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[src/trunk]: src/libexec/ld.elf_so As seen on tech-userlevel...
details: https://anonhg.NetBSD.org/src/rev/32fa898f8fdc
branches: trunk
changeset: 537629:32fa898f8fdc
user: mycroft <mycroft%NetBSD.org@localhost>
date: Thu Oct 03 20:35:19 2002 +0000
description:
As seen on tech-userlevel...
There are several optimizations here:
1) Objects on _rtld_list_main do not participate in the DAG structures
at all. This is okay because all symbols must be resolvable at
link/load time, and _rtld_list_main is always searched first, so
any references from those objects must necessarily be resolved to
other objects on _rtld_list_main.
(Making this work completely required setting obj->main a bit
earlier; hence the RTLD_MAIN hack.)
2) Objects on _rtld_list_main are not put on _rtld_list_global,
preventing an extra search.
3) A bit is used to keep track of whether an object is on
_rtld_list_global, so we don't have to do a silly linear search.
4) A small attempt is made to prevent objects being put on the DAG
lists multiple times (using a silly linear search).
The sum of this appears to be a ~10% (.3s) reduction in Mozilla's
startup time on my 800MHz box.
Also, make sure _rtld_objmain->path is always set, just to make the
debug output nicer.
diffstat:
libexec/ld.elf_so/load.c | 15 +++++++++++----
libexec/ld.elf_so/rtld.c | 39 +++++++++++++++++++++++----------------
libexec/ld.elf_so/rtld.h | 8 +++++---
libexec/ld.elf_so/symbol.c | 13 ++++++++++---
4 files changed, 49 insertions(+), 26 deletions(-)
diffs (245 lines):
diff -r 76f11cb97de6 -r 32fa898f8fdc libexec/ld.elf_so/load.c
--- a/libexec/ld.elf_so/load.c Thu Oct 03 20:14:58 2002 +0000
+++ b/libexec/ld.elf_so/load.c Thu Oct 03 20:35:19 2002 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: load.c,v 1.19 2002/09/23 23:56:46 mycroft Exp $ */
+/* $NetBSD: load.c,v 1.20 2002/10/03 20:35:19 mycroft Exp $ */
/*
* Copyright 1996 John D. Polstra.
@@ -153,9 +153,16 @@
free(filepath);
++obj->refcount;
- if ((mode & RTLD_GLOBAL) &&
- _rtld_objlist_find(&_rtld_list_global, obj) == NULL)
+ if (mode & RTLD_MAIN && !obj->mainref) {
+ obj->mainref = 1;
+ rdbg(("adding %p (%s) to _rtld_list_main", obj, obj->path));
+ _rtld_objlist_add(&_rtld_list_main, obj);
+ }
+ if (mode & RTLD_GLOBAL && !obj->globalref) {
+ obj->globalref = 1;
+ rdbg(("adding %p (%s) to _rtld_list_global", obj, obj->path));
_rtld_objlist_add(&_rtld_list_global, obj);
+ }
return obj;
}
@@ -291,7 +298,7 @@
if (preload_path != NULL) {
cp = buf = xstrdup(preload_path);
while ((path = strsep(&cp, " :")) != NULL && status == 0) {
- if (!_rtld_load_object(xstrdup(path), RTLD_GLOBAL))
+ if (!_rtld_load_object(xstrdup(path), RTLD_MAIN))
status = -1;
else
dbg((" preloaded \"%s\"", path));
diff -r 76f11cb97de6 -r 32fa898f8fdc libexec/ld.elf_so/rtld.c
--- a/libexec/ld.elf_so/rtld.c Thu Oct 03 20:14:58 2002 +0000
+++ b/libexec/ld.elf_so/rtld.c Thu Oct 03 20:35:19 2002 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: rtld.c,v 1.83 2002/10/03 01:09:21 mycroft Exp $ */
+/* $NetBSD: rtld.c,v 1.84 2002/10/03 20:35:20 mycroft Exp $ */
/*
* Copyright 1996 John D. Polstra.
@@ -221,7 +221,6 @@
const char *ld_bind_now;
const char **argv;
long argc;
- Obj_Entry *obj;
const char **real___progname;
const Obj_Entry **real___mainprog_obj;
char ***real_environ;
@@ -344,8 +343,8 @@
if (pAUX_execfd != NULL) { /* Load the main program. */
int fd = pAUX_execfd->a_v;
dbg(("loading main program"));
- _rtld_objmain = _rtld_map_object(argv[0] ? xstrdup(argv[0]) :
- xstrdup("main program"), fd, NULL);
+ _rtld_objmain = _rtld_map_object(xstrdup(argv[0] ? argv[0] :
+ "main program"), fd, NULL);
close(fd);
if (_rtld_objmain == NULL)
_rtld_die();
@@ -364,6 +363,8 @@
assert(pAUX_entry != NULL);
entry = (caddr_t) pAUX_entry->a_v;
_rtld_objmain = _rtld_digest_phdr(phdr, phnum, entry);
+ _rtld_objmain->path = xstrdup(argv[0] ? argv[0] :
+ "main program");
}
_rtld_objmain->mainprog = true;
@@ -381,13 +382,16 @@
_rtld_digest_dynamic(_rtld_objmain);
+ /* Link the main program into the list of objects. */
+ *_rtld_objtail = _rtld_objmain;
+ _rtld_objtail = &_rtld_objmain->next;
+
_rtld_linkmap_add(_rtld_objmain);
_rtld_linkmap_add(&_rtld_objself);
- /* Link the main program into the list of objects. */
- *_rtld_objtail = _rtld_objmain;
- _rtld_objtail = &_rtld_objmain->next;
++_rtld_objmain->refcount;
+ _rtld_objmain->mainref = 1;
+ _rtld_objlist_add(&_rtld_list_main, _rtld_objmain);
/* Initialize a fake symbol for resolving undefined weak references. */
_rtld_sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
@@ -402,14 +406,9 @@
_rtld_die();
dbg(("loading needed objects"));
- if (_rtld_load_needed_objects(_rtld_objmain, RTLD_GLOBAL) == -1)
+ if (_rtld_load_needed_objects(_rtld_objmain, RTLD_MAIN) == -1)
_rtld_die();
- for (obj = _rtld_objlist; obj != NULL; obj = obj->next) {
- obj->main = 1;
- _rtld_objlist_add(&_rtld_list_main, obj);
- }
-
dbg(("relocating objects"));
if (_rtld_relocate_objects(_rtld_objmain, bind_now) == -1)
_rtld_die();
@@ -499,9 +498,14 @@
{
const Needed_Entry *needed;
- _rtld_objlist_add(&obj->dldags, root);
- if (!obj->main)
+ if (!obj->mainref) {
+ if (_rtld_objlist_find(&obj->dldags, root))
+ return;
+ rdbg(("add %p (%s) to %p (%s) DAG", obj, obj->path, root,
+ root->path));
+ _rtld_objlist_add(&obj->dldags, root);
_rtld_objlist_add(&root->dagmembers, obj);
+ }
for (needed = obj->needed; needed != NULL; needed = needed->next)
if (needed->obj != NULL)
_rtld_init_dag1(root, needed->obj);
@@ -532,7 +536,10 @@
_rtld_objlist_remove(&elm->obj->dldags, root);
/* Remove the DAG from the RTLD_GLOBAL list. */
- _rtld_objlist_remove(&_rtld_list_global, root);
+ if (root->globalref) {
+ root->globalref = 0;
+ _rtld_objlist_remove(&_rtld_list_global, root);
+ }
/* Unmap all objects that are no longer referenced. */
linkp = &_rtld_objlist->next;
diff -r 76f11cb97de6 -r 32fa898f8fdc libexec/ld.elf_so/rtld.h
--- a/libexec/ld.elf_so/rtld.h Thu Oct 03 20:14:58 2002 +0000
+++ b/libexec/ld.elf_so/rtld.h Thu Oct 03 20:35:19 2002 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: rtld.h,v 1.61 2002/10/03 01:09:21 mycroft Exp $ */
+/* $NetBSD: rtld.h,v 1.62 2002/10/03 20:35:20 mycroft Exp $ */
/*
* Copyright 1996 John D. Polstra.
@@ -115,6 +115,7 @@
#define RTLD_MAGIC 0xd550b87a
#define RTLD_VERSION 1
+#define RTLD_MAIN 0x800
typedef struct Struct_Obj_Entry {
Elf32_Word magic; /* Magic number (sanity check) */
@@ -183,7 +184,8 @@
* "-Bsymbolic" */
printed:1, /* True if ldd has printed it */
isdynamic:1, /* True if this is a pure PIC object */
- main:1; /* True if on _rtld_list_main */
+ mainref:1, /* True if on _rtld_list_main */
+ globalref:1; /* True if on _rtld_list_global */
struct link_map linkmap; /* for GDB */
@@ -258,7 +260,7 @@
const Elf_Sym *_rtld_find_symdef __P((unsigned long, const Obj_Entry *,
const Obj_Entry **, bool));
const Elf_Sym *_rtld_symlook_list(const char *, unsigned long,
- Objlist *, const Obj_Entry **, bool);
+ const Objlist *, const Obj_Entry **, bool);
/* map_object.c */
Obj_Entry *_rtld_map_object __P((char *, int, const struct stat *));
diff -r 76f11cb97de6 -r 32fa898f8fdc libexec/ld.elf_so/symbol.c
--- a/libexec/ld.elf_so/symbol.c Thu Oct 03 20:14:58 2002 +0000
+++ b/libexec/ld.elf_so/symbol.c Thu Oct 03 20:35:19 2002 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: symbol.c,v 1.22 2002/09/24 20:27:07 mycroft Exp $ */
+/* $NetBSD: symbol.c,v 1.23 2002/10/03 20:35:20 mycroft Exp $ */
/*
* Copyright 1996 John D. Polstra.
@@ -74,7 +74,7 @@
}
const Elf_Sym *
-_rtld_symlook_list(const char *name, unsigned long hash, Objlist *objlist,
+_rtld_symlook_list(const char *name, unsigned long hash, const Objlist *objlist,
const Obj_Entry **defobj_out, bool in_plt)
{
const Elf_Sym *symp;
@@ -85,6 +85,7 @@
def = NULL;
defobj = NULL;
SIMPLEQ_FOREACH(elm, objlist, link) {
+ rdbg(("search object %p (%s)", elm->obj, elm->obj->path));
if ((symp = _rtld_symlook_obj(name, hash, elm->obj, in_plt))
!= NULL) {
if ((def == NULL) ||
@@ -127,6 +128,7 @@
assert(symnum < obj->nchains);
symp = obj->symtab + symnum;
strp = obj->strtab + symp->st_name;
+ rdbg(("check %s vs %s in %p", name, strp, obj));
if (name[1] == strp[1] && !strcmp(name, strp)) {
if (symp->st_shndx != SHN_UNDEF)
return symp;
@@ -192,6 +194,7 @@
/* Search all objects loaded at program start up. */
if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
+ rdbg(("search _rtld_list_main"));
symp = _rtld_symlook_list(name, hash, &_rtld_list_main, &obj, in_plt);
if (symp != NULL &&
(def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
@@ -204,6 +207,7 @@
SIMPLEQ_FOREACH(elm, &refobj->dldags, link) {
if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
break;
+ rdbg(("search DAG with root %p (%s)", elm->obj, elm->obj->path));
symp = _rtld_symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt);
if (symp != NULL &&
(def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
@@ -214,6 +218,7 @@
/* Search all RTLD_GLOBAL objects. */
if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
+ rdbg(("search _rtld_list_global"));
symp = _rtld_symlook_list(name, hash, &_rtld_list_global, &obj, in_plt);
if (symp != NULL &&
(def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
@@ -234,8 +239,10 @@
if (def != NULL)
*defobj_out = defobj;
- else
+ else {
+ rdbg(("lookup failed"));
_rtld_error("%s: Undefined %ssymbol \"%s\" (symnum = %ld)",
refobj->path, in_plt ? "PLT " : "", name, symnum);
+ }
return def;
}
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