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

Since __libc_start_main is called very early, lazy binding isn't relevant
here.  Use indirect branch via GOT to avoid extra branch to PLT slot.

	[BZ #19745]
	* sysdeps/x86_64/start.S (_start): __libc_start_main@PLT
	with *__libc_start_main@GOTPCREL(%rip) in call.
This commit is contained in:
H.J. Lu 2016-03-04 15:28:59 -08:00
parent 684ce7e0fc
commit 21683b5a7d
2 changed files with 10 additions and 2 deletions

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@ -1,3 +1,9 @@
2016-03-04 H.J. Lu <hongjiu.lu@intel.com>
[BZ #19745]
* sysdeps/x86_64/start.S (_start): Replace __libc_start_main@PLT
with *__libc_start_main@GOTPCREL(%rip) in call.
2016-03-04 Roland McGrath <roland@hack.frob.com>
* Makefile (tests-special): Add $(objpfx)c++-types-check.out only

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@ -104,8 +104,10 @@ ENTRY (_start)
mov main@GOTPCREL(%rip), %RDI_LP
/* Call the user's main function, and exit with its value.
But let the libc call main. */
call __libc_start_main@PLT
But let the libc call main. Since __libc_start_main is
called very early, lazy binding isn't relevant here. Use
indirect branch via GOT to avoid extra branch to PLT slot. */
call *__libc_start_main@GOTPCREL(%rip)
#else
/* Pass address of our own entry points to .fini and .init. */
mov $__libc_csu_fini, %R8_LP