Patch "arm64: Make sure SPsel is always set" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

arm64: Make sure SPsel is always set

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm64-make-sure-spsel-is-always-set.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Marc Zyngier <[email protected]>
Date: Tue, 26 Sep 2017 15:57:16 +0100
Subject: arm64: Make sure SPsel is always set

From: Marc Zyngier <[email protected]>

commit 5371513fb338fb9989c569dc071326d369d6ade8 upstream.

When the kernel is entered at EL2 on an ARMv8.0 system, we construct the EL1 pstate and make sure this uses the the EL1 stack pointer (we perform an exception return to EL1h).

But if the kernel is either entered at EL1 or stays at EL2 (because we're on a VHE-capable system), we fail to set SPsel, and use whatever stack selection the higher exception level has choosen for us.

Let's not take any chance, and make sure that SPsel is set to one before we decide the mode we're going to run in.

---
 arch/arm64/kernel/head.S |    1 +
 1 file changed, 1 insertion(+)

@@ -486,6 +486,7 @@ ENTRY(kimage_vaddr)
  * booted in EL1 or EL2 respectively.
  */
 ENTRY(el2_setup)
+	msr	SPsel, #1			// We want to use SP_EL{1,2}
 	mrs	x0, CurrentEL
 	cmp	x0, #CurrentEL_EL2
 	b.ne	1f

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/arm64-make-sure-spsel-is-always-set.patch