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Re: PING^3: [PATCH 1/2] Add ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA to x86
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Sun, 29 Mar 2015 09:34:23 -0700
- Subject: Re: PING^3: [PATCH 1/2] Add ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA to x86
- Authentication-results: sourceware.org; auth=none
- References: <CAMe9rOrNY=Di55u98NOSqnHrppVgUUg7TrbJkgpXs7DAmgE-5A at mail dot gmail dot com>
On Wed, Mar 25, 2015 at 4:33 PM, H.J. Lu <firstname.lastname@example.org> wrote:
> On Wed, Mar 18, 2015 at 7:43 AM, H.J. Lu <email@example.com> wrote:
>> On Wed, Mar 11, 2015 at 10:24 AM, H.J. Lu <firstname.lastname@example.org> wrote:
>>> On Thu, Mar 5, 2015 at 4:19 PM, H.J. Lu <email@example.com> wrote:
>>>> With copy relocation, address of protected data defined in the shared
>>>> library may be external. When there is a relocation against the
>>>> protected data symbol within the shared library, we need to check if we
>>>> should skip the definition in the executable copied from the protected
>>>> data. This patch adds ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA and defines
>>>> it for x86. If ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA isn't 0, do_lookup_x
>>>> will skip the data definition in the executable from copy reloc.
>>>> I only defined DL_EXTERN_PROTECTED_DATA for x86. Other targets can
>>>> define DL_EXTERN_PROTECTED_DATA and update elf_machine_type_class to
>>>> support copy relocation on protected data.
>>>> I will submit a testcase in a separate email.
>>>> Tested on x86-32 and x86-64. OK for master?
>>>> [BZ #17711]
>>>> * elf/dl-lookup.c (do_lookup_x): When UNDEF_MAP is NULL, which
>>>> indicates it is called from do_lookup_x on relocation against
>>>> protected data, skip the data definion in the executable from
>>>> copy reloc.
>>>> (_dl_lookup_symbol_x): Pass ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA,
>>>> instead of ELF_RTYPE_CLASS_PLT, to do_lookup_x for
>>>> EXTERN_PROTECTED_DATA relocation against STT_OBJECT symbol.
>>>> * sysdeps/generic/ldsodefs.h * (ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA):
>>>> New. Defined to 4 if DL_EXTERN_PROTECTED_DATA is defined,
>>>> otherwise to 0.
>>>> * sysdeps/i386/dl-lookupcfg.h (DL_EXTERN_PROTECTED_DATA): New.
>>>> * sysdeps/i386/dl-machine.h (elf_machine_type_class): Set class
>>>> to ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA for R_386_GLOB_DAT.
>>>> * sysdeps/x86_64/dl-lookupcfg.h (DL_EXTERN_PROTECTED_DATA): New.
>>>> * sysdeps/x86_64/dl-machine.h (elf_machine_type_class): Set class
>>>> to ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA for R_X86_64_GLOB_DAT.
> Any comments, objections? The patch is at
GCC bug has been fixed for GCC 5. I will check in this patch
on Tuesday, March 31.