UPSTREAM: maccess: unexport probe_kernel_write()

Patch series "clean up and streamline probe_kernel_* and friends", v4.

This series start cleaning up the safe kernel and user memory probing
helpers in mm/maccess.c, and then allows architectures to implement the
kernel probing without overriding the address space limit and temporarily
allowing access to user memory.  It then switches x86 over to this new
mechanism by reusing the unsafe_* uaccess logic.

This version also switches to the saner copy_{from,to}_kernel_nofault
naming suggested by Linus.

I kept the x86 helpers as-is without calling unsage_{get,put}_user as that
avoids a number of hard to trace casts, and it will still work with the
asm-goto based version easily.

This patch (of 20):

probe_kernel_write() is not used by any modular code.

[[email protected]: turns out that probe_user_write is used in modular code]
  Link: http://lkml.kernel.org/r/[email protected]

Change-Id: I0db542d1963bf6a1e83572471e0a9ba00a918931
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Stephen Rothwell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

mm/maccess.c

@@ -174,7 +174,6 @@ long probe_kernel_write(void *dst, const void *src, size_t size)
 		return -EFAULT;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(probe_kernel_write);
 
 /**
  * probe_user_write(): safely attempt to write to a user-space location