Since we've already stepped away from ENABLE is a JMP and DISABLE is a
NOP with the branch_default bits, and are going to make it even worse,
rename it to make it all clearer.

This way we don't mix multiple levels of logic attributes, but have a
plain 'physical' name for what the current instruction patching status
of a jump label is.

This is a first step in removing the naming confusion that has led to
a stream of avoidable bugs such as:

  a833581e372a ("x86, perf: Fix static_key bug in load_mm_cr4()")

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
[ Beefed up the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

Should do what other architectures do and wrap all that code into
the appropriate ifdef

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

This patch adds support for the new "jump label" feature.

Unlike x86 and sparc we just merrily patch the code with no locks etc,
as far as I know this is safe, but I'm not really sure what the x86/sparc
code is protecting against so maybe it's not.

I also don't see any reason for us to implement the poke_early() routine,
even though sparc does.

[BenH: Updated the patch to upstream generic changes]

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>