Re: PING^1: [PATCH 1/2] Mark ld.so internal mmap functions hidden in ld.so

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

Checking of the dissassemble ld.so for i686 I see no PLT stub 
being generated for mmap or it being called through it:

$ objdump -d elf/ld.so
[...]
    5cdc:       89 04 24                mov    %eax,(%esp)
    5cdf:       e8 fc 49 01 00          call   1a6e0 <__mmap>
[...]

Also regarding mmap I see that generated assembly generated is
not different without the patch. I do see that for the part 02
of the patch for the __libc_{open,close} with the patch a 
call to __x86.get_pc_thunk.bx is removed (which is the intention
of the patch).

Am I missing something here?

On 14-12-2015 12:10, H.J. Lu wrote:
> Ping.
> 
> On Mon, Dec 7, 2015 at 11:00 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> Since ld.so internal mmap functions are only used internally in ld.so,
>> they can be made hidden.  Don't hide __mmap on Hurd, since __mmap in
>> ld.so will be preempted by the one in libc.so after bootstrap.
>>
>>          [BZ #19122]
>>          * include/sys/mman.h [IS_IN (rtld)]: Include <dl-mman.h>.
>>          * sysdeps/generic/dl-mman.h: New file.
>>          * sysdeps/mach/hurd/dl-mman.h: Likewise.
>> ---
>>  include/sys/mman.h          |  4 ++++
>>  sysdeps/generic/dl-mman.h   | 22 ++++++++++++++++++++++
>>  sysdeps/mach/hurd/dl-mman.h | 23 +++++++++++++++++++++++
>>  3 files changed, 49 insertions(+)
>>  create mode 100644 sysdeps/generic/dl-mman.h
>>  create mode 100644 sysdeps/mach/hurd/dl-mman.h
>>
>> diff --git a/include/sys/mman.h b/include/sys/mman.h
>> index fd125ec..7026f69 100644
>> --- a/include/sys/mman.h
>> +++ b/include/sys/mman.h
>> @@ -16,6 +16,10 @@ libc_hidden_proto (__madvise)
>>  /* This one is Linux specific.  */
>>  extern void *__mremap (void *__addr, size_t __old_len,
>>                        size_t __new_len, int __flags, ...);
>> +
>> +# if IS_IN (rtld)
>> +#  include <dl-mman.h>
>> +# endif
>>  #endif
>>
>>  #endif
>> diff --git a/sysdeps/generic/dl-mman.h b/sysdeps/generic/dl-mman.h
>> new file mode 100644
>> index 0000000..9087218
>> --- /dev/null
>> +++ b/sysdeps/generic/dl-mman.h
>> @@ -0,0 +1,22 @@
>> +/* Functions with hidden attribute internal to ld.so, which are declared
>> +   in include/sys/mman.h.  Generic version.
>> +   Copyright (C) 2015 Free Software Foundation, Inc.
>> +   This file is part of the GNU C Library.
>> +
>> +   The GNU C Library is free software; you can redistribute it and/or
>> +   modify it under the terms of the GNU Lesser General Public
>> +   License as published by the Free Software Foundation; either
>> +   version 2.1 of the License, or (at your option) any later version.
>> +
>> +   The GNU C Library is distributed in the hope that it will be useful,
>> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> +   Lesser General Public License for more details.
>> +
>> +   You should have received a copy of the GNU Lesser General Public
>> +   License along with the GNU C Library; if not, see
>> +   <http://www.gnu.org/licenses/>.  */
>> +
>> +extern __typeof (__mmap) __mmap attribute_hidden;
>> +extern __typeof (__mprotect) __mprotect attribute_hidden;
>> +extern __typeof (__munmap) __munmap attribute_hidden;
>> diff --git a/sysdeps/mach/hurd/dl-mman.h b/sysdeps/mach/hurd/dl-mman.h
>> new file mode 100644
>> index 0000000..f9d7996
>> --- /dev/null
>> +++ b/sysdeps/mach/hurd/dl-mman.h
>> @@ -0,0 +1,23 @@
>> +/* Functions with hidden attribute internal to ld.so, which are declared
>> +   in include/sys/mman.h.  Hurd version.
>> +   Copyright (C) 2015 Free Software Foundation, Inc.
>> +   This file is part of the GNU C Library.
>> +
>> +   The GNU C Library is free software; you can redistribute it and/or
>> +   modify it under the terms of the GNU Lesser General Public
>> +   License as published by the Free Software Foundation; either
>> +   version 2.1 of the License, or (at your option) any later version.
>> +
>> +   The GNU C Library is distributed in the hope that it will be useful,
>> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> +   Lesser General Public License for more details.
>> +
>> +   You should have received a copy of the GNU Lesser General Public
>> +   License along with the GNU C Library; if not, see
>> +   <http://www.gnu.org/licenses/>.  */
>> +
>> +/* Can't hide __mmap on Hurd, since __mmap in ld.so will be preempted by
>> +   the one in libc.so after bootstrap.  */
>> +extern __typeof (__mprotect) __mprotect attribute_hidden;
>> +extern __typeof (__munmap) __munmap attribute_hidden;
>> --
>> 2.5.0
>>
> 
> 
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