KEYS: Extend TIF_NOTIFY_RESUME to (almost) all architectures [try #6]

Implement TIF_NOTIFY_RESUME for most of those architectures in which isn't yet
available, and, whilst we're at it, have it call the appropriate tracehook.

After this patch, blackfin, m68k* and xtensa still lack support and need
alteration of assembly code to make it work.

Resume notification can then be used (by a later patch) to install a new
session keyring on the parent of a process.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>

cc: linux-arch@vger.kernel.org
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index e552e54..8c4712b 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -948,7 +948,7 @@
 	/* As above */
 	mfctl   %cr30,%r1
 	LDREG	TI_FLAGS(%r1),%r19
-	ldi	(_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK), %r20
+	ldi	(_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK|_TIF_NOTIFY_RESUME), %r20
 	and,COND(<>)	%r19, %r20, %r0
 	b,n	intr_restore	/* skip past if we've nothing to do */
 
diff --git a/arch/parisc/kernel/signal.c b/arch/parisc/kernel/signal.c
index f825442..b3bfc43 100644
--- a/arch/parisc/kernel/signal.c
+++ b/arch/parisc/kernel/signal.c
@@ -645,4 +645,9 @@
 	if (test_thread_flag(TIF_SIGPENDING) ||
 	    test_thread_flag(TIF_RESTORE_SIGMASK))
 		do_signal(regs, in_syscall);
+
+	if (test_thread_flag(TIF_NOTIFY_RESUME)) {
+		clear_thread_flag(TIF_NOTIFY_RESUME);
+		tracehook_notify_resume(regs);
+	}
 }