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linux/fs/debugfs/file.c
Robin Getz e4792aa30f debugfs: use specified mode to possibly mark files read/write only 
In many SoC implementations there are hardware registers can be read or
write only.  This extends the debugfs to enforce the file permissions for
these types of registers by providing a set of fops which are read or
write only.  This assumes that the kernel developer knows more about the
hardware than the user (even root users) -- which is normally true.

Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2009-06-15 21:30:28 -07:00

514 lines
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/*
* file.c - part of debugfs, a tiny little debug file system
*
* Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
* Copyright (C) 2004 IBM Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* debugfs is for people to use instead of /proc or /sys.
* See Documentation/DocBook/filesystems for more details.
*
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/namei.h>
#include <linux/debugfs.h>
static ssize_t default_read_file(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
return 0;
}
static ssize_t default_write_file(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
return count;
}
static int default_open(struct inode *inode, struct file *file)
{
if (inode->i_private)
file->private_data = inode->i_private;
return 0;
}
const struct file_operations debugfs_file_operations = {
.read = default_read_file,
.write = default_write_file,
.open = default_open,
};
static void *debugfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
nd_set_link(nd, dentry->d_inode->i_private);
return NULL;
}
const struct inode_operations debugfs_link_operations = {
.readlink = generic_readlink,
.follow_link = debugfs_follow_link,
};
static int debugfs_u8_set(void *data, u64 val)
{
*(u8 *)data = val;
return 0;
}
static int debugfs_u8_get(void *data, u64 *val)
{
*val = *(u8 *)data;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u8_ro, debugfs_u8_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u8_wo, NULL, debugfs_u8_set, "%llu\n");
/**
* debugfs_create_u8 - create a debugfs file that is used to read and write an unsigned 8-bit value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*
* This function creates a file in debugfs with the given name that
* contains the value of the variable @value. If the @mode variable is so
* set, it can be read from, and written to.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_u8(const char *name, mode_t mode,
struct dentry *parent, u8 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u8_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u8_wo);
return debugfs_create_file(name, mode, parent, value, &fops_u8);
}
EXPORT_SYMBOL_GPL(debugfs_create_u8);
static int debugfs_u16_set(void *data, u64 val)
{
*(u16 *)data = val;
return 0;
}
static int debugfs_u16_get(void *data, u64 *val)
{
*val = *(u16 *)data;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u16_ro, debugfs_u16_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u16_wo, NULL, debugfs_u16_set, "%llu\n");
/**
* debugfs_create_u16 - create a debugfs file that is used to read and write an unsigned 16-bit value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*
* This function creates a file in debugfs with the given name that
* contains the value of the variable @value. If the @mode variable is so
* set, it can be read from, and written to.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_u16(const char *name, mode_t mode,
struct dentry *parent, u16 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u16_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u16_wo);
return debugfs_create_file(name, mode, parent, value, &fops_u16);
}
EXPORT_SYMBOL_GPL(debugfs_create_u16);
static int debugfs_u32_set(void *data, u64 val)
{
*(u32 *)data = val;
return 0;
}
static int debugfs_u32_get(void *data, u64 *val)
{
*val = *(u32 *)data;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u32_ro, debugfs_u32_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u32_wo, NULL, debugfs_u32_set, "%llu\n");
/**
* debugfs_create_u32 - create a debugfs file that is used to read and write an unsigned 32-bit value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*
* This function creates a file in debugfs with the given name that
* contains the value of the variable @value. If the @mode variable is so
* set, it can be read from, and written to.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_u32(const char *name, mode_t mode,
struct dentry *parent, u32 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u32_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u32_wo);
return debugfs_create_file(name, mode, parent, value, &fops_u32);
}
EXPORT_SYMBOL_GPL(debugfs_create_u32);
static int debugfs_u64_set(void *data, u64 val)
{
*(u64 *)data = val;
return 0;
}
static int debugfs_u64_get(void *data, u64 *val)
{
*val = *(u64 *)data;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u64, debugfs_u64_get, debugfs_u64_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u64_ro, debugfs_u64_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u64_wo, NULL, debugfs_u64_set, "%llu\n");
/**
* debugfs_create_u64 - create a debugfs file that is used to read and write an unsigned 64-bit value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*
* This function creates a file in debugfs with the given name that
* contains the value of the variable @value. If the @mode variable is so
* set, it can be read from, and written to.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_u64(const char *name, mode_t mode,
struct dentry *parent, u64 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u64_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u64_wo);
return debugfs_create_file(name, mode, parent, value, &fops_u64);
}
EXPORT_SYMBOL_GPL(debugfs_create_u64);
DEFINE_SIMPLE_ATTRIBUTE(fops_x8, debugfs_u8_get, debugfs_u8_set, "0x%02llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x8_ro, debugfs_u8_get, NULL, "0x%02llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x8_wo, NULL, debugfs_u8_set, "0x%02llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x16, debugfs_u16_get, debugfs_u16_set, "0x%04llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x16_ro, debugfs_u16_get, NULL, "0x%04llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x16_wo, NULL, debugfs_u16_set, "0x%04llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x32, debugfs_u32_get, debugfs_u32_set, "0x%08llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x32_ro, debugfs_u32_get, NULL, "0x%08llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x32_wo, NULL, debugfs_u32_set, "0x%08llx\n");
/*
* debugfs_create_x{8,16,32} - create a debugfs file that is used to read and write an unsigned {8,16,32}-bit value
*
* These functions are exactly the same as the above functions (but use a hex
* output for the decimal challenged). For details look at the above unsigned
* decimal functions.
*/
/**
* debugfs_create_x8 - create a debugfs file that is used to read and write an unsigned 8-bit value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*/
struct dentry *debugfs_create_x8(const char *name, mode_t mode,
struct dentry *parent, u8 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x8_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x8_wo);
return debugfs_create_file(name, mode, parent, value, &fops_x8);
}
EXPORT_SYMBOL_GPL(debugfs_create_x8);
/**
* debugfs_create_x16 - create a debugfs file that is used to read and write an unsigned 16-bit value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*/
struct dentry *debugfs_create_x16(const char *name, mode_t mode,
struct dentry *parent, u16 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x16_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x16_wo);
return debugfs_create_file(name, mode, parent, value, &fops_x16);
}
EXPORT_SYMBOL_GPL(debugfs_create_x16);
/**
* debugfs_create_x32 - create a debugfs file that is used to read and write an unsigned 32-bit value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*/
struct dentry *debugfs_create_x32(const char *name, mode_t mode,
struct dentry *parent, u32 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x32_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x32_wo);
return debugfs_create_file(name, mode, parent, value, &fops_x32);
}
EXPORT_SYMBOL_GPL(debugfs_create_x32);
static int debugfs_size_t_set(void *data, u64 val)
{
*(size_t *)data = val;
return 0;
}
static int debugfs_size_t_get(void *data, u64 *val)
{
*val = *(size_t *)data;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_size_t, debugfs_size_t_get, debugfs_size_t_set,
"%llu\n"); /* %llu and %zu are more or less the same */
/**
* debugfs_create_size_t - create a debugfs file that is used to read and write an size_t value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*/
struct dentry *debugfs_create_size_t(const char *name, mode_t mode,
struct dentry *parent, size_t *value)
{
return debugfs_create_file(name, mode, parent, value, &fops_size_t);
}
EXPORT_SYMBOL_GPL(debugfs_create_size_t);
static ssize_t read_file_bool(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
char buf[3];
u32 *val = file->private_data;
if (*val)
buf[0] = 'Y';
else
buf[0] = 'N';
buf[1] = '\n';
buf[2] = 0x00;
return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
}
static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
size_t count, loff_t *ppos)
{
char buf[32];
int buf_size;
u32 *val = file->private_data;
buf_size = min(count, (sizeof(buf)-1));
if (copy_from_user(buf, user_buf, buf_size))
return -EFAULT;
switch (buf[0]) {
case 'y':
case 'Y':
case '1':
*val = 1;
break;
case 'n':
case 'N':
case '0':
*val = 0;
break;
}
return count;
}
static const struct file_operations fops_bool = {
.read = read_file_bool,
.write = write_file_bool,
.open = default_open,
};
/**
* debugfs_create_bool - create a debugfs file that is used to read and write a boolean value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*
* This function creates a file in debugfs with the given name that
* contains the value of the variable @value. If the @mode variable is so
* set, it can be read from, and written to.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_bool(const char *name, mode_t mode,
struct dentry *parent, u32 *value)
{
return debugfs_create_file(name, mode, parent, value, &fops_bool);
}
EXPORT_SYMBOL_GPL(debugfs_create_bool);
static ssize_t read_file_blob(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
struct debugfs_blob_wrapper *blob = file->private_data;
return simple_read_from_buffer(user_buf, count, ppos, blob->data,
blob->size);
}
static const struct file_operations fops_blob = {
.read = read_file_blob,
.open = default_open,
};
/**
* debugfs_create_blob - create a debugfs file that is used to read a binary blob
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer
* to the blob data and the size of the data.
*
* This function creates a file in debugfs with the given name that exports
* @blob->data as a binary blob. If the @mode variable is so set it can be
* read from. Writing is not supported.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_blob(const char *name, mode_t mode,
struct dentry *parent,
struct debugfs_blob_wrapper *blob)
{
return debugfs_create_file(name, mode, parent, blob, &fops_blob);
}
EXPORT_SYMBOL_GPL(debugfs_create_blob);
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