.
	281	move.l %sp, %fp
	282	\| Jump to the user's entry point.
	283	jmp (%a4)");