1 files changed, 279 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/msr.c b/arch/x86_64/kernel/msr.c
new file mode 100644
index 000000000000..598953ab0154
--- /dev/null
+++ b/arch/x86_64/kernel/msr.c
@@ -0,0 +1,279 @@
+/* ----------------------------------------------------------------------- *
+ *   
+ *   Copyright 2000 H. Peter Anvin - All Rights Reserved
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
+ *   USA; either version 2 of the License, or (at your option) any later
+ *   version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * msr.c
+ *
+ * x86 MSR access device
+ *
+ * This device is accessed by lseek() to the appropriate register number
+ * and then read/write in chunks of 8 bytes.  A larger size means multiple
+ * reads or writes of the same register.
+ *
+ * This driver uses /dev/cpu/%d/msr where %d is the minor number, and on
+ * an SMP box will direct the access to CPU %d.
+ */
+
+#include <linux/module.h>
+#include <linux/config.h>
+
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/fcntl.h>
+#include <linux/init.h>
+#include <linux/poll.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/major.h>
+#include <linux/fs.h>
+
+#include <asm/processor.h>
+#include <asm/msr.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+
+/* Note: "err" is handled in a funny way below.  Otherwise one version
+   of gcc or another breaks. */
+
+static inline int wrmsr_eio(u32 reg, u32 eax, u32 edx)
+{
+        int err;
+
+        asm volatile ("1:       wrmsr\n"
+                      "2:\n"
+                      ".section .fixup,\"ax\"\n"
+                      "3:       movl %4,%0\n"
+                      " jmp 2b\n"
+                      ".previous\n"
+                      ".section __ex_table,\"a\"\n"
+                      " .align 8\n" "   .quad 1b,3b\n" ".previous":"=&bDS" (err)
+                      :"a"(eax), "d"(edx), "c"(reg), "i"(-EIO), "0"(0));
+
+        return err;
+}
+
+static inline int rdmsr_eio(u32 reg, u32 *eax, u32 *edx)
+{
+        int err;
+
+        asm volatile ("1:       rdmsr\n"
+                      "2:\n"
+                      ".section .fixup,\"ax\"\n"
+                      "3:       movl %4,%0\n"
+                      " jmp 2b\n"
+                      ".previous\n"
+                      ".section __ex_table,\"a\"\n"
+                      " .align 8\n"
+                      " .quad 1b,3b\n"
+                      ".previous":"=&bDS" (err), "=a"(*eax), "=d"(*edx)
+                      :"c"(reg), "i"(-EIO), "0"(0));
+
+        return err;
+}
+
+#ifdef CONFIG_SMP
+
+struct msr_command {
+        int cpu;
+        int err;
+        u32 reg;
+        u32 data[2];
+};
+
+static void msr_smp_wrmsr(void *cmd_block)
+{
+        struct msr_command *cmd = (struct msr_command *)cmd_block;
+
+        if (cmd->cpu == smp_processor_id())
+                cmd->err = wrmsr_eio(cmd->reg, cmd->data[0], cmd->data[1]);
+}
+
+static void msr_smp_rdmsr(void *cmd_block)
+{
+        struct msr_command *cmd = (struct msr_command *)cmd_block;
+
+        if (cmd->cpu == smp_processor_id())
+                cmd->err = rdmsr_eio(cmd->reg, &cmd->data[0], &cmd->data[1]);
+}
+
+static inline int do_wrmsr(int cpu, u32 reg, u32 eax, u32 edx)
+{
+        struct msr_command cmd;
+        int ret;
+
+        preempt_disable();
+        if (cpu == smp_processor_id()) {
+                ret = wrmsr_eio(reg, eax, edx);
+        } else {
+                cmd.cpu = cpu;
+                cmd.reg = reg;
+                cmd.data[0] = eax;
+                cmd.data[1] = edx;
+
+                smp_call_function(msr_smp_wrmsr, &cmd, 1, 1);
+                ret = cmd.err;
+        }
+        preempt_enable();
+        return ret;
+}
+
+static inline int do_rdmsr(int cpu, u32 reg, u32 * eax, u32 * edx)
+{
+        struct msr_command cmd;
+        int ret;
+
+        preempt_disable();
+        if (cpu == smp_processor_id()) {
+                ret = rdmsr_eio(reg, eax, edx);
+        } else {
+                cmd.cpu = cpu;
+                cmd.reg = reg;
+
+                smp_call_function(msr_smp_rdmsr, &cmd, 1, 1);
+
+                *eax = cmd.data[0];
+                *edx = cmd.data[1];
+
+                ret = cmd.err;
+        }
+        preempt_enable();
+        return ret;
+}
+
+#else                           /* ! CONFIG_SMP */
+
+static inline int do_wrmsr(int cpu, u32 reg, u32 eax, u32 edx)
+{
+        return wrmsr_eio(reg, eax, edx);
+}
+
+static inline int do_rdmsr(int cpu, u32 reg, u32 *eax, u32 *edx)
+{
+        return rdmsr_eio(reg, eax, edx);
+}
+
+#endif                          /* ! CONFIG_SMP */
+
+static loff_t msr_seek(struct file *file, loff_t offset, int orig)
+{
+        loff_t ret = -EINVAL;
+
+        lock_kernel();
+        switch (orig) {
+        case 0:
+                file->f_pos = offset;
+                ret = file->f_pos;
+                break;
+        case 1:
+                file->f_pos += offset;
+                ret = file->f_pos;
+        }
+        unlock_kernel();
+        return ret;
+}
+
+static ssize_t msr_read(struct file *file, char __user * buf,
+                        size_t count, loff_t * ppos)
+{
+        u32 __user *tmp = (u32 __user *) buf;
+        u32 data[2];
+        size_t rv;
+        u32 reg = *ppos;
+        int cpu = iminor(file->f_dentry->d_inode);
+        int err;
+
+        if (count % 8)
+                return -EINVAL; /* Invalid chunk size */
+
+        for (rv = 0; count; count -= 8) {
+                err = do_rdmsr(cpu, reg, &data[0], &data[1]);
+                if (err)
+                        return err;
+                if (copy_to_user(tmp, &data, 8))
+                        return -EFAULT;
+                tmp += 2;
+        }
+
+        return ((char __user *)tmp) - buf;
+}
+
+static ssize_t msr_write(struct file *file, const char __user *buf,
+                         size_t count, loff_t *ppos)
+{
+        const u32 __user *tmp = (const u32 __user *)buf;
+        u32 data[2];
+        size_t rv;
+        u32 reg = *ppos;
+        int cpu = iminor(file->f_dentry->d_inode);
+        int err;
+
+        if (count % 8)
+                return -EINVAL; /* Invalid chunk size */
+
+        for (rv = 0; count; count -= 8) {
+                if (copy_from_user(&data, tmp, 8))
+                        return -EFAULT;
+                err = do_wrmsr(cpu, reg, data[0], data[1]);
+                if (err)
+                        return err;
+                tmp += 2;
+        }
+
+        return ((char __user *)tmp) - buf;
+}
+
+static int msr_open(struct inode *inode, struct file *file)
+{
+        unsigned int cpu = iminor(file->f_dentry->d_inode);
+        struct cpuinfo_x86 *c = &(cpu_data)[cpu];
+
+        if (cpu >= NR_CPUS || !cpu_online(cpu))
+                return -ENXIO;  /* No such CPU */
+        if (!cpu_has(c, X86_FEATURE_MSR))
+                return -EIO;    /* MSR not supported */
+
+        return 0;
+}
+
+/*
+ * File operations we support
+ */
+static struct file_operations msr_fops = {
+        .owner = THIS_MODULE,
+        .llseek = msr_seek,
+        .read = msr_read,
+        .write = msr_write,
+        .open = msr_open,
+};
+
+static int __init msr_init(void)
+{
+        if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
+                printk(KERN_ERR "msr: unable to get major %d for msr\n",
+                       MSR_MAJOR);
+                return -EBUSY;
+        }
+
+        return 0;
+}
+
+static void __exit msr_exit(void)
+{
+        unregister_chrdev(MSR_MAJOR, "cpu/msr");
+}
+
+module_init(msr_init);
+module_exit(msr_exit)
+
+MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
+MODULE_DESCRIPTION("x86 generic MSR driver");
+MODULE_LICENSE("GPL");