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Re: [committed, PATCH] PR ld/19031: R_386_PC32 does not imply a call


Thanks!

On 30 September 2015 at 11:46, H.J. Lu <hongjiu.lu@intel.com> wrote:
> Since something like ".long foo - ." may be used as pointer, we make
> sure that PLT is used if foo is a function defined in a shared library.
>
> bfd/
>
>         PR ld/19031
>         * elf32-i386.c (elf_i386_check_relocs): Set
>         pointer_equality_needed for R_386_PC32 reloc in non-code
>         sections.
>
> ld/testsuite/
>
>         PR ld/19031
>         * ld-i386/i386.exp: Run PR ld/19031 test.
>         * ld/testsuite/ld-i386/pr19031.out: New file.
>         * ld/testsuite/ld-i386/pr19031a.c: Likewise.
>         * ld/testsuite/ld-i386/pr19031b.S: Likewise.
>         * ld/testsuite/ld-i386/pr19031c.c: Likewise.
> ---
>  bfd/ChangeLog                    |  7 +++++++
>  bfd/elf32-i386.c                 | 10 +++++++++-
>  ld/testsuite/ChangeLog           |  9 +++++++++
>  ld/testsuite/ld-i386/i386.exp    | 16 ++++++++++++++++
>  ld/testsuite/ld-i386/pr19031.out |  1 +
>  ld/testsuite/ld-i386/pr19031a.c  |  4 ++++
>  ld/testsuite/ld-i386/pr19031b.S  | 23 +++++++++++++++++++++++
>  ld/testsuite/ld-i386/pr19031c.c  | 14 ++++++++++++++
>  8 files changed, 83 insertions(+), 1 deletion(-)
>  create mode 100644 ld/testsuite/ld-i386/pr19031.out
>  create mode 100644 ld/testsuite/ld-i386/pr19031a.c
>  create mode 100644 ld/testsuite/ld-i386/pr19031b.S
>  create mode 100644 ld/testsuite/ld-i386/pr19031c.c
>
> diff --git a/bfd/ChangeLog b/bfd/ChangeLog
> index a218d44..3610948 100644
> --- a/bfd/ChangeLog
> +++ b/bfd/ChangeLog
> @@ -1,5 +1,12 @@
>  2015-09-30  H.J. Lu  <hongjiu.lu@intel.com>
>
> +       PR ld/19031
> +       * elf32-i386.c (elf_i386_check_relocs): Set
> +       pointer_equality_needed for R_386_PC32 reloc in non-code
> +       sections.
> +
> +2015-09-30  H.J. Lu  <hongjiu.lu@intel.com>
> +
>         PR ld/19013
>         * elflink.c (_bfd_elf_merge_sections): Only merge input bfds
>         that have the compatible ELF machine code with the output bfd.
> diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
> index 9390450..0a06191 100644
> --- a/bfd/elf32-i386.c
> +++ b/bfd/elf32-i386.c
> @@ -1772,7 +1772,15 @@ elf_i386_check_relocs (bfd *abfd,
>               /* We may need a .plt entry if the function this reloc
>                  refers to is in a shared lib.  */
>               h->plt.refcount += 1;
> -             if (r_type != R_386_PC32)
> +             if (r_type == R_386_PC32)
> +               {
> +                 /* Since something like ".long foo - ." may be used
> +                    as pointer, make sure that PLT is used if foo is
> +                    a function defined in a shared library.  */
> +                 if ((sec->flags & SEC_CODE) == 0)
> +                   h->pointer_equality_needed = 1;
> +               }
> +             else
>                 {
>                   h->pointer_equality_needed = 1;
>                   /* R_386_32 can be resolved at run-time.  */
> diff --git a/ld/testsuite/ChangeLog b/ld/testsuite/ChangeLog
> index 7f1b7ac..9c77301 100644
> --- a/ld/testsuite/ChangeLog
> +++ b/ld/testsuite/ChangeLog
> @@ -1,5 +1,14 @@
>  2015-09-30  H.J. Lu  <hongjiu.lu@intel.com>
>
> +       PR ld/19031
> +       * ld-i386/i386.exp: Run PR ld/19031 test.
> +       * ld/testsuite/ld-i386/pr19031.out: New file.
> +       * ld/testsuite/ld-i386/pr19031a.c: Likewise.
> +       * ld/testsuite/ld-i386/pr19031b.S: Likewise.
> +       * ld/testsuite/ld-i386/pr19031c.c: Likewise.
> +
> +2015-09-30  H.J. Lu  <hongjiu.lu@intel.com>
> +
>         PR ld/19013
>         * ld-x86-64/pr19013-nacl.d: New file.
>         * ld-x86-64/pr19013-x32.d: Likewise.
> diff --git a/ld/testsuite/ld-i386/i386.exp b/ld/testsuite/ld-i386/i386.exp
> index 6213dbe..8cddfce 100644
> --- a/ld/testsuite/ld-i386/i386.exp
> +++ b/ld/testsuite/ld-i386/i386.exp
> @@ -490,6 +490,14 @@ if { [isnative]
>             {{readelf {-Wrd} pr18900b.rd}} \
>             "pr18900b" \
>         ] \
> +       [list \
> +           "Build pr19031.so" \
> +           "-shared" \
> +           "-fPIC" \
> +           { pr19031a.c } \
> +           "" \
> +           "pr19031.so" \
> +       ] \
>      ]
>
>      run_ld_link_exec_tests [] [list \
> @@ -552,6 +560,14 @@ if { [isnative]
>             "pr18900" \
>             "pr18900.out" \
>         ] \
> +       [list \
> +           "Run pr19031" \
> +           "tmpdir/pr19031.so" \
> +           "" \
> +           { pr19031b.S pr19031c.c } \
> +           "pr19031" \
> +           "pr19031.out" \
> +       ] \
>      ]
>  }
>
> diff --git a/ld/testsuite/ld-i386/pr19031.out b/ld/testsuite/ld-i386/pr19031.out
> new file mode 100644
> index 0000000..d86bac9
> --- /dev/null
> +++ b/ld/testsuite/ld-i386/pr19031.out
> @@ -0,0 +1 @@
> +OK
> diff --git a/ld/testsuite/ld-i386/pr19031a.c b/ld/testsuite/ld-i386/pr19031a.c
> new file mode 100644
> index 0000000..fa34d37
> --- /dev/null
> +++ b/ld/testsuite/ld-i386/pr19031a.c
> @@ -0,0 +1,4 @@
> +void
> +f (void)
> +{
> +}
> diff --git a/ld/testsuite/ld-i386/pr19031b.S b/ld/testsuite/ld-i386/pr19031b.S
> new file mode 100644
> index 0000000..3249652
> --- /dev/null
> +++ b/ld/testsuite/ld-i386/pr19031b.S
> @@ -0,0 +1,23 @@
> +       .text
> +       .globl g
> +       .type g, @function
> +g:
> +        calll .Lfoo
> +.Lfoo:
> +        popl %eax
> +.Lbar:
> +        addl $_GLOBAL_OFFSET_TABLE_+(.Lbar-.Lfoo), %eax
> +       movl f@GOT(%eax), %eax
> +       ret
> +
> +       .globl h
> +       .type h, @function
> +h:
> +        leal zed, %eax
> +        movl zed, %ebx
> +        addl %ebx, %eax
> +       ret
> +
> +       .data
> +zed:
> +        .long f - .
> diff --git a/ld/testsuite/ld-i386/pr19031c.c b/ld/testsuite/ld-i386/pr19031c.c
> new file mode 100644
> index 0000000..60eccaf
> --- /dev/null
> +++ b/ld/testsuite/ld-i386/pr19031c.c
> @@ -0,0 +1,14 @@
> +#include <stdio.h>
> +
> +extern void *h (void);
> +extern void *g (void);
> +
> +int
> +main (void)
> +{
> +
> +  if (h () == g ())
> +    printf ("OK\n");
> +
> +  return 0;
> +}
> --
> 2.4.3
>


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