Patch "MIPS: smp-cps: Fix retrieval of VPE mask on big endian CPUs" 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

MIPS: smp-cps: Fix retrieval of VPE mask on big endian CPUs

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:
mips-smp-cps-fix-retrieval-of-vpe-mask-on-big-endian-cpus.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: Matt Redfearn <[email protected]>
Date: Tue, 21 Mar 2017 14:39:19 +0000
Subject: MIPS: smp-cps: Fix retrieval of VPE mask on big endian CPUs

From: Matt Redfearn <[email protected]>

[ Upstream commit fb2155e3c30dc2043b52020e26965067a3e7779c ]

The vpe_mask member of struct core_boot_config is of type atomic_t, which is a 32bit type. In cps-vec.S this member was being retrieved by a PTR_L macro, which on 64bit systems is a 64bit load. On little endian systems this is OK, since the double word that is retrieved will have the required less significant word in the correct position. However, on big endian systems the less significant word of the load is retrieved from address+4, and the more significant from address+0. The destination register therefore ends up with the required word in the more significant word
e.g. when starting the second VP of a big endian 64bit system, the load

PTR_L ta2, COREBOOTCFG_VPEMASK(a0)

ends up setting register ta2 to 0x0000000300000000

When this value is written to the CPC it is ignored, since it is invalid to write anything larger than 4 bits. This results in any VP other than VP0 in a core failing to start in 64bit big endian systems.

Change the load to a 32bit load word instruction to fix the bug.

Patchwork: https://patchwork.linux-mips.org/patch/15787/

---
 arch/mips/kernel/cps-vec.S |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -361,7 +361,7 @@ LEAF(mips_cps_get_bootcfg)
 	END(mips_cps_get_bootcfg)
 
 LEAF(mips_cps_boot_vpes)
-	PTR_L	ta2, COREBOOTCFG_VPEMASK(a0)
+	lw	ta2, COREBOOTCFG_VPEMASK(a0)
 	PTR_L	ta3, COREBOOTCFG_VPECONFIG(a0)
 
 #if defined(CONFIG_CPU_MIPSR6)

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

queue-4.9/mips-irq-stack-unwind-irq-stack-onto-task-stack.patch queue-4.9/mips-smp-cps-fix-retrieval-of-vpe-mask-on-big-endian-cpus.patch