Commit f4b4bc10 authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

x86/xen: Support objtool vmlinux.o validation in xen-head.S 



The Xen hypercall page is filled with zeros, causing objtool to fall
through all the empty hypercall functions until it reaches a real
function, resulting in a stack state mismatch.

The build-time contents of the hypercall page don't matter because the
page gets rewritten by the hypervisor.  Make it more palatable to
objtool by making each hypervisor function a true empty function, with
nops and a return.

Cc: Juergen Gross <jgross@suse.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/0883bde1d7a1fb3b6a4c952bc0200e873752f609.1611263462.git.jpoimboe@redhat.com
parent cde07a4e

arch/x86/xen/xen-head.S

+3 −2
Original line number Diff line number Diff line
@@ -68,8 +68,9 @@ SYM_CODE_END(asm_cpu_bringup_and_idle) 
	.balign PAGE_SIZE

SYM_CODE_START(hypercall_page)

	.rept (PAGE_SIZE / 32)

		UNWIND_HINT_EMPTY

		.skip 32

		UNWIND_HINT_FUNC

		.skip 31, 0x90

		ret

	.endr



#define HYPERCALL(n) \