Patch "ARM: BCM5301X: Add back handler ignoring external imprecise aborts" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    ARM: BCM5301X: Add back handler ignoring external imprecise aborts

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:
     arm-bcm5301x-add-back-handler-ignoring-external-imprecise-aborts.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 <stable@vger.kernel.org> know about it.


>From 09f3510fb70a46c8921f2cf4a90dbcae460a6820 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Date: Sat, 29 Oct 2016 13:12:29 +0200
Subject: ARM: BCM5301X: Add back handler ignoring external imprecise aborts
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Rafał Miłecki <rafal@milecki.pl>

commit 09f3510fb70a46c8921f2cf4a90dbcae460a6820 upstream.

Since early BCM5301X days we got abort handler that was removed by
commit 937b12306ea79 ("ARM: BCM5301X: remove workaround imprecise abort
fault handler"). It assumed we need to deal only with pending aborts
left by the bootloader. Unfortunately this isn't true for BCM5301X.

When probing PCI config space (device enumeration) it is expected to
have master aborts on the PCI bus. Most bridges don't forward (or they
allow disabling it) these errors onto the AXI/AMBA bus but not the
Northstar (BCM5301X) one.

iProc PCIe controller on Northstar seems to be some older one, without
a control register for errors forwarding. It means we need to workaround
this at platform level. All newer platforms are not affected by this
issue.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm/mach-bcm/bcm_5301x.c |   28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

--- a/arch/arm/mach-bcm/bcm_5301x.c
+++ b/arch/arm/mach-bcm/bcm_5301x.c
@@ -9,14 +9,42 @@
 #include <asm/hardware/cache-l2x0.h>
 
 #include <asm/mach/arch.h>
+#include <asm/siginfo.h>
+#include <asm/signal.h>
+
+#define FSR_EXTERNAL		(1 << 12)
+#define FSR_READ		(0 << 10)
+#define FSR_IMPRECISE		0x0406
 
 static const char *const bcm5301x_dt_compat[] __initconst = {
 	"brcm,bcm4708",
 	NULL,
 };
 
+static int bcm5301x_abort_handler(unsigned long addr, unsigned int fsr,
+				  struct pt_regs *regs)
+{
+	/*
+	 * We want to ignore aborts forwarded from the PCIe bus that are
+	 * expected and shouldn't really be passed by the PCIe controller.
+	 * The biggest disadvantage is the same FSR code may be reported when
+	 * reading non-existing APB register and we shouldn't ignore that.
+	 */
+	if (fsr == (FSR_EXTERNAL | FSR_READ | FSR_IMPRECISE))
+		return 0;
+
+	return 1;
+}
+
+static void __init bcm5301x_init_early(void)
+{
+	hook_fault_code(16 + 6, bcm5301x_abort_handler, SIGBUS, BUS_OBJERR,
+			"imprecise external abort");
+}
+
 DT_MACHINE_START(BCM5301X, "BCM5301X")
 	.l2c_aux_val	= 0,
 	.l2c_aux_mask	= ~0,
 	.dt_compat	= bcm5301x_dt_compat,
+	.init_early	= bcm5301x_init_early,
 MACHINE_END


Patches currently in stable-queue which might be from rafal@milecki.pl are

queue-4.9/arm-bcm5301x-add-back-handler-ignoring-external-imprecise-aborts.patch