Commit 91219bcb authored by Jaswinder Singh Rajput's avatar Jaswinder Singh Rajput Committed by Ingo Molnar

x86: cpu_debug add write support for MSRs

Supported write flag for registers.
currently write is enabled only for PMC MSR.

[root@ht]# cat /sys/kernel/debug/x86/cpu/cpu1/pmc/0x300/value
0x0

[root@ht]# echo 1234 > /sys/kernel/debug/x86/cpu/cpu1/pmc/0x300/value
[root@ht]# cat /sys/kernel/debug/x86/cpu/cpu1/pmc/0x300/value
0x4d2

[root@ht]# echo 0x1234 > /sys/kernel/debug/x86/cpu/cpu1/pmc/0x300/value
[root@ht]# cat /sys/kernel/debug/x86/cpu/cpu1/pmc/0x300/value
0x1234
Signed-off-by: default avatarJaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 02dde8b4
......@@ -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 {
......
......@@ -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,
};
......
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