x86/build: Fix linker fill bytes quirk/incompatibility for ld.lld

With ":text =0xcccc", ld.lld fills unused text area with 0xcccc0000.
Example objdump -D output:

ffffffff82b04203: 00 00 add %al,(%rax)
ffffffff82b04205: cc int3
ffffffff82b04206: cc int3
ffffffff82b04207: 00 00 add %al,(%rax)
ffffffff82b04209: cc int3
ffffffff82b0420a: cc int3

Replace it with ":text =0xcccccccc", so we get the following instead:

ffffffff82b04203: cc int3
ffffffff82b04204: cc int3
ffffffff82b04205: cc int3
ffffffff82b04206: cc int3
ffffffff82b04207: cc int3
ffffffff82b04208: cc int3

gcc/ld doesn't seem to have the same issue. The generated code stays the
same for gcc/ld.

Signed-off-by: Song Liu <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Acked-by: Peter Zijlstra (Intel) <[e-mail]>
Fixes: 7705dc855797 ("x86/vmlinux: Use INT3 instead of NOP for linker fill bytes")
Link: https://lore.kernel.org/r/[e-mail]

arch/x86/kernel/vmlinux.lds.S

···
 		ALIGN_ENTRY_TEXT_END
 		*(.gnu.warning)
 
-	} :text =0xcccc
+	} :text = 0xcccccccc
 
 	/* End of text section, which should occupy whole number of pages */
 	_etext = .;