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* include/link.h (struct link_map): Add l_lookup_cache element.
	* elf/dl-reloc.c (RESOLVE): Add symbol caching here.
	(RESOLVE_MAP): Likewise.
	(_dl_relocate_object): Remove cache initialization.
	* elf/dl-lookup.c: Rip out cache handling code.
	* sysdeps/generic/ldsodefs.h: Remove lookup_cache struct and variable
	declarations.

	* elf/dl-lookup.c (_dl_lookup_symbol): Reorder some conditions and
	remove some __builtin_expect.
	(_dl_lookup_versioned_symbol): Likewise.

	R_386_RELATIVE handling for ld.so startup.  Reduce RTLD_BOOTSTRAP
	case to almost no code.
This commit is contained in:
Ulrich Drepper 2001-08-26 10:50:26 +00:00
parent a711b01d34
commit 680254fe22
6 changed files with 83 additions and 107 deletions
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15
ChangeLog
View File

@ -1,11 +1,24 @@
2001-08-26 Ulrich Drepper <drepper@redhat.com>
* include/link.h (struct link_map): Add l_lookup_cache element.
* elf/dl-reloc.c (RESOLVE): Add symbol caching here.
(RESOLVE_MAP): Likewise.
(_dl_relocate_object): Remove cache initialization.
* elf/dl-lookup.c: Rip out cache handling code.
* sysdeps/generic/ldsodefs.h: Remove lookup_cache struct and variable
declarations.
* elf/dl-lookup.c (_dl_lookup_symbol): Reorder some conditions and
remove some __builtin_expect.
(_dl_lookup_versioned_symbol): Likewise.
* config.h.in: Add HAVE_Z_COMBRELOC.
* configure.in: Add test for -z combreloc.
* sysdeps/i386/dl-machine.h (elf_machine_rel): Minor cleanups and
optimizations. Use HAVE_Z_COMBRELOC to avoid generaton of
R_386_RELATIVE handling for ld.so startup.
R_386_RELATIVE handling for ld.so startup. Reduce RTLD_BOOTSTRAP
case to almost no code.
2001-08-25 Ulrich Drepper <drepper@redhat.com>

82
elf/dl-lookup.c
View File

@ -60,7 +60,6 @@ struct sym_val
/* Statistics function. */
unsigned long int _dl_num_relocations;
unsigned long int _dl_num_cache_relocations;
/* We have two different situations when looking up a simple: with or
@ -185,8 +184,6 @@ _dl_do_lookup_versioned (const char *undef_name, unsigned long int hash,
const struct r_found_version *const version,
struct link_map *skip, int noexec, int noplt);
struct lookup_cache _dl_lookup_cache;
struct lookup_cache _dl_lookup_cache_versioned;
/* Search loaded objects' symbol tables for a definition of the symbol
UNDEF_NAME. */
@ -197,29 +194,15 @@ _dl_lookup_symbol (const char *undef_name, struct link_map *undef_map,
const ElfW(Sym) **ref, struct r_scope_elem *symbol_scope[],
int reloc_type, int explicit)
{
unsigned long int hash;
struct sym_val current_value;
unsigned long int hash = _dl_elf_hash (undef_name);
struct sym_val current_value = { NULL, NULL };
struct r_scope_elem **scope;
int protected;
int noexec = elf_machine_lookup_noexec_p (reloc_type);
int noplt = elf_machine_lookup_noplt_p (reloc_type);
/* First check if we can find it in the cache. */
if (__builtin_expect (*ref == _dl_lookup_cache.sym, 0)
&& _dl_lookup_cache.map == undef_map
&& _dl_lookup_cache.noexec == noexec
&& _dl_lookup_cache.noplt == noplt)
{
++_dl_num_cache_relocations;
*ref = _dl_lookup_cache.ret;
return _dl_lookup_cache.value;
}
++_dl_num_relocations;
hash = _dl_elf_hash (undef_name);
current_value = ((struct sym_val) { NULL, NULL });
/* Search the relevant loaded objects for a definition. */
for (scope = symbol_scope; *scope; ++scope)
if (do_lookup (undef_name, hash, *ref, &current_value, *scope, 0, NULL,
@ -229,13 +212,12 @@ _dl_lookup_symbol (const char *undef_name, struct link_map *undef_map,
in the global scope which was dynamically loaded. In this case
we have to prevent the latter from being unloaded unless the
UNDEF_MAP object is also unloaded. */
if (__builtin_expect (current_value.m->l_global, 0)
&& (__builtin_expect (current_value.m->l_type, lt_library)
== lt_loaded)
if (__builtin_expect (current_value.m->l_type == lt_loaded, 0)
&& current_value.m->l_global
&& undef_map != current_value.m
/* Don't do this for explicit lookups as opposed to implicit
runtime lookups. */
&& __builtin_expect (! explicit, 1)
&& ! explicit
/* Add UNDEF_MAP to the dependencies. */
&& add_dependency (undef_map, current_value.m) < 0)
/* Something went wrong. Perhaps the object we tried to reference
@ -246,11 +228,6 @@ _dl_lookup_symbol (const char *undef_name, struct link_map *undef_map,
break;
}
/* Update common information in the cache. */
_dl_lookup_cache.sym = *ref;
_dl_lookup_cache.noexec = noexec;
_dl_lookup_cache.noplt = noplt;
if (__builtin_expect (current_value.s == NULL, 0))
{
const char *reference_name = undef_map ? undef_map->l_name : NULL;
@ -262,8 +239,6 @@ _dl_lookup_symbol (const char *undef_name, struct link_map *undef_map,
? reference_name
: (_dl_argv[0] ?: "<main program>")),
make_string (undefined_msg, undef_name));
_dl_lookup_cache.ret = NULL;
_dl_lookup_cache.value = 0;
*ref = NULL;
return 0;
}
@ -284,8 +259,6 @@ _dl_lookup_symbol (const char *undef_name, struct link_map *undef_map,
if (__builtin_expect (protected == 0, 1))
{
_dl_lookup_cache.ret = current_value.s;
_dl_lookup_cache.value = LOOKUP_VALUE (current_value.m);
*ref = current_value.s;
return LOOKUP_VALUE (current_value.m);
}
@ -302,13 +275,9 @@ _dl_lookup_symbol (const char *undef_name, struct link_map *undef_map,
if (protected_value.s == NULL || protected_value.m == undef_map)
{
_dl_lookup_cache.ret = current_value.s;
_dl_lookup_cache.value = LOOKUP_VALUE (current_value.m);
*ref = current_value.s;
return LOOKUP_VALUE (current_value.m);
}
_dl_lookup_cache.ret = *ref;
_dl_lookup_cache.value = LOOKUP_VALUE (undef_map);
return LOOKUP_VALUE (undef_map);
}
@ -407,30 +376,15 @@ _dl_lookup_versioned_symbol (const char *undef_name,
const struct r_found_version *version,
int reloc_type, int explicit)
{
unsigned long int hash;
struct sym_val current_value;
unsigned long int hash = _dl_elf_hash (undef_name);
struct sym_val current_value = { NULL, NULL };
struct r_scope_elem **scope;
int protected;
int noexec = elf_machine_lookup_noexec_p (reloc_type);
int noplt = elf_machine_lookup_noplt_p (reloc_type);
/* First check if we can find it in the cache. */
if (__builtin_expect (*ref == _dl_lookup_cache_versioned.sym, 0)
&& _dl_lookup_cache_versioned.map == undef_map
&& _dl_lookup_cache_versioned.noexec == noexec
&& _dl_lookup_cache_versioned.noplt == noplt
&& _dl_lookup_cache_versioned.version == version)
{
++_dl_num_cache_relocations;
*ref = _dl_lookup_cache_versioned.ret;
return _dl_lookup_cache_versioned.value;
}
++_dl_num_relocations;
hash = _dl_elf_hash (undef_name);
current_value = ((struct sym_val) { NULL, NULL });
/* Search the relevant loaded objects for a definition. */
for (scope = symbol_scope; *scope; ++scope)
{
@ -442,13 +396,12 @@ _dl_lookup_versioned_symbol (const char *undef_name,
in the global scope which was dynamically loaded. In this case
we have to prevent the latter from being unloaded unless the
UNDEF_MAP object is also unloaded. */
if (__builtin_expect (current_value.m->l_global, 0)
&& (__builtin_expect (current_value.m->l_type, lt_library)
== lt_loaded)
if (__builtin_expect (current_value.m->l_type == lt_loaded, 0)
&& current_value.m->l_global
&& undef_map != current_value.m
/* Don't do this for explicit lookups as opposed to implicit
runtime lookups. */
&& __builtin_expect (! explicit, 1)
&& ! explicit
/* Add UNDEF_MAP to the dependencies. */
&& add_dependency (undef_map, current_value.m) < 0)
/* Something went wrong. Perhaps the object we tried to reference
@ -482,12 +435,6 @@ _dl_lookup_versioned_symbol (const char *undef_name,
}
}
/* Update common information in the cache. */
_dl_lookup_cache_versioned.sym = *ref;
_dl_lookup_cache_versioned.noexec = noexec;
_dl_lookup_cache_versioned.noplt = noplt;
_dl_lookup_cache_versioned.version = version;
if (__builtin_expect (current_value.s == NULL, 0))
{
if (*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK)
@ -503,9 +450,6 @@ _dl_lookup_versioned_symbol (const char *undef_name,
", version ",
version->name ?: NULL));
}
_dl_lookup_cache_versioned.ret = NULL;
_dl_lookup_cache_versioned.value = 0;
*ref = NULL;
return 0;
}
@ -527,8 +471,6 @@ _dl_lookup_versioned_symbol (const char *undef_name,
if (__builtin_expect (protected == 0, 1))
{
_dl_lookup_cache_versioned.ret = current_value.s;
_dl_lookup_cache_versioned.value = LOOKUP_VALUE (current_value.m);
*ref = current_value.s;
return LOOKUP_VALUE (current_value.m);
}
@ -545,14 +487,10 @@ _dl_lookup_versioned_symbol (const char *undef_name,
if (protected_value.s == NULL || protected_value.m == undef_map)
{
_dl_lookup_cache_versioned.ret = current_value.s;
_dl_lookup_cache_versioned.value = LOOKUP_VALUE (current_value.m);
*ref = current_value.s;
return LOOKUP_VALUE (current_value.m);
}
_dl_lookup_cache_versioned.ret = *ref;
_dl_lookup_cache_versioned.value = LOOKUP_VALUE (undef_map);
return LOOKUP_VALUE (undef_map);
}
}

55
elf/dl-reloc.c
View File

@ -27,6 +27,9 @@
#include <sys/types.h>
#include "dynamic-link.h"
/* Statistics function. */
unsigned long int _dl_num_cache_relocations;
void
_dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
@ -74,31 +77,51 @@ cannot make segment writable for relocation"));
/* This macro is used as a callback from the ELF_DYNAMIC_RELOCATE code. */
#define RESOLVE_MAP(ref, version, flags) \
(ELFW(ST_BIND) ((*ref)->st_info) != STB_LOCAL \
? ((version) != NULL && (version)->hash != 0 \
? _dl_lookup_versioned_symbol (strtab + (*ref)->st_name, l, (ref), \
scope, (version), (flags), 0) \
: _dl_lookup_symbol (strtab + (*ref)->st_name, l, (ref), scope, \
(flags), 0)) \
? ((__builtin_expect ((*ref) == l->l_lookup_cache.sym, 0) \
&& elf_machine_lookup_noexec_p (flags) == l->l_lookup_cache.noexec \
&& elf_machine_lookup_noplt_p (flags) == l->l_lookup_cache.noplt) \
? (++_dl_num_cache_relocations, \
(*ref) = l->l_lookup_cache.ret, \
l->l_lookup_cache.value) \
: ({ lookup_t _lr; \
l->l_lookup_cache.sym = (*ref); \
l->l_lookup_cache.noexec = elf_machine_lookup_noexec_p (flags); \
l->l_lookup_cache.noplt = elf_machine_lookup_noplt_p (flags); \
_lr = ((version) != NULL && (version)->hash != 0 \
? _dl_lookup_versioned_symbol (strtab + (*ref)->st_name, \
l, (ref), scope, \
(version), (flags), 0) \
: _dl_lookup_symbol (strtab + (*ref)->st_name, l, (ref), \
scope, (flags), 0)); \
l->l_lookup_cache.ret = (*ref); \
l->l_lookup_cache.value = _lr; })) \
: l)
#define RESOLVE(ref, version, flags) \
(ELFW(ST_BIND) ((*ref)->st_info) != STB_LOCAL \
? ((version) != NULL && (version)->hash != 0 \
? _dl_lookup_versioned_symbol (strtab + (*ref)->st_name, l, (ref), \
scope, (version), (flags), 0) \
: _dl_lookup_symbol (strtab + (*ref)->st_name, l, (ref), scope, \
(flags), 0)) \
? ((__builtin_expect ((*ref) == l->l_lookup_cache.sym, 0) \
&& elf_machine_lookup_noexec_p (flags) == l->l_lookup_cache.noexec \
&& elf_machine_lookup_noplt_p (flags) == l->l_lookup_cache.noplt) \
? (++_dl_num_cache_relocations, \
(*ref) = l->l_lookup_cache.ret, \
l->l_lookup_cache.value) \
: ({ lookup_t _lr; \
l->l_lookup_cache.sym = (*ref); \
l->l_lookup_cache.noexec = elf_machine_lookup_noexec_p (flags); \
l->l_lookup_cache.noplt = elf_machine_lookup_noplt_p (flags); \
_lr = ((version) != NULL && (version)->hash != 0 \
? _dl_lookup_versioned_symbol (strtab + (*ref)->st_name, \
l, (ref), scope, \
(version), (flags), 0) \
: _dl_lookup_symbol (strtab + (*ref)->st_name, l, (ref), \
scope, (flags), 0)); \
l->l_lookup_cache.ret = (*ref); \
l->l_lookup_cache.value = _lr; })) \
: l->l_addr)
#include "dynamic-link.h"
/* Start symbol lookup caching for this object. */
_dl_lookup_cache.map = l;
_dl_lookup_cache_versioned.map = l;
ELF_DYNAMIC_RELOCATE (l, lazy, consider_profiling);
_dl_lookup_cache.map = NULL;
_dl_lookup_cache_versioned.map = NULL;
if (__builtin_expect (consider_profiling, 0))
{
/* Allocate the array which will contain the already found

16
include/link.h
View File

@ -1,6 +1,6 @@
/* Data structure for communication from the run-time dynamic linker for
loaded ELF shared objects.
Copyright (C) 1995-1999, 2000 Free Software Foundation, Inc.
Copyright (C) 1995-1999, 2000, 2001 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
@ -34,6 +34,7 @@
#include <bits/elfclass.h> /* Defines __ELF_NATIVE_CLASS. */
#include <bits/link.h>
#include <dl-lookupcfg.h>
/* Rendezvous structure used by the run-time dynamic linker to communicate
details of shared object loading to the debugger. If the executable's
@ -231,6 +232,19 @@ struct link_map
unsigned int l_idx;
struct link_map_machine l_mach;
struct
{
const ElfW(Sym) *sym;
int noexec;
int noplt;
#ifdef DL_LOOKUP_RETURNS_MAP
struct link_map *value;
#else
ElfW(Addr) value;
#endif
const ElfW(Sym) *ret;
} l_lookup_cache;
};
struct dl_phdr_info

15
sysdeps/generic/ldsodefs.h
View File

@ -327,21 +327,6 @@ extern void _dl_map_object_deps (struct link_map *map,
/* Cache the locations of MAP's hash table. */
extern void _dl_setup_hash (struct link_map *map) internal_function;
/* This holds symbol lookup cache. */
struct lookup_cache
{
const ElfW(Sym) *sym;
struct link_map *map;
const struct r_found_version *version;
int noexec;
int noplt;
lookup_t value;
const ElfW(Sym) *ret;
};
extern struct lookup_cache _dl_lookup_cache;
extern struct lookup_cache _dl_lookup_cache_versioned;
/* Search loaded objects' symbol tables for a definition of the symbol
referred to by UNDEF. *SYM is the symbol table entry containing the

7
sysdeps/i386/dl-machine.h
View File

@ -334,13 +334,16 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc,
if (sym)
value += sym->st_value;
#ifdef RTLD_BOOTSTRAP
assert (r_type == R_386_GLOB_DAT || r_type == R_386_JMP_SLOT);
*reloc_addr = value;
#else
switch (r_type)
{
case R_386_GLOB_DAT:
case R_386_JMP_SLOT:
*reloc_addr = value;
break;
#ifndef RTLD_BOOTSTRAP
case R_386_32:
*reloc_addr += value;
break;
@ -372,8 +375,8 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc,
if we are still debugging. */
_dl_reloc_bad_type (map, r_type, 0);
break;
#endif
}
#endif
}
}