[2/6] uaccess: add probe_kernel_write()

Ingo Molnar
2008-02-10T07:14:17Z

From: Ingo Molnar <mingo@elte.hu>

add probe_kernel_write() - copy & paste of the existing
probe_kernel_access(), extended to writes.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/uaccess.h | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

Index: linux-kgdb.q/include/linux/uaccess.h
===================================================================
--- linux-kgdb.q.orig/include/linux/uaccess.h
+++ linux-kgdb.q/include/linux/uaccess.h
@@ -84,4 +84,26 @@ static inline unsigned long __copy_from_
ret; \
})

+/**
+ * probe_kernel_write(): safely attempt to write to a location
+ * @addr: address to write to - its type is type typeof(rdval)*
+ * @rdval: write to this variable
+ *
+ * Safely write to address @addr from variable @rdval. If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+#define probe_kernel_write(addr, rdval) \
+ ({ \
+ long ret; \
+ mm_segment_t old_fs = get_fs(); \
+ \
+ set_fs(KERNEL_DS); \
+ pagefault_disable(); \
+ ret = __put_user(rdval, \
+ (__force typeof(rdval) __user *)(addr)); \
+ pagefault_enable(); \
+ set_fs(old_fs); \
+ ret; \
+ })