patch-2.2.18 linux/arch/i386/kernel/msr.c

• Lines: 271
• Date: Thu Oct 19 01:25:23 2000
• Orig file: v2.2.17/arch/i386/kernel/msr.c
• Orig date: Thu Jan 1 01:00:00 1970

diff -u --new-file --recursive --exclude-from /usr/src/exclude v2.2.17/arch/i386/kernel/msr.c linux/arch/i386/kernel/msr.c
@@ -0,0 +1,270 @@
+#ident "$Id$"
+/* ----------------------------------------------------------------------- *
+ *   
+ *   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/major.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. */
+
+extern 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 4\n"
+	       "	.long 1b,3b\n"
+	       ".previous"
+	       : "=&bDS" (err)
+	       : "a" (eax), "d" (edx), "c" (reg), "i" (-EIO), "0" (0));
+
+  return err;
+}
+
+extern 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 4\n"
+	       "	.long 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]);
+}
+
+extern inline int do_wrmsr(int cpu, u32 reg, u32 eax, u32 edx)
+{
+  struct msr_command cmd;
+
+  if ( cpu == smp_processor_id() ) {
+    return 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);
+    return cmd.err;
+  }
+}
+
+extern inline int do_rdmsr(int cpu, u32 reg, u32 *eax, u32 *edx)
+{
+  struct msr_command cmd;
+
+  if ( cpu == smp_processor_id() ) {
+    return 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];
+
+    return cmd.err;
+  }
+}
+
+#else /* ! CONFIG_SMP */
+
+extern inline int do_wrmsr(int cpu, u32 reg, u32 eax, u32 edx)
+{
+  return wrmsr_eio(reg, eax, edx);
+}
+
+extern 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)
+{
+  switch (orig) {
+  case 0:
+    file->f_pos = offset;
+    return file->f_pos;
+  case 1:
+    file->f_pos += offset;
+    return file->f_pos;
+  default:
+    return -EINVAL;	/* SEEK_END not supported */
+  }
+}
+
+static ssize_t msr_read(struct file * file, char * buf,
+			size_t count, loff_t *ppos)
+{
+  u32 *tmp = (u32 *)buf;
+  u32 data[2];
+  size_t rv;
+  u32 reg = *ppos;
+  int cpu = MINOR(file->f_dentry->d_inode->i_rdev);
+  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 *)tmp) - buf;
+}
+
+static ssize_t msr_write(struct file * file, const char * buf,
+			 size_t count, loff_t *ppos)
+{
+  const u32 *tmp = (const u32 *)buf;
+  u32 data[2];
+  size_t rv;
+  u32 reg = *ppos;
+  int cpu = MINOR(file->f_dentry->d_inode->i_rdev);
+  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 *)tmp) - buf;
+}
+
+static int msr_open(struct inode *inode, struct file *file)
+{
+  int cpu = MINOR(file->f_dentry->d_inode->i_rdev);
+  struct cpuinfo_x86 *c = &(cpu_data)[cpu];
+  
+  if ( !(cpu_online_map & (1UL << cpu)) )
+    return -ENXIO;		/* No such CPU */
+  if ( !(c->x86_capability & X86_FEATURE_MSR) )
+    return -EIO;		/* MSR not supported */
+  
+  return 0;
+}
+
+/*
+ * File operations we support
+ */
+static struct file_operations msr_fops = {
+  llseek:	msr_seek,
+  read:		msr_read,
+  write:	msr_write,
+  open:		msr_open,
+};
+
+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 msr_exit(void)
+{
+}
+
+module_init(msr_init);
+module_exit(msr_exit);
+
+MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
+MODULE_DESCRIPTION("x86 generic MSR driver");
+EXPORT_NO_SYMBOLS;