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authorH.J. Lu <hjl.tools@gmail.com>2016-03-04 15:28:59 -0800
committerH.J. Lu <hjl.tools@gmail.com>2016-03-04 16:15:41 -0800
commit21683b5a7d9b8460e120e061f66a6ad84fa47e98 (patch)
tree213f6c1b6e68e9e4ff61eb76055925b0759476dd /sysdeps/x86_64
parent684ce7e0fc57830ff7c5909e5794f571631ee83f (diff)
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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.
Diffstat (limited to 'sysdeps/x86_64')
-rw-r--r--sysdeps/x86_64/start.S6
1 files changed, 4 insertions, 2 deletions
diff --git a/sysdeps/x86_64/start.S b/sysdeps/x86_64/start.S
index 1374974307..2369b69ec3 100644
--- 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