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From: wata2ki <wata2ki@gmail.com>
To: linux-edac@vger.kernel.org
Cc: Naoto Yamaguchi <i33399_YAMAGUCHI@aisin-aw.co.jp>
Subject: [PATCH] EDAC/mc: Fix memory alignment calculation formula
Date: Sun, 17 May 2020 01:21:15 +0900
Message-ID: <20200516162115.16545-1-wata2ki@gmail.com> (raw)

From: Naoto Yamaguchi <i33399_YAMAGUCHI@aisin-aw.co.jp>

During the development of the off-tree driver, we found a bug that
causes alignment fault exception in mutex_lock.

Line of the code:
ffffffc010536ce4: c85ffe62 ldaxr x2, [x19]

Register value:
x19: ffffff800e90f6c4

This problem was caused by the alignment error of pvt_info
in struct mem_ctl_info.  It is caused by a calculation formula
error in edac_align_ptr.

Existing calculation formula is using variable p, but this
variable is address of the pointer variable not memory offset.
In this calculation formula should use *p.

Signed-off-by: Naoto Yamaguchi <i33399_YAMAGUCHI@aisin-aw.co.jp>
---
 drivers/edac/edac_mc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 mode change 100644 => 100755 drivers/edac/edac_mc.c

diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
old mode 100644
new mode 100755
index 75ede27bdf6a..70929f136dd7
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -271,7 +271,7 @@ void *edac_align_ptr(void **p, unsigned int size, int n_elems)
 	else
 		return (char *)ptr;
 
-	r = (unsigned long)p % align;
+	r = (unsigned long)(*p) % align;
 
 	if (r == 0)
 		return (char *)ptr;
-- 
2.17.1


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