[PATCH v2 4/6] ARM: idmap: use idmap_pgd when setting up mm for reboot

[Catalin Marinas]

On 28 November 2011 18:28, Will Deacon <will.deacon at arm.com> wrote:
> For soft-rebooting a system, it is necessary to map the MMU-off code
> with an identity mapping so that execution can continue safely once the
> MMU has been switched off.
>
> Currently, switch_mm_for_reboot takes out a 1:1 mapping from 0x0 to
> TASK_SIZE during reboot in the hope that the reset code lives at a
> physical address corresponding to a userspace virtual address.
>
> This patch modifies the code so that we switch to the idmap_pgd tables,
> which contain a 1:1 mapping of the cpu_reset code. This has the
> advantage of only remapping the code that we need and also means we
> don't need to worry about allocating a pgd from an atomic context in the
> case that the physical address of the cpu_reset code aliases with the
> virtual space used by the kernel.
>
> Acked-by: Dave Martin <dave.martin at linaro.org>
> Signed-off-by: Will Deacon <will.deacon at arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>

-- 
Catalin