[Bug target/65248] New: [5 Regression] Copy relocation in PIE against protected symbol

[Bug target/65248] New: [5 Regression] Copy relocation in PIE against protected symbol

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248

            Bug ID: 65248
           Summary: [5 Regression] Copy relocation in PIE against
                    protected symbol
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
                CC: tmsriram at google dot com

Copy relocation doesn't work with protected symbol and BFD linker
enforces it.  GCC 5 uses copy relocation in PIE. It either causes
linker error or run-time error:

[hjl@gnu-6 copyreloc-prot]$ cat x.c
extern int a;

extern void bar (void);

int main()
{
  bar ();
  if (a != 30)
    __builtin_abort();
  return 0;
}
[hjl@gnu-6 copyreloc-prot]$ cat bar.c
int a;

__attribute__((visibility("protected"))) int a;

void
bar ()
{
  a = 30;
}
[hjl@gnu-6 copyreloc-prot]$ make
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -pie -O3 -fpie    -c -o x.o x.c
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -pie -O3 -fpic    -c -o bar.o
bar.c
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -pie  -shared -o libbar.so
bar.o
/export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -pie -O3 -o x x.o libbar.so
-Wl,-R,.
/usr/local/bin/ld: copy reloc against protected `a' is invalid
/usr/local/bin/ld: failed to set dynamic section sizes: Bad value
collect2: error: ld returned 1 exit status
make: *** [x] Error 1
[hjl@gnu-6 copyreloc-prot]$ /export/build/gnu/gcc/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc/build-x86_64-linux/gcc/ -pie -O3 -o x x.o libbar.so
-Wl,-R,. -fuse-ld=gold
[hjl@gnu-6 copyreloc-prot]$ ./x
Aborted
[hjl@gnu-6 copyreloc-prot]$

[Bug target/65248] [5 Regression] Copy relocation in PIE against protected symbol

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-02-28
   Target Milestone|---                         |5.0
     Ever confirmed|0                           |1

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
A patch is posted at

https://gcc.gnu.org/ml/gcc-patches/2015-02/msg01746.html

[Bug target/65248] [5 Regression] Copy relocation in PIE against protected symbol

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|                            |x86_64-*-*, i?86-*-*
           Priority|P3                          |P1

[Bug target/65248] Copy relocation in PIE against protected symbol

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[5 Regression] Copy         |Copy relocation in PIE
                   |relocation in PIE against   |against protected symbol
                   |protected symbol            |

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
It never worked with normal executable.  I proposed a solution:

https://groups.google.com/forum/#!topic/x86-64-abi/Nbfw6bX0DpI

[Bug target/65248] Copy relocation against protected symbol doesn't work

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
BInutils, glibc and GCC patches are posted at

https://gcc.gnu.org/ml/gcc-patches/2015-03/msg00257.html

[Bug target/65248] Copy relocation against protected symbol doesn't work

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugdal at aerifal dot cx

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> ---
*** Bug 55012 has been marked as a duplicate of this bug. ***

[Bug target/65248] Copy relocation against protected symbol doesn't work

[hjl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248

--- Comment #5 from hjl at gcc dot gnu.org <hjl at gcc dot gnu.org> ---
Author: hjl
Date: Fri Mar 27 18:11:00 2015
New Revision: 221742

URL: https://gcc.gnu.org/viewcvs?rev=221742&root=gcc&view=rev
Log:
Add default_binds_local_p_2 and use it for x86

Protected data symbol means that it can't be pre-emptied.  It doesn't mean
its address won't be external.  This is true for pointer to protected
function.  With copy relocation, address of protected data defined in the
shared library may also be external.  We only know that for sure at
run-time.  TARGET_BINDS_LOCAL_P should return false on protected data
symbol.

gcc/

    PR target/65248
    * output.h (default_binds_local_p_2): New.
    * varasm.c (default_binds_local_p_2): Renamed to ...
    (default_binds_local_p_3): This.  Don't return true on protected
    data symbol if protected data may be external.
    (default_binds_local_p): Use default_binds_local_p_3.
    (default_binds_local_p_1): Likewise.
    (default_binds_local_p_2): New.
    * config/i386/i386.c (TARGET_BINDS_LOCAL_P): Set to
    default_binds_local_p_2 if TARGET_MACHO is undefined.

gcc/testsuite/

    PR target/65248
    * gcc.target/i386/pr65248-1.c: New file.
    * gcc.target/i386/pr65248-2.c: Likewise.
    * gcc.target/i386/pr65248-3.c: Likewise.
    * gcc.target/i386/pr65248-4.c: Likewise.

Added:
    trunk/gcc/testsuite/gcc.target/i386/pr65248-1.c
    trunk/gcc/testsuite/gcc.target/i386/pr65248-2.c
    trunk/gcc/testsuite/gcc.target/i386/pr65248-3.c
    trunk/gcc/testsuite/gcc.target/i386/pr65248-4.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/i386/i386.c
    trunk/gcc/output.h
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/varasm.c

[Bug target/65248] Copy relocation against protected symbol doesn't work

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65248

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #6 from H.J. Lu <hjl.tools at gmail dot com> ---
Fixed for GCC 5. No plan for backport.