5 files changed, 55 insertions, 19 deletions

diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index 247d89478f24..f590afc1f673 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -107,18 +107,18 @@ static void omap_uart_set_noidle(struct platform_device *pdev)
 	omap_hwmod_set_slave_idlemode(od->hwmods[0], HWMOD_IDLEMODE_NO);
 }
 
-static void omap_uart_set_forceidle(struct platform_device *pdev)
+static void omap_uart_set_smartidle(struct platform_device *pdev)
 {
 	struct omap_device *od = to_omap_device(pdev);
 
-	omap_hwmod_set_slave_idlemode(od->hwmods[0], HWMOD_IDLEMODE_FORCE);
+	omap_hwmod_set_slave_idlemode(od->hwmods[0], HWMOD_IDLEMODE_SMART);
 }
 
 #else
 static void omap_uart_enable_wakeup(struct platform_device *pdev, bool enable)
 {}
 static void omap_uart_set_noidle(struct platform_device *pdev) {}
-static void omap_uart_set_forceidle(struct platform_device *pdev) {}
+static void omap_uart_set_smartidle(struct platform_device *pdev) {}
 #endif /* CONFIG_PM */
 
 #ifdef CONFIG_OMAP_MUX
@@ -349,7 +349,7 @@ void __init omap_serial_init_port(struct omap_board_data *bdata,
 	omap_up.uartclk = OMAP24XX_BASE_BAUD * 16;
 	omap_up.flags = UPF_BOOT_AUTOCONF;
 	omap_up.get_context_loss_count = omap_pm_get_dev_context_loss_count;
-	omap_up.set_forceidle = omap_uart_set_forceidle;
+	omap_up.set_forceidle = omap_uart_set_smartidle;
 	omap_up.set_noidle = omap_uart_set_noidle;
 	omap_up.enable_wakeup = omap_uart_enable_wakeup;
 	omap_up.dma_rx_buf_size = info->dma_rx_buf_size;
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 6919e936345b..a29571821b99 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -29,7 +29,7 @@ extern unsigned int sig_xstate_size;
 extern void fpu_init(void);
 extern void mxcsr_feature_mask_init(void);
 extern int init_fpu(struct task_struct *child);
-extern asmlinkage void math_state_restore(void);
+extern void math_state_restore(void);
 extern void __math_state_restore(void);
 extern int dump_fpu(struct pt_regs *, struct user_i387_struct *);
 
@@ -307,9 +307,54 @@ static inline void __clear_fpu(struct task_struct *tsk)
 	}
 }
 
+/*
+ * Were we in an interrupt that interrupted kernel mode?
+ *
+ * We can do a kernel_fpu_begin/end() pair *ONLY* if that
+ * pair does nothing at all: TS_USEDFPU must be clear (so
+ * that we don't try to save the FPU state), and TS must
+ * be set (so that the clts/stts pair does nothing that is
+ * visible in the interrupted kernel thread).
+ */
+static inline bool interrupted_kernel_fpu_idle(void)
+{
+	return !(current_thread_info()->status & TS_USEDFPU) &&
+		(read_cr0() & X86_CR0_TS);
+}
+
+/*
+ * Were we in user mode (or vm86 mode) when we were
+ * interrupted?
+ *
+ * Doing kernel_fpu_begin/end() is ok if we are running
+ * in an interrupt context from user mode - we'll just
+ * save the FPU state as required.
+ */
+static inline bool interrupted_user_mode(void)
+{
+	struct pt_regs *regs = get_irq_regs();
+	return regs && user_mode_vm(regs);
+}
+
+/*
+ * Can we use the FPU in kernel mode with the
+ * whole "kernel_fpu_begin/end()" sequence?
+ *
+ * It's always ok in process context (ie "not interrupt")
+ * but it is sometimes ok even from an irq.
+ */
+static inline bool irq_fpu_usable(void)
+{
+	return !in_interrupt() ||
+		interrupted_user_mode() ||
+		interrupted_kernel_fpu_idle();
+}
+
 static inline void kernel_fpu_begin(void)
 {
 	struct thread_info *me = current_thread_info();
+
+	WARN_ON_ONCE(!irq_fpu_usable());
 	preempt_disable();
 	if (me->status & TS_USEDFPU)
 		__save_init_fpu(me->task);
@@ -323,14 +368,6 @@ static inline void kernel_fpu_end(void)
 	preempt_enable();
 }
 
-static inline bool irq_fpu_usable(void)
-{
-	struct pt_regs *regs;
-
-	return !in_interrupt() || !(regs = get_irq_regs()) || \
-		user_mode(regs) || (read_cr0() & X86_CR0_TS);
-}
-
 /*
  * Some instructions like VIA's padlock instructions generate a spurious
  * DNA fault but don't modify SSE registers. And these instructions
@@ -367,6 +404,7 @@ static inline void irq_ts_restore(int TS_state)
  */
 static inline void save_init_fpu(struct task_struct *tsk)
 {
+	WARN_ON_ONCE(task_thread_info(tsk)->status & TS_USEDFPU);
 	preempt_disable();
 	__save_init_fpu(tsk);
 	stts();
diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 73da6b64f5b7..d6bd49faa40c 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -439,7 +439,6 @@ void intel_pmu_pebs_enable(struct perf_event *event)
 	hwc->config &= ~ARCH_PERFMON_EVENTSEL_INT;
 
 	cpuc->pebs_enabled |= 1ULL << hwc->idx;
-	WARN_ON_ONCE(cpuc->enabled);
 
 	if (x86_pmu.intel_cap.pebs_trap && event->attr.precise_ip > 1)
 		intel_pmu_lbr_enable(event);
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index 3fab3de3ce96..47a7e63bfe54 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -72,8 +72,6 @@ void intel_pmu_lbr_enable(struct perf_event *event)
 	if (!x86_pmu.lbr_nr)
 		return;
 
-	WARN_ON_ONCE(cpuc->enabled);
-
 	/*
 	 * Reset the LBR stack if we changed task context to
 	 * avoid data leaks.
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 482ec3af2067..8ba27dbc107a 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -599,10 +599,10 @@ void __math_state_restore(void)
  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
  * Don't touch unless you *really* know how it works.
  *
- * Must be called with kernel preemption disabled (in this case,
- * local interrupts are disabled at the call-site in entry.S).
+ * Must be called with kernel preemption disabled (eg with local
+ * local interrupts as in the case of do_device_not_available).
  */
-asmlinkage void math_state_restore(void)
+void math_state_restore(void)
 {
 	struct thread_info *thread = current_thread_info();
 	struct task_struct *tsk = thread->task;
@@ -631,6 +631,7 @@ EXPORT_SYMBOL_GPL(math_state_restore);
 dotraplinkage void __kprobes
 do_device_not_available(struct pt_regs *regs, long error_code)
 {
+	WARN_ON_ONCE(!user_mode_vm(regs));
 #ifdef CONFIG_MATH_EMULATION
 	if (read_cr0() & X86_CR0_EM) {
 		struct math_emu_info info = { };