[PATCH] sh: Enable the mmu in start_secondary()

[PATCH] sh: Enable the mmu in start_secondary()

[Matt Fleming]

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>
---
 arch/sh/kernel/smp.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c
index e124cf7..002cc61 100644
--- 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;
-- 
1.6.4.rc0

Re: [PATCH] sh: Enable the mmu in start_secondary()

[Paul Mundt]

On Sun, Mar 28, 2010 at 09:08:25PM +0100, Matt Fleming wrote:
> 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>

Applied, thanks.