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Introduce TLS descriptors for i386 and x86_64.

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* include/inline-hashtab.h: New file, copied from 2005's
	libiberty, with fix for memory leak imported afterwards by
	Glauber de Oliveira Costa.
	* elf/tlsdeschtab.h: New file.
	* elf/dl-reloc.c (_dl_try_allocate_static_tls): Extract from...
	(_dl_allocate_static_tls): ... here.  Rearrange failure path.
	(CHECK_STATIC_TLS): Move to...
	* elf/dynamic-link.h: ... this file.
	(TRY_STATIC_TLS): New macro.
	* elf/dl-conflict.c (CHECK_STATIC_TLS, TRY_STATIC_TLS): Override.
	* elf/elf.h (R_386_TLS_GOTDESC, R_386_TLS_DESC_CALL,
	R_386_TLS_DESC): Define.
	(R_X86_64_PC64, R_X86_GOTOFF64, R_X86_64_GOTPC32): Merge from
	binutils.
	(R_X86_64_GOTPC32_TLSDESC, R_X86_64_TLSDESC_CALL,
	R_X86_64_TLSDESC): Define.
	(R_386_NUM, R_X86_64_NUM): Adjust.
	* sysdeps/i386/Makefile (sysdep-dl-routines, sysdep_routines,
	systep-rtld-routines): Add tlsdesc and dl-tlsdesc for elf subdir.
	(gen-as-const-headers): Add tlsdesc.sym to csu subdir.
	* sysdeps/i386/dl-lookupcfg.h: New file.  Introduce _dl_unmap to
	release tlsdesc_table.
	* sysdeps/i386/dl-machine.h: Include dl-tlsdesc.h.
	(elf_machine_type_class): Mark R_386_TLS_DESC as PLT class.
	(elf_machine_rel): Handle R_386_TLS_DESC.
	(elf_machine_rela): Likewise.
	(elf_machine_lazy_rel): Likewise.
	(elf_machine_lazy_rela): Likewise.
	* sysdeps/i386/dl-tls.h (struct dl_tls_index): Name it.
	* sysdeps/i386/dl-tlsdesc.S: New file.
	* sysdeps/i386/dl-tlsdesc.h: New file.
	* sysdeps/i386/tlsdesc.c: New file.
	* sysdeps/i386/tlsdesc.sym: New file.
	* sysdeps/i386/bits/linkmap.h (struct link_map_machine): Add
	tlsdesc_table.
	* sysdeps/x86_64/Makefile (sysdep-dl-routines, sysdep_routines,
	systep-rtld-routines): Add tlsdesc and dl-tlsdesc for elf subdir.
	(gen-as-const-headers): Add tlsdesc.sym to csu subdir.
	* sysdeps/x86_64/dl-lookupcfg.h: New file.  Introduce _dl_unmap to
	release tlsdesc_table.
	* sysdeps/x86_64/dl-machine.h: Include dl-tlsdesc.h.
	(elf_machine_runtime_setup): Set up lazy TLSDESC GOT entry.
	(elf_machine_type_class): Mark R_X86_64_TLSDESC as PLT class.
	(elf_machine_rel): Handle R_X86_64_TLSDESC.
	(elf_machine_rela): Likewise.
	(elf_machine_lazy_rel): Likewise.
	* sysdeps/x86_64/dl-tls.h (struct dl_tls_index): Name it.
	(__tls_get_addr): Do not declare for non-shared compiles.
	* sysdeps/x86_64/dl-tlsdesc.S: New file.
	* sysdeps/x86_64/dl-tlsdesc.h: New file.
	* sysdeps/x86_64/tlsdesc.c: New file.
	* sysdeps/x86_64/tlsdesc.sym: New file.
	* sysdeps/x86_64/bits/linkmap.h (struct link_map_machine): Add
	tlsdesc_table for both 32- and 64-bit structs.
This commit is contained in:
Ulrich Drepper 2008-05-13 05:41:30 +00:00
parent a3636e8b89
commit c9ff0187a6
25 changed files with 1967 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
ChangeLog
View File

@ -1,3 +1,61 @@
2008-01-30 Alexandre Oliva <aoliva@redhat.com>
Introduce TLS descriptors for i386 and x86_64.
* include/inline-hashtab.h: New file, copied from 2005's
libiberty, with fix for memory leak imported afterwards by
Glauber de Oliveira Costa.
* elf/tlsdeschtab.h: New file.
* elf/dl-reloc.c (_dl_try_allocate_static_tls): Extract from...
(_dl_allocate_static_tls): ... here. Rearrange failure path.
(CHECK_STATIC_TLS): Move to...
* elf/dynamic-link.h: ... this file.
(TRY_STATIC_TLS): New macro.
* elf/dl-conflict.c (CHECK_STATIC_TLS, TRY_STATIC_TLS): Override.
* elf/elf.h (R_386_TLS_GOTDESC, R_386_TLS_DESC_CALL,
R_386_TLS_DESC): Define.
(R_X86_64_PC64, R_X86_GOTOFF64, R_X86_64_GOTPC32): Merge from
binutils.
(R_X86_64_GOTPC32_TLSDESC, R_X86_64_TLSDESC_CALL,
R_X86_64_TLSDESC): Define.
(R_386_NUM, R_X86_64_NUM): Adjust.
* sysdeps/i386/Makefile (sysdep-dl-routines, sysdep_routines,
systep-rtld-routines): Add tlsdesc and dl-tlsdesc for elf subdir.
(gen-as-const-headers): Add tlsdesc.sym to csu subdir.
* sysdeps/i386/dl-lookupcfg.h: New file. Introduce _dl_unmap to
release tlsdesc_table.
* sysdeps/i386/dl-machine.h: Include dl-tlsdesc.h.
(elf_machine_type_class): Mark R_386_TLS_DESC as PLT class.
(elf_machine_rel): Handle R_386_TLS_DESC.
(elf_machine_rela): Likewise.
(elf_machine_lazy_rel): Likewise.
(elf_machine_lazy_rela): Likewise.
* sysdeps/i386/dl-tls.h (struct dl_tls_index): Name it.
* sysdeps/i386/dl-tlsdesc.S: New file.
* sysdeps/i386/dl-tlsdesc.h: New file.
* sysdeps/i386/tlsdesc.c: New file.
* sysdeps/i386/tlsdesc.sym: New file.
* sysdeps/i386/bits/linkmap.h (struct link_map_machine): Add
tlsdesc_table.
* sysdeps/x86_64/Makefile (sysdep-dl-routines, sysdep_routines,
systep-rtld-routines): Add tlsdesc and dl-tlsdesc for elf subdir.
(gen-as-const-headers): Add tlsdesc.sym to csu subdir.
* sysdeps/x86_64/dl-lookupcfg.h: New file. Introduce _dl_unmap to
release tlsdesc_table.
* sysdeps/x86_64/dl-machine.h: Include dl-tlsdesc.h.
(elf_machine_runtime_setup): Set up lazy TLSDESC GOT entry.
(elf_machine_type_class): Mark R_X86_64_TLSDESC as PLT class.
(elf_machine_rel): Handle R_X86_64_TLSDESC.
(elf_machine_rela): Likewise.
(elf_machine_lazy_rel): Likewise.
* sysdeps/x86_64/dl-tls.h (struct dl_tls_index): Name it.
(__tls_get_addr): Do not declare for non-shared compiles.
* sysdeps/x86_64/dl-tlsdesc.S: New file.
* sysdeps/x86_64/dl-tlsdesc.h: New file.
* sysdeps/x86_64/tlsdesc.c: New file.
* sysdeps/x86_64/tlsdesc.sym: New file.
* sysdeps/x86_64/bits/linkmap.h (struct link_map_machine): Add
tlsdesc_table for both 32- and 64-bit structs.
2008-05-11 Ulrich Drepper <drepper@redhat.com>
* elf/dl-tls.c (__tls_get_addr): Optimize by moving slow path in

9
elf/dl-conflict.c
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@ -1,5 +1,5 @@
/* Resolve conflicts against already prelinked libraries.
Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
Copyright (C) 2001, 2002, 2003, 2004, 2005, 2008 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Jakub Jelinek <jakub@redhat.com>, 2001.
@ -44,7 +44,6 @@ _dl_resolve_conflicts (struct link_map *l, ElfW(Rela) *conflict,
/* This macro is used as a callback from the ELF_DYNAMIC_RELOCATE code. */
#define RESOLVE_MAP(ref, version, flags) (*ref = NULL, NULL)
#define RESOLVE(ref, version, flags) (*ref = NULL, 0)
#define CHECK_STATIC_TLS(ref_map, sym_map) ((void) 0)
#define RESOLVE_CONFLICT_FIND_MAP(map, r_offset) \
do { \
while ((resolve_conflict_map->l_map_end < (ElfW(Addr)) (r_offset)) \
@ -61,6 +60,12 @@ _dl_resolve_conflicts (struct link_map *l, ElfW(Rela) *conflict,
#include "dynamic-link.h"
/* Override these, defined in dynamic-link.h. */
#undef CHECK_STATIC_TLS
#define CHECK_STATIC_TLS(ref_map, sym_map) ((void) 0)
#undef TRY_STATIC_TLS
#define TRY_STATIC_TLS(ref_map, sym_map) (0)
GL(dl_num_cache_relocations) += conflictend - conflict;
for (; conflict < conflictend; ++conflict)

42
elf/dl-reloc.c
View File

@ -1,5 +1,5 @@
/* Relocate a shared object and resolve its references to other loaded objects.
Copyright (C) 1995-2004, 2005, 2006 Free Software Foundation, Inc.
Copyright (C) 1995-2004, 2005, 2006, 2008 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
@ -43,9 +43,9 @@
This function intentionally does not return any value but signals error
directly, as static TLS should be rare and code handling it should
not be inlined as much as possible. */
void
internal_function __attribute_noinline__
_dl_allocate_static_tls (struct link_map *map)
int
internal_function
_dl_try_allocate_static_tls (struct link_map *map)
{
/* If we've already used the variable with dynamic access, or if the
alignment requirements are too high, fail. */
@ -53,8 +53,7 @@ _dl_allocate_static_tls (struct link_map *map)
|| map->l_tls_align > GL(dl_tls_static_align))
{
fail:
_dl_signal_error (0, map->l_name, NULL, N_("\
cannot allocate memory in static TLS block"));
return -1;
}
#if TLS_TCB_AT_TP
@ -108,6 +107,20 @@ cannot allocate memory in static TLS block"));
}
else
map->l_need_tls_init = 1;
return 0;
}
void
internal_function __attribute_noinline__
_dl_allocate_static_tls (struct link_map *map)
{
if (map->l_tls_offset == FORCED_DYNAMIC_TLS_OFFSET
|| _dl_try_allocate_static_tls (map))
{
_dl_signal_error (0, map->l_name, NULL, N_("\
cannot allocate memory in static TLS block"));
}
}
/* Initialize static TLS area and DTV for current (only) thread.
@ -248,23 +261,6 @@ _dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
l->l_lookup_cache.value = _lr; })) \
: l)
/* This macro is used as a callback from elf_machine_rel{a,} when a
static TLS reloc is about to be performed. Since (in dl-load.c) we
permit dynamic loading of objects that might use such relocs, we
have to check whether each use is actually doable. If the object
whose TLS segment the reference resolves to was allocated space in
the static TLS block at startup, then it's ok. Otherwise, we make
an attempt to allocate it in surplus space on the fly. If that
can't be done, we fall back to the error that DF_STATIC_TLS is
intended to produce. */
#define CHECK_STATIC_TLS(map, sym_map) \
do { \
if (__builtin_expect ((sym_map)->l_tls_offset == NO_TLS_OFFSET \
|| ((sym_map)->l_tls_offset \
== FORCED_DYNAMIC_TLS_OFFSET), 0)) \
_dl_allocate_static_tls (sym_map); \
} while (0)
#include "dynamic-link.h"
ELF_DYNAMIC_RELOCATE (l, lazy, consider_profiling);

27
elf/dynamic-link.h
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@ -1,5 +1,5 @@
/* Inline functions for dynamic linking.
Copyright (C) 1995-2005, 2006 Free Software Foundation, Inc.
Copyright (C) 1995-2005, 2006, 2008 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
@ -17,6 +17,31 @@
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
/* This macro is used as a callback from elf_machine_rel{a,} when a
static TLS reloc is about to be performed. Since (in dl-load.c) we
permit dynamic loading of objects that might use such relocs, we
have to check whether each use is actually doable. If the object
whose TLS segment the reference resolves to was allocated space in
the static TLS block at startup, then it's ok. Otherwise, we make
an attempt to allocate it in surplus space on the fly. If that
can't be done, we fall back to the error that DF_STATIC_TLS is
intended to produce. */
#define CHECK_STATIC_TLS(map, sym_map) \
do { \
if (__builtin_expect ((sym_map)->l_tls_offset == NO_TLS_OFFSET \
|| ((sym_map)->l_tls_offset \
== FORCED_DYNAMIC_TLS_OFFSET), 0)) \
_dl_allocate_static_tls (sym_map); \
} while (0)
#define TRY_STATIC_TLS(map, sym_map) \
(__builtin_expect ((sym_map)->l_tls_offset \
!= FORCED_DYNAMIC_TLS_OFFSET, 1) \
&& (__builtin_expect ((sym_map)->l_tls_offset != NO_TLS_OFFSET, 1) \
|| _dl_try_allocate_static_tls (sym_map) == 0))
int internal_function _dl_try_allocate_static_tls (struct link_map *map);
#include <elf.h>
#include <assert.h>

22
elf/elf.h
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@ -1159,8 +1159,17 @@ typedef struct
#define R_386_TLS_DTPMOD32 35 /* ID of module containing symbol */
#define R_386_TLS_DTPOFF32 36 /* Offset in TLS block */
#define R_386_TLS_TPOFF32 37 /* Negated offset in static TLS block */
/* 38? */
#define R_386_TLS_GOTDESC 39 /* GOT offset for TLS descriptor. */
#define R_386_TLS_DESC_CALL 40 /* Marker of call through TLS
descriptor for
relaxation. */
#define R_386_TLS_DESC 41 /* TLS descriptor containing
pointer to code and to
argument, returning the TLS
offset for the symbol. */
/* Keep this the last entry. */
#define R_386_NUM 38
#define R_386_NUM 42
/* SUN SPARC specific definitions. */
@ -2557,8 +2566,17 @@ typedef Elf32_Addr Elf32_Conflict;
#define R_X86_64_GOTTPOFF 22 /* 32 bit signed PC relative offset
to GOT entry for IE symbol */
#define R_X86_64_TPOFF32 23 /* Offset in initial TLS block */
#define R_X86_64_PC64 24 /* PC relative 64 bit */
#define R_X86_64_GOTOFF64 25 /* 64 bit offset to GOT */
#define R_X86_64_GOTPC32 26 /* 32 bit signed pc relative
offset to GOT */
/* 27 .. 33 */
#define R_X86_64_GOTPC32_TLSDESC 34 /* GOT offset for TLS descriptor. */
#define R_X86_64_TLSDESC_CALL 35 /* Marker for call through TLS
descriptor. */
#define R_X86_64_TLSDESC 36 /* TLS descriptor. */
#define R_X86_64_NUM 24
#define R_X86_64_NUM 37
/* AM33 relocations. */

157
elf/tlsdeschtab.h Normal file
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@ -0,0 +1,157 @@
/* Hash table for TLS descriptors.
Copyright (C) 2005, 2008 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Alexandre Oliva <aoliva@redhat.com>
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 TLSDESCHTAB_H
# define TLSDESCHTAB_H 1
# ifdef SHARED
# include <inline-hashtab.h>
inline static int
hash_tlsdesc (void *p)
{
struct tlsdesc_dynamic_arg *td = p;
/* We know all entries are for the same module, so ti_offset is the
only distinguishing entry. */
return td->tlsinfo.ti_offset;
}
inline static int
eq_tlsdesc (void *p, void *q)
{
struct tlsdesc_dynamic_arg *tdp = p, *tdq = q;
return tdp->tlsinfo.ti_offset == tdq->tlsinfo.ti_offset;
}
inline static int
map_generation (struct link_map *map)
{
size_t idx = map->l_tls_modid;
struct dtv_slotinfo_list *listp = GL(dl_tls_dtv_slotinfo_list);
/* Find the place in the dtv slotinfo list. */
do
{
/* Does it fit in the array of this list element? */
if (idx < listp->len)
{
/* We should never get here for a module in static TLS, so
we can assume that, if the generation count is zero, we
still haven't determined the generation count for this
module. */
if (listp->slotinfo[idx].gen)
return listp->slotinfo[idx].gen;
else
break;
}
idx -= listp->len;
listp = listp->next;
}
while (listp != NULL);
/* If we get to this point, the module still hasn't been assigned an
entry in the dtv slotinfo data structures, and it will when we're
done with relocations. At that point, the module will get a
generation number that is one past the current generation, so
return exactly that. */
return GL(dl_tls_generation) + 1;
}
void *
internal_function
_dl_make_tlsdesc_dynamic (struct link_map *map, size_t ti_offset)
{
struct hashtab *ht;
void **entry;
struct tlsdesc_dynamic_arg *td, test;
/* FIXME: We could use a per-map lock here, but is it worth it? */
__rtld_lock_lock_recursive (GL(dl_load_lock));
ht = map->l_mach.tlsdesc_table;
if (! ht)
{
ht = htab_create ();
if (! ht)
{
__rtld_lock_unlock_recursive (GL(dl_load_lock));
return 0;
}
map->l_mach.tlsdesc_table = ht;
}
test.tlsinfo.ti_module = map->l_tls_modid;
test.tlsinfo.ti_offset = ti_offset;
entry = htab_find_slot (ht, &test, 1, hash_tlsdesc, eq_tlsdesc);
if (*entry)
{
td = *entry;
__rtld_lock_unlock_recursive (GL(dl_load_lock));
return td;
}
*entry = td = malloc (sizeof (struct tlsdesc_dynamic_arg));
/* This may be higher than the map's generation, but it doesn't
matter much. Worst case, we'll have one extra DTV update per
thread. */
td->gen_count = map_generation (map);
td->tlsinfo = test.tlsinfo;
__rtld_lock_unlock_recursive (GL(dl_load_lock));
return td;
}
# endif /* SHARED */
/* The idea of the following two functions is to stop multiple threads
from attempting to resolve the same TLS descriptor without busy
waiting. Ideally, we should be able to release the lock right
after changing td->entry, and then using say a condition variable
or a futex wake to wake up any waiting threads, but let's try to
avoid introducing such dependencies. */
inline static int
_dl_tlsdesc_resolve_early_return_p (struct tlsdesc volatile *td, void *caller)
{
if (caller != td->entry)
return 1;
__rtld_lock_lock_recursive (GL(dl_load_lock));
if (caller != td->entry)
{
__rtld_lock_unlock_recursive (GL(dl_load_lock));
return 1;
}
td->entry = _dl_tlsdesc_resolve_hold;
return 0;
}
inline static void
_dl_tlsdesc_wake_up_held_fixups (void)
{
__rtld_lock_unlock_recursive (GL(dl_load_lock));
}
#endif

302
include/inline-hashtab.h Normal file
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@ -0,0 +1,302 @@
/* Fully-inline hash table, used mainly for managing TLS descriptors.
Copyright (C) 1999, 2000, 2001, 2002, 2003, 2005, 2008
Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Alexandre Oliva <aoliva@redhat.com>
This file is derived from a 2003's version of libiberty's
hashtab.c, contributed by Vladimir Makarov (vmakarov@cygnus.com),
but with most adaptation points and support for deleting elements
removed.
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 INLINE_HASHTAB_H
# define INLINE_HASHTAB_H 1
extern void weak_function free (void *ptr);
inline static unsigned long
higher_prime_number (unsigned long n)
{
/* These are primes that are near, but slightly smaller than, a
power of two. */
static const uint32_t primes[] = {
UINT32_C (7),
UINT32_C (13),
UINT32_C (31),
UINT32_C (61),
UINT32_C (127),
UINT32_C (251),
UINT32_C (509),
UINT32_C (1021),
UINT32_C (2039),
UINT32_C (4093),
UINT32_C (8191),
UINT32_C (16381),
UINT32_C (32749),
UINT32_C (65521),
UINT32_C (131071),
UINT32_C (262139),
UINT32_C (524287),
UINT32_C (1048573),
UINT32_C (2097143),
UINT32_C (4194301),
UINT32_C (8388593),
UINT32_C (16777213),
UINT32_C (33554393),
UINT32_C (67108859),
UINT32_C (134217689),
UINT32_C (268435399),
UINT32_C (536870909),
UINT32_C (1073741789),
UINT32_C (2147483647),
/* 4294967291L */
UINT32_C (2147483647) + UINT32_C (2147483644)
};
const uint32_t *low = &primes[0];
const uint32_t *high = &primes[sizeof (primes) / sizeof (primes[0])];
while (low != high)
{
const unsigned long *mid = low + (high - low) / 2;
if (n > *mid)
low = mid + 1;
else
high = mid;
}
#if 0
/* If we've run out of primes, abort. */
if (n > *low)
{
fprintf (stderr, "Cannot find prime bigger than %lu\n", n);
abort ();
}
#endif
return *low;
}
struct hashtab
{
/* Table itself. */
void **entries;
/* Current size (in entries) of the hash table */
size_t size;
/* Current number of elements. */
size_t n_elements;
/* Free function for the entries array. This may vary depending on
how early the array was allocated. If it is NULL, then the array
can't be freed. */
void (*free) (void *ptr);
};
inline static struct hashtab *
htab_create (void)
{
struct hashtab *ht = malloc (sizeof (struct hashtab));
if (! ht)
return NULL;
ht->size = 3;
ht->entries = malloc (sizeof (void *) * ht->size);
ht->free = free;
if (! ht->entries)
{
if (ht->free)
ht->free (ht);
return NULL;
}
ht->n_elements = 0;
memset (ht->entries, 0, sizeof (void *) * ht->size);
return ht;
}
/* This is only called from _dl_unmap, so it's safe to call
free(). */
inline static void
htab_delete (struct hashtab *htab)
{
int i;
for (i = htab->size - 1; i >= 0; i--)
if (htab->entries[i])
free (htab->entries[i]);
if (htab->free)
htab->free (htab->entries);
free (htab);
}
/* Similar to htab_find_slot, but without several unwanted side effects:
- Does not call htab->eq_f when it finds an existing entry.
- Does not change the count of elements/searches/collisions in the
hash table.
This function also assumes there are no deleted entries in the table.
HASH is the hash value for the element to be inserted. */
inline static void **
find_empty_slot_for_expand (struct hashtab *htab, int hash)
{
size_t size = htab->size;
unsigned int index = hash % size;
void **slot = htab->entries + index;
int hash2;
if (! *slot)
return slot;
hash2 = 1 + hash % (size - 2);
for (;;)
{
index += hash2;
if (index >= size)
index -= size;
slot = htab->entries + index;
if (! *slot)
return slot;
}
}
/* The following function changes size of memory allocated for the
entries and repeatedly inserts the table elements. The occupancy
of the table after the call will be about 50%. Naturally the hash
table must already exist. Remember also that the place of the
table entries is changed. If memory allocation failures are allowed,
this function will return zero, indicating that the table could not be
expanded. If all goes well, it will return a non-zero value. */
inline static int
htab_expand (struct hashtab *htab, int (*hash_fn) (void *))
{
void **oentries;
void **olimit;
void **p;
void **nentries;
size_t nsize;
oentries = htab->entries;
olimit = oentries + htab->size;
/* Resize only when table after removal of unused elements is either
too full or too empty. */
if (htab->n_elements * 2 > htab->size)
nsize = higher_prime_number (htab->n_elements * 2);
else
nsize = htab->size;
nentries = malloc (sizeof (void *) * nsize);
memset (nentries, 0, sizeof (void *) * nsize);
if (nentries == NULL)
return 0;
htab->entries = nentries;
htab->size = nsize;
p = oentries;
do
{
if (*p)
*find_empty_slot_for_expand (htab, hash_fn (*p))
= *p;
p++;
}
while (p < olimit);
/* Without recording the free corresponding to the malloc used to
allocate the table, we couldn't tell whether this was allocated
by the malloc() built into ld.so or the one in the main
executable or libc. Calling free() for something that was
allocated by the early malloc(), rather than the final run-time
malloc() could do Very Bad Things (TM). We will waste memory
allocated early as long as there's no corresponding free(), but
this isn't so much memory as to be significant. */
if (htab->free)
htab->free (oentries);
/* Use the free() corresponding to the malloc() above to free this
up. */
htab->free = free;
return 1;
}
/* This function searches for a hash table slot containing an entry
equal to the given element. To delete an entry, call this with
INSERT = 0, then call htab_clear_slot on the slot returned (possibly
after doing some checks). To insert an entry, call this with
INSERT = 1, then write the value you want into the returned slot.
When inserting an entry, NULL may be returned if memory allocation
fails. */
inline static void **
htab_find_slot (struct hashtab *htab, void *ptr, int insert,
int (*hash_fn)(void *), int (*eq_fn)(void *, void *))
{
unsigned int index;
int hash, hash2;
size_t size;
void **entry;
if (htab->size * 3 <= htab->n_elements * 4
&& htab_expand (htab, hash_fn) == 0)
return NULL;
hash = hash_fn (ptr);
size = htab->size;
index = hash % size;
entry = &htab->entries[index];
if (!*entry)
goto empty_entry;
else if (eq_fn (*entry, ptr))
return entry;
hash2 = 1 + hash % (size - 2);
for (;;)
{
index += hash2;
if (index >= size)
index -= size;
entry = &htab->entries[index];
if (!*entry)
goto empty_entry;
else if (eq_fn (*entry, ptr))
return entry;
}
empty_entry:
if (!insert)
return NULL;
htab->n_elements++;
return entry;
}
#endif /* INLINE_HASHTAB_H */

10
sysdeps/i386/Makefile
View File

@ -65,3 +65,13 @@ endif
ifneq (,$(filter -mno-tls-direct-seg-refs,$(CFLAGS)))
defines += -DNO_TLS_DIRECT_SEG_REFS
endif
ifeq ($(subdir),elf)
sysdep-dl-routines += tlsdesc dl-tlsdesc
sysdep_routines += tlsdesc dl-tlsdesc
sysdep-rtld-routines += tlsdesc dl-tlsdesc
endif
ifeq ($(subdir),csu)
gen-as-const-headers += tlsdesc.sym
endif

1
sysdeps/i386/bits/linkmap.h
View File

@ -2,4 +2,5 @@ struct link_map_machine
{
Elf32_Addr plt; /* Address of .plt + 0x16 */
Elf32_Addr gotplt; /* Address of .got + 0x0c */
void *tlsdesc_table; /* Address of TLS descriptor hash table. */
};

28
sysdeps/i386/dl-lookupcfg.h Normal file
View File

@ -0,0 +1,28 @@
/* Configuration of lookup functions.
Copyright (C) 2005, 2008 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. */
#define DL_UNMAP_IS_SPECIAL
#include_next <dl-lookupcfg.h>
struct link_map;
extern void internal_function _dl_unmap (struct link_map *map);
#define DL_UNMAP(map) _dl_unmap (map)

131
sysdeps/i386/dl-machine.h
View File

@ -25,6 +25,7 @@
#include <sys/param.h>
#include <sysdep.h>
#include <tls.h>
#include <dl-tlsdesc.h>
/* Return nonzero iff ELF header is compatible with the running host. */
static inline int __attribute__ ((unused))
@ -246,7 +247,7 @@ _dl_start_user:\n\
# define elf_machine_type_class(type) \
((((type) == R_386_JMP_SLOT || (type) == R_386_TLS_DTPMOD32 \
|| (type) == R_386_TLS_DTPOFF32 || (type) == R_386_TLS_TPOFF32 \
|| (type) == R_386_TLS_TPOFF) \
|| (type) == R_386_TLS_TPOFF || (type) == R_386_TLS_DESC) \
* ELF_RTYPE_CLASS_PLT) \
| (((type) == R_386_COPY) * ELF_RTYPE_CLASS_COPY))
#else
@ -373,6 +374,38 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc,
*reloc_addr = sym->st_value;
# endif
break;
case R_386_TLS_DESC:
{
struct tlsdesc volatile *td =
(struct tlsdesc volatile *)reloc_addr;
# ifndef RTLD_BOOTSTRAP
if (! sym)
td->entry = _dl_tlsdesc_undefweak;
else
# endif
{
# ifndef RTLD_BOOTSTRAP
# ifndef SHARED
CHECK_STATIC_TLS (map, sym_map);
# else
if (!TRY_STATIC_TLS (map, sym_map))
{
td->arg = _dl_make_tlsdesc_dynamic
(sym_map, sym->st_value + (ElfW(Word))td->arg);
td->entry = _dl_tlsdesc_dynamic;
}
else
# endif
# endif
{
td->arg = (void*)(sym->st_value - sym_map->l_tls_offset
+ (ElfW(Word))td->arg);
td->entry = _dl_tlsdesc_return;
}
}
break;
}
case R_386_TLS_TPOFF32:
/* The offset is positive, backward from the thread pointer. */
# ifdef RTLD_BOOTSTRAP
@ -485,6 +518,41 @@ elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
Therefore the offset is already correct. */
*reloc_addr = (sym == NULL ? 0 : sym->st_value) + reloc->r_addend;
break;
case R_386_TLS_DESC:
{
struct tlsdesc volatile *td =
(struct tlsdesc volatile *)reloc_addr;
# ifndef RTLD_BOOTSTRAP
if (!sym)
{
td->arg = (void*)reloc->r_addend;
td->entry = _dl_tlsdesc_undefweak;
}
else
# endif
{
# ifndef RTLD_BOOTSTRAP
# ifndef SHARED
CHECK_STATIC_TLS (map, sym_map);
# else
if (!TRY_STATIC_TLS (map, sym_map))
{
td->arg = _dl_make_tlsdesc_dynamic
(sym_map, sym->st_value + reloc->r_addend);
td->entry = _dl_tlsdesc_dynamic;
}
else
# endif
# endif
{
td->arg = (void*)(sym->st_value - sym_map->l_tls_offset
+ reloc->r_addend);
td->entry = _dl_tlsdesc_return;
}
}
}
break;
case R_386_TLS_TPOFF32:
/* The offset is positive, backward from the thread pointer. */
/* We know the offset of object the symbol is contained in.
@ -578,6 +646,53 @@ elf_machine_lazy_rel (struct link_map *map,
*reloc_addr = (map->l_mach.plt
+ (((Elf32_Addr) reloc_addr) - map->l_mach.gotplt) * 4);
}
else if (__builtin_expect (r_type == R_386_TLS_DESC, 1))
{
struct tlsdesc volatile * __attribute__((__unused__)) td =
(struct tlsdesc volatile *)reloc_addr;
/* Handle relocations that reference the local *ABS* in a simple
way, so as to preserve a potential addend. */
if (ELF32_R_SYM (reloc->r_info) == 0)
td->entry = _dl_tlsdesc_resolve_abs_plus_addend;
/* Given a known-zero addend, we can store a pointer to the
reloc in the arg position. */
else if (td->arg == 0)
{
td->arg = (void*)reloc;
td->entry = _dl_tlsdesc_resolve_rel;
}
else
{
/* We could handle non-*ABS* relocations with non-zero addends
by allocating dynamically an arg to hold a pointer to the
reloc, but that sounds pointless. */
const Elf32_Rel *const r = reloc;
/* The code below was borrowed from elf_dynamic_do_rel(). */
const ElfW(Sym) *const symtab =
(const void *) D_PTR (map, l_info[DT_SYMTAB]);
#ifdef RTLD_BOOTSTRAP
/* The dynamic linker always uses versioning. */
assert (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL);
#else
if (map->l_info[VERSYMIDX (DT_VERSYM)])
#endif
{
const ElfW(Half) *const version =
(const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
ElfW(Half) ndx = version[ELFW(R_SYM) (r->r_info)] & 0x7fff;
elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)],
&map->l_versions[ndx],
(void *) (l_addr + r->r_offset));
}
#ifndef RTLD_BOOTSTRAP
else
elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)], NULL,
(void *) (l_addr + r->r_offset));
#endif
}
}
else
_dl_reloc_bad_type (map, r_type, 1);
}
@ -589,6 +704,20 @@ __attribute__ ((always_inline))
elf_machine_lazy_rela (struct link_map *map,
Elf32_Addr l_addr, const Elf32_Rela *reloc)
{
Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
if (__builtin_expect (r_type == R_386_JMP_SLOT, 1))
;
else if (__builtin_expect (r_type == R_386_TLS_DESC, 1))
{
struct tlsdesc volatile * __attribute__((__unused__)) td =
(struct tlsdesc volatile *)reloc_addr;
td->arg = (void*)reloc;
td->entry = _dl_tlsdesc_resolve_rela;
}
else
_dl_reloc_bad_type (map, r_type, 1);
}
#endif /* !RTLD_BOOTSTRAP */

2
sysdeps/i386/dl-tls.h
View File

@ -19,7 +19,7 @@
/* Type used for the representation of TLS information in the GOT. */
typedef struct
typedef struct dl_tls_index
{
unsigned long int ti_module;
unsigned long int ti_offset;

290
sysdeps/i386/dl-tlsdesc.S Normal file
View File

@ -0,0 +1,290 @@
/* Thread-local storage handling in the ELF dynamic linker. i386 version.
Copyright (C) 2004, 2005, 2008 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. */
#include <sysdep.h>
#include <tls.h>
#include "tlsdesc.h"
.text
/* This function is used to compute the TP offset for symbols in
Static TLS, i.e., whose TP offset is the same for all
threads.
The incoming %eax points to the TLS descriptor, such that
0(%eax) points to _dl_tlsdesc_return itself, and 4(%eax) holds
the TP offset of the symbol corresponding to the object
denoted by the argument. */
.hidden _dl_tlsdesc_return
.global _dl_tlsdesc_return
.type _dl_tlsdesc_return,@function
cfi_startproc
.align 16
_dl_tlsdesc_return:
movl 4(%eax), %eax
ret
cfi_endproc
.size _dl_tlsdesc_return, .-_dl_tlsdesc_return
/* This function is used for undefined weak TLS symbols, for
which the base address (i.e., disregarding any addend) should
resolve to NULL.
%eax points to the TLS descriptor, such that 0(%eax) points to
_dl_tlsdesc_undefweak itself, and 4(%eax) holds the addend.
We return the addend minus the TP, such that, when the caller
adds TP, it gets the addend back. If that's zero, as usual,
that's most likely a NULL pointer. */
.hidden _dl_tlsdesc_undefweak
.global _dl_tlsdesc_undefweak
.type _dl_tlsdesc_undefweak,@function
cfi_startproc
.align 16
_dl_tlsdesc_undefweak:
movl 4(%eax), %eax
subl %gs:0, %eax
ret
cfi_endproc
.size _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
#ifdef SHARED
.hidden _dl_tlsdesc_dynamic
.global _dl_tlsdesc_dynamic
.type _dl_tlsdesc_dynamic,@function
/* This function is used for symbols that need dynamic TLS.
%eax points to the TLS descriptor, such that 0(%eax) points to
_dl_tlsdesc_dynamic itself, and 4(%eax) points to a struct
tlsdesc_dynamic_arg object. It must return in %eax the offset
between the thread pointer and the object denoted by the
argument, without clobbering any registers.
The assembly code that follows is a rendition of the following
C code, hand-optimized a little bit.
ptrdiff_t
__attribute__ ((__regparm__ (1)))
_dl_tlsdesc_dynamic (struct tlsdesc *tdp)
{
struct tlsdesc_dynamic_arg *td = tdp->arg;
dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
if (__builtin_expect (td->gen_count <= dtv[0].counter
&& (dtv[td->tlsinfo.ti_module].pointer.val
!= TLS_DTV_UNALLOCATED),
1))
return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
- __thread_pointer;
return ___tls_get_addr (&td->tlsinfo) - __thread_pointer;
}
*/
cfi_startproc
.align 16
_dl_tlsdesc_dynamic:
/* Like all TLS resolvers, preserve call-clobbered registers.
We need two scratch regs anyway. */
subl $28, %esp
cfi_adjust_cfa_offset (28)
movl %ecx, 20(%esp)
movl %edx, 24(%esp)
movl TLSDESC_ARG(%eax), %eax
movl %gs:DTV_OFFSET, %edx
movl TLSDESC_GEN_COUNT(%eax), %ecx
cmpl (%edx), %ecx
ja .Lslow
movl TLSDESC_MODID(%eax), %ecx
movl (%edx,%ecx,8), %edx
cmpl $-1, %edx
je .Lslow
movl TLSDESC_MODOFF(%eax), %eax
addl %edx, %eax
.Lret:
movl 20(%esp), %ecx
subl %gs:0, %eax
movl 24(%esp), %edx
addl $28, %esp
cfi_adjust_cfa_offset (-28)
ret
.p2align 4,,7
.Lslow:
cfi_adjust_cfa_offset (28)
movl %ebx, 16(%esp)
call __i686.get_pc_thunk.bx
addl $_GLOBAL_OFFSET_TABLE_, %ebx
call ___tls_get_addr@PLT
movl 16(%esp), %ebx
jmp .Lret
cfi_endproc
.size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
#endif /* SHARED */
/* This function is a wrapper for a lazy resolver for TLS_DESC
REL relocations that reference the *ABS* segment in their own
link maps. %ebx points to the caller's GOT. %eax points to a
TLS descriptor, such that 0(%eax) holds the address of the
resolver wrapper itself (unless some other thread beat us to
it) and 4(%eax) holds the addend in the relocation.
When the actual resolver returns, it will have adjusted the
TLS descriptor such that we can tail-call it for it to return
the TP offset of the symbol. */
.hidden _dl_tlsdesc_resolve_abs_plus_addend
.global _dl_tlsdesc_resolve_abs_plus_addend
.type _dl_tlsdesc_resolve_abs_plus_addend,@function
cfi_startproc
.align 16
_dl_tlsdesc_resolve_abs_plus_addend:
0:
pushl %eax
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %edx
cfi_adjust_cfa_offset (4)
movl $1f - 0b, %ecx
movl 4(%ebx), %edx
call _dl_tlsdesc_resolve_abs_plus_addend_fixup
1:
popl %edx
cfi_adjust_cfa_offset (-4)
popl %ecx
cfi_adjust_cfa_offset (-4)
popl %eax
cfi_adjust_cfa_offset (-4)
jmp *(%eax)
cfi_endproc
.size _dl_tlsdesc_resolve_abs_plus_addend, .-_dl_tlsdesc_resolve_abs_plus_addend
/* This function is a wrapper for a lazy resolver for TLS_DESC
REL relocations that had zero addends. %ebx points to the
caller's GOT. %eax points to a TLS descriptor, such that
0(%eax) holds the address of the resolver wrapper itself
(unless some other thread beat us to it) and 4(%eax) holds a
pointer to the relocation.
When the actual resolver returns, it will have adjusted the
TLS descriptor such that we can tail-call it for it to return
the TP offset of the symbol. */
.hidden _dl_tlsdesc_resolve_rel
.global _dl_tlsdesc_resolve_rel
.type _dl_tlsdesc_resolve_rel,@function
cfi_startproc
.align 16
_dl_tlsdesc_resolve_rel:
0:
pushl %eax
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %edx
cfi_adjust_cfa_offset (4)
movl $1f - 0b, %ecx
movl 4(%ebx), %edx
call _dl_tlsdesc_resolve_rel_fixup
1:
popl %edx
cfi_adjust_cfa_offset (-4)
popl %ecx
cfi_adjust_cfa_offset (-4)
popl %eax
cfi_adjust_cfa_offset (-4)
jmp *(%eax)
cfi_endproc
.size _dl_tlsdesc_resolve_rel, .-_dl_tlsdesc_resolve_rel
/* This function is a wrapper for a lazy resolver for TLS_DESC
RELA relocations. %ebx points to the caller's GOT. %eax
points to a TLS descriptor, such that 0(%eax) holds the
address of the resolver wrapper itself (unless some other
thread beat us to it) and 4(%eax) holds a pointer to the
relocation.
When the actual resolver returns, it will have adjusted the
TLS descriptor such that we can tail-call it for it to return
the TP offset of the symbol. */
.hidden _dl_tlsdesc_resolve_rela
.global _dl_tlsdesc_resolve_rela
.type _dl_tlsdesc_resolve_rela,@function
cfi_startproc
.align 16
_dl_tlsdesc_resolve_rela:
0:
pushl %eax
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %edx
cfi_adjust_cfa_offset (4)
movl $1f - 0b, %ecx
movl 4(%ebx), %edx
call _dl_tlsdesc_resolve_rela_fixup
1:
popl %edx
cfi_adjust_cfa_offset (-4)
popl %ecx
cfi_adjust_cfa_offset (-4)
popl %eax
cfi_adjust_cfa_offset (-4)
jmp *(%eax)
cfi_endproc
.size _dl_tlsdesc_resolve_rela, .-_dl_tlsdesc_resolve_rela
/* This function is a placeholder for lazy resolving of TLS
relocations. Once some thread starts resolving a TLS
relocation, it sets up the TLS descriptor to use this
resolver, such that other threads that would attempt to
resolve it concurrently may skip the call to the original lazy
resolver and go straight to a condition wait.
When the actual resolver returns, it will have adjusted the
TLS descriptor such that we can tail-call it for it to return
the TP offset of the symbol. */
.hidden _dl_tlsdesc_resolve_hold
.global _dl_tlsdesc_resolve_hold
.type _dl_tlsdesc_resolve_hold,@function
cfi_startproc
.align 16
_dl_tlsdesc_resolve_hold:
0:
pushl %eax
cfi_adjust_cfa_offset (4)
pushl %ecx
cfi_adjust_cfa_offset (4)
pushl %edx
cfi_adjust_cfa_offset (4)
movl $1f - 0b, %ecx
movl 4(%ebx), %edx
call _dl_tlsdesc_resolve_hold_fixup
1:
popl %edx
cfi_adjust_cfa_offset (-4)
popl %ecx
cfi_adjust_cfa_offset (-4)
popl %eax
cfi_adjust_cfa_offset (-4)
jmp *(%eax)
cfi_endproc
.size _dl_tlsdesc_resolve_hold, .-_dl_tlsdesc_resolve_hold

61
sysdeps/i386/dl-tlsdesc.h Normal file
View File

@ -0,0 +1,61 @@
/* Thread-local storage descriptor handling in the ELF dynamic linker.
i386 version.
Copyright (C) 2005, 2008 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 _I386_DL_TLSDESC_H
# define _I386_DL_TLSDESC_H 1
/* Type used to represent a TLS descriptor in the GOT. */
struct tlsdesc
{
ptrdiff_t __attribute__ ((regparm (1))) (*entry) (struct tlsdesc *);
void *arg;
};
typedef struct dl_tls_index
{
unsigned long int ti_module;
unsigned long int ti_offset;
} tls_index;
/* Type used as the argument in a TLS descriptor for a symbol that
needs dynamic TLS offsets. */
struct tlsdesc_dynamic_arg
{
tls_index tlsinfo;
size_t gen_count;
};
extern ptrdiff_t attribute_hidden __attribute__ ((regparm (1)))
_dl_tlsdesc_return (struct tlsdesc *),
_dl_tlsdesc_undefweak (struct tlsdesc *),
_dl_tlsdesc_resolve_abs_plus_addend (struct tlsdesc *),
_dl_tlsdesc_resolve_rel (struct tlsdesc *),
_dl_tlsdesc_resolve_rela (struct tlsdesc *),
_dl_tlsdesc_resolve_hold (struct tlsdesc *);
# ifdef SHARED
extern void *internal_function _dl_make_tlsdesc_dynamic (struct link_map *map,
size_t ti_offset);
extern ptrdiff_t attribute_hidden __attribute__ ((regparm (1)))
_dl_tlsdesc_dynamic (struct tlsdesc *);
# endif
#endif

269
sysdeps/i386/tlsdesc.c Normal file
View File

@ -0,0 +1,269 @@
/* Manage TLS descriptors. i386 version.
Copyright (C) 2005, 2008 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. */
#include <link.h>
#include <ldsodefs.h>
#include <elf/dynamic-link.h>
#include <tls.h>
#include <dl-tlsdesc.h>
#include <tlsdeschtab.h>
/* The following 4 functions take an entry_check_offset argument.
It's computed by the caller as an offset between its entry point
and the call site, such that by adding the built-in return address
that is implicitly passed to the function with this offset, we can
easily obtain the caller's entry point to compare with the entry
point given in the TLS descriptor. If it's changed, we want to
return immediately. */
/* This function is used to lazily resolve TLS_DESC REL relocations
that reference the *ABS* segment in their own link maps. The
argument is the addend originally stored there. */
void
__attribute__ ((regparm (3))) attribute_hidden
_dl_tlsdesc_resolve_abs_plus_addend_fixup (struct tlsdesc volatile *td,
struct link_map *l,
ptrdiff_t entry_check_offset)
{
ptrdiff_t addend = (ptrdiff_t) td->arg;
if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
- entry_check_offset))
return;
#ifndef SHARED
CHECK_STATIC_TLS (l, l);
#else
if (!TRY_STATIC_TLS (l, l))
{
td->arg = _dl_make_tlsdesc_dynamic (l, addend);
td->entry = _dl_tlsdesc_dynamic;
}
else
#endif
{
td->arg = (void*) (addend - l->l_tls_offset);
td->entry = _dl_tlsdesc_return;
}
_dl_tlsdesc_wake_up_held_fixups ();
}
/* This function is used to lazily resolve TLS_DESC REL relocations
that originally had zero addends. The argument location, that
originally held the addend, is used to hold a pointer to the
relocation, but it has to be restored before we call the function
that applies relocations. */
void
__attribute__ ((regparm (3))) attribute_hidden
_dl_tlsdesc_resolve_rel_fixup (struct tlsdesc volatile *td,
struct link_map *l,
ptrdiff_t entry_check_offset)
{
const ElfW(Rel) *reloc = td->arg;
if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
- entry_check_offset))
return;
/* The code below was borrowed from _dl_fixup(),
except for checking for STB_LOCAL. */
const ElfW(Sym) *const symtab
= (const void *) D_PTR (l, l_info[DT_SYMTAB]);
const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
lookup_t result;
/* Look up the target symbol. If the normal lookup rules are not
used don't look in the global scope. */
if (ELFW(ST_BIND) (sym->st_info) != STB_LOCAL
&& __builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
{
const struct r_found_version *version = NULL;
if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
{
const ElfW(Half) *vernum =
(const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
version = &l->l_versions[ndx];
if (version->hash == 0)
version = NULL;
}
result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym,
l->l_scope, version, ELF_RTYPE_CLASS_PLT,
DL_LOOKUP_ADD_DEPENDENCY, NULL);
}
else
{
/* We already found the symbol. The module (and therefore its load
address) is also known. */
result = l;
}
if (!sym)
{
td->arg = 0;
td->entry = _dl_tlsdesc_undefweak;
}
else
{
# ifndef SHARED
CHECK_STATIC_TLS (l, result);
# else
if (!TRY_STATIC_TLS (l, result))
{
td->arg = _dl_make_tlsdesc_dynamic (result, sym->st_value);
td->entry = _dl_tlsdesc_dynamic;
}
else
# endif
{
td->arg = (void*)(sym->st_value - result->l_tls_offset);
td->entry = _dl_tlsdesc_return;
}
}
_dl_tlsdesc_wake_up_held_fixups ();
}
/* This function is used to lazily resolve TLS_DESC RELA relocations.
The argument location is used to hold a pointer to the relocation. */
void
__attribute__ ((regparm (3))) attribute_hidden
_dl_tlsdesc_resolve_rela_fixup (struct tlsdesc volatile *td,
struct link_map *l,
ptrdiff_t entry_check_offset)
{
const ElfW(Rela) *reloc = td->arg;
if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
- entry_check_offset))
return;
/* The code below was borrowed from _dl_fixup(),
except for checking for STB_LOCAL. */
const ElfW(Sym) *const symtab
= (const void *) D_PTR (l, l_info[DT_SYMTAB]);
const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
lookup_t result;
/* Look up the target symbol. If the normal lookup rules are not
used don't look in the global scope. */
if (ELFW(ST_BIND) (sym->st_info) != STB_LOCAL
&& __builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
{
const struct r_found_version *version = NULL;
if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
{
const ElfW(Half) *vernum =
(const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
version = &l->l_versions[ndx];
if (version->hash == 0)
version = NULL;
}
result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym,
l->l_scope, version, ELF_RTYPE_CLASS_PLT,
DL_LOOKUP_ADD_DEPENDENCY, NULL);
}
else
{
/* We already found the symbol. The module (and therefore its load
address) is also known. */
result = l;
}
if (!sym)
{
td->arg = (void*).reloc->r_addend;
td->entry = _dl_tlsdesc_undefweak;
}
else
{
# ifndef SHARED
CHECK_STATIC_TLS (l, result);
# else
if (!TRY_STATIC_TLS (l, result))
{
td->arg = _dl_make_tlsdesc_dynamic (result, sym->st_value
+ reloc->r_addend);
td->entry = _dl_tlsdesc_dynamic;
}
else
# endif
{
td->arg = (void*).(sym->st_value - result->l_tls_offset
. + reloc->r_addend);
td->entry = _dl_tlsdesc_return;
}
}
_dl_tlsdesc_wake_up_held_fixups ();
}
/* This function is used to avoid busy waiting for other threads to
complete the lazy relocation. Once another thread wins the race to
relocate a TLS descriptor, it sets the descriptor up such that this
function is called to wait until the resolver releases the
lock. */
void
__attribute__ ((regparm (3))) attribute_hidden
_dl_tlsdesc_resolve_hold_fixup (struct tlsdesc volatile *td,
struct link_map *l __attribute__((__unused__)),
ptrdiff_t entry_check_offset)
{
/* Maybe we're lucky and can return early. */
if (__builtin_return_address (0) - entry_check_offset != td->entry)
return;
/* Locking here will stop execution until the running resolver runs
_dl_tlsdesc_wake_up_held_fixups(), releasing the lock.
FIXME: We'd be better off waiting on a condition variable, such
that we didn't have to hold the lock throughout the relocation
processing. */
__rtld_lock_lock_recursive (GL(dl_load_lock));
__rtld_lock_unlock_recursive (GL(dl_load_lock));
}
/* Unmap the dynamic object, but also release its TLS descriptor table
if there is one. */
void
internal_function
_dl_unmap (struct link_map *map)
{
__munmap ((void *) (map)->l_map_start,
(map)->l_map_end - (map)->l_map_start);
#if SHARED
if (map->l_mach.tlsdesc_table)
htab_delete (map->l_mach.tlsdesc_table);
#endif
}

17
sysdeps/i386/tlsdesc.sym Normal file
View File

@ -0,0 +1,17 @@
#include <stddef.h>
#include <sysdep.h>
#include <tls.h>
#include <link.h>
#include <dl-tlsdesc.h>
--
-- Abuse tls.h macros to derive offsets relative to the thread register.
DTV_OFFSET offsetof(struct pthread, header.dtv)
TLSDESC_ARG offsetof(struct tlsdesc, arg)
TLSDESC_GEN_COUNT offsetof(struct tlsdesc_dynamic_arg, gen_count)
TLSDESC_MODID offsetof(struct tlsdesc_dynamic_arg, tlsinfo.ti_module)
TLSDESC_MODOFF offsetof(struct tlsdesc_dynamic_arg, tlsinfo.ti_offset)

10
sysdeps/x86_64/Makefile
View File

@ -13,3 +13,13 @@ endif
ifeq ($(subdir),string)
sysdep_routines += cacheinfo
endif
ifeq ($(subdir),elf)
sysdep-dl-routines += tlsdesc dl-tlsdesc
sysdep_routines += tlsdesc dl-tlsdesc
sysdep-rtld-routines += tlsdesc dl-tlsdesc
endif
ifeq ($(subdir),csu)
gen-as-const-headers += tlsdesc.sym
endif

2
sysdeps/x86_64/bits/linkmap.h
View File

@ -3,6 +3,7 @@ struct link_map_machine
{
Elf64_Addr plt; /* Address of .plt + 0x16 */
Elf64_Addr gotplt; /* Address of .got + 0x18 */
void *tlsdesc_table; /* Address of TLS descriptor hash table. */
};
#else
@ -10,5 +11,6 @@ struct link_map_machine
{
Elf32_Addr plt; /* Address of .plt + 0x16 */
Elf32_Addr gotplt; /* Address of .got + 0x0c */
void *tlsdesc_table; /* Address of TLS descriptor hash table. */
};
#endif

28
sysdeps/x86_64/dl-lookupcfg.h Normal file
View File

@ -0,0 +1,28 @@
/* Configuration of lookup functions.
Copyright (C) 2005, 2008 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. */
#define DL_UNMAP_IS_SPECIAL
#include_next <dl-lookupcfg.h>
struct link_map;
extern void internal_function _dl_unmap (struct link_map *map);
#define DL_UNMAP(map) _dl_unmap (map)

53
sysdeps/x86_64/dl-machine.h
View File

@ -26,6 +26,7 @@
#include <sys/param.h>
#include <sysdep.h>
#include <tls.h>
#include <dl-tlsdesc.h>
/* Return nonzero iff ELF header is compatible with the running host. */
static inline int __attribute__ ((unused))
@ -131,6 +132,10 @@ elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
got[2] = (Elf64_Addr) &_dl_runtime_resolve;
}
if (l->l_info[ADDRIDX (DT_TLSDESC_GOT)] && lazy)
*(Elf64_Addr*)(D_PTR (l, l_info[ADDRIDX (DT_TLSDESC_GOT)]) + l->l_addr)
= (Elf64_Addr) &_dl_tlsdesc_resolve_rela;
return lazy;
}
@ -194,7 +199,9 @@ _dl_start_user:\n\
# define elf_machine_type_class(type) \
((((type) == R_X86_64_JUMP_SLOT \
|| (type) == R_X86_64_DTPMOD64 \
|| (type) == R_X86_64_DTPOFF64 || (type) == R_X86_64_TPOFF64) \
|| (type) == R_X86_64_DTPOFF64 \
|| (type) == R_X86_64_TPOFF64 \
|| (type) == R_X86_64_TLSDESC) \
* ELF_RTYPE_CLASS_PLT) \
| (((type) == R_X86_64_COPY) * ELF_RTYPE_CLASS_COPY))
#else
@ -323,6 +330,41 @@ elf_machine_rela (struct link_map *map, const Elf64_Rela *reloc,
*reloc_addr = sym->st_value + reloc->r_addend;
# endif
break;
case R_X86_64_TLSDESC:
{
struct tlsdesc volatile *td =
(struct tlsdesc volatile *)reloc_addr;
# ifndef RTLD_BOOTSTRAP
if (! sym)
{
td->arg = (void*)reloc->r_addend;
td->entry = _dl_tlsdesc_undefweak;
}
else
# endif
{
# ifndef RTLD_BOOTSTRAP
# ifndef SHARED
CHECK_STATIC_TLS (map, sym_map);
# else
if (!TRY_STATIC_TLS (map, sym_map))
{
td->arg = _dl_make_tlsdesc_dynamic
(sym_map, sym->st_value + reloc->r_addend);
td->entry = _dl_tlsdesc_dynamic;
}
else
# endif
# endif
{
td->arg = (void*)(sym->st_value - sym_map->l_tls_offset
+ reloc->r_addend);
td->entry = _dl_tlsdesc_return;
}
}
break;
}
case R_X86_64_TPOFF64:
/* The offset is negative, forward from the thread pointer. */
# ifndef RTLD_BOOTSTRAP
@ -435,6 +477,15 @@ elf_machine_lazy_rel (struct link_map *map,
map->l_mach.plt
+ (((Elf64_Addr) reloc_addr) - map->l_mach.gotplt) * 2;
}
else if (__builtin_expect (r_type == R_X86_64_TLSDESC, 1))
{
struct tlsdesc volatile * __attribute__((__unused__)) td =
(struct tlsdesc volatile *)reloc_addr;
td->arg = (void*)reloc;
td->entry = (void*)(D_PTR (map, l_info[ADDRIDX (DT_TLSDESC_PLT)])
+ map->l_addr);
}
else
_dl_reloc_bad_type (map, r_type, 1);
}

4
sysdeps/x86_64/dl-tls.h
View File

@ -1,5 +1,5 @@
/* Thread-local storage handling in the ELF dynamic linker. x86-64 version.
Copyright (C) 2002 Free Software Foundation, Inc.
Copyright (C) 2002, 2005 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
@ -19,7 +19,7 @@
/* Type used for the representation of TLS information in the GOT. */
typedef struct
typedef struct dl_tls_index
{
unsigned long int ti_module;
unsigned long int ti_offset;

245
sysdeps/x86_64/dl-tlsdesc.S Normal file
View File

@ -0,0 +1,245 @@
/* Thread-local storage handling in the ELF dynamic linker. x86_64 version.
Copyright (C) 2004, 2005, 2008 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. */
#include <sysdep.h>
#include <tls.h>
#include "tlsdesc.h"
.text
/* This function is used to compute the TP offset for symbols in
Static TLS, i.e., whose TP offset is the same for all
threads.
The incoming %rax points to the TLS descriptor, such that
0(%rax) points to _dl_tlsdesc_return itself, and 8(%rax) holds
the TP offset of the symbol corresponding to the object
denoted by the argument. */
.hidden _dl_tlsdesc_return
.global _dl_tlsdesc_return
.type _dl_tlsdesc_return,@function
cfi_startproc
.align 16
_dl_tlsdesc_return:
movq 8(%rax), %rax
ret
cfi_endproc
.size _dl_tlsdesc_return, .-_dl_tlsdesc_return
/* This function is used for undefined weak TLS symbols, for
which the base address (i.e., disregarding any addend) should
resolve to NULL.
%rax points to the TLS descriptor, such that 0(%rax) points to
_dl_tlsdesc_undefweak itself, and 8(%rax) holds the addend.
We return the addend minus the TP, such that, when the caller
adds TP, it gets the addend back. If that's zero, as usual,
that's most likely a NULL pointer. */
.hidden _dl_tlsdesc_undefweak
.global _dl_tlsdesc_undefweak
.type _dl_tlsdesc_undefweak,@function
cfi_startproc
.align 16
_dl_tlsdesc_undefweak:
movq 8(%rax), %rax
subq %fs:0, %rax
ret
cfi_endproc
.size _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak
#ifdef SHARED
.hidden _dl_tlsdesc_dynamic
.global _dl_tlsdesc_dynamic
.type _dl_tlsdesc_dynamic,@function
/* %rax points to the TLS descriptor, such that 0(%rax) points to
_dl_tlsdesc_dynamic itself, and 8(%rax) points to a struct
tlsdesc_dynamic_arg object. It must return in %rax the offset
between the thread pointer and the object denoted by the
argument, without clobbering any registers.
The assembly code that follows is a rendition of the following
C code, hand-optimized a little bit.
ptrdiff_t
_dl_tlsdesc_dynamic (register struct tlsdesc *tdp asm ("%rax"))
{
struct tlsdesc_dynamic_arg *td = tdp->arg;
dtv_t *dtv = *(dtv_t **)((char *)__thread_pointer + DTV_OFFSET);
if (__builtin_expect (td->gen_count <= dtv[0].counter
&& (dtv[td->tlsinfo.ti_module].pointer.val
!= TLS_DTV_UNALLOCATED),
1))
return dtv[td->tlsinfo.ti_module].pointer.val + td->tlsinfo.ti_offset
- __thread_pointer;
return __tls_get_addr_internal (&td->tlsinfo) - __thread_pointer;
}
*/
cfi_startproc
.align 16
_dl_tlsdesc_dynamic:
/* Preserve call-clobbered registers that we modify.
We need two scratch regs anyway. */
movq %rsi, -16(%rsp)
movq %fs:DTV_OFFSET, %rsi
movq %rdi, -8(%rsp)
movq TLSDESC_ARG(%rax), %rdi
movq (%rsi), %rax
cmpq %rax, TLSDESC_GEN_COUNT(%rdi)
ja .Lslow
movq TLSDESC_MODID(%rdi), %rax
salq $4, %rax
movq (%rax,%rsi), %rax
cmpq $-1, %rax
je .Lslow
addq TLSDESC_MODOFF(%rdi), %rax
.Lret:
movq -16(%rsp), %rsi
subq %fs:0, %rax
movq -8(%rsp), %rdi
ret
.Lslow:
/* Besides rdi and rsi, saved above, save rdx, rcx, r8, r9,
r10 and r11. Also, align the stack, that's off by 8 bytes. */
subq $72, %rsp
cfi_adjust_cfa_offset (72)
movq %rdx, 8(%rsp)
movq %rcx, 16(%rsp)
movq %r8, 24(%rsp)
movq %r9, 32(%rsp)
movq %r10, 40(%rsp)
movq %r11, 48(%rsp)
/* %rdi already points to the tlsinfo data structure. */
call __tls_get_addr@PLT
movq 8(%rsp), %rdx
movq 16(%rsp), %rcx
movq 24(%rsp), %r8
movq 32(%rsp), %r9
movq 40(%rsp), %r10
movq 48(%rsp), %r11
addq $72, %rsp
cfi_adjust_cfa_offset (-72)
jmp .Lret
cfi_endproc
.size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
#endif /* SHARED */
/* This function is a wrapper for a lazy resolver for TLS_DESC
RELA relocations. The incoming 0(%rsp) points to the caller's
link map, pushed by the dynamic object's internal lazy TLS
resolver front-end before tail-calling us. We need to pop it
ourselves. %rax points to a TLS descriptor, such that 0(%rax)
holds the address of the internal resolver front-end (unless
some other thread beat us to resolving it) and 8(%rax) holds a
pointer to the relocation.
When the actual resolver returns, it will have adjusted the
TLS descriptor such that we can tail-call it for it to return
the TP offset of the symbol. */
.hidden _dl_tlsdesc_resolve_rela
.global _dl_tlsdesc_resolve_rela
.type _dl_tlsdesc_resolve_rela,@function
cfi_startproc
.align 16
/* The PLT entry will have pushed the link_map pointer. */
_dl_tlsdesc_resolve_rela:
cfi_adjust_cfa_offset (8)
/* Save all call-clobbered registers. */
subq $72, %rsp
cfi_adjust_cfa_offset (72)
movq %rax, (%rsp)
movq %rdi, 8(%rsp)
movq %rax, %rdi /* Pass tlsdesc* in %rdi. */
movq %rsi, 16(%rsp)
movq 72(%rsp), %rsi /* Pass link_map* in %rsi. */
movq %r8, 24(%rsp)
movq %r9, 32(%rsp)
movq %r10, 40(%rsp)
movq %r11, 48(%rsp)
movq %rdx, 56(%rsp)
movq %rcx, 64(%rsp)
call _dl_tlsdesc_resolve_rela_fixup
movq (%rsp), %rax
movq 8(%rsp), %rdi
movq 16(%rsp), %rsi
movq 24(%rsp), %r8
movq 32(%rsp), %r9
movq 40(%rsp), %r10
movq 48(%rsp), %r11
movq 56(%rsp), %rdx
movq 64(%rsp), %rcx
addq $80, %rsp
cfi_adjust_cfa_offset (-80)
jmp *(%rax)
cfi_endproc
.size _dl_tlsdesc_resolve_rela, .-_dl_tlsdesc_resolve_rela
/* This function is a placeholder for lazy resolving of TLS
relocations. Once some thread starts resolving a TLS
relocation, it sets up the TLS descriptor to use this
resolver, such that other threads that would attempt to
resolve it concurrently may skip the call to the original lazy
resolver and go straight to a condition wait.
When the actual resolver returns, it will have adjusted the
TLS descriptor such that we can tail-call it for it to return
the TP offset of the symbol. */
.hidden _dl_tlsdesc_resolve_hold
.global _dl_tlsdesc_resolve_hold
.type _dl_tlsdesc_resolve_hold,@function
cfi_startproc
.align 16
_dl_tlsdesc_resolve_hold:
0:
/* Save all call-clobbered registers. */
subq $72, %rsp
cfi_adjust_cfa_offset (72)
movq %rax, (%rsp)
movq %rdi, 8(%rsp)
movq %rax, %rdi /* Pass tlsdesc* in %rdi. */
movq %rsi, 16(%rsp)
/* Pass _dl_tlsdesc_resolve_hold's address in %rsi. */
leaq . - _dl_tlsdesc_resolve_hold(%rip), %rsi
movq %r8, 24(%rsp)
movq %r9, 32(%rsp)
movq %r10, 40(%rsp)
movq %r11, 48(%rsp)
movq %rdx, 56(%rsp)
movq %rcx, 64(%rsp)
call _dl_tlsdesc_resolve_hold_fixup
1:
movq (%rsp), %rax
movq 8(%rsp), %rdi
movq 16(%rsp), %rsi
movq 24(%rsp), %r8
movq 32(%rsp), %r9
movq 40(%rsp), %r10
movq 48(%rsp), %r11
movq 56(%rsp), %rdx
movq 64(%rsp), %rcx
addq $72, %rsp
cfi_adjust_cfa_offset (-72)
jmp *(%eax)
cfi_endproc
.size _dl_tlsdesc_resolve_hold, .-_dl_tlsdesc_resolve_hold

64
sysdeps/x86_64/dl-tlsdesc.h Normal file
View File

@ -0,0 +1,64 @@
/* Thread-local storage descriptor handling in the ELF dynamic linker.
x86_64 version.
Copyright (C) 2005, 2008 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 _X86_64_DL_TLSDESC_H
# define _X86_64_DL_TLSDESC_H 1
/* Use this to access DT_TLSDESC_PLT and DT_TLSDESC_GOT. */
#ifndef ADDRIDX
# define ADDRIDX(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM \
+ DT_EXTRANUM + DT_VALNUM + DT_ADDRTAGIDX (tag))
#endif
/* Type used to represent a TLS descriptor in the GOT. */
struct tlsdesc
{
ptrdiff_t (*entry)(struct tlsdesc *on_rax);
void *arg;
};
typedef struct dl_tls_index
{
unsigned long int ti_module;
unsigned long int ti_offset;
} tls_index;
/* Type used as the argument in a TLS descriptor for a symbol that
needs dynamic TLS offsets. */
struct tlsdesc_dynamic_arg
{
tls_index tlsinfo;
size_t gen_count;
};
extern ptrdiff_t attribute_hidden
_dl_tlsdesc_return(struct tlsdesc *on_rax),
_dl_tlsdesc_undefweak(struct tlsdesc *on_rax),
_dl_tlsdesc_resolve_rela(struct tlsdesc *on_rax),
_dl_tlsdesc_resolve_hold(struct tlsdesc *on_rax);
# ifdef SHARED
extern void *internal_function _dl_make_tlsdesc_dynamic (struct link_map *map,
size_t ti_offset);
extern ptrdiff_t attribute_hidden _dl_tlsdesc_dynamic(struct tlsdesc *);
# endif
#endif

151
sysdeps/x86_64/tlsdesc.c Normal file
View File

@ -0,0 +1,151 @@
/* Manage TLS descriptors. x86_64 version.
Copyright (C) 2005, 2008 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. */
#include <link.h>
#include <ldsodefs.h>
#include <elf/dynamic-link.h>
#include <tls.h>
#include <dl-tlsdesc.h>
#include <tlsdeschtab.h>
/* The following 2 functions take a caller argument, that contains the
address expected to be in the TLS descriptor. If it's changed, we
want to return immediately. */
/* This function is used to lazily resolve TLS_DESC RELA relocations.
The argument location is used to hold a pointer to the relocation. */
void
attribute_hidden
_dl_tlsdesc_resolve_rela_fixup (struct tlsdesc volatile *td,
struct link_map *l)
{
const ElfW(Rela) *reloc = td->arg;
if (_dl_tlsdesc_resolve_early_return_p
(td, (void*)(D_PTR (l, l_info[ADDRIDX (DT_TLSDESC_PLT)]) + l->l_addr)))
return;
/* The code below was borrowed from _dl_fixup(). */
const ElfW(Sym) *const symtab
= (const void *) D_PTR (l, l_info[DT_SYMTAB]);
const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
lookup_t result;
/* Look up the target symbol. If the normal lookup rules are not
used don't look in the global scope. */
if (ELFW(ST_BIND) (sym->st_info) != STB_LOCAL
&& __builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
{
const struct r_found_version *version = NULL;
if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
{
const ElfW(Half) *vernum =
(const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
version = &l->l_versions[ndx];
if (version->hash == 0)
version = NULL;
}
result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym,
l->l_scope, version, ELF_RTYPE_CLASS_PLT,
DL_LOOKUP_ADD_DEPENDENCY, NULL);
}
else
{
/* We already found the symbol. The module (and therefore its load
address) is also known. */
result = l;
}
if (! sym)
{
td->arg = (void*)reloc->r_addend;
td->entry = _dl_tlsdesc_undefweak;
}
else
{
# ifndef SHARED
CHECK_STATIC_TLS (l, result);
# else
if (!TRY_STATIC_TLS (l, result))
{
td->arg = _dl_make_tlsdesc_dynamic (result, sym->st_value
+ reloc->r_addend);
td->entry = _dl_tlsdesc_dynamic;
}
else
# endif
{
td->arg = (void*)(sym->st_value - result->l_tls_offset
+ reloc->r_addend);
td->entry = _dl_tlsdesc_return;
}
}
_dl_tlsdesc_wake_up_held_fixups ();
}
/* This function is used to avoid busy waiting for other threads to
complete the lazy relocation. Once another thread wins the race to
relocate a TLS descriptor, it sets the descriptor up such that this
function is called to wait until the resolver releases the
lock. */
void
attribute_hidden
_dl_tlsdesc_resolve_hold_fixup (struct tlsdesc volatile *td,
void *caller)
{
/* Maybe we're lucky and can return early. */
if (caller != td->entry)
return;
/* Locking here will stop execution until the running resolver runs
_dl_tlsdesc_wake_up_held_fixups(), releasing the lock.
FIXME: We'd be better off waiting on a condition variable, such
that we didn't have to hold the lock throughout the relocation
processing. */
__rtld_lock_lock_recursive (GL(dl_load_lock));
__rtld_lock_unlock_recursive (GL(dl_load_lock));
}
/* Unmap the dynamic object, but also release its TLS descriptor table
if there is one. */
void
internal_function
_dl_unmap (struct link_map *map)
{
__munmap ((void *) (map)->l_map_start,
(map)->l_map_end - (map)->l_map_start);
#if SHARED
/* _dl_unmap is only called for dlopen()ed libraries, for which
calling free() is safe, or before we've completed the initial
relocation, in which case calling free() is probably pointless,
but still safe. */
if (map->l_mach.tlsdesc_table)
htab_delete (map->l_mach.tlsdesc_table);
#endif
}

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#include <stddef.h>
#include <sysdep.h>
#include <tls.h>
#include <link.h>
#include <dl-tlsdesc.h>
--
-- Abuse tls.h macros to derive offsets relative to the thread register.
DTV_OFFSET offsetof(struct pthread, header.dtv)
TLSDESC_ARG offsetof(struct tlsdesc, arg)
TLSDESC_GEN_COUNT offsetof(struct tlsdesc_dynamic_arg, gen_count)
TLSDESC_MODID offsetof(struct tlsdesc_dynamic_arg, tlsinfo.ti_module)
TLSDESC_MODOFF offsetof(struct tlsdesc_dynamic_arg, tlsinfo.ti_offset)