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, 11 insertions, 2 deletions

diff --git a/arch/avr32/include/asm/thread_info.h b/arch/avr32/include/asm/thread_info.h
index fc42de5ca209..fd0c5d7e9337 100644
--- a/arch/avr32/include/asm/thread_info.h
+++ b/arch/avr32/include/asm/thread_info.h
@@ -84,6 +84,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_MEMDIE              6
 #define TIF_RESTORE_SIGMASK     7       /* restore signal mask in do_signal */
 #define TIF_CPU_GOING_TO_SLEEP  8       /* CPU is entering sleep 0 mode */
+#define TIF_NOTIFY_RESUME       9       /* callback before returning to user */
 #define TIF_FREEZE              29
 #define TIF_DEBUG               30      /* debugging enabled */
 #define TIF_USERSPACE           31      /* true if FS sets userspace */
@@ -96,6 +97,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_MEMDIE             (1 << TIF_MEMDIE)
 #define _TIF_RESTORE_SIGMASK    (1 << TIF_RESTORE_SIGMASK)
 #define _TIF_CPU_GOING_TO_SLEEP (1 << TIF_CPU_GOING_TO_SLEEP)
+#define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
 #define _TIF_FREEZE             (1 << TIF_FREEZE)
 
 /* Note: The masks below must never span more than 16 bits! */
@@ -103,13 +105,15 @@ static inline struct thread_info *current_thread_info(void)
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK                          \
         ((1 << TIF_SIGPENDING)                  \
+         | _TIF_NOTIFY_RESUME                   \
          | (1 << TIF_NEED_RESCHED)              \
          | (1 << TIF_POLLING_NRFLAG)            \
          | (1 << TIF_BREAKPOINT)                \
          | (1 << TIF_RESTORE_SIGMASK))
 
 /* work to do on any return to userspace */
-#define _TIF_ALLWORK_MASK       (_TIF_WORK_MASK | (1 << TIF_SYSCALL_TRACE))
+#define _TIF_ALLWORK_MASK       (_TIF_WORK_MASK | (1 << TIF_SYSCALL_TRACE) | \
+                                 _TIF_NOTIFY_RESUME)
 /* work to do on return from debug mode */
 #define _TIF_DBGWORK_MASK       (_TIF_WORK_MASK & ~(1 << TIF_BREAKPOINT))
 
diff --git a/arch/avr32/kernel/entry-avr32b.S b/arch/avr32/kernel/entry-avr32b.S
index 009a80155d67..169268c40ae2 100644
--- a/arch/avr32/kernel/entry-avr32b.S
+++ b/arch/avr32/kernel/entry-avr32b.S
@@ -281,7 +281,7 @@ syscall_exit_work:
         ld.w    r1, r0[TI_flags]
         rjmp    1b
 
-2:      mov     r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK
+2:      mov     r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK | _TIF_NOTIFY_RESUME
         tst     r1, r2
         breq    3f
         unmask_interrupts
diff --git a/arch/avr32/kernel/signal.c b/arch/avr32/kernel/signal.c
index 27227561bad6..62d242e2d033 100644
--- a/arch/avr32/kernel/signal.c
+++ b/arch/avr32/kernel/signal.c
@@ -322,4 +322,9 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
 
         if (ti->flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
                 do_signal(regs, &current->blocked, syscall);
+
+        if (ti->flags & _TIF_NOTIFY_RESUME) {
+                clear_thread_flag(TIF_NOTIFY_RESUME);
+                tracehook_notify_resume(regs);
+        }
 }