x86/xen: Add ANNOTATE_NOENDBR to startup_xen()

The startup_xen() kernel entry point is referenced by the ".note.Xen"
section, and is the real entry point of the VM. Control transfer is
through IRET, which *could* set NEED_ENDBR, however Xen currently does
no such thing.

Add ANNOTATE_NOENDBR to silence future objtool warnings.

Fixes: ed53a0d97192 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Link: https://lkml.kernel.org/r/a87bd48b06d11ec4b98122a429e71e489b4e48c3.1650300597.git.jpoimboe@redhat.com

diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index ac17196..3a2cd93 100644 (file)
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -45,6 +45,7 @@ SYM_CODE_END(hypercall_page)
        __INIT
 SYM_CODE_START(startup_xen)
        UNWIND_HINT_EMPTY
+       ANNOTATE_NOENDBR
        cld
 
        /* Clear .bss */