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/* -*- linux-c -*-
* Systemtap Memory1 Test Module
* Copyright (C) 2013 Red Hat Inc.
*
* This file is part of systemtap, and is free software. You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/compiler.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
/* The purpose of this module is to provide a kernel string we can
* safely read. We use a /proc file to trigger the function call from
* user context. Then systemtap scripts set probes on the functions
* and run tests to see if the expected output is received. This is
* better than using the kernel because kernel internals frequently
* change. */
static struct proc_dir_entry *stm_ctl = NULL;
static char buffer[100] = "";
void noinline stp_memory1_set_str(const char *string, size_t bytes)
{
asm ("");
memcpy(buffer, string, bytes);
}
char * noinline stp_memory1_get_str(void)
{
asm ("");
return buffer;
}
EXPORT_SYMBOL(stp_memory1_set_str);
EXPORT_SYMBOL(stp_memory1_get_str);
static ssize_t stm_write (struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
char tmp[100];
size_t bytes;
bytes = (count >= sizeof(tmp) - 1) ? sizeof(tmp) - 1 : count;
if (copy_from_user(tmp, buf, bytes))
return -EFAULT;
tmp[bytes] = '\0';
stp_memory1_set_str(tmp, bytes);
return bytes;
}
static ssize_t stm_read(struct file *file, char __user *buffer,
size_t buflen, loff_t *fpos)
{
char *data = stp_memory1_get_str();
size_t bytes = strlen(data);
if (buflen == 0 || *fpos >= bytes)
return 0;
bytes = min(bytes - (size_t)*fpos, buflen);
if (copy_to_user(buffer, data + *fpos, bytes))
return -EFAULT;
*fpos += bytes;
return bytes;
}
static struct file_operations stm_fops_cmd = {
.owner = THIS_MODULE,
.write = stm_write,
.read = stm_read,
};
int init_module(void)
{
stm_ctl = proc_create ("stap_memory1_test", 0666, NULL, &stm_fops_cmd);
if (stm_ctl == NULL)
return -1;
return 0;
}
void cleanup_module(void)
{
if (stm_ctl)
remove_proc_entry ("stap_memory1_test", NULL);
}
MODULE_DESCRIPTION("systemtap memory1 test module");
MODULE_LICENSE("GPL");
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