Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal

Pull third pile of signal handling patches from Al Viro:
 "This time it's mostly helpers and conversions to them; there's a lot
  of stuff remaining in the tree, but that'll either go in -rc2
  (isolated bug fixes, ideally via arch maintainers' trees) or will sit
  there until the next cycle."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal:
  x86: get rid of calling do_notify_resume() when returning to kernel mode
  blackfin: check __get_user() return value
  whack-a-mole with TIF_FREEZE
  FRV: Optimise the system call exit path in entry.S [ver #2]
  FRV: Shrink TIF_WORK_MASK [ver #2]
  FRV: Prevent syscall exit tracing and notify_resume at end of kernel exceptions
  new helper: signal_delivered()
  powerpc: get rid of restore_sigmask()
  most of set_current_blocked() callers want SIGKILL/SIGSTOP removed from set
  set_restore_sigmask() is never called without SIGPENDING (and never should be)
  TIF_RESTORE_SIGMASK can be set only when TIF_SIGPENDING is set
  don't call try_to_freeze() from do_signal()
  pull clearing RESTORE_SIGMASK into block_sigmask()
  sh64: failure to build sigframe != signal without handler
  openrisc: tracehook_signal_handler() is supposed to be called on success
  new helper: sigmask_to_save()
  new helper: restore_saved_sigmask()
  new helpers: {clear,test,test_and_clear}_restore_sigmask()
  HAVE_RESTORE_SIGMASK is defined on all architectures now

3 files changed, 39 insertions, 70 deletions

diff --git a/arch/sh/include/asm/thread_info.h b/arch/sh/include/asm/thread_info.h
index 0c04ffc4f12c..bc13b57cdc83 100644
--- a/arch/sh/include/asm/thread_info.h
+++ b/arch/sh/include/asm/thread_info.h
@@ -169,7 +169,7 @@ static inline void set_restore_sigmask(void)
 {
         struct thread_info *ti = current_thread_info();
         ti->status |= TS_RESTORE_SIGMASK;
-        set_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags);
+        WARN_ON(!test_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags));
 }
 
 #define TI_FLAG_FAULT_CODE_SHIFT        24
@@ -189,6 +189,23 @@ static inline unsigned int get_thread_fault_code(void)
         struct thread_info *ti = current_thread_info();
         return ti->flags >> TI_FLAG_FAULT_CODE_SHIFT;
 }
+
+static inline void clear_restore_sigmask(void)
+{
+        current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
+}
+static inline bool test_restore_sigmask(void)
+{
+        return current_thread_info()->status & TS_RESTORE_SIGMASK;
+}
+static inline bool test_and_clear_restore_sigmask(void)
+{
+        struct thread_info *ti = current_thread_info();
+        if (!(ti->status & TS_RESTORE_SIGMASK))
+                return false;
+        ti->status &= ~TS_RESTORE_SIGMASK;
+        return true;
+}
 #endif  /* !__ASSEMBLY__ */
 
 #endif /* __KERNEL__ */
diff --git a/arch/sh/kernel/signal_32.c b/arch/sh/kernel/signal_32.c
index 9d7bfd66f189..d6b7b6154f87 100644
--- a/arch/sh/kernel/signal_32.c
+++ b/arch/sh/kernel/signal_32.c
@@ -32,8 +32,6 @@
 #include <asm/syscalls.h>
 #include <asm/fpu.h>
 
-#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
-
 struct fdpic_func_descriptor {
         unsigned long   text;
         unsigned long   GOT;
@@ -226,7 +224,6 @@ asmlinkage int sys_sigreturn(unsigned long r4, unsigned long r5,
                                     sizeof(frame->extramask))))
                 goto badframe;
 
-        sigdelsetmask(&set, ~_BLOCKABLE);
         set_current_blocked(&set);
 
         if (restore_sigcontext(regs, &frame->sc, &r0))
@@ -256,7 +253,6 @@ asmlinkage int sys_rt_sigreturn(unsigned long r4, unsigned long r5,
         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
                 goto badframe;
 
-        sigdelsetmask(&set, ~_BLOCKABLE);
         set_current_blocked(&set);
 
         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
@@ -522,10 +518,11 @@ handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
 /*
  * OK, we're invoking a handler
  */
-static int
+static void
 handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
-              sigset_t *oldset, struct pt_regs *regs, unsigned int save_r0)
+              struct pt_regs *regs, unsigned int save_r0)
 {
+        sigset_t *oldset = sigmask_to_save();
         int ret;
 
         /* Set up the stack frame */
@@ -534,10 +531,10 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
         else
                 ret = setup_frame(sig, ka, oldset, regs);
 
-        if (ret == 0)
-                block_sigmask(ka, sig);
-
-        return ret;
+        if (ret)
+                return;
+        signal_delivered(sig, info, ka, regs,
+                        test_thread_flag(TIF_SINGLESTEP));
 }
 
 /*
@@ -554,7 +551,6 @@ static void do_signal(struct pt_regs *regs, unsigned int save_r0)
         siginfo_t info;
         int signr;
         struct k_sigaction ka;
-        sigset_t *oldset;
 
         /*
          * We want the common case to go fast, which
@@ -565,30 +561,12 @@ static void do_signal(struct pt_regs *regs, unsigned int save_r0)
         if (!user_mode(regs))
                 return;
 
-        if (current_thread_info()->status & TS_RESTORE_SIGMASK)
-                oldset = &current->saved_sigmask;
-        else
-                oldset = &current->blocked;
-
         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
         if (signr > 0) {
                 handle_syscall_restart(save_r0, regs, &ka.sa);
 
                 /* Whee!  Actually deliver the signal.  */
-                if (handle_signal(signr, &ka, &info, oldset,
-                                  regs, save_r0) == 0) {
-                        /*
-                         * A signal was successfully delivered; the saved
-                         * sigmask will have been stored in the signal frame,
-                         * and will be restored by sigreturn, so we can simply
-                         * clear the TS_RESTORE_SIGMASK flag
-                         */
-                        current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
-
-                        tracehook_signal_handler(signr, &info, &ka, regs,
-                                        test_thread_flag(TIF_SINGLESTEP));
-                }
-
+                handle_signal(signr, &ka, &info, regs, save_r0);
                 return;
         }
 
@@ -610,10 +588,7 @@ static void do_signal(struct pt_regs *regs, unsigned int save_r0)
          * If there's no signal to deliver, we just put the saved sigmask
          * back.
          */
-        if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
-                current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
-                sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
-        }
+        restore_saved_sigmask();
 }
 
 asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
diff --git a/arch/sh/kernel/signal_64.c b/arch/sh/kernel/signal_64.c
index aa6428430842..6b5b3dfe886b 100644
--- a/arch/sh/kernel/signal_64.c
+++ b/arch/sh/kernel/signal_64.c
@@ -41,11 +41,9 @@
 
 #define DEBUG_SIG 0
 
-#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
-
-static int
+static void
 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
-                sigset_t *oldset, struct pt_regs * regs);
+                struct pt_regs * regs);
 
 static inline void
 handle_syscall_restart(struct pt_regs *regs, struct sigaction *sa)
@@ -88,7 +86,6 @@ static void do_signal(struct pt_regs *regs)
         siginfo_t info;
         int signr;
         struct k_sigaction ka;
-        sigset_t *oldset;
 
         /*
          * We want the common case to go fast, which
@@ -99,28 +96,13 @@ static void do_signal(struct pt_regs *regs)
         if (!user_mode(regs))
                 return;
 
-        if (current_thread_info()->status & TS_RESTORE_SIGMASK)
-                oldset = &current->saved_sigmask;
-        else
-                oldset = &current->blocked;
-
         signr = get_signal_to_deliver(&info, &ka, regs, 0);
         if (signr > 0) {
                 handle_syscall_restart(regs, &ka.sa);
 
                 /* Whee!  Actually deliver the signal.  */
-                if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
-                        /*
-                         * If a signal was successfully delivered, the
-                         * saved sigmask is in its frame, and we can
-                         * clear the TS_RESTORE_SIGMASK flag.
-                         */
-                        current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
-
-                        tracehook_signal_handler(signr, &info, &ka, regs,
-                                        test_thread_flag(TIF_SINGLESTEP));
-                        return;
-                }
+                handle_signal(signr, &info, &ka, regs);
+                return;
         }
 
         /* Did we come from a system call? */
@@ -143,12 +125,7 @@ static void do_signal(struct pt_regs *regs)
         }
 
         /* No signal to deliver -- put the saved sigmask back */
-        if (current_thread_info()->status & TS_RESTORE_SIGMASK) {
-                current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
-                sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
-        }
-
-        return;
+        restore_saved_sigmask();
 }
 
 /*
@@ -351,7 +328,6 @@ asmlinkage int sys_sigreturn(unsigned long r2, unsigned long r3,
                                     sizeof(frame->extramask))))
                 goto badframe;
 
-        sigdelsetmask(&set, ~_BLOCKABLE);
         set_current_blocked(&set);
 
         if (restore_sigcontext(regs, &frame->sc, &ret))
@@ -384,7 +360,6 @@ asmlinkage int sys_rt_sigreturn(unsigned long r2, unsigned long r3,
         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
                 goto badframe;
 
-        sigdelsetmask(&set, ~_BLOCKABLE);
         set_current_blocked(&set);
 
         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ret))
@@ -659,10 +634,11 @@ give_sigsegv:
 /*
  * OK, we're invoking a handler
  */
-static int
+static void
 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
-                sigset_t *oldset, struct pt_regs * regs)
+                struct pt_regs * regs)
 {
+        sigset_t *oldset = sigmask_to_save();
         int ret;
 
         /* Set up the stack frame */
@@ -671,10 +647,11 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
         else
                 ret = setup_frame(sig, ka, oldset, regs);
 
-        if (ret == 0)
-                block_sigmask(ka, sig);
+        if (ret)
+                return;
 
-        return ret;
+        signal_delivered(sig, info, ka, regs,
+                        test_thread_flag(TIF_SINGLESTEP));
 }
 
 asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)