1 files changed, 39 insertions, 28 deletions

diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
index 29376f0e725c..9a32f7419d78 100644
--- a/arch/s390/kernel/nmi.c
+++ b/arch/s390/kernel/nmi.c
@@ -98,7 +98,7 @@ EXPORT_SYMBOL_GPL(s390_handle_mcck);
  * returns 0 if all registers could be validated
  * returns 1 otherwise
  */
-static int notrace s390_validate_registers(union mci mci)
+static int notrace s390_validate_registers(union mci mci, int umode)
 {
 	int kill_task;
 	u64 zero;
@@ -110,26 +110,41 @@ static int notrace s390_validate_registers(union mci mci)
 	if (!mci.gr) {
 		/*
 		 * General purpose registers couldn't be restored and have
-		 * unknown contents. Process needs to be terminated.
+		 * unknown contents. Stop system or terminate process.
 		 */
+		if (!umode)
+			s390_handle_damage();
 		kill_task = 1;
 	}
 	if (!mci.fp) {
 		/*
-		 * Floating point registers can't be restored and
-		 * therefore the process needs to be terminated.
+		 * Floating point registers can't be restored. If the
+		 * kernel currently uses floating point registers the
+		 * system is stopped. If the process has its floating
+		 * pointer registers loaded it is terminated.
+		 * Otherwise just revalidate the registers.
 		 */
-		kill_task = 1;
+		if (S390_lowcore.fpu_flags & KERNEL_VXR_V0V7)
+			s390_handle_damage();
+		if (!test_cpu_flag(CIF_FPU))
+			kill_task = 1;
 	}
 	fpt_save_area = &S390_lowcore.floating_pt_save_area;
 	fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
 	if (!mci.fc) {
 		/*
 		 * Floating point control register can't be restored.
-		 * Task will be terminated.
+		 * If the kernel currently uses the floating pointer
+		 * registers and needs the FPC register the system is
+		 * stopped. If the process has its floating pointer
+		 * registers loaded it is terminated. Otherwiese the
+		 * FPC is just revalidated.
 		 */
+		if (S390_lowcore.fpu_flags & KERNEL_FPC)
+			s390_handle_damage();
 		asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
-		kill_task = 1;
+		if (!test_cpu_flag(CIF_FPU))
+			kill_task = 1;
 	} else
 		asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
 
@@ -159,10 +174,16 @@ static int notrace s390_validate_registers(union mci mci)
 
 		if (!mci.vr) {
 			/*
-			 * Vector registers can't be restored and therefore
-			 * the process needs to be terminated.
+			 * Vector registers can't be restored. If the kernel
+			 * currently uses vector registers the system is
+			 * stopped. If the process has its vector registers
+			 * loaded it is terminated. Otherwise just revalidate
+			 * the registers.
 			 */
-			kill_task = 1;
+			if (S390_lowcore.fpu_flags & KERNEL_VXR)
+				s390_handle_damage();
+			if (!test_cpu_flag(CIF_FPU))
+				kill_task = 1;
 		}
 		cr0.val = S390_lowcore.cregs_save_area[0];
 		cr0.afp = cr0.vx = 1;
@@ -250,13 +271,11 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
 	struct mcck_struct *mcck;
 	unsigned long long tmp;
 	union mci mci;
-	int umode;
 
 	nmi_enter();
 	inc_irq_stat(NMI_NMI);
 	mci.val = S390_lowcore.mcck_interruption_code;
 	mcck = this_cpu_ptr(&cpu_mcck);
-	umode = user_mode(regs);
 
 	if (mci.sd) {
 		/* System damage -> stopping machine */
@@ -297,22 +316,14 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
 			s390_handle_damage();
 		}
 	}
-	if (s390_validate_registers(mci)) {
-		if (umode) {
-			/*
-			 * Couldn't restore all register contents while in
-			 * user mode -> mark task for termination.
-			 */
-			mcck->kill_task = 1;
-			mcck->mcck_code = mci.val;
-			set_cpu_flag(CIF_MCCK_PENDING);
-		} else {
-			/*
-			 * Couldn't restore all register contents while in
-			 * kernel mode -> stopping machine.
-			 */
-			s390_handle_damage();
-		}
+	if (s390_validate_registers(mci, user_mode(regs))) {
+		/*
+		 * Couldn't restore all register contents for the
+		 * user space process -> mark task for termination.
+		 */
+		mcck->kill_task = 1;
+		mcck->mcck_code = mci.val;
+		set_cpu_flag(CIF_MCCK_PENDING);
 	}
 	if (mci.cd) {
 		/* Timing facility damage */