23 files changed, 200 insertions, 82 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 1d14cc6b79ad..70a97c33163b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -155,10 +155,10 @@ config ARCH_MAY_HAVE_PC_FDC
 	def_bool ISA_DMA_API
 
 config RWSEM_GENERIC_SPINLOCK
-	def_bool !X86_XADD
+	def_bool !X86_XADD || PREEMPT_RT_FULL
 
 config RWSEM_XCHGADD_ALGORITHM
-	def_bool X86_XADD
+	def_bool X86_XADD && !RWSEM_GENERIC_SPINLOCK && !PREEMPT_RT_FULL
 
 config ARCH_HAS_CPU_IDLE_WAIT
 	def_bool y
@@ -750,7 +750,7 @@ config IOMMU_HELPER
 config MAXSMP
 	bool "Enable Maximum number of SMP Processors and NUMA Nodes"
 	depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
-	select CPUMASK_OFFSTACK
+	select CPUMASK_OFFSTACK if !PREEMPT_RT_FULL
 	---help---
 	  Enable maximum number of CPUS and NUMA Nodes for this architecture.
 	  If unsure, say N.
diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
index c799352e24fc..0efa5144a640 100644
--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -290,14 +290,14 @@ static int ecb_encrypt(struct blkcipher_desc *desc,
 	err = blkcipher_walk_virt(desc, &walk);
 	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
 
-	kernel_fpu_begin();
 	while ((nbytes = walk.nbytes)) {
+		kernel_fpu_begin();
 		aesni_ecb_enc(ctx, walk.dst.virt.addr, walk.src.virt.addr,
-			      nbytes & AES_BLOCK_MASK);
+				nbytes & AES_BLOCK_MASK);
+		kernel_fpu_end();
 		nbytes &= AES_BLOCK_SIZE - 1;
 		err = blkcipher_walk_done(desc, &walk, nbytes);
 	}
-	kernel_fpu_end();
 
 	return err;
 }
@@ -314,14 +314,14 @@ static int ecb_decrypt(struct blkcipher_desc *desc,
 	err = blkcipher_walk_virt(desc, &walk);
 	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
 
-	kernel_fpu_begin();
 	while ((nbytes = walk.nbytes)) {
+		kernel_fpu_begin();
 		aesni_ecb_dec(ctx, walk.dst.virt.addr, walk.src.virt.addr,
 			      nbytes & AES_BLOCK_MASK);
+		kernel_fpu_end();
 		nbytes &= AES_BLOCK_SIZE - 1;
 		err = blkcipher_walk_done(desc, &walk, nbytes);
 	}
-	kernel_fpu_end();
 
 	return err;
 }
@@ -360,14 +360,14 @@ static int cbc_encrypt(struct blkcipher_desc *desc,
 	err = blkcipher_walk_virt(desc, &walk);
 	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
 
-	kernel_fpu_begin();
 	while ((nbytes = walk.nbytes)) {
+		kernel_fpu_begin();
 		aesni_cbc_enc(ctx, walk.dst.virt.addr, walk.src.virt.addr,
 			      nbytes & AES_BLOCK_MASK, walk.iv);
+		kernel_fpu_end();
 		nbytes &= AES_BLOCK_SIZE - 1;
 		err = blkcipher_walk_done(desc, &walk, nbytes);
 	}
-	kernel_fpu_end();
 
 	return err;
 }
@@ -384,14 +384,14 @@ static int cbc_decrypt(struct blkcipher_desc *desc,
 	err = blkcipher_walk_virt(desc, &walk);
 	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
 
-	kernel_fpu_begin();
 	while ((nbytes = walk.nbytes)) {
+		kernel_fpu_begin();
 		aesni_cbc_dec(ctx, walk.dst.virt.addr, walk.src.virt.addr,
 			      nbytes & AES_BLOCK_MASK, walk.iv);
+		kernel_fpu_end();
 		nbytes &= AES_BLOCK_SIZE - 1;
 		err = blkcipher_walk_done(desc, &walk, nbytes);
 	}
-	kernel_fpu_end();
 
 	return err;
 }
@@ -446,18 +446,20 @@ static int ctr_crypt(struct blkcipher_desc *desc,
 	err = blkcipher_walk_virt_block(desc, &walk, AES_BLOCK_SIZE);
 	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
 
-	kernel_fpu_begin();
 	while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
+		kernel_fpu_begin();
 		aesni_ctr_enc(ctx, walk.dst.virt.addr, walk.src.virt.addr,
 			      nbytes & AES_BLOCK_MASK, walk.iv);
+		kernel_fpu_end();
 		nbytes &= AES_BLOCK_SIZE - 1;
 		err = blkcipher_walk_done(desc, &walk, nbytes);
 	}
 	if (walk.nbytes) {
+		kernel_fpu_begin();
 		ctr_crypt_final(ctx, &walk);
+		kernel_fpu_end();
 		err = blkcipher_walk_done(desc, &walk, 0);
 	}
-	kernel_fpu_end();
 
 	return err;
 }
diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
index 610001d385dd..c1c23d256ac6 100644
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h
@@ -51,8 +51,8 @@
 
 #define ACPI_ASM_MACROS
 #define BREAKPOINT3
-#define ACPI_DISABLE_IRQS() local_irq_disable()
-#define ACPI_ENABLE_IRQS()  local_irq_enable()
+#define ACPI_DISABLE_IRQS() local_irq_disable_nort()
+#define ACPI_ENABLE_IRQS()  local_irq_enable_nort()
 #define ACPI_FLUSH_CPU_CACHE()	wbinvd()
 
 int __acpi_acquire_global_lock(unsigned int *lock);
diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 7639dbf5d223..0883ecdbc905 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -14,12 +14,21 @@
 #define IRQ_STACK_ORDER 2
 #define IRQ_STACK_SIZE (PAGE_SIZE << IRQ_STACK_ORDER)
 
-#define STACKFAULT_STACK 1
-#define DOUBLEFAULT_STACK 2
-#define NMI_STACK 3
-#define DEBUG_STACK 4
-#define MCE_STACK 5
-#define N_EXCEPTION_STACKS 5  /* hw limit: 7 */
+#ifdef CONFIG_PREEMPT_RT_FULL
+# define STACKFAULT_STACK 0
+# define DOUBLEFAULT_STACK 1
+# define NMI_STACK 2
+# define DEBUG_STACK 0
+# define MCE_STACK 3
+# define N_EXCEPTION_STACKS 3  /* hw limit: 7 */
+#else
+# define STACKFAULT_STACK 1
+# define DOUBLEFAULT_STACK 2
+# define NMI_STACK 3
+# define DEBUG_STACK 4
+# define MCE_STACK 5
+# define N_EXCEPTION_STACKS 5  /* hw limit: 7 */
+#endif
 
 #define PUD_PAGE_SIZE		(_AC(1, UL) << PUD_SHIFT)
 #define PUD_PAGE_MASK		(~(PUD_PAGE_SIZE-1))
diff --git a/arch/x86/include/asm/signal.h b/arch/x86/include/asm/signal.h
index 598457cbd0f8..1213ebd7bee7 100644
--- a/arch/x86/include/asm/signal.h
+++ b/arch/x86/include/asm/signal.h
@@ -31,6 +31,19 @@ typedef struct {
 	unsigned long sig[_NSIG_WORDS];
 } sigset_t;
 
+/*
+ * Because some traps use the IST stack, we must keep
+ * preemption disabled while calling do_trap(), but do_trap()
+ * may call force_sig_info() which will grab the signal spin_locks
+ * for the task, which in PREEMPT_RT_FULL are mutexes.
+ * By defining ARCH_RT_DELAYS_SIGNAL_SEND the force_sig_info() will
+ * set TIF_NOTIFY_RESUME and set up the signal to be sent on exit
+ * of the trap.
+ */
+#if defined(CONFIG_PREEMPT_RT_FULL) && defined(CONFIG_X86_64)
+#define ARCH_RT_DELAYS_SIGNAL_SEND
+#endif
+
 #else
 /* Here we must cater to libcs that poke about in kernel headers.  */
 
diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h
index b5d9533d2c38..0f3d7b1cf9fb 100644
--- a/arch/x86/include/asm/stackprotector.h
+++ b/arch/x86/include/asm/stackprotector.h
@@ -57,7 +57,7 @@
  */
 static __always_inline void boot_init_stack_canary(void)
 {
-	u64 canary;
+	u64 uninitialized_var(canary);
 	u64 tsc;
 
 #ifdef CONFIG_X86_64
@@ -68,8 +68,16 @@ static __always_inline void boot_init_stack_canary(void)
 	 * of randomness. The TSC only matters for very early init,
 	 * there it already has some randomness on most systems. Later
 	 * on during the bootup the random pool has true entropy too.
+	 *
+	 * For preempt-rt we need to weaken the randomness a bit, as
+	 * we can't call into the random generator from atomic context
+	 * due to locking constraints. We just leave canary
+	 * uninitialized and use the TSC based randomness on top of
+	 * it.
 	 */
+#ifndef CONFIG_PREEMPT_RT_FULL
 	get_random_bytes(&canary, sizeof(canary));
+#endif
 	tsc = __native_read_tsc();
 	canary += tsc + (tsc << 32UL);
 
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index e88300d8e80a..01c76a0f2845 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2555,7 +2555,8 @@ atomic_t irq_mis_count;
 static inline bool ioapic_irqd_mask(struct irq_data *data, struct irq_cfg *cfg)
 {
 	/* If we are moving the irq we need to mask it */
-	if (unlikely(irqd_is_setaffinity_pending(data))) {
+	if (unlikely(irqd_is_setaffinity_pending(data) &&
+		     !irqd_irq_inprogress(data))) {
 		mask_ioapic(cfg);
 		return true;
 	}
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 67e258362a3d..97256335ad73 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1056,7 +1056,9 @@ DEFINE_PER_CPU(struct task_struct *, fpu_owner_task);
  */
 static const unsigned int exception_stack_sizes[N_EXCEPTION_STACKS] = {
 	  [0 ... N_EXCEPTION_STACKS - 1]	= EXCEPTION_STKSZ,
+#if DEBUG_STACK > 0
 	  [DEBUG_STACK - 1]			= DEBUG_STKSZ
+#endif
 };
 
 static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index d086a09c087d..bb761c950c5a 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -38,6 +38,7 @@
 #include <linux/debugfs.h>
 #include <linux/irq_work.h>
 #include <linux/export.h>
+#include <linux/jiffies.h>
 
 #include <asm/processor.h>
 #include <asm/mce.h>
@@ -1229,17 +1230,14 @@ void mce_log_therm_throt_event(__u64 status)
  * poller finds an MCE, poll 2x faster.  When the poller finds no more
  * errors, poll 2x slower (up to check_interval seconds).
  */
-static int check_interval = 5 * 60; /* 5 minutes */
+static unsigned long check_interval = 5 * 60; /* 5 minutes */
 
-static DEFINE_PER_CPU(int, mce_next_interval); /* in jiffies */
-static DEFINE_PER_CPU(struct timer_list, mce_timer);
+static DEFINE_PER_CPU(unsigned long, mce_next_interval); /* in jiffies */
+static DEFINE_PER_CPU(struct hrtimer, mce_timer);
 
-static void mce_start_timer(unsigned long data)
+static enum hrtimer_restart mce_start_timer(struct hrtimer *timer)
 {
-	struct timer_list *t = &per_cpu(mce_timer, data);
-	int *n;
-
-	WARN_ON(smp_processor_id() != data);
+	unsigned long *n;
 
 	if (mce_available(__this_cpu_ptr(&cpu_info))) {
 		machine_check_poll(MCP_TIMESTAMP,
@@ -1252,21 +1250,22 @@ static void mce_start_timer(unsigned long data)
 	 */
 	n = &__get_cpu_var(mce_next_interval);
 	if (mce_notify_irq())
-		*n = max(*n/2, HZ/100);
+		*n = max(*n/2, HZ/100UL);
 	else
-		*n = min(*n*2, (int)round_jiffies_relative(check_interval*HZ));
+		*n = min(*n*2, round_jiffies_relative(check_interval*HZ));
 
-	t->expires = jiffies + *n;
-	add_timer_on(t, smp_processor_id());
+	hrtimer_forward(timer, timer->base->get_time(),
+			ns_to_ktime(jiffies_to_usecs(*n) * 1000));
+	return HRTIMER_RESTART;
 }
 
-/* Must not be called in IRQ context where del_timer_sync() can deadlock */
+/* Must not be called in IRQ context where hrtimer_cancel() can deadlock */
 static void mce_timer_delete_all(void)
 {
 	int cpu;
 
 	for_each_online_cpu(cpu)
-		del_timer_sync(&per_cpu(mce_timer, cpu));
+		hrtimer_cancel(&per_cpu(mce_timer, cpu));
 }
 
 static void mce_do_trigger(struct work_struct *work)
@@ -1496,10 +1495,11 @@ static void __mcheck_cpu_init_vendor(struct cpuinfo_x86 *c)
 
 static void __mcheck_cpu_init_timer(void)
 {
-	struct timer_list *t = &__get_cpu_var(mce_timer);
-	int *n = &__get_cpu_var(mce_next_interval);
+	struct hrtimer *t = &__get_cpu_var(mce_timer);
+	unsigned long *n = &__get_cpu_var(mce_next_interval);
 
-	setup_timer(t, mce_start_timer, smp_processor_id());
+	hrtimer_init(t, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	t->function = mce_start_timer;
 
 	if (mce_ignore_ce)
 		return;
@@ -1507,8 +1507,9 @@ static void __mcheck_cpu_init_timer(void)
 	*n = check_interval * HZ;
 	if (!*n)
 		return;
-	t->expires = round_jiffies(jiffies + *n);
-	add_timer_on(t, smp_processor_id());
+
+	hrtimer_start_range_ns(t, ns_to_ktime(jiffies_to_usecs(*n) * 1000),
+			       0 , HRTIMER_MODE_REL_PINNED);
 }
 
 /* Handle unconfigured int18 (should never happen) */
@@ -2160,6 +2161,8 @@ static void __cpuinit mce_disable_cpu(void *h)
 	if (!mce_available(__this_cpu_ptr(&cpu_info)))
 		return;
 
+	hrtimer_cancel(&__get_cpu_var(mce_timer));
+
 	if (!(action & CPU_TASKS_FROZEN))
 		cmci_clear();
 	for (i = 0; i < banks; i++) {
@@ -2186,6 +2189,7 @@ static void __cpuinit mce_reenable_cpu(void *h)
 		if (b->init)
 			wrmsrl(MSR_IA32_MCx_CTL(i), b->ctl);
 	}
+	__mcheck_cpu_init_timer();
 }
 
 /* Get notified when a cpu comes on/off. Be hotplug friendly. */
@@ -2193,7 +2197,6 @@ static int __cpuinit
 mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 {
 	unsigned int cpu = (unsigned long)hcpu;
-	struct timer_list *t = &per_cpu(mce_timer, cpu);
 
 	switch (action) {
 	case CPU_ONLINE:
@@ -2210,16 +2213,10 @@ mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
 		break;
 	case CPU_DOWN_PREPARE:
 	case CPU_DOWN_PREPARE_FROZEN:
-		del_timer_sync(t);
 		smp_call_function_single(cpu, mce_disable_cpu, &action, 1);
 		break;
 	case CPU_DOWN_FAILED:
 	case CPU_DOWN_FAILED_FROZEN:
-		if (!mce_ignore_ce && check_interval) {
-			t->expires = round_jiffies(jiffies +
-					   __get_cpu_var(mce_next_interval));
-			add_timer_on(t, cpu);
-		}
 		smp_call_function_single(cpu, mce_reenable_cpu, &action, 1);
 		break;
 	case CPU_POST_DEAD:
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 17107bd6e1f0..9d50b3012dab 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -21,10 +21,14 @@
 		(N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)
 
 static char x86_stack_ids[][8] = {
+#if DEBUG_STACK > 0
 		[ DEBUG_STACK-1			]	= "#DB",
+#endif
 		[ NMI_STACK-1			]	= "NMI",
 		[ DOUBLEFAULT_STACK-1		]	= "#DF",
+#if STACKFAULT_STACK > 0
 		[ STACKFAULT_STACK-1		]	= "#SS",
+#endif
 		[ MCE_STACK-1			]	= "#MC",
 #if DEBUG_STKSZ > EXCEPTION_STKSZ
 		[ N_EXCEPTION_STACKS ...
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 9b9f18b49918..d15f575a861b 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -169,25 +169,9 @@ static struct console early_serial_console = {
 	.index =	-1,
 };
 
-/* Direct interface for emergencies */
-static struct console *early_console = &early_vga_console;
-static int __initdata early_console_initialized;
-
-asmlinkage void early_printk(const char *fmt, ...)
-{
-	char buf[512];
-	int n;
-	va_list ap;
-
-	va_start(ap, fmt);
-	n = vscnprintf(buf, sizeof(buf), fmt, ap);
-	early_console->write(early_console, buf, n);
-	va_end(ap);
-}
-
 static inline void early_console_register(struct console *con, int keep_early)
 {
-	if (early_console->index != -1) {
+	if (con->index != -1) {
 		printk(KERN_CRIT "ERROR: earlyprintk= %s already used\n",
 		       con->name);
 		return;
@@ -207,9 +191,8 @@ static int __init setup_early_printk(char *buf)
 	if (!buf)
 		return 0;
 
-	if (early_console_initialized)
+	if (early_console)
 		return 0;
-	early_console_initialized = 1;
 
 	keep = (strstr(buf, "keep") != NULL);
 
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index cdc79b5cfcd9..1bfb07bc643c 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1240,6 +1240,7 @@ ENTRY(kernel_execve)
 	CFI_ENDPROC
 END(kernel_execve)
 
+#ifndef CONFIG_PREEMPT_RT_FULL
 /* Call softirq on interrupt stack. Interrupts are off. */
 ENTRY(call_softirq)
 	CFI_STARTPROC
@@ -1259,6 +1260,7 @@ ENTRY(call_softirq)
 	ret
 	CFI_ENDPROC
 END(call_softirq)
+#endif
 
 #ifdef CONFIG_XEN
 zeroentry xen_hypervisor_callback xen_do_hypervisor_callback
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index ad0de0c2714e..230a200763aa 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -8,6 +8,7 @@
 #include <linux/slab.h>
 #include <linux/hpet.h>
 #include <linux/init.h>
+#include <linux/dmi.h>
 #include <linux/cpu.h>
 #include <linux/pm.h>
 #include <linux/io.h>
@@ -570,6 +571,30 @@ static void init_one_hpet_msi_clockevent(struct hpet_dev *hdev, int cpu)
 #define RESERVE_TIMERS 0
 #endif
 
+static int __init dmi_disable_hpet_msi(const struct dmi_system_id *d)
+{
+	hpet_msi_disable = 1;
+	return 0;
+}
+
+static struct dmi_system_id __initdata dmi_hpet_table[] = {
+	/*
+	 * MSI based per cpu timers lose interrupts when intel_idle()
+	 * is enabled - independent of the c-state. With idle=poll the
+	 * problem cannot be observed. We have no idea yet, whether
+	 * this is a W510 specific issue or a general chipset oddity.
+	 */
+	{
+	 .callback = dmi_disable_hpet_msi,
+	 .ident = "Lenovo W510",
+	 .matches = {
+		     DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+		     DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad W510"),
+		     },
+	 },
+	{}
+};
+
 static void hpet_msi_capability_lookup(unsigned int start_timer)
 {
 	unsigned int id;
@@ -577,6 +602,8 @@ static void hpet_msi_capability_lookup(unsigned int start_timer)
 	unsigned int num_timers_used = 0;
 	int i;
 
+	dmi_check_system(dmi_hpet_table);
+
 	if (hpet_msi_disable)
 		return;
 
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index 58b7f27cb3e9..a7b4e1b2e6eb 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -149,6 +149,7 @@ void __cpuinit irq_ctx_init(int cpu)
 	       cpu, per_cpu(hardirq_ctx, cpu),  per_cpu(softirq_ctx, cpu));
 }
 
+#ifndef CONFIG_PREEMPT_RT_FULL
 asmlinkage void do_softirq(void)
 {
 	unsigned long flags;
@@ -179,6 +180,7 @@ asmlinkage void do_softirq(void)
 
 	local_irq_restore(flags);
 }
+#endif
 
 bool handle_irq(unsigned irq, struct pt_regs *regs)
 {
diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index d04d3ecded62..831f247b5798 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -88,7 +88,7 @@ bool handle_irq(unsigned irq, struct pt_regs *regs)
 	return true;
 }
 
-
+#ifndef CONFIG_PREEMPT_RT_FULL
 extern void call_softirq(void);
 
 asmlinkage void do_softirq(void)
@@ -108,3 +108,4 @@ asmlinkage void do_softirq(void)
 	}
 	local_irq_restore(flags);
 }
+#endif
diff --git a/arch/x86/kernel/irq_work.c b/arch/x86/kernel/irq_work.c
index ca8f703a1e70..129b8bb73de2 100644
--- a/arch/x86/kernel/irq_work.c
+++ b/arch/x86/kernel/irq_work.c
@@ -18,6 +18,7 @@ void smp_irq_work_interrupt(struct pt_regs *regs)
 	irq_exit();
 }
 
+#ifndef CONFIG_PREEMPT_RT_FULL
 void arch_irq_work_raise(void)
 {
 #ifdef CONFIG_X86_LOCAL_APIC
@@ -28,3 +29,4 @@ void arch_irq_work_raise(void)
 	apic_wait_icr_idle();
 #endif
 }
+#endif
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index e213fc8408d2..b9edf1a32cf8 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -486,7 +486,6 @@ setup_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *k
 		 * stepping.
 		 */
 		regs->ip = (unsigned long)p->ainsn.insn;
-		preempt_enable_no_resched();
 		return;
 	}
 #endif
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index ae6847303e26..2b0882add416 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -36,6 +36,7 @@
 #include <linux/uaccess.h>
 #include <linux/io.h>
 #include <linux/kdebug.h>
+#include <linux/highmem.h>
 
 #include <asm/pgtable.h>
 #include <asm/ldt.h>
@@ -285,6 +286,41 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 		     task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
 		__switch_to_xtra(prev_p, next_p, tss);
 
+#if defined CONFIG_PREEMPT_RT_FULL && defined CONFIG_HIGHMEM
+	/*
+	 * Save @prev's kmap_atomic stack
+	 */
+	prev_p->kmap_idx = __this_cpu_read(__kmap_atomic_idx);
+	if (unlikely(prev_p->kmap_idx)) {
+		int i;
+
+		for (i = 0; i < prev_p->kmap_idx; i++) {
+			int idx = i + KM_TYPE_NR * smp_processor_id();
+
+			pte_t *ptep = kmap_pte - idx;
+			prev_p->kmap_pte[i] = *ptep;
+			kpte_clear_flush(ptep, __fix_to_virt(FIX_KMAP_BEGIN + idx));
+		}
+
+		__this_cpu_write(__kmap_atomic_idx, 0);
+	}
+
+	/*
+	 * Restore @next_p's kmap_atomic stack
+	 */
+	if (unlikely(next_p->kmap_idx)) {
+		int i;
+
+		__this_cpu_write(__kmap_atomic_idx, next_p->kmap_idx);
+
+		for (i = 0; i < next_p->kmap_idx; i++) {
+			int idx = i + KM_TYPE_NR * smp_processor_id();
+
+			set_pte(kmap_pte - idx, next_p->kmap_pte[i]);
+		}
+	}
+#endif
+
 	/*
 	 * Leave lazy mode, flushing any hypercalls made here.
 	 * This must be done before restoring TLS segments so
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 115eac431483..c67d83fe0d00 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -824,6 +824,15 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 		mce_notify_process();
 #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */
 
+#ifdef ARCH_RT_DELAYS_SIGNAL_SEND
+	if (unlikely(current->forced_info.si_signo)) {
+		struct task_struct *t = current;
+		force_sig_info(t->forced_info.si_signo,
+					&t->forced_info, t);
+		t->forced_info.si_signo = 0;
+	}
+#endif
+
 	/* deal with pending signal delivery */
 	if (thread_info_flags & _TIF_SIGPENDING)
 		do_signal(regs);
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index ff9281f16029..0b019777d8f3 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -87,9 +87,21 @@ static inline void conditional_sti(struct pt_regs *regs)
 		local_irq_enable();
 }
 
-static inline void preempt_conditional_sti(struct pt_regs *regs)
+static inline void conditional_sti_ist(struct pt_regs *regs)
 {
+#ifdef CONFIG_X86_64
+	/*
+	 * X86_64 uses a per CPU stack on the IST for certain traps
+	 * like int3. The task can not be preempted when using one
+	 * of these stacks, thus preemption must be disabled, otherwise
+	 * the stack can be corrupted if the task is scheduled out,
+	 * and another task comes in and uses this stack.
+	 *
+	 * On x86_32 the task keeps its own stack and it is OK if the
+	 * task schedules out.
+	 */
 	inc_preempt_count();
+#endif
 	if (regs->flags & X86_EFLAGS_IF)
 		local_irq_enable();
 }
@@ -100,11 +112,13 @@ static inline void conditional_cli(struct pt_regs *regs)
 		local_irq_disable();
 }
 
-static inline void preempt_conditional_cli(struct pt_regs *regs)
+static inline void conditional_cli_ist(struct pt_regs *regs)
 {
 	if (regs->flags & X86_EFLAGS_IF)
 		local_irq_disable();
+#ifdef CONFIG_X86_64
 	dec_preempt_count();
+#endif
 }
 
 static void __kprobes
@@ -226,9 +240,9 @@ dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
 	if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
 			X86_TRAP_SS, SIGBUS) == NOTIFY_STOP)
 		return;
-	preempt_conditional_sti(regs);
+	conditional_sti_ist(regs);
 	do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
-	preempt_conditional_cli(regs);
+	conditional_cli_ist(regs);
 }
 
 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
@@ -320,9 +334,9 @@ dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
 	 * as we may switch to the interrupt stack.
 	 */
 	debug_stack_usage_inc();
-	preempt_conditional_sti(regs);
+	conditional_sti_ist(regs);
 	do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
-	preempt_conditional_cli(regs);
+	conditional_cli_ist(regs);
 	debug_stack_usage_dec();
 }
 
@@ -423,12 +437,12 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 	debug_stack_usage_inc();
 
 	/* It's safe to allow irq's after DR6 has been saved */
-	preempt_conditional_sti(regs);
+	conditional_sti_ist(regs);
 
 	if (regs->flags & X86_VM_MASK) {
 		handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code,
 					X86_TRAP_DB);
-		preempt_conditional_cli(regs);
+		conditional_cli_ist(regs);
 		debug_stack_usage_dec();
 		return;
 	}
@@ -448,7 +462,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 	si_code = get_si_code(tsk->thread.debugreg6);
 	if (tsk->thread.debugreg6 & (DR_STEP | DR_TRAP_BITS) || user_icebp)
 		send_sigtrap(tsk, regs, error_code, si_code);
-	preempt_conditional_cli(regs);
+	conditional_cli_ist(regs);
 	debug_stack_usage_dec();
 
 	return;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4044ce0bf7c1..47337cf39b3f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4882,6 +4882,13 @@ int kvm_arch_init(void *opaque)
 		goto out;
 	}
 
+#ifdef CONFIG_PREEMPT_RT_FULL
+	if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) {
+		printk(KERN_ERR "RT requires X86_FEATURE_CONSTANT_TSC\n");
+		return -EOPNOTSUPP;
+	}
+#endif
+
 	r = kvm_mmu_module_init();
 	if (r)
 		goto out;
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 3ecfd1aaf214..9d57357c2e1d 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1094,7 +1094,7 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code)
 	 * If we're in an interrupt, have no user context or are running
 	 * in an atomic region then we must not take the fault:
 	 */
-	if (unlikely(in_atomic() || !mm)) {
+	if (unlikely(!mm || pagefault_disabled())) {
 		bad_area_nosemaphore(regs, error_code, address);
 		return;
 	}
diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c
index 6f31ee56c008..ab8683ade5c8 100644
--- a/arch/x86/mm/highmem_32.c
+++ b/arch/x86/mm/highmem_32.c
@@ -43,7 +43,7 @@ void *kmap_atomic_prot(struct page *page, pgprot_t prot)
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
-	BUG_ON(!pte_none(*(kmap_pte-idx)));
+	WARN_ON(!pte_none(*(kmap_pte-idx)));
 	set_pte(kmap_pte-idx, mk_pte(page, prot));
 	arch_flush_lazy_mmu_mode();