Patch "ARM: fix PTRACE_SETVFPREGS on SMP systems" has been added to the 4.6-stable tree

Patch "ARM: fix PTRACE_SETVFPREGS on SMP systems" has been added to the 4.6-stable tree

[gregkh]

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

    ARM: fix PTRACE_SETVFPREGS on SMP systems

to the 4.6-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:
     arm-fix-ptrace_setvfpregs-on-smp-systems.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From e2dfb4b880146bfd4b6aa8e138c0205407cebbaf Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Mon, 30 May 2016 23:14:56 +0100
Subject: ARM: fix PTRACE_SETVFPREGS on SMP systems

From: Russell King <rmk+kernel@armlinux.org.uk>

commit e2dfb4b880146bfd4b6aa8e138c0205407cebbaf upstream.

PTRACE_SETVFPREGS fails to properly mark the VFP register set to be
reloaded, because it undoes one of the effects of vfp_flush_hwstate().

Specifically vfp_flush_hwstate() sets thread->vfpstate.hard.cpu to
an invalid CPU number, but vfp_set() overwrites this with the original
CPU number, thereby rendering the hardware state as apparently "valid",
even though the software state is more recent.

Fix this by reverting the previous change.

Fixes: 8130b9d7b9d8 ("ARM: 7308/1: vfp: flush thread hwstate before copying ptrace registers")
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Simon Marchi <simon.marchi@ericsson.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm/kernel/ptrace.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -733,8 +733,8 @@ static int vfp_set(struct task_struct *t
 	if (ret)
 		return ret;
 
-	vfp_flush_hwstate(thread);
 	thread->vfpstate.hard = new_vfp;
+	vfp_flush_hwstate(thread);
 
 	return 0;
 }


Patches currently in stable-queue which might be from rmk+kernel@armlinux.org.uk are

queue-4.6/net-mvneta-fix-lacking-spinlock-initialization.patch
queue-4.6/arm-fix-ptrace_setvfpregs-on-smp-systems.patch