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.
git-mirror · Mar 5, 2016 · 21683b5 · 21683b5
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diff --git a/ChangeLog b/ChangeLog
@@ -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

diff --git a/sysdeps/x86_64/start.S b/sysdeps/x86_64/start.S
@@ -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