ARM: 8732/1: NOMMU: Allow userspace to access background MPU region

Currently, with MPU enabled, we prohibit userspace access to anything
except RAM. Benjamin, reported that because of that his userspace
application cannot access framebuffer's memory he reserved in device
tree. It turns out we have no option other than to allow userspace
access memory covered by background region.

Reported-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

diff --git a/arch/arm/mm/pmsa-v7.c b/arch/arm/mm/pmsa-v7.c
index 976df60ac4261bb89d8053c2cd91cca3bdf0d6ed..650998912c1c4c034ab4acd9b86f32bbd661952d 100644 (file)
--- a/arch/arm/mm/pmsa-v7.c
+++ b/arch/arm/mm/pmsa-v7.c
@@ -433,7 +433,7 @@ void __init mpu_setup(void)
 
        /* Background */
        err |= mpu_setup_region(region++, 0, 32,
-                               MPU_ACR_XN | MPU_RGN_STRONGLY_ORDERED | MPU_AP_PL1RW_PL0NA,
+                               MPU_ACR_XN | MPU_RGN_STRONGLY_ORDERED | MPU_AP_PL1RW_PL0RW,
                                0, false);
 
 #ifdef CONFIG_XIP_KERNEL