microblaze: Unprivileged stream instruction awareness

Add cpuinfo support for the new MicroBlaze option permitting userspace
(unprivileged) access to the streaming instructions (FSL / AXI-stream).

Emit a noisy warning at bootup if this is enabled, because bad user code
can potentially lockup the CPU.

Signed-off-by: John A. Williams <john.williams@petalogix.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/microblaze/kernel/cpu/cpuinfo.c b/arch/microblaze/kernel/cpu/cpuinfo.c
index c1640c52711f..44394d80a683 100644
--- a/arch/microblaze/kernel/cpu/cpuinfo.c
+++ b/arch/microblaze/kernel/cpu/cpuinfo.c
@@ -88,4 +88,8 @@ void __init setup_cpuinfo(void)
                 printk(KERN_WARNING "%s: Unsupported PVR setting\n", __func__);
                 set_cpuinfo_static(&cpuinfo, cpu);
         }
+
+        if (cpuinfo.mmu_privins)
+                printk(KERN_WARNING "%s: Stream instructions enabled"
+                        " - USERSPACE CAN LOCK THIS KERNEL!\n", __func__);
 }