linux-kernel - [PATCH 4.9 29/29] x86/xen: Add unwind hint annotations to xen_setup

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Date:   Mon,  4 Jun 2018 08:58:25 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Josh Poimboeuf <jpoimboe@...hat.com>
Subject: [PATCH 4.9 29/29] x86/xen: Add unwind hint annotations to xen_setup_gdt

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

Not needed in mainline as this function got rewritten in 4.12

This enables objtool to grok the iret in the middle of a C function.

This matches commit 76846bf3cb09 ("x86/asm: Add unwind hint annotations
to sync_core()")

Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/xen/enlighten.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -75,6 +75,7 @@
 #include <asm/mwait.h>
 #include <asm/pci_x86.h>
 #include <asm/cpu.h>
+#include <asm/unwind_hints.h>
 
 #ifdef CONFIG_ACPI
 #include <linux/acpi.h>
@@ -1452,10 +1453,12 @@ static void __ref xen_setup_gdt(int cpu)
 		 * GDT. The new GDT has  __KERNEL_CS with CS.L = 1
 		 * and we are jumping to reload it.
 		 */
-		asm volatile ("pushq %0\n"
+		asm volatile (UNWIND_HINT_SAVE
+			      "pushq %0\n"
 			      "leaq 1f(%%rip),%0\n"
 			      "pushq %0\n"
 			      "lretq\n"
+			      UNWIND_HINT_RESTORE
 			      "1:\n"
 			      : "=&r" (dummy) : "0" (__KERNEL_CS));