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From: "hjl.tools at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/65248] New: [5 Regression] Copy relocation in PIE against protected symbol
Date: Sat, 28 Feb 2015 09:24:00 -0000
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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]$