[PATCH 1/2] proc: fix kpage[count,flags] interfaces to account for ARCH_PFN_OFFSET

[PATCH 1/2] proc: fix kpage[count,flags] interfaces to account for ARCH_PFN_OFFSET

[Bartlomiej Zolnierkiewicz]

From: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: [PATCH] proc: fix kpage[count,flags] interfaces to account for ARCH_PFN_OFFSET

ARCH_PFN_OFFSET gives us the first PFN number (i.e. on ARM Exynos4
platform it is equal to 262144) while max_pfn is only the total
number of PFNs (i.e. on ARM Exynos4 Universal C210 board it is equal
to 131072) so currently it is impossible to read page count/flags
values on affected archs/platforms throught /proc/kpage[count,flags]
interfaces.  Fix it by making code aware of ARCH_PFN_OFFSET.

[ For x86 the resulting code remains unchanged as ARCH_PFN_OFFSET
  is eual to 0. ]

Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
 fs/proc/page.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Index: b/fs/proc/page.c
===================================================================
--- a/fs/proc/page.c	2012-05-31 15:45:27.887110216 +0200
+++ b/fs/proc/page.c	2012-05-31 16:33:37.455109659 +0200
@@ -31,7 +31,8 @@ static ssize_t kpagecount_read(struct fi
 	u64 pcount;
 
 	pfn = src / KPMSIZE;
-	count = min_t(size_t, count, (max_pfn * KPMSIZE) - src);
+	count = min_t(size_t, count,
+		      ((ARCH_PFN_OFFSET + max_pfn) * KPMSIZE) - src);
 	if (src & KPMMASK || count & KPMMASK)
 		return -EINVAL;
 
@@ -174,7 +175,8 @@ static ssize_t kpageflags_read(struct fi
 	ssize_t ret = 0;
 
 	pfn = src / KPMSIZE;
-	count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
+	count = min_t(unsigned long, count,
+		      ((ARCH_PFN_OFFSET + max_pfn) * KPMSIZE) - src);
 	if (src & KPMMASK || count & KPMMASK)
 		return -EINVAL;
 

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