powerpc: Tell about irq stack coverage
powerpc: Tell about irq stack coverage

Now that powerpc runs irq_exit() under the irq stack,
let the softirq core know about that so that we spare
the needless stack switch on irq exit's softirq processing.

Acked-by: Benjamin Herrenschmidt <a7089bb6e7e92505d88aaff006cbdd60cc9120b6@kernel.crashing.org>
Acked-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <e8a1bf9163cb25e93cfd6540f223b3872ea7ee55@gmail.com>
Cc: Benjamin Herrenschmidt <a7089bb6e7e92505d88aaff006cbdd60cc9120b6@kernel.crashing.org>
Cc: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@au1.ibm.com>
Cc: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@kernel.org>
Cc: Thomas Gleixner <00e4cf8f46a57000a44449bf9dd8cbbcc209fd2a@linutronix.de>
Cc: Peter Zijlstra <3fddac958924aef220f202ca567388ddab3f14a8@infradead.org>
Cc: H. Peter Anvin <8a453bad9912ffe59bc0f0b8abe03df9be19379e@zytor.com>
Cc: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>
Cc: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@au1.ibm.com>
Cc: James Hogan <547fa85bb3888a0222eed8ec39e36708605c6d53@imgtec.com>
Cc: James E.J. Bottomley <78abc16a0671a4bb8f94993f5c9afbb002942fb1@parisc-linux.org>
Cc: Helge Deller <5b1e7895819cf7d6bc77091b09bbfd6d330a4e74@gmx.de>
Cc: Martin Schwidefsky <52616596d8f5df0d597e85ab515377f92f939c68@de.ibm.com>
Cc: Heiko Carstens <8dcf0f69152f32f23184f83357a3731522e56b9c@de.ibm.com>
Cc: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>
Cc: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs