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

6 files changed, 40 insertions, 57 deletions

diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 98bd70faccc5..daeca56211e3 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -273,7 +273,6 @@ asmlinkage long sys32_sigreturn(struct pt_regs *regs)
 				    sizeof(frame->extramask))))
 		goto badframe;
 
-	sigdelsetmask(&set, ~_BLOCKABLE);
 	set_current_blocked(&set);
 
 	if (ia32_restore_sigcontext(regs, &frame->sc, &ax))
@@ -299,7 +298,6 @@ asmlinkage long sys32_rt_sigreturn(struct pt_regs *regs)
 	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 		goto badframe;
 
-	sigdelsetmask(&set, ~_BLOCKABLE);
 	set_current_blocked(&set);
 
 	if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
diff --git a/arch/x86/include/asm/sighandling.h b/arch/x86/include/asm/sighandling.h
index ada93b3b8c66..beff97f7df37 100644
--- a/arch/x86/include/asm/sighandling.h
+++ b/arch/x86/include/asm/sighandling.h
@@ -7,8 +7,6 @@
 
 #include <asm/processor-flags.h>
 
-#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
-
 #define __FIX_EFLAGS	(X86_EFLAGS_AC | X86_EFLAGS_OF | \
 			 X86_EFLAGS_DF | X86_EFLAGS_TF | X86_EFLAGS_SF | \
 			 X86_EFLAGS_ZF | X86_EFLAGS_AF | X86_EFLAGS_PF | \
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 5c25de07cba8..89f794f007ec 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -248,7 +248,23 @@ 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));
+}
+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;
 }
 
 static inline bool is_ia32_task(void)
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 01ccf9b71473..623f28837476 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -316,7 +316,6 @@ ret_from_exception:
 	preempt_stop(CLBR_ANY)
 ret_from_intr:
 	GET_THREAD_INFO(%ebp)
-resume_userspace_sig:
 #ifdef CONFIG_VM86
 	movl PT_EFLAGS(%esp), %eax	# mix EFLAGS and CS
 	movb PT_CS(%esp), %al
@@ -615,9 +614,13 @@ work_notifysig:				# deal with pending signals and
 					# vm86-space
 	TRACE_IRQS_ON
 	ENABLE_INTERRUPTS(CLBR_NONE)
+	movb PT_CS(%esp), %bl
+	andb $SEGMENT_RPL_MASK, %bl
+	cmpb $USER_RPL, %bl
+	jb resume_kernel
 	xorl %edx, %edx
 	call do_notify_resume
-	jmp resume_userspace_sig
+	jmp resume_userspace
 
 	ALIGN
 work_notifysig_v86:
@@ -630,9 +633,13 @@ work_notifysig_v86:
 #endif
 	TRACE_IRQS_ON
 	ENABLE_INTERRUPTS(CLBR_NONE)
+	movb PT_CS(%esp), %bl
+	andb $SEGMENT_RPL_MASK, %bl
+	cmpb $USER_RPL, %bl
+	jb resume_kernel
 	xorl %edx, %edx
 	call do_notify_resume
-	jmp resume_userspace_sig
+	jmp resume_userspace
 END(work_pending)
 
 	# perform syscall exit tracing
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 2e937a5ad531..21af737053aa 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -555,7 +555,6 @@ unsigned long sys_sigreturn(struct pt_regs *regs)
 				    sizeof(frame->extramask))))
 		goto badframe;
 
-	sigdelsetmask(&set, ~_BLOCKABLE);
 	set_current_blocked(&set);
 
 	if (restore_sigcontext(regs, &frame->sc, &ax))
@@ -581,7 +580,6 @@ long sys_rt_sigreturn(struct pt_regs *regs)
 	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, &ax))
@@ -647,42 +645,28 @@ setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 		struct pt_regs *regs)
 {
 	int usig = signr_convert(sig);
-	sigset_t *set = &current->blocked;
-	int ret;
-
-	if (current_thread_info()->status & TS_RESTORE_SIGMASK)
-		set = &current->saved_sigmask;
+	sigset_t *set = sigmask_to_save();
 
 	/* Set up the stack frame */
 	if (is_ia32) {
 		if (ka->sa.sa_flags & SA_SIGINFO)
-			ret = ia32_setup_rt_frame(usig, ka, info, set, regs);
+			return ia32_setup_rt_frame(usig, ka, info, set, regs);
 		else
-			ret = ia32_setup_frame(usig, ka, set, regs);
+			return ia32_setup_frame(usig, ka, set, regs);
 #ifdef CONFIG_X86_X32_ABI
 	} else if (is_x32) {
-		ret = x32_setup_rt_frame(usig, ka, info,
+		return x32_setup_rt_frame(usig, ka, info,
 					 (compat_sigset_t *)set, regs);
 #endif
 	} else {
-		ret = __setup_rt_frame(sig, ka, info, set, regs);
-	}
-
-	if (ret) {
-		force_sigsegv(sig, current);
-		return -EFAULT;
+		return __setup_rt_frame(sig, ka, info, set, regs);
 	}
-
-	current_thread_info()->status &= ~TS_RESTORE_SIGMASK;
-	return ret;
 }
 
-static int
+static void
 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 		struct pt_regs *regs)
 {
-	int ret;
-
 	/* Are we from a system call? */
 	if (syscall_get_nr(current, regs) >= 0) {
 		/* If so, check system call restarting.. */
@@ -713,10 +697,10 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 	    likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
 		regs->flags &= ~X86_EFLAGS_TF;
 
-	ret = setup_rt_frame(sig, ka, info, regs);
-
-	if (ret)
-		return ret;
+	if (setup_rt_frame(sig, ka, info, regs) < 0) {
+		force_sigsegv(sig, current);
+		return;
+	}
 
 	/*
 	 * Clear the direction flag as per the ABI for function entry.
@@ -731,12 +715,8 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 	 */
 	regs->flags &= ~X86_EFLAGS_TF;
 
-	block_sigmask(ka, sig);
-
-	tracehook_signal_handler(sig, info, ka, regs,
-				 test_thread_flag(TIF_SINGLESTEP));
-
-	return 0;
+	signal_delivered(sig, info, ka, regs,
+			 test_thread_flag(TIF_SINGLESTEP));
 }
 
 #ifdef CONFIG_X86_32
@@ -757,16 +737,6 @@ static void do_signal(struct pt_regs *regs)
 	siginfo_t info;
 	int signr;
 
-	/*
-	 * We want the common case to go fast, which is why we may in certain
-	 * cases get here from kernel mode. Just return without doing anything
-	 * if so.
-	 * X86_32: vm86 regs switched out by assembly code before reaching
-	 * here, so testing against kernel CS suffices.
-	 */
-	if (!user_mode(regs))
-		return;
-
 	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 	if (signr > 0) {
 		/* Whee! Actually deliver the signal.  */
@@ -796,10 +766,7 @@ static void do_signal(struct pt_regs *regs)
 	 * 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;
-		set_current_blocked(&current->saved_sigmask);
-	}
+	restore_saved_sigmask();
 }
 
 /*
@@ -934,7 +901,6 @@ asmlinkage long sys32_x32_rt_sigreturn(struct pt_regs *regs)
 	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, &ax))
diff --git a/arch/x86/um/signal.c b/arch/x86/um/signal.c
index bb0fb03b9f85..a508cea13503 100644
--- a/arch/x86/um/signal.c
+++ b/arch/x86/um/signal.c
@@ -486,7 +486,6 @@ long sys_sigreturn(struct pt_regs *regs)
 	    copy_from_user(&set.sig[1], extramask, sig_size))
 		goto segfault;
 
-	sigdelsetmask(&set, ~_BLOCKABLE);
 	set_current_blocked(&set);
 
 	if (copy_sc_from_user(&current->thread.regs, sc))
@@ -600,7 +599,6 @@ long sys_rt_sigreturn(struct pt_regs *regs)
 	if (copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
 		goto segfault;
 
-	sigdelsetmask(&set, ~_BLOCKABLE);
 	set_current_blocked(&set);
 
 	if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))