x86/xen: Make hypercall_page noinstr

vmlinux.o: warning: objtool: xen_set_debugreg()+0x3: call to hypercall_page() leaves .noinstr.text section
vmlinux.o: warning: objtool: xen_get_debugreg()+0x3: call to hypercall_page() leaves .noinstr.text section
vmlinux.o: warning: objtool: xen_irq_enable()+0x24: call to hypercall_page() leaves .noinstr.text section
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20210624095148.810950584@infradead.org

arch/x86/xen/xen-head.S

@@ -20,7 +20,7 @@
 #include <xen/interface/xen-mca.h>
 #include <asm/xen/interface.h>
 
-.pushsection .text
+.pushsection .noinstr.text, "ax"
 	.balign PAGE_SIZE
 SYM_CODE_START(hypercall_page)
 	.rept (PAGE_SIZE / 32)