| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.10 010/130] x86/xen: Support objtool vmlinux.o validation in xen-head.S | Date | Tue, 12 Jul 2022 20:37:36 +0200 |
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From: Josh Poimboeuf <jpoimboe@redhat.com>
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@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/0883bde1d7a1fb3b6a4c952bc0200e873752f609.1611263462.git.jpoimboe@redhat.com Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- 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) \
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