linux-kernel - [PATCH 2/4] x86,xen,objtool: Add UNWIND hint

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Date:   Fri, 08 Apr 2022 11:45:54 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        rick.p.edgecombe@...el.com, jpoimboe@...hat.com,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 2/4] x86,xen,objtool: Add UNWIND hint

SYM_CODE_START*() doesn't get auto-validated and needs an UNWIND hint
to get checked, add one.

  vmlinux.o: warning: objtool: pvh_start_xen()+0x0: unreachable

Reported-by: Thomas Gleixner <tglx@...utronix.de>
Reported-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/platform/pvh/head.S |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/x86/platform/pvh/head.S
+++ b/arch/x86/platform/pvh/head.S
@@ -50,6 +50,7 @@
 #define PVH_DS_SEL		(PVH_GDT_ENTRY_DS * 8)
 
 SYM_CODE_START_LOCAL(pvh_start_xen)
+	UNWIND_HINT_EMPTY
 	cld
 
 	lgdt (_pa(gdt))