[3.16.y-ckt stable] Patch "ARM: 8471/1: need to save/restore arm register(r11) when it is corrupted" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ARM: 8471/1: need to save/restore arm register(r11) when it is corrupted

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt23.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

---8<------------------------------------------------------------

>From c2dc4f1218c53570bdf16b76f05cf92fbabf984b Mon Sep 17 00:00:00 2001
From: Anson Huang <Anson.Huang at freescale.com>
Date: Mon, 7 Dec 2015 10:09:19 +0100
Subject: ARM: 8471/1: need to save/restore arm register(r11) when it is
 corrupted

commit fa0708b320f6da4c1104fe56e01b7abf66fd16ad upstream.

In cpu_v7_do_suspend routine, r11 is used while it is NOT
saved/restored, different compiler may have different usage
of ARM general registers, so it may cause issues during
calling cpu_v7_do_suspend.

We meet kernel fault occurs when using GCC 4.8.3, r11 contains
valid value before calling into cpu_v7_do_suspend, but when returned
from this routine, r11 is corrupted and lead to kernel fault.
Doing save/restore for those corrupted registers is a must in
assemble code.

Signed-off-by: Anson Huang <Anson.Huang at freescale.com>
Reviewed-by: Nicolas Pitre <nico at linaro.org>
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/arm/mm/proc-v7.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 0eba0d1fd65a..ce9444e9d001 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -95,7 +95,7 @@ ENDPROC(cpu_v7_dcache_clean_area)
 .equ	cpu_v7_suspend_size, 4 * 9
 #ifdef CONFIG_ARM_CPU_SUSPEND
 ENTRY(cpu_v7_do_suspend)
-	stmfd	sp!, {r4 - r10, lr}
+	stmfd	sp!, {r4 - r11, lr}
 	mrc	p15, 0, r4, c13, c0, 0	@ FCSE/PID
 	mrc	p15, 0, r5, c13, c0, 3	@ User r/o thread ID
 	stmia	r0!, {r4 - r5}
@@ -112,7 +112,7 @@ ENTRY(cpu_v7_do_suspend)
 	mrc	p15, 0, r9, c1, c0, 1	@ Auxiliary control register
 	mrc	p15, 0, r10, c1, c0, 2	@ Co-processor access control
 	stmia	r0, {r5 - r11}
-	ldmfd	sp!, {r4 - r10, pc}
+	ldmfd	sp!, {r4 - r11, pc}
 ENDPROC(cpu_v7_do_suspend)

 ENTRY(cpu_v7_do_resume)