sh: Enable the mmu in start_secondary()

For the boot, enable_mmu() is called from setup_arch() but we don't call
setup_arch() for any of the other cpus. So turn on the non-boot cpu's
mmu inside of start_secondary().

I noticed this bug on an SMP board when trying to map I/O memory
(smsc911x registers) into the kernel address space. Since the Address
Translation bit in MMUCR wasn't set, accessing the virtual address where
the smsc911x registers were supposedly mapped actually performed a
physical address access.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
Cc: stable@kernel.org
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c
index e124cf7008df46ed2e6de79f450901bd4161fbc5..002cc612deef5ce9c93499e8a2ea4043050eb189 100644 (file)
--- a/arch/sh/kernel/smp.c
+++ b/arch/sh/kernel/smp.c
@@ -69,6 +69,7 @@ asmlinkage void __cpuinit start_secondary(void)
        unsigned int cpu;
        struct mm_struct *mm = &init_mm;
 
+       enable_mmu();
        atomic_inc(&mm->mm_count);
        atomic_inc(&mm->mm_users);
        current->active_mm = mm;