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>

2 files changed, 9 insertions, 1 deletions

diff --git a/arch/alpha/include/asm/thread_info.h b/arch/alpha/include/asm/thread_info.h
index 60c83abfde70..5076a8860b18 100644
--- a/arch/alpha/include/asm/thread_info.h
+++ b/arch/alpha/include/asm/thread_info.h
@@ -75,6 +75,7 @@ register struct thread_info *__current_thread_info __asm__("$8");
 #define TIF_UAC_SIGBUS          7
 #define TIF_MEMDIE              8
 #define TIF_RESTORE_SIGMASK     9       /* restore signal mask in do_signal */
+#define TIF_NOTIFY_RESUME       10      /* callback before returning to user */
 #define TIF_FREEZE              16      /* is freezing for suspend */
 
 #define _TIF_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)
@@ -82,10 +83,12 @@ register struct thread_info *__current_thread_info __asm__("$8");
 #define _TIF_NEED_RESCHED       (1<<TIF_NEED_RESCHED)
 #define _TIF_POLLING_NRFLAG     (1<<TIF_POLLING_NRFLAG)
 #define _TIF_RESTORE_SIGMASK    (1<<TIF_RESTORE_SIGMASK)
+#define _TIF_NOTIFY_RESUME      (1<<TIF_NOTIFY_RESUME)
 #define _TIF_FREEZE             (1<<TIF_FREEZE)
 
 /* Work to do on interrupt/exception return.  */
-#define _TIF_WORK_MASK          (_TIF_SIGPENDING | _TIF_NEED_RESCHED)
+#define _TIF_WORK_MASK          (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+                                 _TIF_NOTIFY_RESUME)
 
 /* Work to do on any return to userspace.  */
 #define _TIF_ALLWORK_MASK       (_TIF_WORK_MASK         \
diff --git a/arch/alpha/kernel/signal.c b/arch/alpha/kernel/signal.c
index df65eaa84c4c..04e17c1f0f1b 100644
--- a/arch/alpha/kernel/signal.c
+++ b/arch/alpha/kernel/signal.c
@@ -683,4 +683,9 @@ do_notify_resume(struct pt_regs *regs, struct switch_stack *sw,
 {
         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
                 do_signal(regs, sw, r0, r19);
+
+        if (thread_info_flags & _TIF_NOTIFY_RESUME) {
+                clear_thread_flag(TIF_NOTIFY_RESUME);
+                tracehook_notify_resume(regs);
+        }
 }