This is a note to let you know that I've just added the patch titled
ARC: fix page address calculation if PAGE_OFFSET != LINUX_LINK_BASE
to the 3.18-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:
arc-fix-page-address-calculation-if-page_offset-linux_link_base.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 06f34e1c28f3608b0ce5b310e41102d3fe7b65a1 Mon Sep 17 00:00:00 2001
From: Alexey Brodkin <abrodkin@xxxxxxxxxxxx>
Date: Thu, 12 Feb 2015 21:10:11 +0300
Subject: ARC: fix page address calculation if PAGE_OFFSET != LINUX_LINK_BASE
From: Alexey Brodkin <abrodkin@xxxxxxxxxxxx>
commit 06f34e1c28f3608b0ce5b310e41102d3fe7b65a1 upstream.
We used to calculate page address differently in 2 cases:
1. In virt_to_page(x) we do
--->8---
mem_map + (x - CONFIG_LINUX_LINK_BASE) >> PAGE_SHIFT
--->8---
2. In in pte_page(x) we do
--->8---
mem_map + (pte_val(x) - PAGE_OFFSET) >> PAGE_SHIFT
--->8---
That leads to problems in case PAGE_OFFSET != CONFIG_LINUX_LINK_BASE -
different pages will be selected depending on where and how we calculate
page address.
In particular in the STAR 9000853582 when gdb attempted to read memory
of another process it got improper page in get_user_pages() because this
is exactly one of the places where we search for a page by pte_page().
The fix is trivial - we need to calculate page address similarly in both
cases.
Signed-off-by: Alexey Brodkin <abrodkin@xxxxxxxxxxxx>
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arc/include/asm/pgtable.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/arc/include/asm/pgtable.h
+++ b/arch/arc/include/asm/pgtable.h
@@ -259,7 +259,8 @@ static inline void pmd_set(pmd_t *pmdp,
#define pmd_clear(xp) do { pmd_val(*(xp)) = 0; } while (0)
#define pte_page(x) (mem_map + \
- (unsigned long)(((pte_val(x) - PAGE_OFFSET) >> PAGE_SHIFT)))
+ (unsigned long)(((pte_val(x) - CONFIG_LINUX_LINK_BASE) >> \
+ PAGE_SHIFT)))
#define mk_pte(page, pgprot) \
({ \
Patches currently in stable-queue which might be from abrodkin@xxxxxxxxxxxx are
queue-3.18/arc-fix-page-address-calculation-if-page_offset-linux_link_base.patch
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