2 files changed, 97 insertions, 37 deletions

diff --git a/arch/x86/include/asm/cpu_debug.h b/arch/x86/include/asm/cpu_debug.h
index d24d64fcee04..56f1635e4617 100755
--- a/arch/x86/include/asm/cpu_debug.h
+++ b/arch/x86/include/asm/cpu_debug.h
@@ -171,16 +171,22 @@ struct cpu_private {
 struct cpu_debug_base {
         char                    *name;          /* Register name        */
         unsigned                flag;           /* Register flag        */
+        unsigned                write;          /* Register write flag  */
 };
 
-struct cpu_cpuX_base {
-        struct dentry           *dentry;        /* Register dentry      */
-        int                     init;           /* Register index file  */
-};
-
+/*
+ * Currently it looks similar to cpu_debug_base but once we add more files
+ * cpu_file_base will go in different direction
+ */
 struct cpu_file_base {
         char                    *name;          /* Register file name   */
         unsigned                flag;           /* Register file flag   */
+        unsigned                write;          /* Register write flag  */
+};
+
+struct cpu_cpuX_base {
+        struct dentry           *dentry;        /* Register dentry      */
+        int                     init;           /* Register index file  */
 };
 
 struct cpu_debug_range {
diff --git a/arch/x86/kernel/cpu/cpu_debug.c b/arch/x86/kernel/cpu/cpu_debug.c
index 9abbcbd933cc..21c0cf8ced18 100755
--- a/arch/x86/kernel/cpu/cpu_debug.c
+++ b/arch/x86/kernel/cpu/cpu_debug.c
@@ -11,6 +11,7 @@
 #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>
@@ -40,41 +41,41 @@ 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 */
+        { "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       },
+        { "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     },      /* index                */
-        { "value",      CPU_REG_ALL     },      /* value                */
+        { "index",      CPU_REG_ALL,    0       },
+        { "value",      CPU_REG_ALL,    1       },
 };
 
 /* Intel Registers Range */
@@ -608,9 +609,62 @@ static int cpu_seq_open(struct inode *inode, struct file *file)
         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,
 };