linux-kernel - [PATCH 1/3] probe_kernel_address() can use __probe_kernel

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Date:	Mon, 27 Oct 2014 20:54:05 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Kirill Tkhai <ktkhai@...allels.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	Vladimir Davydov <vdavydov@...allels.com>,
	Kirill Tkhai <tkhai@...dex.ru>,
	Christoph Lameter <cl@...ux.com>
Subject: [PATCH 1/3] probe_kernel_address() can use __probe_kernel_read()

probe_kernel_address() can just do __probe_kernel_read(sizeof(retval)),
no need to open-code its implementation.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 include/linux/uaccess.h |   17 ++---------------
 1 files changed, 2 insertions(+), 15 deletions(-)

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index ecd3319..effb637 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -66,22 +66,9 @@ static inline unsigned long __copy_from_user_nocache(void *to,
  * already holds mmap_sem, or other locks which nest inside mmap_sem.
  * This must be a macro because __get_user() needs to know the types of the
  * args.
- *
- * We don't include enough header files to be able to do the set_fs().  We
- * require that the probe_kernel_address() caller will do that.
  */
-#define probe_kernel_address(addr, retval)		\
-	({						\
-		long ret;				\
-		mm_segment_t old_fs = get_fs();		\
-							\
-		set_fs(KERNEL_DS);			\
-		pagefault_disable();			\
-		ret = __copy_from_user_inatomic(&(retval), (__force typeof(retval) __user *)(addr), sizeof(retval));		\
-		pagefault_enable();			\
-		set_fs(old_fs);				\
-		ret;					\
-	})
+#define probe_kernel_address(addr, retval)	\
+	__probe_kernel_read(&(retval), (__force void *)(addr), sizeof(retval))
 
 /*
  * probe_kernel_read(): safely attempt to read from a location
-- 
1.5.5.1


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