powerpc: Add TIF_NOTIFY_RESUME support for tracehook

This adds TIF_NOTIFY_RESUME support for powerpc.  When set,
we call tracehook_notify_resume() on the way to user mode.
This overloads do_signal() to do the work, but changes its
arguments to it has the TIF_* bits handy in a register and
drops the useless first argument that was always zero.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

5 files changed, 20 insertions, 8 deletions

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index e6fca6a9014d..1cbbf7033641 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -1060,8 +1060,8 @@ do_user_signal:			/* r10 contains MSR_KERNEL here */
         SAVE_NVGPRS(r1)
         rlwinm  r3,r3,0,0,30
         stw     r3,_TRAP(r1)
-2:      li      r3,0
-        addi    r4,r1,STACK_FRAME_OVERHEAD
+2:      addi    r3,r1,STACK_FRAME_OVERHEAD
+        mr      r4,r9
         bl      do_signal
         REST_NVGPRS(r1)
         b       recheck
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 79c089e97ce4..2d802e97097c 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -643,8 +643,7 @@ user_work:
         b       .ret_from_except_lite
 
 1:      bl      .save_nvgprs
-        li      r3,0
-        addi    r4,r1,STACK_FRAME_OVERHEAD
+        addi    r3,r1,STACK_FRAME_OVERHEAD
         bl      .do_signal
         b       .ret_from_except
 
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index e74aa0ed4e9e..a54405ebd7b0 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -112,7 +112,7 @@ static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
         }
 }
 
-int do_signal(sigset_t *oldset, struct pt_regs *regs)
+static int do_signal_pending(sigset_t *oldset, struct pt_regs *regs)
 {
         siginfo_t info;
         int signr;
@@ -188,6 +188,17 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
         return ret;
 }
 
+void do_signal(struct pt_regs *regs, unsigned long thread_info_flags)
+{
+        if (thread_info_flags & _TIF_SIGPENDING)
+                do_signal_pending(NULL, regs);
+
+        if (thread_info_flags & _TIF_NOTIFY_RESUME) {
+                clear_thread_flag(TIF_NOTIFY_RESUME);
+                tracehook_notify_resume(regs);
+        }
+}
+
 long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
                 unsigned long r5, unsigned long r6, unsigned long r7,
                 unsigned long r8, struct pt_regs *regs)
diff --git a/include/asm-powerpc/signal.h b/include/asm-powerpc/signal.h
index a8c7babf4950..a7360cdd99eb 100644
--- a/include/asm-powerpc/signal.h
+++ b/include/asm-powerpc/signal.h
@@ -122,8 +122,7 @@ typedef struct sigaltstack {
 
 #ifdef __KERNEL__
 struct pt_regs;
-extern int do_signal(sigset_t *oldset, struct pt_regs *regs);
-extern int do_signal32(sigset_t *oldset, struct pt_regs *regs);
+extern void do_signal(struct pt_regs *regs, unsigned long thread_info_flags);
 #define ptrace_signal_deliver(regs, cookie) do { } while (0)
 #endif /* __KERNEL__ */
 
diff --git a/include/asm-powerpc/thread_info.h b/include/asm-powerpc/thread_info.h
index a9db562df69a..9665a26a253a 100644
--- a/include/asm-powerpc/thread_info.h
+++ b/include/asm-powerpc/thread_info.h
@@ -108,6 +108,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SECCOMP             10      /* secure computing */
 #define TIF_RESTOREALL          11      /* Restore all regs (implies NOERROR) */
 #define TIF_NOERROR             12      /* Force successful syscall return */
+#define TIF_NOTIFY_RESUME       13      /* callback before returning to user */
 #define TIF_FREEZE              14      /* Freezing for suspend */
 #define TIF_RUNLATCH            15      /* Is the runlatch enabled? */
 #define TIF_ABI_PENDING         16      /* 32/64 bit switch needed */
@@ -125,12 +126,14 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SECCOMP            (1<<TIF_SECCOMP)
 #define _TIF_RESTOREALL         (1<<TIF_RESTOREALL)
 #define _TIF_NOERROR            (1<<TIF_NOERROR)
+#define _TIF_NOTIFY_RESUME      (1<<TIF_NOTIFY_RESUME)
 #define _TIF_FREEZE             (1<<TIF_FREEZE)
 #define _TIF_RUNLATCH           (1<<TIF_RUNLATCH)
 #define _TIF_ABI_PENDING        (1<<TIF_ABI_PENDING)
 #define _TIF_SYSCALL_T_OR_A     (_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP)
 
-#define _TIF_USER_WORK_MASK     (_TIF_SIGPENDING | _TIF_NEED_RESCHED)
+#define _TIF_USER_WORK_MASK     (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+                                 _TIF_NOTIFY_RESUME)
 #define _TIF_PERSYSCALL_MASK    (_TIF_RESTOREALL|_TIF_NOERROR)
 
 /* Bits in local_flags */