PATCH: Replace @PLT with @GOTPCREL(%rip) in call

[H.J. Lu]

On Thu, Mar 3, 2016 at 4:03 PM, Roland McGrath <roland@hack.frob.com> wrote:
>> --- a/sysdeps/x86_64/crti.S
>> +++ b/sysdeps/x86_64/crti.S
>> @@ -66,7 +66,7 @@ _init:
>>       movq PREINIT_FUNCTION@GOTPCREL(%rip), %rax
>>       testq %rax, %rax
>>       je .Lno_weak_fn
>> -     call PREINIT_FUNCTION@PLT
>> +     call *PREINIT_FUNCTION@GOTPCREL(%rip)
>
> Can't this just be "call *%rax"?

Good idea.

>> --- a/sysdeps/x86_64/start.S
>> +++ b/sysdeps/x86_64/start.S
>> @@ -105,7 +105,7 @@ ENTRY (_start)
>>
>>       /* Call the user's main function, and exit with its value.
>>          But let the libc call main.    */
>> -     call __libc_start_main@PLT
>> +     call *__libc_start_main@GOTPCREL(%rip)
>>  #else
>>       /* Pass address of our own entry points to .fini and .init.  */
>>       mov $__libc_csu_fini, %R8_LP
>
> In the general case, foo@PLT is preferable to foo@GOTPCREL(%rip) because it
> allows for lazy resolution.  That's not worthwhile here because _start is
> presumably always run and run very early.  But it merits a comment saying
> why it's not following the normal pattern for PIC calls.
>

Here are updated patches.


-- 
H.J.
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