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authorWill Deacon <will.deacon@arm.com>2011-06-08 15:53:34 +0100
committerWill Deacon <will.deacon@arm.com>2011-12-06 14:04:15 +0000
commit2c8951ab0c337cb198236df07ad55f9dd4892c26 (patch)
treecfbc338f1d2b9642af2036dffd9fbf76024d2732 /arch/arm/mm/idmap.c
parent1a4baafa7d203da1cceb302c2df38f0fea1c17a1 (diff)
downloadlinux-2c8951ab0c337cb198236df07ad55f9dd4892c26.tar.bz2
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>
Diffstat (limited to 'arch/arm/mm/idmap.c')
-rw-r--r--arch/arm/mm/idmap.c19
1 files changed, 10 insertions, 9 deletions
diff --git a/arch/arm/mm/idmap.c b/arch/arm/mm/idmap.c
index cda5ea3157a7..b01760e6da18 100644
--- a/arch/arm/mm/idmap.c
+++ b/arch/arm/mm/idmap.c
@@ -100,17 +100,18 @@ static int __init init_static_idmap(void)
arch_initcall(init_static_idmap);
/*
- * In order to soft-boot, we need to insert a 1:1 mapping in place of
- * the user-mode pages. This will then ensure that we have predictable
- * results when turning the mmu off
+ * In order to soft-boot, we need to switch to a 1:1 mapping for the
+ * cpu_reset functions. This will then ensure that we have predictable
+ * results when turning off the mmu.
*/
void setup_mm_for_reboot(void)
{
- /*
- * We need to access to user-mode page tables here. For kernel threads
- * we don't have any user-mode mappings so we use the context that we
- * "borrowed".
- */
- identity_mapping_add(current->active_mm->pgd, 0, TASK_SIZE);
+ /* Clean and invalidate L1. */
+ flush_cache_all();
+
+ /* Switch to the identity mapping. */
+ cpu_switch_mm(idmap_pgd, &init_mm);
+
+ /* Flush the TLB. */
local_flush_tlb_all();
}