ARM: idmap: use idmap_pgd when setting up mm for reboot
authorWill Deacon <will.deacon@arm.com>
Wed, 8 Jun 2011 14:53:34 +0000 (15:53 +0100)
committerWill Deacon <will.deacon@arm.com>
Tue, 6 Dec 2011 14:04:15 +0000 (14:04 +0000)
commit2c8951ab0c337cb198236df07ad55f9dd4892c26
treecfbc338f1d2b9642af2036dffd9fbf76024d2732
parent1a4baafa7d203da1cceb302c2df38f0fea1c17a1
ARM: idmap: use idmap_pgd when setting up mm for reboot

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@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
arch/arm/mm/idmap.c