[PATCH] OProfile: IO-APIC based NMI delivery

Use the IO-APIC NMI delivery when the local APIC performance counter delivery is
not available. By Zwane Mwaikambo.

arch/i386/kernel/nmi.c

@@ -23,17 +23,27 @@
 #include <linux/mc146818rtc.h>
 #include <linux/kernel_stat.h>
 #include <linux/module.h>
+#include <linux/nmi.h>
 #include <linux/sysdev.h>
 
 #include <asm/smp.h>
 #include <asm/mtrr.h>
 #include <asm/mpspec.h>
+#include <asm/nmi.h>
 
 unsigned int nmi_watchdog = NMI_NONE;
 static unsigned int nmi_hz = HZ;
 unsigned int nmi_perfctr_msr;	/* the MSR to reset in NMI handler */
 extern void show_registers(struct pt_regs *regs);
 
+/* nmi_active:
+ * +1: the lapic NMI watchdog is active, but can be disabled
+ *  0: the lapic NMI watchdog has not been set up, and cannot
+ *     be enabled
+ * -1: the lapic NMI watchdog is disabled, but can be enabled
+ */
+static int nmi_active;
+
 #define K7_EVNTSEL_ENABLE	(1 << 22)
 #define K7_EVNTSEL_INT		(1 << 20)
 #define K7_EVNTSEL_OS		(1 << 17)
@@ -91,6 +101,7 @@ int __init check_nmi_watchdog (void)
 			continue;
 		if (nmi_count(cpu) - prev_nmi_count[cpu] <= 5) {
 			printk("CPU#%d: NMI appears to be stuck!\n", cpu);
+			nmi_active = 0;
 			return -1;
 		}
 	}
@@ -131,21 +142,15 @@ static int __init setup_nmi_watchdog(char *str)
 	 * We can enable the IO-APIC watchdog
 	 * unconditionally.
 	 */
-	if (nmi == NMI_IO_APIC)
+	if (nmi == NMI_IO_APIC) {
+		nmi_active = 1;
 		nmi_watchdog = nmi;
+	}
 	return 1;
 }
 
 __setup("nmi_watchdog=", setup_nmi_watchdog);
 
-/* nmi_active:
- * +1: the lapic NMI watchdog is active, but can be disabled
- *  0: the lapic NMI watchdog has not been set up, and cannot
- *     be enabled
- * -1: the lapic NMI watchdog is disabled, but can be enabled
- */
-static int nmi_active;
-
 void disable_lapic_nmi_watchdog(void)
 {
 	if (nmi_active <= 0)
@@ -179,6 +184,27 @@ void enable_lapic_nmi_watchdog(void)
 	}
 }
 
+void disable_timer_nmi_watchdog(void)
+{
+	if ((nmi_watchdog != NMI_IO_APIC) || (nmi_active <= 0))
+		return;
+
+	disable_irq(0);
+	unset_nmi_callback();
+	nmi_active = -1;
+	nmi_watchdog = NMI_NONE;
+}
+
+void enable_timer_nmi_watchdog(void)
+{
+	if (nmi_active < 0) {
+		nmi_watchdog = NMI_IO_APIC;
+		touch_nmi_watchdog();
+		nmi_active = 1;
+		enable_irq(0);
+	}
+}
+
 #ifdef CONFIG_PM
 
 static int nmi_pm_active; /* nmi_active before suspend */
@@ -429,3 +455,5 @@ void nmi_watchdog_tick (struct pt_regs * regs)
 EXPORT_SYMBOL(nmi_watchdog);
 EXPORT_SYMBOL(disable_lapic_nmi_watchdog);
 EXPORT_SYMBOL(enable_lapic_nmi_watchdog);
+EXPORT_SYMBOL(disable_timer_nmi_watchdog);
+EXPORT_SYMBOL(enable_timer_nmi_watchdog);

arch/i386/oprofile/Makefile

@@ -9,3 +9,4 @@ DRIVER_OBJS = $(addprefix ../../../drivers/oprofile/, \
 oprofile-y				:= $(DRIVER_OBJS) init.o
 oprofile-$(CONFIG_X86_LOCAL_APIC) 	+= nmi_int.o op_model_athlon.o \
 					   op_model_ppro.o op_model_p4.o
+oprofile-$(CONFIG_X86_IO_APIC)		+= nmi_timer_int.o

arch/i386/oprofile/init.c

@@ -16,15 +16,21 @@
  */
  
 extern int nmi_init(struct oprofile_operations ** ops);
+extern int nmi_timer_init(struct oprofile_operations **ops);
 extern void nmi_exit(void);
 
 int __init oprofile_arch_init(struct oprofile_operations ** ops)
 {
+	int ret = -ENODEV;
 #ifdef CONFIG_X86_LOCAL_APIC
-	return nmi_init(ops);
-#else
-	return -ENODEV;
+	ret = nmi_init(ops);
 #endif
+
+#ifdef CONFIG_X86_IO_APIC
+	if (ret < 0)
+		ret = nmi_timer_init(ops);
+#endif
+	return ret;
 }
 
 

arch/i386/oprofile/nmi_timer_int.c

+/**
+ * @file nmi_timer_int.c
+ *
+ * @remark Copyright 2003 OProfile authors
+ * @remark Read the file COPYING
+ *
+ * @author Zwane Mwaikambo <zwane@linuxpower.ca>
+ */
+
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/irq.h>
+#include <linux/oprofile.h>
+#include <linux/rcupdate.h>
+
+
+#include <asm/nmi.h>
+#include <asm/apic.h>
+#include <asm/ptrace.h>
+ 
+static int nmi_timer_callback(struct pt_regs * regs, int cpu)
+{
+	unsigned long eip = instruction_pointer(regs);
+ 
+	oprofile_add_sample(eip, !user_mode(regs), 0, cpu);
+	return 1;
+}
+
+static int timer_start(void)
+{
+	disable_timer_nmi_watchdog();
+	set_nmi_callback(nmi_timer_callback);
+	return 0;
+}
+
+
+static void timer_stop(void)
+{
+	enable_timer_nmi_watchdog();
+	unset_nmi_callback();
+	synchronize_kernel();
+}
+
+
+static struct oprofile_operations nmi_timer_ops = {
+	.start	= timer_start,
+	.stop	= timer_stop,
+	.cpu_type = "timer"
+};
+
+ 
+int __init nmi_timer_init(struct oprofile_operations ** ops)
+{
+	*ops = &nmi_timer_ops;
+	printk(KERN_INFO "oprofile: using NMI timer interrupt.\n");
+	return 0;
+}

include/asm-i386/apic.h

@@ -81,6 +81,8 @@ extern void setup_secondary_APIC_clock (void);
 extern void setup_apic_nmi_watchdog (void);
 extern void disable_lapic_nmi_watchdog(void);
 extern void enable_lapic_nmi_watchdog(void);
+extern void disable_timer_nmi_watchdog(void);
+extern void enable_timer_nmi_watchdog(void);
 extern inline void nmi_watchdog_tick (struct pt_regs * regs);
 extern int APIC_init_uniprocessor (void);
 extern void disable_APIC_timer(void);