[PATCH] oprofile - NMI hook

This provides a simple api to let oprofile hook into the NMI interrupt
for the perfctr profiler.

arch/i386/kernel/i386_ksyms.c

@@ -29,6 +29,7 @@
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
+#include <asm/nmi.h>
 
 extern void dump_thread(struct pt_regs *, struct user *);
 extern spinlock_t rtc_lock;
@@ -151,6 +152,10 @@ EXPORT_SYMBOL(smp_call_function);
 EXPORT_SYMBOL(flush_tlb_page);
 #endif
 
+#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_PM)
+EXPORT_SYMBOL_GPL(set_nmi_pm_callback);
+EXPORT_SYMBOL_GPL(unset_nmi_pm_callback);
+#endif
 #ifdef CONFIG_X86_IO_APIC
 EXPORT_SYMBOL(IO_APIC_get_PCI_irq_vector);
 #endif
@@ -169,6 +174,8 @@ EXPORT_SYMBOL(rtc_lock);
 
 EXPORT_SYMBOL_GPL(register_profile_notifier);
 EXPORT_SYMBOL_GPL(unregister_profile_notifier);
+EXPORT_SYMBOL_GPL(set_nmi_callback);
+EXPORT_SYMBOL_GPL(unset_nmi_callback);
  
 #undef memcpy
 #undef memset

arch/i386/kernel/nmi.c

@@ -175,6 +175,18 @@ static int nmi_pm_callback(struct pm_dev *dev, pm_request_t rqst, void *data)
 	return 0;
 }
 
+struct pm_dev * set_nmi_pm_callback(pm_callback callback)
+{
+	apic_pm_unregister(nmi_pmdev);
+	return apic_pm_register(PM_SYS_DEV, 0, callback);
+}
+
+void unset_nmi_pm_callback(struct pm_dev * dev)
+{
+	apic_pm_unregister(dev);
+	nmi_pmdev = apic_pm_register(PM_SYS_DEV, 0, nmi_pm_callback);
+}
+ 
 static void nmi_pm_init(void)
 {
 	if (!nmi_pmdev)

arch/i386/kernel/traps.c

@@ -40,6 +40,7 @@
 #include <asm/debugreg.h>
 #include <asm/desc.h>
 #include <asm/i387.h>
+#include <asm/nmi.h>
 
 #include <asm/smp.h>
 #include <asm/pgalloc.h>
@@ -478,17 +479,16 @@ static void unknown_nmi_error(unsigned char reason, struct pt_regs * regs)
 		return;
 	}
 #endif
-	printk("Uhhuh. NMI received for unknown reason %02x.\n", reason);
+	printk("Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
+		reason, smp_processor_id());
 	printk("Dazed and confused, but trying to continue\n");
 	printk("Do you have a strange power saving mode enabled?\n");
 }
 
-asmlinkage void do_nmi(struct pt_regs * regs, long error_code)
+static void default_do_nmi(struct pt_regs * regs)
 {
 	unsigned char reason = inb(0x61);
-
-	++nmi_count(smp_processor_id());
-
+ 
 	if (!(reason & 0xc0)) {
 #if CONFIG_X86_LOCAL_APIC
 		/*
@@ -517,6 +517,33 @@ asmlinkage void do_nmi(struct pt_regs * regs, long error_code)
 	inb(0x71);		/* dummy */
 }
 
+static int dummy_nmi_callback(struct pt_regs * regs, int cpu)
+{
+	return 0;
+}
+ 
+static nmi_callback_t nmi_callback = dummy_nmi_callback;
+ 
+asmlinkage void do_nmi(struct pt_regs * regs, long error_code)
+{
+	int cpu = smp_processor_id();
+
+	++nmi_count(cpu);
+
+	if (!nmi_callback(regs, cpu))
+		default_do_nmi(regs);
+}
+
+void set_nmi_callback(nmi_callback_t callback)
+{
+	nmi_callback = callback;
+}
+
+void unset_nmi_callback(void)
+{
+	nmi_callback = dummy_nmi_callback;
+}
+
 /*
  * Our handling of the processor debug registers is non-trivial.
  * We do not clear them on entry and exit from the kernel. Therefore

include/asm-i386/nmi.h

+/*
+ *  linux/include/asm-i386/nmi.h
+ */
+#ifndef ASM_NMI_H
+#define ASM_NMI_H
+
+#include <linux/pm.h>
+ 
+struct pt_regs;
+ 
+typedef int (*nmi_callback_t)(struct pt_regs * regs, int cpu);
+ 
+/** 
+ * set_nmi_callback
+ *
+ * Set a handler for an NMI. Only one handler may be
+ * set. Return 1 if the NMI was handled.
+ */
+void set_nmi_callback(nmi_callback_t callback);
+ 
+/** 
+ * unset_nmi_callback
+ *
+ * Remove the handler previously set.
+ */
+void unset_nmi_callback(void);
+ 
+#ifdef CONFIG_PM
+ 
+/** Replace the PM callback routine for NMI. */
+struct pm_dev * set_nmi_pm_callback(pm_callback callback);
+
+/** Unset the PM callback routine back to the default. */
+void unset_nmi_pm_callback(struct pm_dev * dev);
+
+#else
+
+static inline struct pm_dev * set_nmi_pm_callback(pm_callback callback)
+{
+	return 0;
+} 
+ 
+static inline void unset_nmi_pm_callback(struct pm_dev * dev)
+{
+}
+
+#endif /* CONFIG_PM */
+ 
+#endif /* ASM_NMI_H */