x86/asm/entry/64: Reduce padding in execve stubs

execve stubs are 7 bytes only. Padding them to 16 bytes is a
waste.

   text	   data	    bss	    dec	    hex	filename
  12594	      0	      0	  12594	   3132	entry_64.o.before
  12530	      0	      0	  12530	   30f2	entry_64.o

Run-tested.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1428439424-7258-8-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/entry_64.S

@@ -511,8 +511,12 @@ return_from_execve:
 	jmp	int_ret_from_sys_call
 	CFI_ENDPROC
 END(stub_execve)
-
-ENTRY(stub_execveat)
+/*
+ * Remaining execve stubs are only 7 bytes long.
+ * ENTRY() often aligns to 16 bytes, which in this case has no benefits.
+ */
+	.align	8
+GLOBAL(stub_execveat)
 	CFI_STARTPROC
 	DEFAULT_FRAME 0, 8
 	call	sys_execveat
@@ -521,14 +525,16 @@ ENTRY(stub_execveat)
 END(stub_execveat)
 
 #ifdef CONFIG_X86_X32_ABI
-ENTRY(stub_x32_execve)
+	.align	8
+GLOBAL(stub_x32_execve)
 	CFI_STARTPROC
 	DEFAULT_FRAME 0, 8
 	call	compat_sys_execve
 	jmp	return_from_execve
 	CFI_ENDPROC
 END(stub_x32_execve)
-ENTRY(stub_x32_execveat)
+	.align	8
+GLOBAL(stub_x32_execveat)
 	CFI_STARTPROC
 	DEFAULT_FRAME 0, 8
 	call	compat_sys_execveat
@@ -538,13 +544,15 @@ END(stub_x32_execveat)
 #endif
 
 #ifdef CONFIG_IA32_EMULATION
-ENTRY(stub32_execve)
+	.align	8
+GLOBAL(stub32_execve)
 	CFI_STARTPROC
 	call	compat_sys_execve
 	jmp	return_from_execve
 	CFI_ENDPROC
 END(stub32_execve)
-ENTRY(stub32_execveat)
+	.align	8
+GLOBAL(stub32_execveat)
 	CFI_STARTPROC
 	call	compat_sys_execveat
 	jmp	return_from_execve