CPU: Introduce ARCH_HAS_CPU_AUTOPROBE and X86 parts

This patch is based on Andi Kleen's work:
Implement autoprobing/loading of modules serving CPU
specific features (x86cpu autoloading).

And Kay Siever's work to get rid of sysdev cpu structures
and making use of struct device instead.

Before, the cpuid driver had to be loaded to get the x86cpu
autoloading feature. With this patch autoloading works through
the /sys/devices/system/cpu object

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/x86/Kconfig

@@ -179,6 +179,9 @@ config ARCH_HAS_DEFAULT_IDLE
 config ARCH_HAS_CACHE_LINE_SIZE
 	def_bool y
 
+config ARCH_HAS_CPU_AUTOPROBE
+	def_bool y
+
 config HAVE_SETUP_PER_CPU_AREA
 	def_bool y
 

arch/x86/kernel/cpu/match.c

@@ -2,6 +2,7 @@
 #include <asm/processor.h>
 #include <linux/cpu.h>
 #include <linux/module.h>
+#include <linux/slab.h>
 
 /**
  * x86_match_cpu - match current CPU again an array of x86_cpu_ids
@@ -46,3 +47,46 @@ const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match)
 	return NULL;
 }
 EXPORT_SYMBOL(x86_match_cpu);
+
+ssize_t arch_print_cpu_modalias(struct device *dev,
+				struct device_attribute *attr,
+				char *bufptr)
+{
+	int size = PAGE_SIZE;
+	int i, n;
+	char *buf = bufptr;
+
+	n = snprintf(buf, size, "x86cpu:vendor:%04X:family:%04X:"
+		     "model:%04X:feature:",
+		boot_cpu_data.x86_vendor,
+		boot_cpu_data.x86,
+		boot_cpu_data.x86_model);
+	size -= n;
+	buf += n;
+	size -= 2;
+	for (i = 0; i < NCAPINTS*32; i++) {
+		if (boot_cpu_has(i)) {
+			n = snprintf(buf, size, ",%04X", i);
+			if (n < 0) {
+				WARN(1, "x86 features overflow page\n");
+				break;
+			}
+			size -= n;
+			buf += n;
+		}
+	}
+	*buf++ = ',';
+	*buf++ = '\n';
+	return buf - bufptr;
+}
+
+int arch_cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (buf) {
+		arch_print_cpu_modalias(NULL, NULL, buf);
+		add_uevent_var(env, "MODALIAS=%s", buf);
+		kfree(buf);
+	}
+	return 0;
+}

arch/x86/kernel/cpuid.c

@@ -40,7 +40,6 @@
 #include <linux/notifier.h>
 #include <linux/uaccess.h>
 #include <linux/gfp.h>
-#include <linux/slab.h>
 
 #include <asm/processor.h>
 #include <asm/msr.h>
@@ -139,57 +138,13 @@ static const struct file_operations cpuid_fops = {
 	.open = cpuid_open,
 };
 
-static ssize_t print_cpu_modalias(struct device *dev,
-				  struct device_attribute *attr,
-				  char *bufptr)
-{
-	int size = PAGE_SIZE;
-	int i, n;
-	char *buf = bufptr;
-
-	n = snprintf(buf, size, "x86cpu:vendor:%04X:family:"
-		     "%04X:model:%04X:feature:",
-		boot_cpu_data.x86_vendor,
-		boot_cpu_data.x86,
-		boot_cpu_data.x86_model);
-	size -= n;
-	buf += n;
-	size -= 2;
-	for (i = 0; i < NCAPINTS*32; i++) {
-		if (boot_cpu_has(i)) {
-			n = snprintf(buf, size, ",%04X", i);
-			if (n < 0) {
-				WARN(1, "x86 features overflow page\n");
-				break;
-			}
-			size -= n;
-			buf += n;
-		}
-	}
-	*buf++ = ',';
-	*buf++ = '\n';
-	return buf - bufptr;
-}
-
-static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
-
 static __cpuinit int cpuid_device_create(int cpu)
 {
 	struct device *dev;
-	int err;
 
 	dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu), NULL,
 			    "cpu%d", cpu);
-	if (IS_ERR(dev))
-		return PTR_ERR(dev);
-
-	err = device_create_file(dev, &dev_attr_modalias);
-	if (err) {
-		/* keep device around on error. attribute is optional. */
-		err = 0;
-	}
-
-	return 0;
+	return IS_ERR(dev) ? PTR_ERR(dev) : 0;
 }
 
 static void cpuid_device_destroy(int cpu)
@@ -227,17 +182,6 @@ static char *cpuid_devnode(struct device *dev, umode_t *mode)
 	return kasprintf(GFP_KERNEL, "cpu/%u/cpuid", MINOR(dev->devt));
 }
 
-static int cpuid_dev_uevent(struct device *dev, struct kobj_uevent_env *env)
-{
-	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
-	if (buf) {
-		print_cpu_modalias(NULL, NULL, buf);
-		add_uevent_var(env, "MODALIAS=%s", buf);
-		kfree(buf);
-	}
-	return 0;
-}
-
 static int __init cpuid_init(void)
 {
 	int i, err = 0;
@@ -256,7 +200,6 @@ static int __init cpuid_init(void)
 		goto out_chrdev;
 	}
 	cpuid_class->devnode = cpuid_devnode;
-	cpuid_class->dev_uevent = cpuid_dev_uevent;
 	for_each_online_cpu(i) {
 		err = cpuid_device_create(i);
 		if (err != 0)

drivers/base/cpu.c

@@ -11,6 +11,7 @@
 #include <linux/device.h>
 #include <linux/node.h>
 #include <linux/gfp.h>
+#include <linux/slab.h>
 #include <linux/percpu.h>
 
 #include "base.h"
@@ -223,6 +224,9 @@ int __cpuinit register_cpu(struct cpu *cpu, int num)
 	cpu->node_id = cpu_to_node(num);
 	cpu->dev.id = num;
 	cpu->dev.bus = &cpu_subsys;
+#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
+	cpu->dev.bus->uevent = arch_cpu_uevent;
+#endif
 	error = device_register(&cpu->dev);
 	if (!error && cpu->hotpluggable)
 		register_cpu_control(cpu);
@@ -247,6 +251,10 @@ struct device *get_cpu_device(unsigned cpu)
 }
 EXPORT_SYMBOL_GPL(get_cpu_device);
 
+#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
+static DEVICE_ATTR(modalias, 0444, arch_print_cpu_modalias, NULL);
+#endif
+
 static struct attribute *cpu_root_attrs[] = {
 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
 	&dev_attr_probe.attr,
@@ -257,6 +265,9 @@ static struct attribute *cpu_root_attrs[] = {
 	&cpu_attrs[2].attr.attr,
 	&dev_attr_kernel_max.attr,
 	&dev_attr_offline.attr,
+#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
+	&dev_attr_modalias.attr,
+#endif
 	NULL
 };
 

include/linux/cpu.h

@@ -44,6 +44,13 @@ extern ssize_t arch_cpu_release(const char *, size_t);
 #endif
 struct notifier_block;
 
+#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
+extern int arch_cpu_uevent(struct device *dev, struct kobj_uevent_env *env);
+extern ssize_t arch_print_cpu_modalias(struct device *dev,
+				       struct device_attribute *attr,
+				       char *bufptr);
+#endif
+
 /*
  * CPU notifier priorities.
  */