Messages in this thread |  | | Date | Tue, 12 Jul 2022 18:38:44 +0200 | From | Greg KH <> | Subject | Build warnings in Xen 5.15.y and 5.10.y with retbleed backports |
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Hi all,
I'm seeing the following build warning: arch/x86/kernel/head_64.o: warning: objtool: xen_hypercall_mmu_update(): can't find starting instruction in the 5.15.y and 5.10.y retbleed backports.
I don't know why just this one hypercall is being called out by objtool, and this warning isn't in 5.18 and Linus's tree due to I think commit 5b2fc51576ef ("x86/ibt,xen: Sprinkle the ENDBR") being there.
But, is this a ret call that we "forgot" here? It's a "real" ret in Linus's branch:
.pushsection .noinstr.text, "ax" .balign PAGE_SIZE SYM_CODE_START(hypercall_page) .rept (PAGE_SIZE / 32) UNWIND_HINT_FUNC ANNOTATE_NOENDBR ANNOTATE_UNRET_SAFE ret /* * Xen will write the hypercall page, and sort out ENDBR. */ .skip 31, 0xcc .endr
while 5.15.y and older has: .pushsection .text .balign PAGE_SIZE SYM_CODE_START(hypercall_page) .rept (PAGE_SIZE / 32) UNWIND_HINT_FUNC .skip 31, 0x90 ANNOTATE_UNRET_SAFE RET .endr
So should the "ret" remain or be turned into "RET" in mainline right now?
thanks,
greg k-h
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