x86: Mark __bss_start, _end and _edata locally defined

__bss_start, _end and _edata are defined by linker to mark regions
within executables and shared libraries.  All references within
executables should be locally resolved.

This patch doesn't change how their references within shared libraries
are resolved.

bfd/

	PR ld/23162
	* elfxx-x86.c (elf_x86_linker_defined): New function.
	(_bfd_x86_elf_link_check_relocs): Use it to mark __bss_start,
	_end and _edata locally defined within executables.

ld/

	PR ld/23162
	* testsuite/ld-elf/pr23162.map: New file.
	* testsuite/ld-elf/pr23162.rd: Likewise.
	* testsuite/ld-elf/pr23162a.c: Likewise.
	* testsuite/ld-elf/pr23162b.c: Likewise.
	* testsuite/ld-elf/shared.exp: Run PR ld/23162 tests.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index d8b3773..10b9679 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,10 @@
+2018-05-14  H.J. Lu  <hongjiu.lu@intel.com>
+
+       PR ld/23162
+       * elfxx-x86.c (elf_x86_linker_defined): New function.
+       (_bfd_x86_elf_link_check_relocs): Use it to mark __bss_start,
+       _end and _edata locally defined within executables.
+
 2018-05-12  Alan Modra  <amodra@gmail.com>
 
        PR 20659

diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
index 40157b8..6c1f4c3 100644 (file)
--- a/bfd/elfxx-x86.c
+++ b/bfd/elfxx-x86.c
@@ -849,6 +849,33 @@ _bfd_x86_elf_compare_relocs (const void *ap, const void *bp)
     return 0;
 }
 
+/* Mark symbol, NAME, as locally defined by linker if it is referenced
+   and not defined in a relocatable object file.  */
+
+static void
+elf_x86_linker_defined (struct bfd_link_info *info, const char *name)
+{
+  struct elf_link_hash_entry *h;
+
+  h = elf_link_hash_lookup (elf_hash_table (info), name,
+                           FALSE, FALSE, FALSE);
+  if (h == NULL)
+    return;
+
+  while (h->root.type == bfd_link_hash_indirect)
+    h = (struct elf_link_hash_entry *) h->root.u.i.link;
+
+  if (h->root.type == bfd_link_hash_new
+      || h->root.type == bfd_link_hash_undefined
+      || h->root.type == bfd_link_hash_undefweak
+      || h->root.type == bfd_link_hash_common
+      || (!h->def_regular && h->def_dynamic))
+    {
+      elf_x86_hash_entry (h)->local_ref = 2;
+      elf_x86_hash_entry (h)->linker_def = 1;
+    }
+}
+
 bfd_boolean
 _bfd_x86_elf_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
 {
@@ -879,17 +906,15 @@ _bfd_x86_elf_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
 
          /* "__ehdr_start" will be defined by linker as a hidden symbol
             later if it is referenced and not defined.  */
-         h = elf_link_hash_lookup (elf_hash_table (info),
-                                   "__ehdr_start",
-                                   FALSE, FALSE, FALSE);
-         if (h != NULL
-             && (h->root.type == bfd_link_hash_new
-                 || h->root.type == bfd_link_hash_undefined
-                 || h->root.type == bfd_link_hash_undefweak
-                 || h->root.type == bfd_link_hash_common))
+         elf_x86_linker_defined (info, "__ehdr_start");
+
+         if (bfd_link_executable (info))
            {
-             elf_x86_hash_entry (h)->local_ref = 2;
-             elf_x86_hash_entry (h)->linker_def = 1;
+             /* References to __bss_start, _end and _edata should be
+                locally resolved within executables.  */
+             elf_x86_linker_defined (info, "__bss_start");
+             elf_x86_linker_defined (info, "_end");
+             elf_x86_linker_defined (info, "_edata");
            }
        }
     }

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 3360959..178ca68 100644 (file)
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,12 @@
+2018-05-14  H.J. Lu  <hongjiu.lu@intel.com>
+
+       PR ld/23162
+       * testsuite/ld-elf/pr23162.map: New file.
+       * testsuite/ld-elf/pr23162.rd: Likewise.
+       * testsuite/ld-elf/pr23162a.c: Likewise.
+       * testsuite/ld-elf/pr23162b.c: Likewise.
+       * testsuite/ld-elf/shared.exp: Run PR ld/23162 tests.
+
 2018-05-12  Alan Modra  <amodra@gmail.com>
 
        PR 20659

diff --git a/ld/testsuite/ld-elf/pr23162.map b/ld/testsuite/ld-elf/pr23162.map
new file mode 100644 (file)
index 0000000..cc817dc
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr23162.map
@@ -0,0 +1,4 @@
+FOO {
+  global:
+    *;
+};

diff --git a/ld/testsuite/ld-elf/pr23162.rd b/ld/testsuite/ld-elf/pr23162.rd
new file mode 100644 (file)
index 0000000..3ac848f
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr23162.rd
@@ -0,0 +1,12 @@
+There are no relocations in this file\.
+
+Symbol table '\.dynsym' contains [0-9]+ entries:
+ +Num: +Value +Size Type +Bind +Vis +Ndx Name
+ +0: 0+ +0 +NOTYPE +LOCAL +DEFAULT +UND +
+#...
+ +[0-9]+: +[a-f0-9]+ +0 +NOTYPE +GLOBAL +DEFAULT +[0-9]+ +_edata
+#...
+ +[0-9]+: +[a-f0-9]+ +0 +NOTYPE +GLOBAL +DEFAULT +[0-9]+ +_end
+#...
+ +[0-9]+: +[a-f0-9]+ +0 +NOTYPE +GLOBAL +DEFAULT +[0-9]+ +__bss_start
+#...

diff --git a/ld/testsuite/ld-elf/pr23162a.c b/ld/testsuite/ld-elf/pr23162a.c
new file mode 100644 (file)
index 0000000..cd0130c
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr23162a.c
@@ -0,0 +1,4 @@
+void
+foo (void)
+{
+}

diff --git a/ld/testsuite/ld-elf/pr23162b.c b/ld/testsuite/ld-elf/pr23162b.c
new file mode 100644 (file)
index 0000000..8476120
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr23162b.c
@@ -0,0 +1,20 @@
+static char *_edata_p;
+static char *_end_p;
+static char *__bss_start_p;
+extern char *_end;
+extern char *_edata;
+extern char *__bss_start;
+
+void
+bar (void)
+{
+  _edata_p = (char*) &_edata;
+  _end_p = (char*) &_end;
+  __bss_start_p = (char*) &__bss_start;
+}
+
+void
+_start ()
+{
+  bar ();
+}

diff --git a/ld/testsuite/ld-elf/shared.exp b/ld/testsuite/ld-elf/shared.exp
index eb54eb9..ef517ba 100644 (file)
--- a/ld/testsuite/ld-elf/shared.exp
+++ b/ld/testsuite/ld-elf/shared.exp
@@ -1349,3 +1349,49 @@ proc mix_pic_and_non_pic {xfails cflags ldflags exe} {
 
 mix_pic_and_non_pic [list "arm*-*-*" "aarch64*-*-*"] "" "" "pr19719"
 mix_pic_and_non_pic [] "-fPIE" "-pie" "pr19719pie"
+
+if { ([istarget "i?86-*-*"]
+      || [istarget "x86_64-*-*"]) } {
+    run_ld_link_tests [list \
+       [list \
+           "Build libpr23162a.so" \
+           "-shared" \
+           "" \
+           "$AFLAGS_PIC" \
+           { pr23162a.c } \
+           "" \
+           "libpr23162a.so" \
+           "-fPIC -O2" \
+       ] \
+       [list \
+           "Build pr23162a" \
+           "-pie --no-as-needed tmpdir/libpr23162a.so" \
+           "" \
+           "-mrelax-relocations=yes" \
+           { pr23162b.c } \
+           {{readelf {--dyn-syms -rW} pr23162.rd}} \
+           "pr23162a" \
+           "-fPIC -O0" \
+       ] \
+       [list \
+           "Build libpr23162b.so" \
+           "-shared --version-script=pr23162.map" \
+           "" \
+           "$AFLAGS_PIC" \
+           { pr23162a.c } \
+           "" \
+           "libpr23162b.so" \
+           "-fPIC -O2" \
+       ] \
+       [list \
+           "Build pr23162b" \
+           "-pie --no-as-needed tmpdir/libpr23162b.so" \
+           "" \
+           "-mrelax-relocations=yes" \
+           { pr23162b.c } \
+           {{readelf {--dyn-syms -rW} pr23162.rd}} \
+           "pr23162b" \
+           "-fPIC -O0" \
+       ] \
+    ]
+}