From a985e9b9deabd81e16754584f4397a638e9d3f36 Mon Sep 17 00:00:00 2001

From: Nick Clifton <nickc@redhat.com>

Date: Mon, 5 Feb 2018 09:12:42 +0000

Subject: [PATCH] Import patch from mainline to remove PROVODE qualifiers

 around definitions of __CTOR_LIST__ and __DTOR_LIST__ in PE linker scripts.

	PR 22762

	* scripttempl/pe.sc: Remove PROVIDE()s from __CTOR_LIST__ and

	__DTOR_LIST__ symbols.  Add a comment explaining why this is

	necessary.

	* scripttemp/pep.sc: Likewise.

	* ld.texinfo (PROVIDE): Add a note about the effect of common

	symbols.

---

 ld/ChangeLog          | 14 ++++++++++++++

 ld/ld.texinfo         |  6 ++++++

 ld/scripttempl/pe.sc  | 24 ++++++++++++++++++++----

 ld/scripttempl/pep.sc | 24 ++++++++++++++++++++----

 4 files changed, 60 insertions(+), 8 deletions(-)

diff --git a/ld/ChangeLog b/ld/ChangeLog

index 0f00265029c..bf129a121cc 100644

--- a/ld/ChangeLog

+++ b/ld/ChangeLog

@@ -1,3 +1,17 @@

+2018-02-05  Nick Clifton  <nickc@redhat.com>

+

+	Import from mainline:

+

+	2018-02-03  Nick Clifton  <nickc@redhat.com>

+

+	PR 22762

+	* scripttempl/pe.sc: Remove PROVIDE()s from __CTOR_LIST__ and

+	__DTOR_LIST__ symbols.  Add a comment explaining why this is

+	necessary.

+	* scripttemp/pep.sc: Likewise.

+	* ld.texinfo (PROVIDE): Add a note about the effect of common

+	symbols.

+

 2018-01-27  Nick Clifton  <nickc@redhat.com>

 	This is the 2.30 release:

diff --git a/ld/ld.texinfo b/ld/ld.texinfo

index c89915f1aaa..764c4017c7b 100644

--- a/ld/ld.texinfo

+++ b/ld/ld.texinfo

@@ -4001,6 +4001,12 @@ underscore), the linker will silently use the definition in the program.

 If the program references @samp{etext} but does not define it, the

 linker will use the definition in the linker script.

+Note - the @code{PROVIDE} directive considers a common symbol to be

+defined, even though such a symbol could be combined with the symbol

+that the @code{PROVIDE} would create.  This is particularly important

+when considering constructor and destructor list symbols such as

+@samp{__CTOR_LIST__} as these are often defined as common symbols.

+

 @node PROVIDE_HIDDEN

 @subsection PROVIDE_HIDDEN

 @cindex PROVIDE_HIDDEN

diff --git a/ld/scripttempl/pe.sc b/ld/scripttempl/pe.sc

index c8a45ca09d1..f56d783ea03 100644

--- a/ld/scripttempl/pe.sc

+++ b/ld/scripttempl/pe.sc

@@ -98,8 +98,22 @@ SECTIONS

     ${RELOCATING+*(.glue_7t)}

     ${RELOCATING+*(.glue_7)}

     ${CONSTRUCTING+

-       PROVIDE(___CTOR_LIST__ = .);

-       PROVIDE(__CTOR_LIST__ = .);

+       /* Note: we always define __CTOR_LIST__ and ___CTOR_LIST__ here,

+          we do not PROVIDE them.  This is because the ctors.o startup

+	  code in libgcc defines them as common symbols, with the 

+          expectation that they will be overridden by the definitions

+	  here.  If we PROVIDE the symbols then they will not be

+	  overridden and global constructors will not be run.

+	  

+	  This does mean that it is not possible for a user to define

+	  their own __CTOR_LIST__ and __DTOR_LIST__ symbols.  If that

+	  ability is needed a custom linker script will have to be

+	  used.  (The custom script can just be a copy of this script

+	  with the PROVIDE() qualifiers added).

+

+	  See PR 22762 for more details.  */

+       ___CTOR_LIST__ = .;

+       __CTOR_LIST__ = .;

        LONG (-1);

        KEEP(*(.ctors));

        KEEP(*(.ctor));

@@ -107,8 +121,10 @@ SECTIONS

        LONG (0);

      }

     ${CONSTRUCTING+

-       PROVIDE(___DTOR_LIST__ = .);

-       PROVIDE(__DTOR_LIST__ = .);

+       /* See comment about __CTOR_LIST__ above.  The same reasoning

+          applies here too.  */

+       ___DTOR_LIST__ = .;

+       __DTOR_LIST__ = .;

        LONG (-1);

        KEEP(*(.dtors));

        KEEP(*(.dtor));

diff --git a/ld/scripttempl/pep.sc b/ld/scripttempl/pep.sc

index 8daacb27630..3c6c84da9bf 100644

--- a/ld/scripttempl/pep.sc

+++ b/ld/scripttempl/pep.sc

@@ -99,8 +99,22 @@ SECTIONS

     ${RELOCATING+*(.glue_7)}

     ${CONSTRUCTING+. = ALIGN(8);}

     ${CONSTRUCTING+

-       PROVIDE(___CTOR_LIST__ = .);

-       PROVIDE(__CTOR_LIST__ = .);

+       /* Note: we always define __CTOR_LIST__ and ___CTOR_LIST__ here,

+          we do not PROVIDE them.  This is because the ctors.o startup

+	  code in libgcc defines them as common symbols, with the 

+          expectation that they will be overridden by the definitions

+	  here.  If we PROVIDE the symbols then they will not be

+	  overridden and global constructors will not be run.

+	  

+	  This does mean that it is not possible for a user to define

+	  their own __CTOR_LIST__ and __DTOR_LIST__ symbols.  If that

+	  ability is needed a custom linker script will have to be

+	  used.  (The custom script can just be a copy of this script

+	  with the PROVIDE() qualifiers added).

+

+	  See PR 22762 for more details.  */

+       ___CTOR_LIST__ = .;

+       __CTOR_LIST__ = .;

        LONG (-1); LONG (-1);

        KEEP (*(.ctors));

        KEEP (*(.ctor));

@@ -108,8 +122,10 @@ SECTIONS

        LONG (0); LONG (0);

      }

     ${CONSTRUCTING+

-       PROVIDE(___DTOR_LIST__ = .);

-       PROVIDE(__DTOR_LIST__ = .);

+       /* See comment about __CTOR_LIST__ above.  The same reasoning

+    	  applies here too.  */

+       ___DTOR_LIST__ = .;

+       __DTOR_LIST__ = .;

        LONG (-1); LONG (-1);

        KEEP (*(.dtors));

        KEEP (*(.dtor));

-- 

2.18.2