x86: cpu architecture debug code

Introduce:

 cat /sys/kernel/debug/x86/cpu/*

for Intel and AMD processors to view / debug the state of each CPU.

By using this we can debug whole range of registers and other
cpu information for debugging purpose and monitor how things
are changing.

This can be useful for developers as well as for users.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
LKML-Reference: <1236701373.3387.4.camel@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 786 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index 82db7f4..d4356f8 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -14,6 +14,8 @@ obj-y			+= vmware.o hypervisor.o
 obj-$(CONFIG_X86_32)	+= bugs.o cmpxchg.o
 obj-$(CONFIG_X86_64)	+= bugs_64.o
 
+obj-$(CONFIG_X86_CPU_DEBUG)		+= cpu_debug.o
+
 obj-$(CONFIG_CPU_SUP_INTEL)		+= intel.o
 obj-$(CONFIG_CPU_SUP_AMD)		+= amd.o
 obj-$(CONFIG_CPU_SUP_CYRIX_32)		+= cyrix.o
diff --git a/arch/x86/kernel/cpu/cpu_debug.c b/arch/x86/kernel/cpu/cpu_debug.c
new file mode 100755
index 0000000..0bdf4da
--- /dev/null
+++ b/arch/x86/kernel/cpu/cpu_debug.c
@@ -0,0 +1,784 @@
+/*
+ * 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/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/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(unsigned, cpu_modelflag);
+static DEFINE_PER_CPU(int, cpu_priv_count);
+static DEFINE_PER_CPU(unsigned, cpu_model);
+
+static DEFINE_MUTEX(cpu_debug_lock);
+
+static struct dentry *cpu_debugfs_dir;
+
+static struct cpu_debug_base cpu_base[] = {
+	{ "mc",		CPU_MC		},	/* Machine Check	*/
+	{ "monitor",	CPU_MONITOR	},	/* Monitor		*/
+	{ "time",	CPU_TIME	},	/* Time			*/
+	{ "pmc",	CPU_PMC		},	/* Performance Monitor	*/
+	{ "platform",	CPU_PLATFORM	},	/* Platform		*/
+	{ "apic",	CPU_APIC	},	/* APIC			*/
+	{ "poweron",	CPU_POWERON	},	/* Power-on		*/
+	{ "control",	CPU_CONTROL	},	/* Control		*/
+	{ "features",	CPU_FEATURES	},	/* Features control	*/
+	{ "lastbranch",	CPU_LBRANCH	},	/* Last Branch		*/
+	{ "bios",	CPU_BIOS	},	/* BIOS			*/
+	{ "freq",	CPU_FREQ	},	/* Frequency		*/
+	{ "mtrr",	CPU_MTRR	},	/* MTRR			*/
+	{ "perf",	CPU_PERF	},	/* Performance		*/
+	{ "cache",	CPU_CACHE	},	/* Cache		*/
+	{ "sysenter",	CPU_SYSENTER	},	/* Sysenter		*/
+	{ "therm",	CPU_THERM	},	/* Thermal		*/
+	{ "misc",	CPU_MISC	},	/* Miscellaneous	*/
+	{ "debug",	CPU_DEBUG	},	/* Debug		*/
+	{ "pat",	CPU_PAT		},	/* PAT			*/
+	{ "vmx",	CPU_VMX		},	/* VMX			*/
+	{ "call",	CPU_CALL	},	/* System Call		*/
+	{ "base",	CPU_BASE	},	/* BASE Address		*/
+	{ "smm",	CPU_SMM		},	/* System mgmt mode	*/
+	{ "svm",	CPU_SVM		},	/*Secure Virtial Machine*/
+	{ "osvm",	CPU_OSVM	},	/* OS-Visible Workaround*/
+	{ "tss",	CPU_TSS		},	/* Task Stack Segment	*/
+	{ "cr",		CPU_CR		},	/* Control Registers	*/
+	{ "dt",		CPU_DT		},	/* Descriptor Table	*/
+	{ "registers",	CPU_REG_ALL	},	/* Select all Registers	*/
+};
+
+static struct cpu_file_base cpu_file[] = {
+	{ "index",	CPU_REG_ALL	},	/* index		*/
+	{ "value",	CPU_REG_ALL	},	/* value		*/
+};
+
+/* Intel Registers Range */
+static struct cpu_debug_range cpu_intel_range[] = {
+	{ 0x00000000, 0x00000001, CPU_MC,	CPU_INTEL_ALL		},
+	{ 0x00000006, 0x00000007, CPU_MONITOR,	CPU_CX_AT_XE		},
+	{ 0x00000010, 0x00000010, CPU_TIME,	CPU_INTEL_ALL		},
+	{ 0x00000011, 0x00000013, CPU_PMC,	CPU_INTEL_PENTIUM	},
+	{ 0x00000017, 0x00000017, CPU_PLATFORM,	CPU_PX_CX_AT_XE		},
+	{ 0x0000001B, 0x0000001B, CPU_APIC,	CPU_P6_CX_AT_XE		},
+
+	{ 0x0000002A, 0x0000002A, CPU_POWERON,	CPU_PX_CX_AT_XE		},
+	{ 0x0000002B, 0x0000002B, CPU_POWERON,	CPU_INTEL_XEON		},
+	{ 0x0000002C, 0x0000002C, CPU_FREQ,	CPU_INTEL_XEON		},
+	{ 0x0000003A, 0x0000003A, CPU_CONTROL,	CPU_CX_AT_XE		},
+
+	{ 0x00000040, 0x00000043, CPU_LBRANCH,	CPU_PM_CX_AT_XE		},
+	{ 0x00000044, 0x00000047, CPU_LBRANCH,	CPU_PM_CO_AT		},
+	{ 0x00000060, 0x00000063, CPU_LBRANCH,	CPU_C2_AT		},
+	{ 0x00000064, 0x00000067, CPU_LBRANCH,	CPU_INTEL_ATOM		},
+
+	{ 0x00000079, 0x00000079, CPU_BIOS,	CPU_P6_CX_AT_XE		},
+	{ 0x00000088, 0x0000008A, CPU_CACHE,	CPU_INTEL_P6		},
+	{ 0x0000008B, 0x0000008B, CPU_BIOS,	CPU_P6_CX_AT_XE		},
+	{ 0x0000009B, 0x0000009B, CPU_MONITOR,	CPU_INTEL_XEON		},
+
+	{ 0x000000C1, 0x000000C2, CPU_PMC,	CPU_P6_CX_AT		},
+	{ 0x000000CD, 0x000000CD, CPU_FREQ,	CPU_CX_AT		},
+	{ 0x000000E7, 0x000000E8, CPU_PERF,	CPU_CX_AT		},
+	{ 0x000000FE, 0x000000FE, CPU_MTRR,	CPU_P6_CX_XE		},
+
+	{ 0x00000116, 0x00000116, CPU_CACHE,	CPU_INTEL_P6		},
+	{ 0x00000118, 0x00000118, CPU_CACHE,	CPU_INTEL_P6		},
+	{ 0x00000119, 0x00000119, CPU_CACHE,	CPU_INTEL_PX		},
+	{ 0x0000011A, 0x0000011B, CPU_CACHE,	CPU_INTEL_P6		},
+	{ 0x0000011E, 0x0000011E, CPU_CACHE,	CPU_PX_CX_AT		},
+
+	{ 0x00000174, 0x00000176, CPU_SYSENTER,	CPU_P6_CX_AT_XE		},
+	{ 0x00000179, 0x0000017A, CPU_MC,	CPU_PX_CX_AT_XE		},
+	{ 0x0000017B, 0x0000017B, CPU_MC,	CPU_P6_XE		},
+	{ 0x00000186, 0x00000187, CPU_PMC,	CPU_P6_CX_AT		},
+	{ 0x00000198, 0x00000199, CPU_PERF,	CPU_PM_CX_AT_XE		},
+	{ 0x0000019A, 0x0000019A, CPU_TIME,	CPU_PM_CX_AT_XE		},
+	{ 0x0000019B, 0x0000019D, CPU_THERM,	CPU_PM_CX_AT_XE		},
+	{ 0x000001A0, 0x000001A0, CPU_MISC,	CPU_PM_CX_AT_XE		},
+
+	{ 0x000001C9, 0x000001C9, CPU_LBRANCH,	CPU_PM_CX_AT		},
+	{ 0x000001D7, 0x000001D8, CPU_LBRANCH,	CPU_INTEL_XEON		},
+	{ 0x000001D9, 0x000001D9, CPU_DEBUG,	CPU_CX_AT_XE		},
+	{ 0x000001DA, 0x000001DA, CPU_LBRANCH,	CPU_INTEL_XEON		},
+	{ 0x000001DB, 0x000001DB, CPU_LBRANCH,	CPU_P6_XE		},
+	{ 0x000001DC, 0x000001DC, CPU_LBRANCH,	CPU_INTEL_P6		},
+	{ 0x000001DD, 0x000001DE, CPU_LBRANCH,	CPU_PX_CX_AT_XE		},
+	{ 0x000001E0, 0x000001E0, CPU_LBRANCH,	CPU_INTEL_P6		},
+
+	{ 0x00000200, 0x0000020F, CPU_MTRR,	CPU_P6_CX_XE		},
+	{ 0x00000250, 0x00000250, CPU_MTRR,	CPU_P6_CX_XE		},
+	{ 0x00000258, 0x00000259, CPU_MTRR,	CPU_P6_CX_XE		},
+	{ 0x00000268, 0x0000026F, CPU_MTRR,	CPU_P6_CX_XE		},
+	{ 0x00000277, 0x00000277, CPU_PAT,	CPU_C2_AT_XE		},
+	{ 0x000002FF, 0x000002FF, CPU_MTRR,	CPU_P6_CX_XE		},
+
+	{ 0x00000300, 0x00000308, CPU_PMC,	CPU_INTEL_XEON		},
+	{ 0x00000309, 0x0000030B, CPU_PMC,	CPU_C2_AT_XE		},
+	{ 0x0000030C, 0x00000311, CPU_PMC,	CPU_INTEL_XEON		},
+	{ 0x00000345, 0x00000345, CPU_PMC,	CPU_C2_AT		},
+	{ 0x00000360, 0x00000371, CPU_PMC,	CPU_INTEL_XEON		},
+	{ 0x0000038D, 0x00000390, CPU_PMC,	CPU_C2_AT		},
+	{ 0x000003A0, 0x000003BE, CPU_PMC,	CPU_INTEL_XEON		},
+	{ 0x000003C0, 0x000003CD, CPU_PMC,	CPU_INTEL_XEON		},
+	{ 0x000003E0, 0x000003E1, CPU_PMC,	CPU_INTEL_XEON		},
+	{ 0x000003F0, 0x000003F0, CPU_PMC,	CPU_INTEL_XEON		},
+	{ 0x000003F1, 0x000003F1, CPU_PMC,	CPU_C2_AT_XE		},
+	{ 0x000003F2, 0x000003F2, CPU_PMC,	CPU_INTEL_XEON		},
+
+	{ 0x00000400, 0x00000402, CPU_MC,	CPU_PM_CX_AT_XE		},
+	{ 0x00000403, 0x00000403, CPU_MC,	CPU_INTEL_XEON		},
+	{ 0x00000404, 0x00000406, CPU_MC,	CPU_PM_CX_AT_XE		},
+	{ 0x00000407, 0x00000407, CPU_MC,	CPU_INTEL_XEON		},
+	{ 0x00000408, 0x0000040A, CPU_MC,	CPU_PM_CX_AT_XE		},
+	{ 0x0000040B, 0x0000040B, CPU_MC,	CPU_INTEL_XEON		},
+	{ 0x0000040C, 0x0000040E, CPU_MC,	CPU_PM_CX_XE		},
+	{ 0x0000040F, 0x0000040F, CPU_MC,	CPU_INTEL_XEON		},
+	{ 0x00000410, 0x00000412, CPU_MC,	CPU_PM_CX_AT_XE		},
+	{ 0x00000413, 0x00000417, CPU_MC,	CPU_CX_AT_XE		},
+	{ 0x00000480, 0x0000048B, CPU_VMX,	CPU_CX_AT_XE		},
+
+	{ 0x00000600, 0x00000600, CPU_DEBUG,	CPU_PM_CX_AT_XE		},
+	{ 0x00000680, 0x0000068F, CPU_LBRANCH,	CPU_INTEL_XEON		},
+	{ 0x000006C0, 0x000006CF, CPU_LBRANCH,	CPU_INTEL_XEON		},
+
+	{ 0x000107CC, 0x000107D3, CPU_PMC,	CPU_INTEL_XEON_MP	},
+
+	{ 0xC0000080, 0xC0000080, CPU_FEATURES,	CPU_INTEL_XEON		},
+	{ 0xC0000081, 0xC0000082, CPU_CALL,	CPU_INTEL_XEON		},
+	{ 0xC0000084, 0xC0000084, CPU_CALL,	CPU_INTEL_XEON		},
+	{ 0xC0000100, 0xC0000102, CPU_BASE,	CPU_INTEL_XEON		},
+};
+
+/* AMD Registers Range */
+static struct cpu_debug_range cpu_amd_range[] = {
+	{ 0x00000010, 0x00000010, CPU_TIME,	CPU_ALL,		},
+	{ 0x0000001B, 0x0000001B, CPU_APIC,	CPU_ALL,		},
+	{ 0x000000FE, 0x000000FE, CPU_MTRR,	CPU_ALL,		},
+
+	{ 0x00000174, 0x00000176, CPU_SYSENTER,	CPU_ALL,		},
+	{ 0x00000179, 0x0000017A, CPU_MC,	CPU_ALL,		},
+	{ 0x0000017B, 0x0000017B, CPU_MC,	CPU_ALL,		},
+	{ 0x000001D9, 0x000001D9, CPU_DEBUG,	CPU_ALL,		},
+	{ 0x000001DB, 0x000001DE, CPU_LBRANCH,	CPU_ALL,		},
+
+	{ 0x00000200, 0x0000020F, CPU_MTRR,	CPU_ALL,		},
+	{ 0x00000250, 0x00000250, CPU_MTRR,	CPU_ALL,		},
+	{ 0x00000258, 0x00000259, CPU_MTRR,	CPU_ALL,		},
+	{ 0x00000268, 0x0000026F, CPU_MTRR,	CPU_ALL,		},
+	{ 0x00000277, 0x00000277, CPU_PAT,	CPU_ALL,		},
+	{ 0x000002FF, 0x000002FF, CPU_MTRR,	CPU_ALL,		},
+
+	{ 0x00000400, 0x00000417, CPU_MC,	CPU_ALL,		},
+
+	{ 0xC0000080, 0xC0000080, CPU_FEATURES,	CPU_ALL,		},
+	{ 0xC0000081, 0xC0000084, CPU_CALL,	CPU_ALL,		},
+	{ 0xC0000100, 0xC0000102, CPU_BASE,	CPU_ALL,		},
+	{ 0xC0000103, 0xC0000103, CPU_TIME,	CPU_ALL,		},
+
+	{ 0xC0000408, 0xC000040A, CPU_MC,	CPU_ALL,		},
+
+	{ 0xc0010000, 0xc0010007, CPU_PMC,	CPU_ALL,		},
+	{ 0xc0010010, 0xc0010010, CPU_MTRR,	CPU_ALL,		},
+	{ 0xc0010016, 0xc001001A, CPU_MTRR,	CPU_ALL,		},
+	{ 0xc001001D, 0xc001001D, CPU_MTRR,	CPU_ALL,		},
+	{ 0xc0010030, 0xc0010035, CPU_BIOS,	CPU_ALL,		},
+	{ 0xc0010056, 0xc0010056, CPU_SMM,	CPU_ALL,		},
+	{ 0xc0010061, 0xc0010063, CPU_SMM,	CPU_ALL,		},
+	{ 0xc0010074, 0xc0010074, CPU_MC,	CPU_ALL,		},
+	{ 0xc0010111, 0xc0010113, CPU_SMM,	CPU_ALL,		},
+	{ 0xc0010114, 0xc0010118, CPU_SVM,	CPU_ALL,		},
+	{ 0xc0010119, 0xc001011A, CPU_SMM,	CPU_ALL,		},
+	{ 0xc0010140, 0xc0010141, CPU_OSVM,	CPU_ALL,		},
+	{ 0xc0010156, 0xc0010156, CPU_SMM,	CPU_ALL,		},
+};
+
+
+static int get_cpu_modelflag(unsigned cpu)
+{
+	int flag;
+
+	switch (per_cpu(cpu_model, cpu)) {
+	/* Intel */
+	case 0x0501:
+	case 0x0502:
+	case 0x0504:
+		flag = CPU_INTEL_PENTIUM;
+		break;
+	case 0x0601:
+	case 0x0603:
+	case 0x0605:
+	case 0x0607:
+	case 0x0608:
+	case 0x060A:
+	case 0x060B:
+		flag = CPU_INTEL_P6;
+		break;
+	case 0x0609:
+	case 0x060D:
+		flag = CPU_INTEL_PENTIUM_M;
+		break;
+	case 0x060E:
+		flag = CPU_INTEL_CORE;
+		break;
+	case 0x060F:
+	case 0x0617:
+		flag = CPU_INTEL_CORE2;
+		break;
+	case 0x061C:
+		flag = CPU_INTEL_ATOM;
+		break;
+	case 0x0F00:
+	case 0x0F01:
+	case 0x0F02:
+	case 0x0F03:
+	case 0x0F04:
+		flag = CPU_INTEL_XEON_P4;
+		break;
+	case 0x0F06:
+		flag = CPU_INTEL_XEON_MP;
+		break;
+	default:
+		flag = CPU_NONE;
+		break;
+	}
+
+	return flag;
+}
+
+static int get_cpu_range_count(unsigned cpu)
+{
+	int index;
+
+	switch (per_cpu(cpu_model, cpu) >> 16) {
+	case X86_VENDOR_INTEL:
+		index = ARRAY_SIZE(cpu_intel_range);
+		break;
+	case X86_VENDOR_AMD:
+		index = ARRAY_SIZE(cpu_amd_range);
+		break;
+	default:
+		index = 0;
+		break;
+	}
+
+	return index;
+}
+
+static int is_typeflag_valid(unsigned cpu, unsigned flag)
+{
+	unsigned vendor, modelflag;
+	int i, index;
+
+	/* Standard Registers should be always valid */
+	if (flag >= CPU_TSS)
+		return 1;
+
+	modelflag = per_cpu(cpu_modelflag, cpu);
+	vendor = per_cpu(cpu_model, cpu) >> 16;
+	index = get_cpu_range_count(cpu);
+
+	for (i = 0; i < index; i++) {
+		switch (vendor) {
+		case X86_VENDOR_INTEL:
+			if ((cpu_intel_range[i].model & modelflag) &&
+			    (cpu_intel_range[i].flag & flag))
+				return 1;
+			break;
+		case X86_VENDOR_AMD:
+			if (cpu_amd_range[i].flag & flag)
+				return 1;
+			break;
+		}
+	}
+
+	/* Invalid */
+	return 0;
+}
+
+static unsigned get_cpu_range(unsigned cpu, unsigned *min, unsigned *max,
+			      int index, unsigned flag)
+{
+	unsigned modelflag;
+
+	modelflag = per_cpu(cpu_modelflag, cpu);
+	*max = 0;
+	switch (per_cpu(cpu_model, cpu) >> 16) {
+	case X86_VENDOR_INTEL:
+		if ((cpu_intel_range[index].model & modelflag) &&
+		    (cpu_intel_range[index].flag & flag)) {
+			*min = cpu_intel_range[index].min;
+			*max = cpu_intel_range[index].max;
+		}
+		break;
+	case X86_VENDOR_AMD:
+		if (cpu_amd_range[index].flag & flag) {
+			*min = cpu_amd_range[index].min;
+			*max = cpu_amd_range[index].max;
+		}
+		break;
+	}
+
+	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, range;
+
+	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;
+		}
+	}
+
+	range = get_cpu_range_count(cpu);
+
+	for (i = 0; i < 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);
+	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));
+#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 const struct file_operations cpu_fops = {
+	.open		= cpu_seq_open,
+	.read		= seq_read,
+	.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, range, err = 0;
+	char reg_dir[12];
+	u32 low, high;
+
+	range = get_cpu_range_count(cpu);
+
+	for (i = 0; i < 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;
+		per_cpu(cpu_model, cpu) = ((cpui->x86_vendor << 16) |
+					   (cpui->x86 << 8) |
+					   (cpui->x86_model));
+		per_cpu(cpu_modelflag, cpu) = get_cpu_modelflag(cpu);
+
+		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");