Fix symbol versioning problems in PR 18703.

If a symbol is defined with ".symver foo,foo@VER", the assembler creates two symbols in the object: one unversioned, and one with the (non-default) version "VER". If foo is listed in a version script, gold would then make the first of those symbols the default version, and would ignore the second symbol as a duplicate, without making it a non-default version. While this is arguably reasonable behavior, it doesn't match Gnu ld behavior, so this patch fixes that by allowing the second definition to override the first by resetting the "default version" indication. Several test cases from the Gnu ld testsuite also exposed another related problem, where a symbol defined with ".symver foo,foo@", placed into a shared library, is not handled properly by gold. This patch also fixes that case, binding the symbol to the base version. gold/ PR gold/18703 * dynobj.cc (Versions::record_version): Handle symbol defined with base version. (Versions::symbol_section_contents): Likewise. * symtab.h (Symbol::set_is_not_default): New class method. (Symbol_table::resolve): Add is_default_version parameter. (Symbol_table::should_override): Likewise. * resolve.cc (Symbol_table::resolve): Add is_default_version parameter, and pass to should_override. Adjust all callers and explicit instantiations. (Symbol_table::should_override): Add is_default_value parameter; allow default version in a dynamic object to override existing definition from same object. * symtab.cc (Symbol_table::add_from_object): Handle case where same symbol is defined as unversioned and non-default version in the same object. * testsuite/Makefile.am (ver_test_13): New test case. * testsuite/Makefile.in: Regenerate. * testsuite/ver_test_4.cc: Add test for symbol with base version. * testsuite/ver_test_4.sh: Likewise. * testsuite/ver_test_13.c: New source file. * testsuite/ver_test_13.script: New version script. * testsuite/ver_test_13.sh: New test case.
2015-07-27 15:09:08 -07:00 · 2015-07-27 15:09:08 -07:00 · b45e00b3ed
commit b45e00b3ed
parent e49433d22d
11 changed files with 171 additions and 21 deletions
--- a/gold/dynobj.cc
+++ b/gold/dynobj.cc
@ -1499,6 +1499,10 @@ Versions::record_version(const Symbol_table* symtab,
  gold_assert(!this->is_finalized_);
  gold_assert(sym->version() != NULL);

+  // A symbol defined as "sym@" is bound to an unspecified base version.
+  if (sym->version()[0] == '\0')
+    return;
+
  Stringpool::Key version_key;
  const char* version = dynpool->add(sym->version(), false, &version_key);

@ -1731,15 +1735,17 @@ Versions::symbol_section_contents(const Symbol_table* symtab,
    {
      unsigned int version_index;
      const char* version = (*p)->version();
-      if (version != NULL)
-	version_index = this->version_index(symtab, dynpool, *p);
-      else
+      if (version == NULL)
 	{
 	  if ((*p)->is_defined() && !(*p)->is_from_dynobj())
 	    version_index = elfcpp::VER_NDX_GLOBAL;
 	  else
 	    version_index = elfcpp::VER_NDX_LOCAL;
 	}
+      else if (version[0] == '\0')
+        version_index = elfcpp::VER_NDX_GLOBAL;
+      else
+	version_index = this->version_index(symtab, dynpool, *p);
      // If the symbol was defined as foo@V1 instead of foo@@V1, add
      // the hidden bit.
      if ((*p)->version() != NULL && !(*p)->is_default())
--- a/gold/resolve.cc
+++ b/gold/resolve.cc
@ -243,7 +243,8 @@ Symbol_table::resolve(Sized_symbol<size>* to,
 		      const elfcpp::Sym<size, big_endian>& sym,
 		      unsigned int st_shndx, bool is_ordinary,
 		      unsigned int orig_st_shndx,
-		      Object* object, const char* version)
+		      Object* object, const char* version,
+		      bool is_default_version)
 {
  // It's possible for a symbol to be defined in an object file
  // using .symver to give it a version, and for there to also be
@ -380,7 +381,7 @@ Symbol_table::resolve(Sized_symbol<size>* to,
  typename Sized_symbol<size>::Size_type tosize = to->symsize();
  if (Symbol_table::should_override(to, frombits, fromtype, OBJECT,
 				    object, &adjust_common_sizes,
-				    &adjust_dyndef))
+				    &adjust_dyndef, is_default_version))
    {
      elfcpp::STB tobinding = to->binding();
      typename Sized_symbol<size>::Value_type tovalue = to->value();
@ -449,7 +450,7 @@ bool
 Symbol_table::should_override(const Symbol* to, unsigned int frombits,
 			      elfcpp::STT fromtype, Defined defined,
 			      Object* object, bool* adjust_common_sizes,
-			      bool* adjust_dyndef)
+			      bool* adjust_dyndef, bool is_default_version)
 {
  *adjust_common_sizes = false;
  *adjust_dyndef = false;
@ -596,9 +597,19 @@ Symbol_table::should_override(const Symbol* to, unsigned int frombits,

    case DEF * 16 + DYN_DEF:
    case WEAK_DEF * 16 + DYN_DEF:
+      // Ignore a dynamic definition if we already have a definition.
+      return false;
+
    case DYN_DEF * 16 + DYN_DEF:
    case DYN_WEAK_DEF * 16 + DYN_DEF:
-      // Ignore a dynamic definition if we already have a definition.
+      // Ignore a dynamic definition if we already have a definition,
+      // unless the existing definition is an unversioned definition
+      // in the same dynamic object, and the new definition is a
+      // default version.
+      if (to->object() == object
+          && to->version() == NULL
+          && is_default_version)
+        return true;
      return false;

    case UNDEF * 16 + DYN_DEF:
@ -919,7 +930,7 @@ Symbol_table::should_override_with_special(const Symbol* to,
  unsigned int frombits = global_flag | regular_flag | def_flag;
  bool ret = Symbol_table::should_override(to, frombits, fromtype, defined,
 					   NULL, &adjust_common_sizes,
-					   &adjust_dyn_def);
+					   &adjust_dyn_def, false);
  gold_assert(!adjust_common_sizes && !adjust_dyn_def);
  return ret;
 }
@ -1051,7 +1062,8 @@ Symbol_table::resolve<32, false>(
    bool is_ordinary,
    unsigned int orig_st_shndx,
    Object* object,
-    const char* version);
+    const char* version,
+    bool is_default_version);

 template
 void
@ -1062,7 +1074,8 @@ Symbol_table::resolve<32, true>(
    bool is_ordinary,
    unsigned int orig_st_shndx,
    Object* object,
-    const char* version);
+    const char* version,
+    bool is_default_version);
 #endif

 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
@ -1075,7 +1088,8 @@ Symbol_table::resolve<64, false>(
    bool is_ordinary,
    unsigned int orig_st_shndx,
    Object* object,
-    const char* version);
+    const char* version,
+    bool is_default_version);

 template
 void
@ -1086,7 +1100,8 @@ Symbol_table::resolve<64, true>(
    bool is_ordinary,
    unsigned int orig_st_shndx,
    Object* object,
-    const char* version);
+    const char* version,
+    bool is_default_version);
 #endif

 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
--- a/gold/symtab.cc
+++ b/gold/symtab.cc
@ -737,7 +737,7 @@ Symbol_table::resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from)
  bool is_ordinary;
  unsigned int shndx = from->shndx(&is_ordinary);
  this->resolve(to, esym.sym(), shndx, is_ordinary, shndx, from->object(),
-		from->version());
+		from->version(), true);
  if (from->in_reg())
    to->set_in_reg();
  if (from->in_dyn())
@ -991,13 +991,38 @@ Symbol_table::add_from_object(Object* object,
      was_common = ret->is_common() && ret->object()->pluginobj() == NULL;

      this->resolve(ret, sym, st_shndx, is_ordinary, orig_st_shndx, object,
-		    version);
+		    version, is_default_version);
      if (parameters->options().gc_sections())
        this->gc_mark_dyn_syms(ret);

      if (is_default_version)
 	this->define_default_version<size, big_endian>(ret, insdefault.second,
 						       insdefault.first);
+      else if (version != NULL && ret->is_default())
+	{
+	  // We have seen NAME/VERSION already, and marked it as the
+	  // default version, but now we see a definition for
+	  // NAME/VERSION that is not the default version. This can
+	  // happen when the assembler generates two symbols for
+	  // a symbol as a result of a ".symver foo,foo@VER"
+	  // directive. We see the first unversioned symbol and
+	  // we may mark it as the default version (from a
+	  // version script); then we see the second versioned
+	  // symbol and we need to override the first.
+	  // In any other case, the two symbols should have generated
+	  // a multiple definition error.
+	  // (See PR gold/18703.)
+	  bool dummy;
+	  if (ret->source() == Symbol::FROM_OBJECT
+	      && ret->object() == object
+	      && is_ordinary
+	      && ret->shndx(&dummy) == st_shndx)
+	    {
+	      ret->set_is_not_default();
+	      const Stringpool::Key vnull_key = 0;
+	      this->table_.erase(std::make_pair(name_key, vnull_key));
+	    }
+	}
    }
  else
    {
@ -1015,7 +1040,7 @@ Symbol_table::add_from_object(Object* object,
 	  was_common = ret->is_common() && ret->object()->pluginobj() == NULL;

 	  this->resolve(ret, sym, st_shndx, is_ordinary, orig_st_shndx, object,
-			version);
+			version, is_default_version);
          if (parameters->options().gc_sections())
            this->gc_mark_dyn_syms(ret);
 	  ins.first->second = ret;
--- a/gold/symtab.h
+++ b/gold/symtab.h
@ -140,6 +140,11 @@ class Symbol
  set_is_default()
  { this->is_def_ = true; }

+  // Set that this version is not the default for this symbol name.
+  void
+  set_is_not_default()
+  { this->is_def_ = false; }
+
  // Return the symbol's name as name@version (or name@@version).
  std::string
  versioned_name() const;
@ -1706,7 +1711,8 @@ class Symbol_table
 	  const elfcpp::Sym<size, big_endian>& sym,
 	  unsigned int st_shndx, bool is_ordinary,
 	  unsigned int orig_st_shndx,
-	  Object*, const char* version);
+	  Object*, const char* version,
+	  bool is_default_version);

  template<int size, bool big_endian>
  void
@ -1725,7 +1731,7 @@ class Symbol_table
  // resolve.cc.
  static bool
  should_override(const Symbol*, unsigned int, elfcpp::STT, Defined,
-		  Object*, bool*, bool*);
+		  Object*, bool*, bool*, bool);

  // Report a problem in symbol resolution.
  static void
--- a/gold/testsuite/Makefile.am
+++ b/gold/testsuite/Makefile.am
@ -1563,6 +1563,15 @@ ver_test_12_LDADD = ver_test_12.o
 ver_test_12.o: gcctestdir/ld ver_test_1.o ver_test_2.o ver_test_4.o
 	gcctestdir/ld -r -o $@ ver_test_1.o ver_test_2.o ver_test_4.o

+check_SCRIPTS += ver_test_13.sh
+check_DATA += ver_test_13.syms
+ver_test_13.syms: ver_test_13.so
+	$(TEST_READELF) -s $< >$@ 2>/dev/null
+ver_test_13.so: gcctestdir/ld ver_test_13.o ver_test_13.script
+	$(LINK) -Bgcctestdir/ -shared -Wl,--version-script,$(srcdir)/ver_test_13.script ver_test_13.o
+ver_test_13.o: ver_test_13.c
+	$(COMPILE) -c -fpic -o $@ $<
+
 check_PROGRAMS += protected_1
 protected_1_SOURCES = \
 	protected_main_1.cc protected_main_2.cc protected_main_3.cc
--- a/gold/testsuite/Makefile.in
+++ b/gold/testsuite/Makefile.in
@ -327,7 +327,7 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	ver_test_1.sh ver_test_2.sh \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	ver_test_4.sh ver_test_5.sh \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	ver_test_7.sh ver_test_10.sh \
-@GCC_TRUE@@NATIVE_LINKER_TRUE@	relro_test.sh \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@	ver_test_13.sh relro_test.sh \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	ver_matching_test.sh \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	script_test_3.sh \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	script_test_4.sh \
@ -371,7 +371,7 @@ check_PROGRAMS = $(am__EXEEXT_1) $(am__EXEEXT_2) $(am__EXEEXT_3) \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	ver_test_1.syms ver_test_2.syms \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	ver_test_4.syms ver_test_5.syms \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	ver_test_7.syms ver_test_10.syms \
-@GCC_TRUE@@NATIVE_LINKER_TRUE@	protected_3.err \
+@GCC_TRUE@@NATIVE_LINKER_TRUE@	ver_test_13.syms protected_3.err \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	relro_test.stdout \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	ver_matching_test.stdout \
@GCC_TRUE@@NATIVE_LINKER_TRUE@	script_test_3.stdout \
@ -4432,6 +4432,8 @@ ver_test_7.sh.log: ver_test_7.sh
 	@p='ver_test_7.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
 ver_test_10.sh.log: ver_test_10.sh
 	@p='ver_test_10.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
+ver_test_13.sh.log: ver_test_13.sh
+	@p='ver_test_13.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
 relro_test.sh.log: relro_test.sh
 	@p='relro_test.sh'; $(am__check_pre) $(LOG_COMPILE) "$$tst" $(am__check_post)
 ver_matching_test.sh.log: ver_matching_test.sh
@ -5747,6 +5749,12 @@ uninstall-am:
@GCC_TRUE@@NATIVE_LINKER_TRUE@	$(TEST_AR) rc $@ $^
@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_12.o: gcctestdir/ld ver_test_1.o ver_test_2.o ver_test_4.o
@GCC_TRUE@@NATIVE_LINKER_TRUE@	gcctestdir/ld -r -o $@ ver_test_1.o ver_test_2.o ver_test_4.o
+@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_13.syms: ver_test_13.so
+@GCC_TRUE@@NATIVE_LINKER_TRUE@	$(TEST_READELF) -s $< >$@ 2>/dev/null
+@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_13.so: gcctestdir/ld ver_test_13.o ver_test_13.script
+@GCC_TRUE@@NATIVE_LINKER_TRUE@	$(LINK) -Bgcctestdir/ -shared -Wl,--version-script,$(srcdir)/ver_test_13.script ver_test_13.o
+@GCC_TRUE@@NATIVE_LINKER_TRUE@ver_test_13.o: ver_test_13.c
+@GCC_TRUE@@NATIVE_LINKER_TRUE@	$(COMPILE) -c -fpic -o $@ $<

@GCC_TRUE@@NATIVE_LINKER_TRUE@protected_1.so: gcctestdir/ld protected_1_pic.o protected_2_pic.o protected_3_pic.o
@GCC_TRUE@@NATIVE_LINKER_TRUE@	$(CXXLINK) -Bgcctestdir/ -shared protected_1_pic.o protected_2_pic.o protected_3_pic.o
--- a/gold/testsuite/ver_test_13.c
+++ b/gold/testsuite/ver_test_13.c
@ -0,0 +1,7 @@
+__asm__ (".symver foo, foo@VER_0");
+
+int foo(void);
+
+int foo(void) {
+  return 0;
+}
--- a/gold/testsuite/ver_test_13.script
+++ b/gold/testsuite/ver_test_13.script
@ -0,0 +1,4 @@
+VER_0 {
+  global:
+	foo;
+};
--- a/gold/testsuite/ver_test_13.sh
+++ b/gold/testsuite/ver_test_13.sh
@ -0,0 +1,59 @@
+#!/bin/sh
+
+# ver_test_13.sh -- a test case for version script matching
+
+# Copyright (C) 2015 Free Software Foundation, Inc.
+# Written by Cary Coutant <ccoutant@gmail.com>.
+
+# This file is part of gold.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+# This program 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 General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+# This test verifies that a symbol declared with .symver as a
+# non-default version does not get overridden by the version
+# script and declared as a default version.
+# (See PR gold/18703.)
+
+check()
+{
+    if ! grep -q "$2" "$1"
+    then
+	echo "Did not find expected symbol in $1:"
+	echo "   $2"
+	echo ""
+	echo "Actual output below:"
+	cat "$1"
+	exit 1
+    fi
+}
+
+check_missing()
+{
+    if grep -q "$2" "$1"
+    then
+	echo "Found unexpected symbol in $1:"
+	echo "   $2"
+	echo ""
+	echo "Actual output below:"
+	cat "$1"
+	exit 1
+    fi
+}
+
+check ver_test_13.syms "foo@VER_0$"
+check_missing ver_test_13.syms "foo@@VER_0"
+
+exit 0
--- a/gold/testsuite/ver_test_4.cc
+++ b/gold/testsuite/ver_test_4.cc
@ -22,6 +22,16 @@

 #include "ver_test.h"

+__asm__(".symver t1_2_orig,t1_2@");
+
+extern "C"
+int
+t1_2_orig()
+{
+  TRACE
+  return 12;
+}
+
 __asm__(".symver t1_2_a,t1_2@@VER2");

 extern "C"
--- a/gold/testsuite/ver_test_4.sh
+++ b/gold/testsuite/ver_test_4.sh
@ -24,17 +24,18 @@

 check()
 {
-    if ! grep -q "$2" "$1"
+    if ! sed '/\.symtab/q' "$1" | grep -q "$2"
    then
 	echo "Did not find expected symbol in $1:"
 	echo "   $2"
 	echo ""
 	echo "Actual output below:"
-	cat "$1"
+	sed '/\.symtab/q' "$1"
 	exit 1
    fi
 }

+check ver_test_4.syms "t1_2\$"
 check ver_test_4.syms "t1_2@@VER2"
 check ver_test_4.syms "t2_2@VER1"
 check ver_test_4.syms "t2_2@@VER2"