[src/trunk]: src/libexec/ld.elf_so Instead of using a function to resolve sym...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/a1ce52ee0c9c
branches:  trunk
changeset: 349232:a1ce52ee0c9c
user:      christos <christos%NetBSD.org@localhost>
date:      Thu Dec 01 14:29:15 2016 +0000

description:
Instead of using a function to resolve symbols that should be supplied by
the dynamic linker itself, use a version script that exposes them. From joerg@

diffstat:

 libexec/ld.elf_so/Makefile    |   3 +-
 libexec/ld.elf_so/rtld.c      |  10 +++-----
 libexec/ld.elf_so/symbol.c    |  47 +++---------------------------------------
 libexec/ld.elf_so/symbols.map |  26 +++++++++++++++++++++++
 4 files changed, 36 insertions(+), 50 deletions(-)

diffs (162 lines):

diff -r eba529ab8d7b -r a1ce52ee0c9c libexec/ld.elf_so/Makefile
--- a/libexec/ld.elf_so/Makefile        Thu Dec 01 09:04:37 2016 +0000
+++ b/libexec/ld.elf_so/Makefile        Thu Dec 01 14:29:15 2016 +0000
@@ -1,4 +1,4 @@
-#      $NetBSD: Makefile,v 1.135 2016/10/07 19:10:03 christos Exp $
+#      $NetBSD: Makefile,v 1.136 2016/12/01 14:29:15 christos Exp $
 #
 # NOTE: when changing ld.so, ensure that ldd still compiles.
 #
@@ -124,6 +124,7 @@
 COPTS.rtld.c+= -Wno-stack-protector
 COPTS.symbol.c+=-Wno-stack-protector
 
+LDADD+=                -Wl,--version-script=${.CURDIR}/symbols.map
 LDADD+=                -L${CLIBOBJ} -L${DESTDIR}${LIBDIR}
 .if ${MKPICLIB} != "no"
 LDADD+=                -lc_pic
diff -r eba529ab8d7b -r a1ce52ee0c9c libexec/ld.elf_so/rtld.c
--- a/libexec/ld.elf_so/rtld.c  Thu Dec 01 09:04:37 2016 +0000
+++ b/libexec/ld.elf_so/rtld.c  Thu Dec 01 14:29:15 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: rtld.c,v 1.180 2016/11/30 20:25:23 christos Exp $       */
+/*     $NetBSD: rtld.c,v 1.181 2016/12/01 14:29:15 christos Exp $       */
 
 /*
  * Copyright 1996 John D. Polstra.
@@ -40,7 +40,7 @@
 
 #include <sys/cdefs.h>
 #ifndef lint
-__RCSID("$NetBSD: rtld.c,v 1.180 2016/11/30 20:25:23 christos Exp $");
+__RCSID("$NetBSD: rtld.c,v 1.181 2016/12/01 14:29:15 christos Exp $");
 #endif /* not lint */
 
 #include <sys/param.h>
@@ -1138,14 +1138,12 @@
                         * Search the dynamic linker itself, and possibly
                         * resolve the symbol from there if it is not defined
                         * already or weak. This is how the application links
-                        * to dynamic linker services such as dlopen. Only the
-                        * values listed in the "_rtld_exports" array can be
-                        * resolved from the dynamic linker.
+                        * to dynamic linker services such as dlopen.
                         */
                        if (!def || ELF_ST_BIND(def->st_info) == STB_WEAK) {
                                const Elf_Sym *symp = _rtld_symlook_obj(name,
                                    hash, &_rtld_objself, flags, ventry);
-                               if (symp != NULL && _rtld_is_exported(symp)) {
+                               if (symp != NULL) {
                                        def = symp;
                                        defobj = &_rtld_objself;
                                }
diff -r eba529ab8d7b -r a1ce52ee0c9c libexec/ld.elf_so/symbol.c
--- a/libexec/ld.elf_so/symbol.c        Thu Dec 01 09:04:37 2016 +0000
+++ b/libexec/ld.elf_so/symbol.c        Thu Dec 01 14:29:15 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: symbol.c,v 1.66 2016/11/30 19:43:32 christos Exp $      */
+/*     $NetBSD: symbol.c,v 1.67 2016/12/01 14:29:15 christos Exp $      */
 
 /*
  * Copyright 1996 John D. Polstra.
@@ -40,7 +40,7 @@
 
 #include <sys/cdefs.h>
 #ifndef lint
-__RCSID("$NetBSD: symbol.c,v 1.66 2016/11/30 19:43:32 christos Exp $");
+__RCSID("$NetBSD: symbol.c,v 1.67 2016/12/01 14:29:15 christos Exp $");
 #endif /* not lint */
 
 #include <err.h>
@@ -80,43 +80,6 @@
        return false;
 }
 
-bool
-_rtld_is_exported(const Elf_Sym *def)
-{
-       static const fptr_t _rtld_exports[] = {
-               (fptr_t)dlopen,
-               (fptr_t)dlclose,
-               (fptr_t)dlsym,
-               (fptr_t)dlvsym,
-               (fptr_t)dlerror,
-               (fptr_t)dladdr,
-               (fptr_t)dlinfo,
-               (fptr_t)dl_iterate_phdr,
-               (fptr_t)_dlauxinfo,
-#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
-               (fptr_t)_rtld_tls_allocate,
-               (fptr_t)_rtld_tls_free,
-               (fptr_t)__tls_get_addr,
-#ifdef __i386__
-               (fptr_t)___tls_get_addr,
-#endif
-#endif
-#if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__)
-               (fptr_t)__gnu_Unwind_Find_exidx,        /* for gcc EHABI */
-#endif
-               NULL
-       };
-       int i;
-       fptr_t value;
-
-       value = (fptr_t)(_rtld_objself.relocbase + def->st_value);
-       for (i = 0; _rtld_exports[i] != NULL; i++) {
-               if (value == _rtld_exports[i])
-                       return true;
-       }
-       return false;
-}
-
 /*
  * Hash function for symbol table lookup.  Don't even think about changing
  * this.  It is specified by the System V ABI.
@@ -565,15 +528,13 @@
        /*
         * Search the dynamic linker itself, and possibly resolve the
         * symbol from there.  This is how the application links to
-        * dynamic linker services such as dlopen.  Only the values listed
-        * in the "_rtld_exports" array can be resolved from the dynamic
-        * linker.
+        * dynamic linker services such as dlopen.
         */
        if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
                rdbg(("Search the dynamic linker itself."));
                symp = _rtld_symlook_obj(name, hash, &_rtld_objself, flags,
                    ventry);
-               if (symp != NULL && _rtld_is_exported(symp)) {
+               if (symp != NULL) {
                        def = symp;
                        defobj = &_rtld_objself;
                }
diff -r eba529ab8d7b -r a1ce52ee0c9c libexec/ld.elf_so/symbols.map
--- /dev/null   Thu Jan 01 00:00:00 1970 +0000
+++ b/libexec/ld.elf_so/symbols.map     Thu Dec 01 14:29:15 2016 +0000
@@ -0,0 +1,26 @@
+{
+  global:
+    dlopen;
+    __dlopen;
+    dlclose;
+    __dlclose;
+    dlsym;
+    __dlsym;
+    dlvsym;
+    __dlvsym;
+    dlerror;
+    __dlerror;
+    dladdr;
+    __dladdr;
+    dlinfo;
+    __dlinfo;
+    dl_iterate_phdr;
+    ____dl_iterate_phdr;
+    _dlauxinfo;
+    _rtld_tls_allocate;
+    _rtld_tls_free;
+    __tls_get_addr;
+    ___tls_get_addr;
+    __gnu_Unwind_Find_exidx;
+  local: *;
+};