x86/xen: Mark cpu_bringup_and_idle() as dead_end_function
commit 9af9dcf11bda3e2c0e24c1acaacb8685ad974e93 upstream.
The asm_cpu_bringup_and_idle() function is required to push the return
value on the stack in order to make ORC happy, but the only reason
objtool doesn't complain is because of a happy accident.
The thing is that asm_cpu_bringup_and_idle() doesn't return, so
validate_branch() never terminates and falls through to the next
function, which in the normal case is the hypercall_page. And that, as
it happens, is 4095 NOPs and a RET.
Make asm_cpu_bringup_and_idle() terminate on it's own, by making the
function it calls as a dead-end. This way we no longer rely on what
code happens to come after.
Fixes: c3881eb58d56 ("x86/xen: Make the secondary CPU idle tasks reliable")
Signed-off-by: Peter Zijlstra (Intel) <firstname.lastname@example.org>
Reviewed-by: Juergen Gross <email@example.com>
Reviewed-by: Miroslav Benes <firstname.lastname@example.org>
Signed-off-by: Greg Kroah-Hartman <email@example.com>
1 file changed