From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> commit f4b4bc10b0b85ec66f1a9bf5dddf475e6695b6d2 upstream. 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@xxxxxxxx> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Link: https://lore.kernel.org/r/0883bde1d7a1fb3b6a4c952bc0200e873752f609.1611263462.git.jpoimboe@xxxxxxxxxx Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/xen/xen-head.S | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/arch/x86/xen/xen-head.S +++ b/arch/x86/xen/xen-head.S @@ -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) \
