Patch "MIPS: Fix crash registers on non-crashing CPUs" has been added to the 4.4-stable tree

Patch "MIPS: Fix crash registers on non-crashing CPUs" has been added to the 4.4-stable tree

[gregkh]

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

    MIPS: Fix crash registers on non-crashing CPUs

to the 4.4-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-fix-crash-registers-on-non-crashing-cpus.patch
and it can be found in the queue-4.4 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 c80e1b62ffca52e2d1d865ee58bc79c4c0c55005 Mon Sep 17 00:00:00 2001
From: Corey Minyard <cminyard@mvista.com>
Date: Mon, 11 Apr 2016 09:10:19 -0500
Subject: MIPS: Fix crash registers on non-crashing CPUs

From: Corey Minyard <cminyard@mvista.com>

commit c80e1b62ffca52e2d1d865ee58bc79c4c0c55005 upstream.

As part of handling a crash on an SMP system, an IPI is send to
all other CPUs to save their current registers and stop.  It was
using task_pt_regs(current) to get the registers, but that will
only be accurate if the CPU was interrupted running in userland.
Instead allow the architecture to pass in the registers (all
pass NULL now, but allow for the future) and then use get_irq_regs()
which should be accurate as we are in an interrupt.  Fall back to
task_pt_regs(current) if nothing else is available.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13050/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/kernel/crash.c |   16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

--- a/arch/mips/kernel/crash.c
+++ b/arch/mips/kernel/crash.c
@@ -14,12 +14,22 @@ static int crashing_cpu = -1;
 static cpumask_t cpus_in_crash = CPU_MASK_NONE;
 
 #ifdef CONFIG_SMP
-static void crash_shutdown_secondary(void *ignore)
+static void crash_shutdown_secondary(void *passed_regs)
 {
-	struct pt_regs *regs;
+	struct pt_regs *regs = passed_regs;
 	int cpu = smp_processor_id();
 
-	regs = task_pt_regs(current);
+	/*
+	 * If we are passed registers, use those.  Otherwise get the
+	 * regs from the last interrupt, which should be correct, as
+	 * we are in an interrupt.  But if the regs are not there,
+	 * pull them from the top of the stack.  They are probably
+	 * wrong, but we need something to keep from crashing again.
+	 */
+	if (!regs)
+		regs = get_irq_regs();
+	if (!regs)
+		regs = task_pt_regs(current);
 
 	if (!cpu_online(cpu))
 		return;


Patches currently in stable-queue which might be from cminyard@mvista.com are

queue-4.4/mips-fix-crash-registers-on-non-crashing-cpus.patch