arch/x86/kernel/cpu/cpu_debug.c

/*
 * CPU x86 architecture debug code
 *
 * Copyright(C) 2009 Jaswinder Singh Rajput
 *
 * For licencing details see kernel-base/COPYING
 */

#include <linux/interrupt.h>
#include <linux/compiler.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/smp.h>

#include <asm/cpu_debug.h>
#include <asm/paravirt.h>
#include <asm/system.h>
#include <asm/traps.h>
#include <asm/apic.h>
#include <asm/desc.h>

static DEFINE_PER_CPU(struct cpu_cpuX_base, cpu_arr[CPU_REG_ALL_BIT]);
static DEFINE_PER_CPU(struct cpu_private *, priv_arr[MAX_CPU_FILES]);
static DEFINE_PER_CPU(int, cpu_priv_count);

static DEFINE_MUTEX(cpu_debug_lock);

static struct dentry *cpu_debugfs_dir;

static struct cpu_debug_base cpu_base[] = {
	{ "mc",		CPU_MC,		0	},
	{ "monitor",	CPU_MONITOR,	0	},
	{ "time",	CPU_TIME,	0	},
	{ "pmc",	CPU_PMC,	1	},
	{ "platform",	CPU_PLATFORM,	0	},
	{ "apic",	CPU_APIC,	0	},
	{ "poweron",	CPU_POWERON,	0	},
	{ "control",	CPU_CONTROL,	0	},
	{ "features",	CPU_FEATURES,	0	},
	{ "lastbranch",	CPU_LBRANCH,	0	},
	{ "bios",	CPU_BIOS,	0	},
	{ "freq",	CPU_FREQ,	0	},
	{ "mtrr",	CPU_MTRR,	0	},
	{ "perf",	CPU_PERF,	0	},
	{ "cache",	CPU_CACHE,	0	},
	{ "sysenter",	CPU_SYSENTER,	0	},
	{ "therm",	CPU_THERM,	0	},
	{ "misc",	CPU_MISC,	0	},
	{ "debug",	CPU_DEBUG,	0	},
	{ "pat",	CPU_PAT,	0	},
	{ "vmx",	CPU_VMX,	0	},
	{ "call",	CPU_CALL,	0	},
	{ "base",	CPU_BASE,	0	},
	{ "ver",	CPU_VER,	0	},
	{ "conf",	CPU_CONF,	0	},
	{ "smm",	CPU_SMM,	0	},
	{ "svm",	CPU_SVM,	0	},
	{ "osvm",	CPU_OSVM,	0	},
	{ "tss",	CPU_TSS,	0	},
	{ "cr",		CPU_CR,		0	},
	{ "dt",		CPU_DT,		0	},
	{ "registers",	CPU_REG_ALL,	0	},
};

static struct cpu_file_base cpu_file[] = {
	{ "index",	CPU_REG_ALL,	0	},
	{ "value",	CPU_REG_ALL,	1	},
};

/* CPU Registers Range */
static struct cpu_debug_range cpu_reg_range[] = {
	{ 0x00000000, 0x00000001, CPU_MC,	},
	{ 0x00000006, 0x00000007, CPU_MONITOR,	},
	{ 0x00000010, 0x00000010, CPU_TIME,	},
	{ 0x00000011, 0x00000013, CPU_PMC,	},
	{ 0x00000017, 0x00000017, CPU_PLATFORM,	},
	{ 0x0000001B, 0x0000001B, CPU_APIC,	},
	{ 0x0000002A, 0x0000002B, CPU_POWERON,	},
	{ 0x0000002C, 0x0000002C, CPU_FREQ,	},
	{ 0x0000003A, 0x0000003A, CPU_CONTROL,	},
	{ 0x00000040, 0x00000047, CPU_LBRANCH,	},
	{ 0x00000060, 0x00000067, CPU_LBRANCH,	},
	{ 0x00000079, 0x00000079, CPU_BIOS,	},
	{ 0x00000088, 0x0000008A, CPU_CACHE,	},
	{ 0x0000008B, 0x0000008B, CPU_BIOS,	},
	{ 0x0000009B, 0x0000009B, CPU_MONITOR,	},
	{ 0x000000C1, 0x000000C4, CPU_PMC,	},
	{ 0x000000CD, 0x000000CD, CPU_FREQ,	},
	{ 0x000000E7, 0x000000E8, CPU_PERF,	},
	{ 0x000000FE, 0x000000FE, CPU_MTRR,	},

	{ 0x00000116, 0x0000011E, CPU_CACHE,	},
	{ 0x00000174, 0x00000176, CPU_SYSENTER,	},
	{ 0x00000179, 0x0000017B, CPU_MC,	},
	{ 0x00000186, 0x00000189, CPU_PMC,	},
	{ 0x00000198, 0x00000199, CPU_PERF,	},
	{ 0x0000019A, 0x0000019A, CPU_TIME,	},
	{ 0x0000019B, 0x0000019D, CPU_THERM,	},
	{ 0x000001A0, 0x000001A0, CPU_MISC,	},
	{ 0x000001C9, 0x000001C9, CPU_LBRANCH,	},
	{ 0x000001D7, 0x000001D8, CPU_LBRANCH,	},
	{ 0x000001D9, 0x000001D9, CPU_DEBUG,	},
	{ 0x000001DA, 0x000001E0, CPU_LBRANCH,	},

	{ 0x00000200, 0x0000020F, CPU_MTRR,	},
	{ 0x00000250, 0x00000250, CPU_MTRR,	},
	{ 0x00000258, 0x00000259, CPU_MTRR,	},
	{ 0x00000268, 0x0000026F, CPU_MTRR,	},
	{ 0x00000277, 0x00000277, CPU_PAT,	},
	{ 0x000002FF, 0x000002FF, CPU_MTRR,	},

	{ 0x00000300, 0x00000311, CPU_PMC,	},
	{ 0x00000345, 0x00000345, CPU_PMC,	},
	{ 0x00000360, 0x00000371, CPU_PMC,	},
	{ 0x0000038D, 0x00000390, CPU_PMC,	},
	{ 0x000003A0, 0x000003BE, CPU_PMC,	},
	{ 0x000003C0, 0x000003CD, CPU_PMC,	},
	{ 0x000003E0, 0x000003E1, CPU_PMC,	},
	{ 0x000003F0, 0x000003F2, CPU_PMC,	},

	{ 0x00000400, 0x00000417, CPU_MC,	},
	{ 0x00000480, 0x0000048B, CPU_VMX,	},

	{ 0x00000600, 0x00000600, CPU_DEBUG,	},
	{ 0x00000680, 0x0000068F, CPU_LBRANCH,	},
	{ 0x000006C0, 0x000006CF, CPU_LBRANCH,	},

	{ 0x000107CC, 0x000107D3, CPU_PMC,	},

	{ 0xC0000080, 0xC0000080, CPU_FEATURES,	},
	{ 0xC0000081, 0xC0000084, CPU_CALL,	},
	{ 0xC0000100, 0xC0000102, CPU_BASE,	},
	{ 0xC0000103, 0xC0000103, CPU_TIME,	},

	{ 0xC0010000, 0xC0010007, CPU_PMC,	},
	{ 0xC0010010, 0xC0010010, CPU_CONF,	},
	{ 0xC0010015, 0xC0010015, CPU_CONF,	},
	{ 0xC0010016, 0xC001001A, CPU_MTRR,	},
	{ 0xC001001D, 0xC001001D, CPU_MTRR,	},
	{ 0xC001001F, 0xC001001F, CPU_CONF,	},
	{ 0xC0010030, 0xC0010035, CPU_BIOS,	},
	{ 0xC0010044, 0xC0010048, CPU_MC,	},
	{ 0xC0010050, 0xC0010056, CPU_SMM,	},
	{ 0xC0010058, 0xC0010058, CPU_CONF,	},
	{ 0xC0010060, 0xC0010060, CPU_CACHE,	},
	{ 0xC0010061, 0xC0010068, CPU_SMM,	},
	{ 0xC0010069, 0xC001006B, CPU_SMM,	},
	{ 0xC0010070, 0xC0010071, CPU_SMM,	},
	{ 0xC0010111, 0xC0010113, CPU_SMM,	},
	{ 0xC0010114, 0xC0010118, CPU_SVM,	},
	{ 0xC0010140, 0xC0010141, CPU_OSVM,	},
	{ 0xC0011022, 0xC0011023, CPU_CONF,	},
};

static int is_typeflag_valid(unsigned cpu, unsigned flag)
{
	int i;

	/* Standard Registers should be always valid */
	if (flag >= CPU_TSS)
		return 1;

	for (i = 0; i < ARRAY_SIZE(cpu_reg_range); i++) {
		if (cpu_reg_range[i].flag == flag)
			return 1;
	}

	/* Invalid */
	return 0;
}

static unsigned get_cpu_range(unsigned cpu, unsigned *min, unsigned *max,
			      int index, unsigned flag)
{
	if (cpu_reg_range[index].flag == flag) {
		*min = cpu_reg_range[index].min;
		*max = cpu_reg_range[index].max;
	} else
		*max = 0;

	return *max;
}

/* This function can also be called with seq = NULL for printk */
static void print_cpu_data(struct seq_file *seq, unsigned type,
			   u32 low, u32 high)
{
	struct cpu_private *priv;
	u64 val = high;

	if (seq) {
		priv = seq->private;
		if (priv->file) {
			val = (val << 32) | low;
			seq_printf(seq, "0x%llx\n", val);
		} else
			seq_printf(seq, " %08x: %08x_%08x\n",
				   type, high, low);
	} else
		printk(KERN_INFO " %08x: %08x_%08x\n", type, high, low);
}

/* This function can also be called with seq = NULL for printk */
static void print_msr(struct seq_file *seq, unsigned cpu, unsigned flag)
{
	unsigned msr, msr_min, msr_max;
	struct cpu_private *priv;
	u32 low, high;
	int i;

	if (seq) {
		priv = seq->private;
		if (priv->file) {
			if (!rdmsr_safe_on_cpu(priv->cpu, priv->reg,
					       &low, &high))
				print_cpu_data(seq, priv->reg, low, high);
			return;
		}
	}

	for (i = 0; i < ARRAY_SIZE(cpu_reg_range); i++) {
		if (!get_cpu_range(cpu, &msr_min, &msr_max, i, flag))
			continue;

		for (msr = msr_min; msr <= msr_max; msr++) {
			if (rdmsr_safe_on_cpu(cpu, msr, &low, &high))
				continue;
			print_cpu_data(seq, msr, low, high);
		}
	}
}

static void print_tss(void *arg)
{
	struct pt_regs *regs = task_pt_regs(current);
	struct seq_file *seq = arg;
	unsigned int seg;

	seq_printf(seq, " RAX\t: %016lx\n", regs->ax);
	seq_printf(seq, " RBX\t: %016lx\n", regs->bx);
	seq_printf(seq, " RCX\t: %016lx\n", regs->cx);
	seq_printf(seq, " RDX\t: %016lx\n", regs->dx);

	seq_printf(seq, " RSI\t: %016lx\n", regs->si);
	seq_printf(seq, " RDI\t: %016lx\n", regs->di);
	seq_printf(seq, " RBP\t: %016lx\n", regs->bp);
	seq_printf(seq, " ESP\t: %016lx\n", regs->sp);

#ifdef CONFIG_X86_64
	seq_printf(seq, " R08\t: %016lx\n", regs->r8);
	seq_printf(seq, " R09\t: %016lx\n", regs->r9);
	seq_printf(seq, " R10\t: %016lx\n", regs->r10);
	seq_printf(seq, " R11\t: %016lx\n", regs->r11);
	seq_printf(seq, " R12\t: %016lx\n", regs->r12);
	seq_printf(seq, " R13\t: %016lx\n", regs->r13);
	seq_printf(seq, " R14\t: %016lx\n", regs->r14);
	seq_printf(seq, " R15\t: %016lx\n", regs->r15);
#endif

	asm("movl %%cs,%0" : "=r" (seg));
	seq_printf(seq, " CS\t:             %04x\n", seg);
	asm("movl %%ds,%0" : "=r" (seg));
	seq_printf(seq, " DS\t:             %04x\n", seg);
	seq_printf(seq, " SS\t:             %04lx\n", regs->ss & 0xffff);
	asm("movl %%es,%0" : "=r" (seg));
	seq_printf(seq, " ES\t:             %04x\n", seg);
	asm("movl %%fs,%0" : "=r" (seg));
	seq_printf(seq, " FS\t:             %04x\n", seg);
	asm("movl %%gs,%0" : "=r" (seg));
	seq_printf(seq, " GS\t:             %04x\n", seg);

	seq_printf(seq, " EFLAGS\t: %016lx\n", regs->flags);

	seq_printf(seq, " EIP\t: %016lx\n", regs->ip);
}

static void print_cr(void *arg)
{
	struct seq_file *seq = arg;

	seq_printf(seq, " cr0\t: %016lx\n", read_cr0());
	seq_printf(seq, " cr2\t: %016lx\n", read_cr2());
	seq_printf(seq, " cr3\t: %016lx\n", read_cr3());
	seq_printf(seq, " cr4\t: %016lx\n", read_cr4_safe());
#ifdef CONFIG_X86_64
	seq_printf(seq, " cr8\t: %016lx\n", read_cr8());
#endif
}

static void print_desc_ptr(char *str, struct seq_file *seq, struct desc_ptr dt)
{
	seq_printf(seq, " %s\t: %016llx\n", str, (u64)(dt.address | dt.size));
}

static void print_dt(void *seq)
{
	struct desc_ptr dt;
	unsigned long ldt;

	/* IDT */
	store_idt((struct desc_ptr *)&dt);
	print_desc_ptr("IDT", seq, dt);

	/* GDT */
	store_gdt((struct desc_ptr *)&dt);
	print_desc_ptr("GDT", seq, dt);

	/* LDT */
	store_ldt(ldt);
	seq_printf(seq, " LDT\t: %016lx\n", ldt);

	/* TR */
	store_tr(ldt);
	seq_printf(seq, " TR\t: %016lx\n", ldt);
}

static void print_dr(void *arg)
{
	struct seq_file *seq = arg;
	unsigned long dr;
	int i;

	for (i = 0; i < 8; i++) {
		/* Ignore db4, db5 */
		if ((i == 4) || (i == 5))
			continue;
		get_debugreg(dr, i);
		seq_printf(seq, " dr%d\t: %016lx\n", i, dr);
	}

	seq_printf(seq, "\n MSR\t:\n");
}

static void print_apic(void *arg)
{
	struct seq_file *seq = arg;

#ifdef CONFIG_X86_LOCAL_APIC
	seq_printf(seq, " LAPIC\t:\n");
	seq_printf(seq, " ID\t\t: %08x\n",  apic_read(APIC_ID) >> 24);
	seq_printf(seq, " LVR\t\t: %08x\n",  apic_read(APIC_LVR));
	seq_printf(seq, " TASKPRI\t: %08x\n",  apic_read(APIC_TASKPRI));
	seq_printf(seq, " ARBPRI\t\t: %08x\n",  apic_read(APIC_ARBPRI));
	seq_printf(seq, " PROCPRI\t: %08x\n",  apic_read(APIC_PROCPRI));
	seq_printf(seq, " LDR\t\t: %08x\n",  apic_read(APIC_LDR));
	seq_printf(seq, " DFR\t\t: %08x\n",  apic_read(APIC_DFR));
	seq_printf(seq, " SPIV\t\t: %08x\n",  apic_read(APIC_SPIV));
	seq_printf(seq, " ISR\t\t: %08x\n",  apic_read(APIC_ISR));
	seq_printf(seq, " ESR\t\t: %08x\n",  apic_read(APIC_ESR));
	seq_printf(seq, " ICR\t\t: %08x\n",  apic_read(APIC_ICR));
	seq_printf(seq, " ICR2\t\t: %08x\n",  apic_read(APIC_ICR2));
	seq_printf(seq, " LVTT\t\t: %08x\n",  apic_read(APIC_LVTT));
	seq_printf(seq, " LVTTHMR\t: %08x\n",  apic_read(APIC_LVTTHMR));
	seq_printf(seq, " LVTPC\t\t: %08x\n",  apic_read(APIC_LVTPC));
	seq_printf(seq, " LVT0\t\t: %08x\n",  apic_read(APIC_LVT0));
	seq_printf(seq, " LVT1\t\t: %08x\n",  apic_read(APIC_LVT1));
	seq_printf(seq, " LVTERR\t\t: %08x\n",  apic_read(APIC_LVTERR));
	seq_printf(seq, " TMICT\t\t: %08x\n",  apic_read(APIC_TMICT));
	seq_printf(seq, " TMCCT\t\t: %08x\n",  apic_read(APIC_TMCCT));
	seq_printf(seq, " TDCR\t\t: %08x\n",  apic_read(APIC_TDCR));
	if (boot_cpu_has(X86_FEATURE_EXTAPIC)) {
		unsigned int i, v, maxeilvt;

		v = apic_read(APIC_EFEAT);
		maxeilvt = (v >> 16) & 0xff;
		seq_printf(seq, " EFEAT\t\t: %08x\n", v);
		seq_printf(seq, " ECTRL\t\t: %08x\n", apic_read(APIC_ECTRL));

		for (i = 0; i < maxeilvt; i++) {
			v = apic_read(APIC_EILVTn(i));
			seq_printf(seq, " EILVT%d\t\t: %08x\n", i, v);
		}
	}
#endif /* CONFIG_X86_LOCAL_APIC */
	seq_printf(seq, "\n MSR\t:\n");
}

static int cpu_seq_show(struct seq_file *seq, void *v)
{
	struct cpu_private *priv = seq->private;

	if (priv == NULL)
		return -EINVAL;

	switch (cpu_base[priv->type].flag) {
	case CPU_TSS:
		smp_call_function_single(priv->cpu, print_tss, seq, 1);
		break;
	case CPU_CR:
		smp_call_function_single(priv->cpu, print_cr, seq, 1);
		break;
	case CPU_DT:
		smp_call_function_single(priv->cpu, print_dt, seq, 1);
		break;
	case CPU_DEBUG:
		if (priv->file == CPU_INDEX_BIT)
			smp_call_function_single(priv->cpu, print_dr, seq, 1);
		print_msr(seq, priv->cpu, cpu_base[priv->type].flag);
		break;
	case CPU_APIC:
		if (priv->file == CPU_INDEX_BIT)
			smp_call_function_single(priv->cpu, print_apic, seq, 1);
		print_msr(seq, priv->cpu, cpu_base[priv->type].flag);
		break;

	default:
		print_msr(seq, priv->cpu, cpu_base[priv->type].flag);
		break;
	}
	seq_printf(seq, "\n");

	return 0;
}

static void *cpu_seq_start(struct seq_file *seq, loff_t *pos)
{
	if (*pos == 0) /* One time is enough ;-) */
		return seq;

	return NULL;
}

static void *cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	(*pos)++;

	return cpu_seq_start(seq, pos);
}

static void cpu_seq_stop(struct seq_file *seq, void *v)
{
}

static const struct seq_operations cpu_seq_ops = {
	.start		= cpu_seq_start,
	.next		= cpu_seq_next,
	.stop		= cpu_seq_stop,
	.show		= cpu_seq_show,
};

static int cpu_seq_open(struct inode *inode, struct file *file)
{
	struct cpu_private *priv = inode->i_private;
	struct seq_file *seq;
	int err;

	err = seq_open(file, &cpu_seq_ops);
	if (!err) {
		seq = file->private_data;
		seq->private = priv;
	}

	return err;
}

static int write_msr(struct cpu_private *priv, u64 val)
{
	u32 low, high;

	high = (val >> 32) & 0xffffffff;
	low = val & 0xffffffff;

	if (!wrmsr_safe_on_cpu(priv->cpu, priv->reg, low, high))
		return 0;

	return -EPERM;
}

static int write_cpu_register(struct cpu_private *priv, const char *buf)
{
	int ret = -EPERM;
	u64 val;

	ret = strict_strtoull(buf, 0, &val);
	if (ret < 0)
		return ret;

	/* Supporting only MSRs */
	if (priv->type < CPU_TSS_BIT)
		return write_msr(priv, val);

	return ret;
}

static ssize_t cpu_write(struct file *file, const char __user *ubuf,
			     size_t count, loff_t *off)
{
	struct seq_file *seq = file->private_data;
	struct cpu_private *priv = seq->private;
	char buf[19];

	if ((priv == NULL) || (count >= sizeof(buf)))
		return -EINVAL;

	if (copy_from_user(&buf, ubuf, count))
		return -EFAULT;

	buf[count] = 0;

	if ((cpu_base[priv->type].write) && (cpu_file[priv->file].write))
		if (!write_cpu_register(priv, buf))
			return count;

	return -EACCES;
}

static const struct file_operations cpu_fops = {
	.owner		= THIS_MODULE,
	.open		= cpu_seq_open,
	.read		= seq_read,
	.write		= cpu_write,
	.llseek		= seq_lseek,
	.release	= seq_release,
};

static int cpu_create_file(unsigned cpu, unsigned type, unsigned reg,
			   unsigned file, struct dentry *dentry)
{
	struct cpu_private *priv = NULL;

	/* Already intialized */
	if (file == CPU_INDEX_BIT)
		if (per_cpu(cpu_arr[type].init, cpu))
			return 0;

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	if (priv == NULL)
		return -ENOMEM;

	priv->cpu = cpu;
	priv->type = type;
	priv->reg = reg;
	priv->file = file;
	mutex_lock(&cpu_debug_lock);
	per_cpu(priv_arr[type], cpu) = priv;
	per_cpu(cpu_priv_count, cpu)++;
	mutex_unlock(&cpu_debug_lock);

	if (file)
		debugfs_create_file(cpu_file[file].name, S_IRUGO,
				    dentry, (void *)priv, &cpu_fops);
	else {
		debugfs_create_file(cpu_base[type].name, S_IRUGO,
				    per_cpu(cpu_arr[type].dentry, cpu),
				    (void *)priv, &cpu_fops);
		mutex_lock(&cpu_debug_lock);
		per_cpu(cpu_arr[type].init, cpu) = 1;
		mutex_unlock(&cpu_debug_lock);
	}

	return 0;
}

static int cpu_init_regfiles(unsigned cpu, unsigned int type, unsigned reg,
			     struct dentry *dentry)
{
	unsigned file;
	int err = 0;

	for (file = 0; file <  ARRAY_SIZE(cpu_file); file++) {
		err = cpu_create_file(cpu, type, reg, file, dentry);
		if (err)
			return err;
	}

	return err;
}

static int cpu_init_msr(unsigned cpu, unsigned type, struct dentry *dentry)
{
	struct dentry *cpu_dentry = NULL;
	unsigned reg, reg_min, reg_max;
	int i, err = 0;
	char reg_dir[12];
	u32 low, high;

	for (i = 0; i < ARRAY_SIZE(cpu_reg_range); i++) {
		if (!get_cpu_range(cpu, &reg_min, &reg_max, i,
				   cpu_base[type].flag))
			continue;

		for (reg = reg_min; reg <= reg_max; reg++) {
			if (rdmsr_safe_on_cpu(cpu, reg, &low, &high))
				continue;

			sprintf(reg_dir, "0x%x", reg);
			cpu_dentry = debugfs_create_dir(reg_dir, dentry);
			err = cpu_init_regfiles(cpu, type, reg, cpu_dentry);
			if (err)
				return err;
		}
	}

	return err;
}

static int cpu_init_allreg(unsigned cpu, struct dentry *dentry)
{
	struct dentry *cpu_dentry = NULL;
	unsigned type;
	int err = 0;

	for (type = 0; type <  ARRAY_SIZE(cpu_base) - 1; type++) {
		if (!is_typeflag_valid(cpu, cpu_base[type].flag))
			continue;
		cpu_dentry = debugfs_create_dir(cpu_base[type].name, dentry);
		per_cpu(cpu_arr[type].dentry, cpu) = cpu_dentry;

		if (type < CPU_TSS_BIT)
			err = cpu_init_msr(cpu, type, cpu_dentry);
		else
			err = cpu_create_file(cpu, type, 0, CPU_INDEX_BIT,
					      cpu_dentry);
		if (err)
			return err;
	}

	return err;
}

static int cpu_init_cpu(void)
{
	struct dentry *cpu_dentry = NULL;
	struct cpuinfo_x86 *cpui;
	char cpu_dir[12];
	unsigned cpu;
	int err = 0;

	for (cpu = 0; cpu < nr_cpu_ids; cpu++) {
		cpui = &cpu_data(cpu);
		if (!cpu_has(cpui, X86_FEATURE_MSR))
			continue;

		sprintf(cpu_dir, "cpu%d", cpu);
		cpu_dentry = debugfs_create_dir(cpu_dir, cpu_debugfs_dir);
		err = cpu_init_allreg(cpu, cpu_dentry);

		pr_info("cpu%d(%d) debug files %d\n",
			cpu, nr_cpu_ids, per_cpu(cpu_priv_count, cpu));
		if (per_cpu(cpu_priv_count, cpu) > MAX_CPU_FILES) {
			pr_err("Register files count %d exceeds limit %d\n",
				per_cpu(cpu_priv_count, cpu), MAX_CPU_FILES);
			per_cpu(cpu_priv_count, cpu) = MAX_CPU_FILES;
			err = -ENFILE;
		}
		if (err)
			return err;
	}

	return err;
}

static int __init cpu_debug_init(void)
{
	cpu_debugfs_dir = debugfs_create_dir("cpu", arch_debugfs_dir);

	return cpu_init_cpu();
}

static void __exit cpu_debug_exit(void)
{
	int i, cpu;

	if (cpu_debugfs_dir)
		debugfs_remove_recursive(cpu_debugfs_dir);

	for (cpu = 0; cpu <  nr_cpu_ids; cpu++)
		for (i = 0; i < per_cpu(cpu_priv_count, cpu); i++)
			kfree(per_cpu(priv_arr[i], cpu));
}

module_init(cpu_debug_init);
module_exit(cpu_debug_exit);

MODULE_AUTHOR("Jaswinder Singh Rajput");
MODULE_DESCRIPTION("CPU Debug module");
MODULE_LICENSE("GPL");