This is a note to let you know that I've just added the patch titled
ARM: 8115/1: LPAE: reduce damage caused by idmap to virtual memory layout
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-8115-1-lpae-reduce-damage-caused-by-idmap-to-virtual-memory-layout.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 811a2407a3cf7bbd027fbe92d73416f17485a3d8 Mon Sep 17 00:00:00 2001
From: Konstantin Khlebnikov <k.khlebnikov@xxxxxxxxxxx>
Date: Fri, 25 Jul 2014 09:17:12 +0100
Subject: ARM: 8115/1: LPAE: reduce damage caused by idmap to virtual memory layout
From: Konstantin Khlebnikov <k.khlebnikov@xxxxxxxxxxx>
commit 811a2407a3cf7bbd027fbe92d73416f17485a3d8 upstream.
On LPAE, each level 1 (pgd) page table entry maps 1GiB, and the level 2
(pmd) entries map 2MiB.
When the identity mapping is created on LPAE, the pgd pointers are copied
from the swapper_pg_dir. If we find that we need to modify the contents
of a pmd, we allocate a new empty pmd table and insert it into the
appropriate 1GB slot, before then filling it with the identity mapping.
However, if the 1GB slot covers the kernel lowmem mappings, we obliterate
those mappings.
When replacing a PMD, first copy the old PMD contents to the new PMD, so
that we preserve the existing mappings, particularly the mappings of the
kernel itself.
[rewrote commit message and added code comment -- rmk]
Fixes: ae2de101739c ("ARM: LPAE: Add identity mapping support for the 3-level page table format")
Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@xxxxxxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/mm/idmap.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/arch/arm/mm/idmap.c
+++ b/arch/arm/mm/idmap.c
@@ -22,6 +22,13 @@ static void idmap_add_pmd(pud_t *pud, un
pr_warning("Failed to allocate identity pmd.\n");
return;
}
+ /*
+ * Copy the original PMD to ensure that the PMD entries for
+ * the kernel image are preserved.
+ */
+ if (!pud_none(*pud))
+ memcpy(pmd, pmd_offset(pud, 0),
+ PTRS_PER_PMD * sizeof(pmd_t));
pud_populate(&init_mm, pud, pmd);
pmd += pmd_index(addr);
} else
Patches currently in stable-queue which might be from k.khlebnikov@xxxxxxxxxxx are
queue-3.4/arm-8115-1-lpae-reduce-damage-caused-by-idmap-to-virtual-memory-layout.patch
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