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>

3 files changed, 9 insertions, 2 deletions

diff --git a/arch/parisc/include/asm/thread_info.h b/arch/parisc/include/asm/thread_info.h
index 4ce0edfbe969..ac775a76bff7 100644
--- a/arch/parisc/include/asm/thread_info.h
+++ b/arch/parisc/include/asm/thread_info.h
@@ -59,6 +59,7 @@ struct thread_info {
 #define TIF_MEMDIE              5
 #define TIF_RESTORE_SIGMASK     6       /* restore saved signal mask */
 #define TIF_FREEZE              7       /* is freezing for suspend */
+#define TIF_NOTIFY_RESUME       8       /* callback before returning to user */
 
 #define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
@@ -67,8 +68,9 @@ struct thread_info {
 #define _TIF_32BIT              (1 << TIF_32BIT)
 #define _TIF_RESTORE_SIGMASK    (1 << TIF_RESTORE_SIGMASK)
 #define _TIF_FREEZE             (1 << TIF_FREEZE)
+#define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
 
-#define _TIF_USER_WORK_MASK     (_TIF_SIGPENDING | \
+#define _TIF_USER_WORK_MASK     (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | \
                                  _TIF_NEED_RESCHED | _TIF_RESTORE_SIGMASK)
 
 #endif /* __KERNEL__ */
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index e552e547cb93..8c4712b74dc1 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -948,7 +948,7 @@ intr_check_sig:
         /* 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 f82544225e8e..b3bfc4326703 100644
--- a/arch/parisc/kernel/signal.c
+++ b/arch/parisc/kernel/signal.c
@@ -645,4 +645,9 @@ void do_notify_resume(struct pt_regs *regs, long in_syscall)
         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);
+        }
 }