Re: [git-pull -tip] x86: cpu_debug support read-write opertaions for PMC

[Jaswinder Singh Rajput <jaswinder@kernel.org>]

On Thu, 2009-03-12 at 03:04 +0530, Jaswinder Singh Rajput wrote:
> Currently I added read-write operations for PMC MSRs for cpu_debug:

Now I made generic write support by adding write flag for registers.
currently write is enabled only for PMC MSR but we can also support
another MSRs just changing the write flag.

So here is new pull request:

The following changes since commit 8851485ba842e892adfa343463ce6b74550bb8b1:
  Ingo Molnar (1):
        Merge branch 'x86/urgent'

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/jaswinder/linux-2.6-cpu.git master

Jaswinder Singh Rajput (1):
      x86: cpu_debug add write support for MSRs

 arch/x86/include/asm/cpu_debug.h |   12 ++--
 arch/x86/kernel/cpu/cpu_debug.c  |  117 +++++++++++++++++++++++++++----------
 2 files changed, 92 insertions(+), 37 deletions(-)
Complete diff:
diff --git a/arch/x86/include/asm/cpu_debug.h b/arch/x86/include/asm/cpu_debug.h
index d24d64f..146d9e0 100755
--- a/arch/x86/include/asm/cpu_debug.h
+++ b/arch/x86/include/asm/cpu_debug.h
@@ -171,16 +171,18 @@ struct cpu_private {
 struct cpu_debug_base {
 	char			*name;		/* Register name	*/
 	unsigned		flag;		/* Register flag	*/
-};
-
-struct cpu_cpuX_base {
-	struct dentry		*dentry;	/* Register dentry	*/
-	int			init;		/* Register index file	*/
+	unsigned		write;		/* Register write flag	*/
 };
 
 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 9abbcbd..bb6e5b7 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 +609,61 @@ static int cpu_seq_open(struct inode *inode, struct file *file)
 	return err;
 }
 
+static int write_msr(struct cpu_private *priv, const char *buf)
+{
+	u32 low, high;
+	int ret;
+	u64 val;
+
+	ret = strict_strtoull(buf, 0, &val);
+	if (ret < 0)
+		return ret;
+
+	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)
+{
+	/* Supporting only MSRs */
+	if (priv->type < CPU_TSS_BIT)
+		return write_msr(priv, buf);
+
+	return -EPERM;
+}
+
+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,
 };