diff --git a/arch/s390/include/asm/compat.h b/arch/s390/include/asm/compat.h
index cdb9b78..2e49748b 100644
--- a/arch/s390/include/asm/compat.h
+++ b/arch/s390/include/asm/compat.h
@@ -12,6 +12,7 @@
 #define PSW32_MASK_IO		0x02000000UL
 #define PSW32_MASK_EXT		0x01000000UL
 #define PSW32_MASK_KEY		0x00F00000UL
+#define PSW32_MASK_BASE		0x00080000UL	/* Always one */
 #define PSW32_MASK_MCHECK	0x00040000UL
 #define PSW32_MASK_WAIT		0x00020000UL
 #define PSW32_MASK_PSTATE	0x00010000UL
@@ -19,21 +20,19 @@
 #define PSW32_MASK_CC		0x00003000UL
 #define PSW32_MASK_PM		0x00000f00UL
 
-#define PSW32_ADDR_AMODE31	0x80000000UL
+#define PSW32_MASK_USER		0x00003F00UL
+
+#define PSW32_ADDR_AMODE	0x80000000UL
 #define PSW32_ADDR_INSN		0x7FFFFFFFUL
 
-#define PSW32_BASE_BITS		0x00080000UL
+#define PSW32_DEFAULT_KEY	(((u32) PAGE_DEFAULT_ACC) << 20)
 
 #define PSW32_ASC_PRIMARY	0x00000000UL
 #define PSW32_ASC_ACCREG	0x00004000UL
 #define PSW32_ASC_SECONDARY	0x00008000UL
 #define PSW32_ASC_HOME		0x0000C000UL
 
-#define PSW32_MASK_MERGE(CURRENT,NEW) \
-	(((CURRENT) & ~(PSW32_MASK_CC|PSW32_MASK_PM)) | \
-	 ((NEW) & (PSW32_MASK_CC|PSW32_MASK_PM)))
-
-extern long psw32_user_bits;
+extern u32 psw32_user_bits;
 
 #define COMPAT_USER_HZ		100
 #define COMPAT_UTS_MACHINE	"s390\0\0\0\0"
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 306c93c..20ffb12 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -118,17 +118,17 @@
 /*
  * Do necessary setup to start up a new thread.
  */
-#define start_thread(regs, new_psw, new_stackp) do {		\
-	regs->psw.mask	= psw_user_bits;			\
-	regs->psw.addr	= new_psw | PSW_ADDR_AMODE;		\
-	regs->gprs[15]	= new_stackp;				\
+#define start_thread(regs, new_psw, new_stackp) do {			\
+	regs->psw.mask	= psw_user_bits | PSW_MASK_EA | PSW_MASK_BA;	\
+	regs->psw.addr	= new_psw | PSW_ADDR_AMODE;			\
+	regs->gprs[15]	= new_stackp;					\
 } while (0)
 
-#define start_thread31(regs, new_psw, new_stackp) do {		\
-	regs->psw.mask	= psw_user32_bits;			\
-	regs->psw.addr	= new_psw | PSW_ADDR_AMODE;		\
-	regs->gprs[15]	= new_stackp;				\
-	crst_table_downgrade(current->mm, 1UL << 31);		\
+#define start_thread31(regs, new_psw, new_stackp) do {			\
+	regs->psw.mask	= psw_user_bits | PSW_MASK_BA;			\
+	regs->psw.addr	= new_psw | PSW_ADDR_AMODE;			\
+	regs->gprs[15]	= new_stackp;					\
+	crst_table_downgrade(current->mm, 1UL << 31);			\
 } while (0)
 
 /* Forward declaration, a strange C thing */
@@ -234,24 +234,14 @@
 }
  
 /*
- * Function to stop a processor until an interruption occurred
- */
-static inline void enabled_wait(void)
-{
-	__load_psw_mask(PSW_BASE_BITS | PSW_MASK_IO | PSW_MASK_EXT |
-			PSW_MASK_MCHECK | PSW_MASK_WAIT | PSW_DEFAULT_KEY);
-}
-
-/*
  * Function to drop a processor into disabled wait state
  */
-
 static inline void ATTRIB_NORET disabled_wait(unsigned long code)
 {
         unsigned long ctl_buf;
         psw_t dw_psw;
 
-        dw_psw.mask = PSW_BASE_BITS | PSW_MASK_WAIT;
+	dw_psw.mask = PSW_MASK_BASE | PSW_MASK_WAIT | PSW_MASK_BA | PSW_MASK_EA;
         dw_psw.addr = code;
         /* 
          * Store status and then load disabled wait psw,
diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index 2904cc6..6fc00d2 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -230,6 +230,7 @@
 #define PSW_MASK_IO		0x02000000UL
 #define PSW_MASK_EXT		0x01000000UL
 #define PSW_MASK_KEY		0x00F00000UL
+#define PSW_MASK_BASE		0x00080000UL	/* always one */
 #define PSW_MASK_MCHECK		0x00040000UL
 #define PSW_MASK_WAIT		0x00020000UL
 #define PSW_MASK_PSTATE		0x00010000UL
@@ -239,10 +240,11 @@
 #define PSW_MASK_EA		0x00000000UL
 #define PSW_MASK_BA		0x00000000UL
 
+#define PSW_MASK_USER		0x00003F00UL
+
 #define PSW_ADDR_AMODE		0x80000000UL
 #define PSW_ADDR_INSN		0x7FFFFFFFUL
 
-#define PSW_BASE_BITS		0x00080000UL
 #define PSW_DEFAULT_KEY		(((unsigned long) PAGE_DEFAULT_ACC) << 20)
 
 #define PSW_ASC_PRIMARY		0x00000000UL
@@ -256,6 +258,7 @@
 #define PSW_MASK_DAT		0x0400000000000000UL
 #define PSW_MASK_IO		0x0200000000000000UL
 #define PSW_MASK_EXT		0x0100000000000000UL
+#define PSW_MASK_BASE		0x0000000000000000UL
 #define PSW_MASK_KEY		0x00F0000000000000UL
 #define PSW_MASK_MCHECK		0x0004000000000000UL
 #define PSW_MASK_WAIT		0x0002000000000000UL
@@ -266,11 +269,11 @@
 #define PSW_MASK_EA		0x0000000100000000UL
 #define PSW_MASK_BA		0x0000000080000000UL
 
+#define PSW_MASK_USER		0x00003F0000000000UL
+
 #define PSW_ADDR_AMODE		0x0000000000000000UL
 #define PSW_ADDR_INSN		0xFFFFFFFFFFFFFFFFUL
 
-#define PSW_BASE_BITS		0x0000000180000000UL
-#define PSW_BASE32_BITS		0x0000000080000000UL
 #define PSW_DEFAULT_KEY		(((unsigned long) PAGE_DEFAULT_ACC) << 52)
 
 #define PSW_ASC_PRIMARY		0x0000000000000000UL
@@ -283,18 +286,7 @@
 #ifdef __KERNEL__
 extern long psw_kernel_bits;
 extern long psw_user_bits;
-#ifdef CONFIG_64BIT
-extern long psw_user32_bits;
 #endif
-#endif
-
-/* This macro merges a NEW PSW mask specified by the user into
-   the currently active PSW mask CURRENT, modifying only those
-   bits in CURRENT that the user may be allowed to change: this
-   is the condition code and the program mask bits.  */
-#define PSW_MASK_MERGE(CURRENT,NEW) \
-	(((CURRENT) & ~(PSW_MASK_CC|PSW_MASK_PM)) | \
-	 ((NEW) & (PSW_MASK_CC|PSW_MASK_PM)))
 
 /*
  * The s390_regs structure is used to define the elf_gregset_t.
diff --git a/arch/s390/include/asm/system.h b/arch/s390/include/asm/system.h
index afb849e..d73cc6b 100644
--- a/arch/s390/include/asm/system.h
+++ b/arch/s390/include/asm/system.h
@@ -212,8 +212,10 @@
 	__load_psw_mask(mask | (arch_local_save_flags() & ~(-1UL >> 8)));
 }
 
-#define local_mcck_enable()  __set_psw_mask(psw_kernel_bits)
-#define local_mcck_disable() __set_psw_mask(psw_kernel_bits & ~PSW_MASK_MCHECK)
+#define local_mcck_enable() \
+	__set_psw_mask(psw_kernel_bits | PSW_MASK_DAT | PSW_MASK_MCHECK)
+#define local_mcck_disable() \
+	__set_psw_mask(psw_kernel_bits | PSW_MASK_DAT)
 
 #ifdef CONFIG_SMP
 
diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c
index 53acaa8..24b2187 100644
--- a/arch/s390/kernel/compat_linux.c
+++ b/arch/s390/kernel/compat_linux.c
@@ -60,12 +60,9 @@
 
 #include "compat_linux.h"
 
-long psw_user32_bits	= (PSW_BASE32_BITS | PSW_MASK_DAT | PSW_ASC_HOME |
-			   PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK |
-			   PSW_MASK_PSTATE | PSW_DEFAULT_KEY);
-long psw32_user_bits	= (PSW32_BASE_BITS | PSW32_MASK_DAT | PSW32_ASC_HOME |
-			   PSW32_MASK_IO | PSW32_MASK_EXT | PSW32_MASK_MCHECK |
-			   PSW32_MASK_PSTATE);
+u32 psw32_user_bits = PSW32_MASK_DAT | PSW32_MASK_IO | PSW32_MASK_EXT |
+		      PSW32_DEFAULT_KEY | PSW32_MASK_BASE | PSW32_MASK_MCHECK |
+		      PSW32_MASK_PSTATE | PSW32_ASC_HOME;
  
 /* For this source file, we want overflow handling. */
 
diff --git a/arch/s390/kernel/compat_signal.c b/arch/s390/kernel/compat_signal.c
index 72a1c8d..fd83b69 100644
--- a/arch/s390/kernel/compat_signal.c
+++ b/arch/s390/kernel/compat_signal.c
@@ -300,9 +300,9 @@
 	_s390_regs_common32 regs32;
 	int err, i;
 
-	regs32.psw.mask = PSW32_MASK_MERGE(psw32_user_bits,
-					   (__u32)(regs->psw.mask >> 32));
-	regs32.psw.addr = PSW32_ADDR_AMODE31 | (__u32) regs->psw.addr;
+	regs32.psw.mask = psw32_user_bits |
+		((__u32)(regs->psw.mask >> 32) & PSW32_MASK_USER);
+	regs32.psw.addr = PSW32_ADDR_AMODE | (__u32) regs->psw.addr;
 	for (i = 0; i < NUM_GPRS; i++)
 		regs32.gprs[i] = (__u32) regs->gprs[i];
 	save_access_regs(current->thread.acrs);
@@ -327,8 +327,8 @@
 	err = __copy_from_user(&regs32, &sregs->regs, sizeof(regs32));
 	if (err)
 		return err;
-	regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask,
-				        (__u64)regs32.psw.mask << 32);
+	regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
+		(__u64)(regs32.psw.mask & PSW32_MASK_USER) << 32;
 	regs->psw.addr = (__u64)(regs32.psw.addr & PSW32_ADDR_INSN);
 	for (i = 0; i < NUM_GPRS; i++)
 		regs->gprs[i] = (__u64) regs32.gprs[i];
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index f297456..37394b3 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -252,7 +252,7 @@
 {
 	psw_t psw;
 
-	psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
+	psw.mask = PSW_MASK_BASE | PSW_DEFAULT_KEY | PSW_MASK_EA | PSW_MASK_BA;
 	psw.addr = PSW_ADDR_AMODE | (unsigned long) s390_base_ext_handler;
 	S390_lowcore.external_new_psw = psw;
 	psw.addr = PSW_ADDR_AMODE | (unsigned long) s390_base_pgm_handler;
diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index ca0520c..2964583 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -2033,12 +2033,12 @@
 	__ctl_clear_bit(0,28);
 
 	/* Set new machine check handler */
-	S390_lowcore.mcck_new_psw.mask = psw_kernel_bits & ~PSW_MASK_MCHECK;
+	S390_lowcore.mcck_new_psw.mask = psw_kernel_bits | PSW_MASK_DAT;
 	S390_lowcore.mcck_new_psw.addr =
 		PSW_ADDR_AMODE | (unsigned long) s390_base_mcck_handler;
 
 	/* Set new program check handler */
-	S390_lowcore.program_new_psw.mask = psw_kernel_bits & ~PSW_MASK_MCHECK;
+	S390_lowcore.program_new_psw.mask = psw_kernel_bits | PSW_MASK_DAT;
 	S390_lowcore.program_new_psw.addr =
 		PSW_ADDR_AMODE | (unsigned long) s390_base_pgm_handler;
 
diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index 13a0b52..3cd0f25 100644
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -108,7 +108,7 @@
 #ifdef CONFIG_CRASH_DUMP
 	int (*start_kdump)(int) = (void *)((struct kimage *) image)->start;
 
-	__load_psw_mask(PSW_BASE_BITS | PSW_DEFAULT_KEY);
+	__load_psw_mask(PSW_MASK_BASE | PSW_DEFAULT_KEY | PSW_MASK_EA | PSW_MASK_BA);
 	setup_regs();
 	start_kdump(1);
 #endif
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 541a750..5e64a9a 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -117,7 +117,8 @@
 	struct pt_regs regs;
 
 	memset(&regs, 0, sizeof(regs));
-	regs.psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
+	regs.psw.mask = psw_kernel_bits |
+		PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 	regs.psw.addr = (unsigned long) kernel_thread_starter | PSW_ADDR_AMODE;
 	regs.gprs[9] = (unsigned long) fn;
 	regs.gprs[10] = (unsigned long) arg;
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 3519c99..41e2076 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -169,8 +169,9 @@
 		 */
 		tmp = *(addr_t *)((addr_t) &task_pt_regs(child)->psw + addr);
 		if (addr == (addr_t) &dummy->regs.psw.mask)
-			/* Remove per bit from user psw. */
-			tmp &= ~PSW_MASK_PER;
+			/* Return a clean psw mask. */
+			tmp = psw_user_bits | (tmp & PSW_MASK_USER) |
+				PSW_MASK_EA | PSW_MASK_BA;
 
 	} else if (addr < (addr_t) &dummy->regs.orig_gpr2) {
 		/*
@@ -285,17 +286,18 @@
 static int __poke_user(struct task_struct *child, addr_t addr, addr_t data)
 {
 	struct user *dummy = NULL;
-	addr_t offset;
+	addr_t offset, tmp;
 
 	if (addr < (addr_t) &dummy->regs.acrs) {
 		/*
 		 * psw and gprs are stored on the stack
 		 */
+		tmp = (data & ~PSW_MASK_USER) ^ psw_user_bits;
 		if (addr == (addr_t) &dummy->regs.psw.mask &&
 #ifdef CONFIG_COMPAT
-		    data != PSW_MASK_MERGE(psw_user32_bits, data) &&
+		    tmp != PSW_MASK_BA &&
 #endif
-		    data != PSW_MASK_MERGE(psw_user_bits, data))
+		    tmp != (PSW_MASK_EA | PSW_MASK_BA))
 			/* Invalid psw mask. */
 			return -EINVAL;
 #ifndef CONFIG_64BIT
@@ -505,21 +507,20 @@
 	__u32 tmp;
 
 	if (addr < (addr_t) &dummy32->regs.acrs) {
+		struct pt_regs *regs = task_pt_regs(child);
 		/*
 		 * psw and gprs are stored on the stack
 		 */
 		if (addr == (addr_t) &dummy32->regs.psw.mask) {
 			/* Fake a 31 bit psw mask. */
-			tmp = (__u32)(task_pt_regs(child)->psw.mask >> 32);
-			tmp = PSW32_MASK_MERGE(psw32_user_bits, tmp);
+			tmp = (__u32)(regs->psw.mask >> 32);
+			tmp = psw32_user_bits | (tmp & PSW32_MASK_USER);
 		} else if (addr == (addr_t) &dummy32->regs.psw.addr) {
 			/* Fake a 31 bit psw address. */
-			tmp = (__u32) task_pt_regs(child)->psw.addr |
-				PSW32_ADDR_AMODE31;
+			tmp = (__u32) regs->psw.addr | PSW32_ADDR_AMODE;
 		} else {
 			/* gpr 0-15 */
-			tmp = *(__u32 *)((addr_t) &task_pt_regs(child)->psw +
-					 addr*2 + 4);
+			tmp = *(__u32 *)((addr_t) &regs->psw + addr*2 + 4);
 		}
 	} else if (addr < (addr_t) (&dummy32->regs.orig_gpr2)) {
 		/*
@@ -604,20 +605,20 @@
 	addr_t offset;
 
 	if (addr < (addr_t) &dummy32->regs.acrs) {
+		struct pt_regs *regs = task_pt_regs(child);
 		/*
 		 * psw, gprs, acrs and orig_gpr2 are stored on the stack
 		 */
 		if (addr == (addr_t) &dummy32->regs.psw.mask) {
 			/* Build a 64 bit psw mask from 31 bit mask. */
-			if (tmp != PSW32_MASK_MERGE(psw32_user_bits, tmp))
+			if ((tmp & ~PSW32_MASK_USER) != psw32_user_bits)
 				/* Invalid psw mask. */
 				return -EINVAL;
-			task_pt_regs(child)->psw.mask =
-				PSW_MASK_MERGE(psw_user32_bits, (__u64) tmp << 32);
+			regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
+				(__u64)(tmp & PSW32_MASK_USER) << 32;
 		} else if (addr == (addr_t) &dummy32->regs.psw.addr) {
 			/* Build a 64 bit psw address from 31 bit address. */
-			task_pt_regs(child)->psw.addr =
-				(__u64) tmp & PSW32_ADDR_INSN;
+			regs->psw.addr = (__u64) tmp & PSW32_ADDR_INSN;
 			/*
 			 * The debugger changed the instruction address,
 			 * reset system call restart, see signal.c:do_signal
@@ -625,8 +626,7 @@
 			task_thread_info(child)->system_call = 0;
 		} else {
 			/* gpr 0-15 */
-			*(__u32*)((addr_t) &task_pt_regs(child)->psw
-				  + addr*2 + 4) = tmp;
+			*(__u32*)((addr_t) &regs->psw + addr*2 + 4) = tmp;
 		}
 	} else if (addr < (addr_t) (&dummy32->regs.orig_gpr2)) {
 		/*
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 6f8e377..8ac6bfa 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -62,11 +62,11 @@
 #include <asm/kvm_virtio.h>
 #include <asm/diag.h>
 
-long psw_kernel_bits	= (PSW_BASE_BITS | PSW_MASK_DAT | PSW_ASC_PRIMARY |
-			   PSW_MASK_MCHECK | PSW_DEFAULT_KEY);
-long psw_user_bits	= (PSW_BASE_BITS | PSW_MASK_DAT | PSW_ASC_HOME |
-			   PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK |
-			   PSW_MASK_PSTATE | PSW_DEFAULT_KEY);
+long psw_kernel_bits	= PSW_DEFAULT_KEY | PSW_MASK_BASE | PSW_ASC_PRIMARY |
+			  PSW_MASK_EA | PSW_MASK_BA;
+long psw_user_bits	= PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT |
+			  PSW_DEFAULT_KEY | PSW_MASK_BASE | PSW_MASK_MCHECK |
+			  PSW_MASK_PSTATE | PSW_ASC_HOME;
 
 /*
  * User copy operations.
@@ -278,22 +278,14 @@
 unsigned int user_mode = HOME_SPACE_MODE;
 EXPORT_SYMBOL_GPL(user_mode);
 
-static int set_amode_and_uaccess(unsigned long user_amode,
-				 unsigned long user32_amode)
+static int set_amode_primary(void)
 {
-	psw_user_bits = PSW_BASE_BITS | PSW_MASK_DAT | user_amode |
-			PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK |
-			PSW_MASK_PSTATE | PSW_DEFAULT_KEY;
+	psw_kernel_bits = (psw_kernel_bits & ~PSW_MASK_ASC) | PSW_ASC_HOME;
+	psw_user_bits = (psw_user_bits & ~PSW_MASK_ASC) | PSW_ASC_PRIMARY;
 #ifdef CONFIG_COMPAT
-	psw_user32_bits = PSW_BASE32_BITS | PSW_MASK_DAT | user_amode |
-			  PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK |
-			  PSW_MASK_PSTATE | PSW_DEFAULT_KEY;
-	psw32_user_bits = PSW32_BASE_BITS | PSW32_MASK_DAT | user32_amode |
-			  PSW32_MASK_IO | PSW32_MASK_EXT | PSW32_MASK_MCHECK |
-			  PSW32_MASK_PSTATE;
+	psw32_user_bits =
+		(psw32_user_bits & ~PSW32_MASK_ASC) | PSW32_ASC_PRIMARY;
 #endif
-	psw_kernel_bits = PSW_BASE_BITS | PSW_MASK_DAT | PSW_ASC_HOME |
-			  PSW_MASK_MCHECK | PSW_DEFAULT_KEY;
 
 	if (MACHINE_HAS_MVCOS) {
 		memcpy(&uaccess, &uaccess_mvcos_switch, sizeof(uaccess));
@@ -329,7 +321,7 @@
 static void setup_addressing_mode(void)
 {
 	if (user_mode == PRIMARY_SPACE_MODE) {
-		if (set_amode_and_uaccess(PSW_ASC_PRIMARY, PSW32_ASC_PRIMARY))
+		if (set_amode_primary())
 			pr_info("Address spaces switched, "
 				"mvcos available\n");
 		else
@@ -348,24 +340,25 @@
 	 */
 	BUILD_BUG_ON(sizeof(struct _lowcore) != LC_PAGES * 4096);
 	lc = __alloc_bootmem_low(LC_PAGES * PAGE_SIZE, LC_PAGES * PAGE_SIZE, 0);
-	lc->restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
+	lc->restart_psw.mask = psw_kernel_bits;
 	lc->restart_psw.addr =
 		PSW_ADDR_AMODE | (unsigned long) psw_restart_int_handler;
-	if (user_mode != HOME_SPACE_MODE)
-		lc->restart_psw.mask |= PSW_ASC_HOME;
-	lc->external_new_psw.mask = psw_kernel_bits;
+	lc->external_new_psw.mask = psw_kernel_bits |
+		PSW_MASK_DAT | PSW_MASK_MCHECK;
 	lc->external_new_psw.addr =
 		PSW_ADDR_AMODE | (unsigned long) ext_int_handler;
-	lc->svc_new_psw.mask = psw_kernel_bits | PSW_MASK_IO | PSW_MASK_EXT;
+	lc->svc_new_psw.mask = psw_kernel_bits |
+		PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 	lc->svc_new_psw.addr = PSW_ADDR_AMODE | (unsigned long) system_call;
-	lc->program_new_psw.mask = psw_kernel_bits;
+	lc->program_new_psw.mask = psw_kernel_bits |
+		PSW_MASK_DAT | PSW_MASK_MCHECK;
 	lc->program_new_psw.addr =
-		PSW_ADDR_AMODE | (unsigned long)pgm_check_handler;
-	lc->mcck_new_psw.mask =
-		psw_kernel_bits & ~PSW_MASK_MCHECK & ~PSW_MASK_DAT;
+		PSW_ADDR_AMODE | (unsigned long) pgm_check_handler;
+	lc->mcck_new_psw.mask = psw_kernel_bits;
 	lc->mcck_new_psw.addr =
 		PSW_ADDR_AMODE | (unsigned long) mcck_int_handler;
-	lc->io_new_psw.mask = psw_kernel_bits;
+	lc->io_new_psw.mask = psw_kernel_bits |
+		PSW_MASK_DAT | PSW_MASK_MCHECK;
 	lc->io_new_psw.addr = PSW_ADDR_AMODE | (unsigned long) io_int_handler;
 	lc->clock_comparator = -1ULL;
 	lc->kernel_stack = ((unsigned long) &init_thread_union) + THREAD_SIZE;
@@ -554,7 +547,7 @@
 	 * Setup restart PSW for absolute zero lowcore. This is necesary
 	 * if PSW restart is done on an offline CPU that has lowcore zero
 	 */
-	psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
+	psw.mask = PSW_DEFAULT_KEY | PSW_MASK_BASE | PSW_MASK_EA | PSW_MASK_BA;
 	psw.addr = PSW_ADDR_AMODE | (unsigned long) psw_restart_int_handler;
 	copy_to_absolute_zero(&S390_lowcore.restart_psw, &psw, sizeof(psw));
 }
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index 0e905cb..c197558 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -117,7 +117,8 @@
 
 	/* Copy a 'clean' PSW mask to the user to avoid leaking
 	   information about whether PER is currently on.  */
-	user_sregs.regs.psw.mask = PSW_MASK_MERGE(psw_user_bits, regs->psw.mask);
+	user_sregs.regs.psw.mask = psw_user_bits | PSW_MASK_EA | PSW_MASK_BA |
+				   (regs->psw.mask & PSW_MASK_USER);
 	user_sregs.regs.psw.addr = regs->psw.addr;
 	memcpy(&user_sregs.regs.gprs, &regs->gprs, sizeof(sregs->regs.gprs));
 	memcpy(&user_sregs.regs.acrs, current->thread.acrs,
@@ -144,8 +145,8 @@
 	err = __copy_from_user(&user_sregs, sregs, sizeof(_sigregs));
 	if (err)
 		return err;
-	regs->psw.mask = PSW_MASK_MERGE(regs->psw.mask,
-					user_sregs.regs.psw.mask);
+	regs->psw.mask = (regs->psw.mask & ~PSW_MASK_USER) |
+			 (user_sregs.regs.psw.mask & PSW_MASK_USER);
 	regs->psw.addr = PSW_ADDR_AMODE | user_sregs.regs.psw.addr;
 	memcpy(&regs->gprs, &user_sregs.regs.gprs, sizeof(sregs->regs.gprs));
 	memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index e3f51df..6c8a977 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -108,7 +108,7 @@
 	for_each_online_cpu(cpu) {
 		if (stap() == __cpu_logical_map[cpu]) {
 			/* We are online: Enable DAT again and return */
-			__load_psw_mask(psw_kernel_bits & ~PSW_MASK_MCHECK);
+			__load_psw_mask(psw_kernel_bits | PSW_MASK_DAT);
 			return;
 		}
 	}
@@ -130,14 +130,16 @@
 
 	if (smp_processor_id() == 0)
 		func(data);
-	__load_psw_mask(PSW_BASE_BITS | PSW_DEFAULT_KEY);
+	__load_psw_mask(PSW_DEFAULT_KEY | PSW_MASK_BASE |
+			PSW_MASK_EA | PSW_MASK_BA);
 	/* Disable lowcore protection */
 	__ctl_clear_bit(0, 28);
 	current_lc = lowcore_ptr[smp_processor_id()];
 	lc = lowcore_ptr[0];
 	if (!lc)
 		lc = current_lc;
-	lc->restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
+	lc->restart_psw.mask =
+		PSW_DEFAULT_KEY | PSW_MASK_BASE | PSW_MASK_EA | PSW_MASK_BA;
 	lc->restart_psw.addr = PSW_ADDR_AMODE | (unsigned long) smp_restart_cpu;
 	if (!cpu_online(0))
 		smp_switch_to_cpu(func, data, 0, stap(), __cpu_logical_map[0]);
@@ -159,7 +161,7 @@
 	int cpu, rc;
 
 	/* Disable all interrupts/machine checks */
-	__load_psw_mask(psw_kernel_bits & ~PSW_MASK_MCHECK);
+	__load_psw_mask(psw_kernel_bits | PSW_MASK_DAT);
 	trace_hardirqs_off();
 
 	/* stop all processors */
@@ -501,7 +503,8 @@
 	set_cpu_online(smp_processor_id(), true);
 	ipi_call_unlock();
 	__ctl_clear_bit(0, 28); /* Disable lowcore protection */
-	S390_lowcore.restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
+	S390_lowcore.restart_psw.mask =
+		PSW_DEFAULT_KEY | PSW_MASK_BASE | PSW_MASK_EA | PSW_MASK_BA;
 	S390_lowcore.restart_psw.addr =
 		PSW_ADDR_AMODE | (unsigned long) psw_restart_int_handler;
 	__ctl_set_bit(0, 28); /* Enable lowcore protection */
@@ -549,7 +552,8 @@
 	memset((char *)lowcore + 512, 0, sizeof(*lowcore) - 512);
 	lowcore->async_stack = async_stack + ASYNC_SIZE;
 	lowcore->panic_stack = panic_stack + PAGE_SIZE;
-	lowcore->restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
+	lowcore->restart_psw.mask =
+		PSW_DEFAULT_KEY | PSW_MASK_BASE | PSW_MASK_EA | PSW_MASK_BA;
 	lowcore->restart_psw.addr =
 		PSW_ADDR_AMODE | (unsigned long) restart_int_handler;
 	if (user_mode != HOME_SPACE_MODE)
diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index ffabcd9..79eee3f 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -200,7 +200,7 @@
 	       mask_bits(regs, PSW_MASK_PSTATE), mask_bits(regs, PSW_MASK_ASC),
 	       mask_bits(regs, PSW_MASK_CC), mask_bits(regs, PSW_MASK_PM));
 #ifdef CONFIG_64BIT
-	printk(" EA:%x", mask_bits(regs, PSW_BASE_BITS));
+	printk(" EA:%x", mask_bits(regs, PSW_MASK_EA | PSW_MASK_BA));
 #endif
 	printk("\n%s GPRS: " FOURLONG, mode,
 	       regs->gprs[0], regs->gprs[1], regs->gprs[2], regs->gprs[3]);
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 2d6228f..4f3de98 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -170,7 +170,8 @@
 	psw_t psw;
 
 	/* Wait for external, I/O or machine check interrupt. */
-	psw.mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_IO | PSW_MASK_EXT;
+	psw.mask = psw_kernel_bits | PSW_MASK_WAIT |
+		PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 
 	idle->nohz_delay = 0;
 
@@ -183,7 +184,8 @@
 		 *	set_cpu_timer(VTIMER_MAX_SLICE);
 		 *	idle->idle_enter = get_clock();
 		 *	__load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
-		 *			   PSW_MASK_IO | PSW_MASK_EXT);
+		 *			   PSW_MASK_DAT | PSW_MASK_IO |
+		 *			   PSW_MASK_EXT | PSW_MASK_MCHECK);
 		 * The difference is that the inline assembly makes sure that
 		 * the last three instruction are stpt, stck and lpsw in that
 		 * order. This is done to increase the precision.
@@ -216,7 +218,8 @@
 		 *	vq->idle = get_cpu_timer();
 		 *	idle->idle_enter = get_clock();
 		 *	__load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
-		 *			   PSW_MASK_IO | PSW_MASK_EXT);
+		 *			   PSW_MASK_DAT | PSW_MASK_IO |
+		 *			   PSW_MASK_EXT | PSW_MASK_MCHECK);
 		 * The difference is that the inline assembly makes sure that
 		 * the last three instruction are stpt, stck and lpsw in that
 		 * order. This is done to increase the precision.
diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
index a65229d..db92f04 100644
--- a/arch/s390/lib/delay.c
+++ b/arch/s390/lib/delay.c
@@ -32,7 +32,8 @@
 	u64 clock_saved;
 	u64 end;
 
-	mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;
+	mask = psw_kernel_bits | PSW_MASK_DAT | PSW_MASK_WAIT |
+		PSW_MASK_EXT | PSW_MASK_MCHECK;
 	end = get_clock() + (usecs << 12);
 	clock_saved = local_tick_disable();
 	__ctl_store(cr0_saved, 0, 0);
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index a90fd91..de3af0c 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -454,7 +454,7 @@
 	struct pt_regs regs;
 	int access, fault;
 
-	regs.psw.mask = psw_kernel_bits;
+	regs.psw.mask = psw_kernel_bits | PSW_MASK_DAT | PSW_MASK_MCHECK;
 	if (!irqs_disabled())
 		regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
 	regs.psw.addr = (unsigned long) __builtin_return_address(0);
diff --git a/drivers/s390/char/sclp_cmd.c b/drivers/s390/char/sclp_cmd.c
index 837e010..0b54a91 100644
--- a/drivers/s390/char/sclp_cmd.c
+++ b/drivers/s390/char/sclp_cmd.c
@@ -61,8 +61,8 @@
 	rc = sclp_service_call(cmd, sccb);
 	if (rc)
 		goto out;
-	__load_psw_mask(PSW_BASE_BITS | PSW_MASK_EXT |
-			PSW_MASK_WAIT | PSW_DEFAULT_KEY);
+	__load_psw_mask(PSW_DEFAULT_KEY | PSW_MASK_BASE | PSW_MASK_EA |
+			PSW_MASK_BA | PSW_MASK_EXT | PSW_MASK_WAIT);
 	local_irq_disable();
 out:
 	/* Contents of the sccb might have changed. */
diff --git a/drivers/s390/char/sclp_quiesce.c b/drivers/s390/char/sclp_quiesce.c
index a90a02c..87fc0ac 100644
--- a/drivers/s390/char/sclp_quiesce.c
+++ b/drivers/s390/char/sclp_quiesce.c
@@ -30,7 +30,8 @@
 	psw_t quiesce_psw;
 
 	smp_send_stop();
-	quiesce_psw.mask = PSW_BASE_BITS | PSW_MASK_WAIT;
+	quiesce_psw.mask =
+		PSW_MASK_BASE | PSW_MASK_EA | PSW_MASK_BA | PSW_MASK_WAIT;
 	quiesce_psw.addr = 0xfff;
 	__load_psw(quiesce_psw);
 }