m68k: add TIF_NOTIFY_RESUME and handle it.

TIF_NOTIFY_RESUME added (as bit 5).  That way nommu glue needs no changes at
all; mmu one needs just to replace jmi do_signal_return to jne do_signal_return
There we have flags shifted up, until bit 6 (SIGPENDING) is in MSBit; instead
of checking that MSBit is set (jmi) we check that MSBit or something below it
is set (jne); bits 0..4 are never set, so that's precisely "bit 6 or bit 5 is
set".

Usual handling of NOTIFY_RESUME/SIGPENDING is done in do_notify_resume(); glue
calls it instead of do_signal().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

6 files changed, 21 insertions, 7 deletions

diff --git a/arch/m68k/include/asm/thread_info.h b/arch/m68k/include/asm/thread_info.h
index e8665e6f946..126131f94a2 100644
--- a/arch/m68k/include/asm/thread_info.h
+++ b/arch/m68k/include/asm/thread_info.h
@@ -71,6 +71,7 @@ static inline struct thread_info *current_thread_info(void)
  * bits 0-7 are tested at every exception exit
  * bits 8-15 are also tested at syscall exit
  */
+#define TIF_NOTIFY_RESUME       5       /* callback before returning to user */
 #define TIF_SIGPENDING          6       /* signal pending */
 #define TIF_NEED_RESCHED        7       /* rescheduling necessary */
 #define TIF_DELAYED_TRACE       14      /* single step a syscall */
diff --git a/arch/m68k/kernel/entry_mm.S b/arch/m68k/kernel/entry_mm.S
index 675a854966a..f29e73ca9db 100644
--- a/arch/m68k/kernel/entry_mm.S
+++ b/arch/m68k/kernel/entry_mm.S
@@ -148,7 +148,7 @@ syscall_exit_work:
         jcs     do_trace_exit
         jmi     do_delayed_trace
         lslw    #8,%d0
-        jmi     do_signal_return
+        jne     do_signal_return
         pea     resume_userspace
         jra     schedule
 
@@ -172,7 +172,7 @@ exit_work:
         | save top of frame
         movel   %sp,%curptr@(TASK_THREAD+THREAD_ESP0)
         lslb    #1,%d0
-        jmi     do_signal_return
+        jne     do_signal_return
         pea     resume_userspace
         jra     schedule
 
@@ -182,7 +182,7 @@ do_signal_return:
         subql   #4,%sp                  | dummy return address
         SAVE_SWITCH_STACK
         pea     %sp@(SWITCH_STACK_SIZE)
-        bsrl    do_signal
+        bsrl    do_notify_resume
         addql   #4,%sp
         RESTORE_SWITCH_STACK
         addql   #4,%sp
diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
index d8f6960e8fd..d9f3d1900ee 100644
--- a/arch/m68k/kernel/signal.c
+++ b/arch/m68k/kernel/signal.c
@@ -43,6 +43,7 @@
 #include <linux/tty.h>
 #include <linux/binfmts.h>
 #include <linux/module.h>
+#include <linux/tracehook.h>
 
 #include <asm/setup.h>
 #include <asm/uaccess.h>
@@ -1154,7 +1155,7 @@ handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
  * want to handle. Thus you cannot kill init even with a SIGKILL even by
  * mistake.
  */
-asmlinkage void do_signal(struct pt_regs *regs)
+static void do_signal(struct pt_regs *regs)
 {
         siginfo_t info;
         struct k_sigaction ka;
@@ -1186,3 +1187,15 @@ asmlinkage void do_signal(struct pt_regs *regs)
                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
         }
 }
+
+void do_notify_resume(struct pt_regs *regs)
+{
+        if (test_thread_flag(TIF_SIGPENDING))
+                do_signal(regs);
+
+        if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME)) {
+                tracehook_notify_resume(regs);
+                if (current->replacement_session_keyring)
+                        key_replace_session_keyring();
+        }
+}
diff --git a/arch/m68k/platform/68328/entry.S b/arch/m68k/platform/68328/entry.S
index 5c39b80ed7d..7f91c2fde50 100644
--- a/arch/m68k/platform/68328/entry.S
+++ b/arch/m68k/platform/68328/entry.S
@@ -119,7 +119,7 @@ Lsignal_return:
         subql   #4,%sp                  /* dummy return address*/
         SAVE_SWITCH_STACK
         pea     %sp@(SWITCH_STACK_SIZE)
-        bsrw    do_signal
+        bsrw    do_notify_resume
         addql   #4,%sp
         RESTORE_SWITCH_STACK
         addql   #4,%sp
diff --git a/arch/m68k/platform/68360/entry.S b/arch/m68k/platform/68360/entry.S
index aa47d1d4992..904fd9a4af4 100644
--- a/arch/m68k/platform/68360/entry.S
+++ b/arch/m68k/platform/68360/entry.S
@@ -115,7 +115,7 @@ Lsignal_return:
         subql   #4,%sp                  /* dummy return address*/
         SAVE_SWITCH_STACK
         pea     %sp@(SWITCH_STACK_SIZE)
-        bsrw    do_signal
+        bsrw    do_notify_resume
         addql   #4,%sp
         RESTORE_SWITCH_STACK
         addql   #4,%sp
diff --git a/arch/m68k/platform/coldfire/entry.S b/arch/m68k/platform/coldfire/entry.S
index 281e38c2b6c..881ab8e379d 100644
--- a/arch/m68k/platform/coldfire/entry.S
+++ b/arch/m68k/platform/coldfire/entry.S
@@ -152,7 +152,7 @@ Lsignal_return:
         subql   #4,%sp                  /* dummy return address */
         SAVE_SWITCH_STACK
         pea     %sp@(SWITCH_STACK_SIZE)
-        jsr     do_signal
+        jsr     do_notify_resume
         addql   #4,%sp
         RESTORE_SWITCH_STACK
         addql   #4,%sp