cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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record-example.c (4089B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Sample dynamic sized record fifo implementation
      4 *
      5 * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
      6 */
      7
      8#include <linux/init.h>
      9#include <linux/module.h>
     10#include <linux/proc_fs.h>
     11#include <linux/mutex.h>
     12#include <linux/kfifo.h>
     13
     14/*
     15 * This module shows how to create a variable sized record fifo.
     16 */
     17
     18/* fifo size in elements (bytes) */
     19#define FIFO_SIZE	128
     20
     21/* name of the proc entry */
     22#define	PROC_FIFO	"record-fifo"
     23
     24/* lock for procfs read access */
     25static DEFINE_MUTEX(read_access);
     26
     27/* lock for procfs write access */
     28static DEFINE_MUTEX(write_access);
     29
     30/*
     31 * define DYNAMIC in this example for a dynamically allocated fifo.
     32 *
     33 * Otherwise the fifo storage will be a part of the fifo structure.
     34 */
     35#if 0
     36#define DYNAMIC
     37#endif
     38
     39/*
     40 * struct kfifo_rec_ptr_1 and  STRUCT_KFIFO_REC_1 can handle records of a
     41 * length between 0 and 255 bytes.
     42 *
     43 * struct kfifo_rec_ptr_2 and  STRUCT_KFIFO_REC_2 can handle records of a
     44 * length between 0 and 65535 bytes.
     45 */
     46
     47#ifdef DYNAMIC
     48struct kfifo_rec_ptr_1 test;
     49
     50#else
     51typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
     52
     53static mytest test;
     54#endif
     55
     56static const char *expected_result[] = {
     57	"a",
     58	"bb",
     59	"ccc",
     60	"dddd",
     61	"eeeee",
     62	"ffffff",
     63	"ggggggg",
     64	"hhhhhhhh",
     65	"iiiiiiiii",
     66	"jjjjjjjjjj",
     67};
     68
     69static int __init testfunc(void)
     70{
     71	char		buf[100];
     72	unsigned int	i;
     73	unsigned int	ret;
     74	struct { unsigned char buf[6]; } hello = { "hello" };
     75
     76	printk(KERN_INFO "record fifo test start\n");
     77
     78	kfifo_in(&test, &hello, sizeof(hello));
     79
     80	/* show the size of the next record in the fifo */
     81	printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test));
     82
     83	/* put in variable length data */
     84	for (i = 0; i < 10; i++) {
     85		memset(buf, 'a' + i, i + 1);
     86		kfifo_in(&test, buf, i + 1);
     87	}
     88
     89	/* skip first element of the fifo */
     90	printk(KERN_INFO "skip 1st element\n");
     91	kfifo_skip(&test);
     92
     93	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
     94
     95	/* show the first record without removing from the fifo */
     96	ret = kfifo_out_peek(&test, buf, sizeof(buf));
     97	if (ret)
     98		printk(KERN_INFO "%.*s\n", ret, buf);
     99
    100	/* check the correctness of all values in the fifo */
    101	i = 0;
    102	while (!kfifo_is_empty(&test)) {
    103		ret = kfifo_out(&test, buf, sizeof(buf));
    104		buf[ret] = '\0';
    105		printk(KERN_INFO "item = %.*s\n", ret, buf);
    106		if (strcmp(buf, expected_result[i++])) {
    107			printk(KERN_WARNING "value mismatch: test failed\n");
    108			return -EIO;
    109		}
    110	}
    111	if (i != ARRAY_SIZE(expected_result)) {
    112		printk(KERN_WARNING "size mismatch: test failed\n");
    113		return -EIO;
    114	}
    115	printk(KERN_INFO "test passed\n");
    116
    117	return 0;
    118}
    119
    120static ssize_t fifo_write(struct file *file, const char __user *buf,
    121						size_t count, loff_t *ppos)
    122{
    123	int ret;
    124	unsigned int copied;
    125
    126	if (mutex_lock_interruptible(&write_access))
    127		return -ERESTARTSYS;
    128
    129	ret = kfifo_from_user(&test, buf, count, &copied);
    130
    131	mutex_unlock(&write_access);
    132	if (ret)
    133		return ret;
    134
    135	return copied;
    136}
    137
    138static ssize_t fifo_read(struct file *file, char __user *buf,
    139						size_t count, loff_t *ppos)
    140{
    141	int ret;
    142	unsigned int copied;
    143
    144	if (mutex_lock_interruptible(&read_access))
    145		return -ERESTARTSYS;
    146
    147	ret = kfifo_to_user(&test, buf, count, &copied);
    148
    149	mutex_unlock(&read_access);
    150	if (ret)
    151		return ret;
    152
    153	return copied;
    154}
    155
    156static const struct proc_ops fifo_proc_ops = {
    157	.proc_read	= fifo_read,
    158	.proc_write	= fifo_write,
    159	.proc_lseek	= noop_llseek,
    160};
    161
    162static int __init example_init(void)
    163{
    164#ifdef DYNAMIC
    165	int ret;
    166
    167	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
    168	if (ret) {
    169		printk(KERN_ERR "error kfifo_alloc\n");
    170		return ret;
    171	}
    172#else
    173	INIT_KFIFO(test);
    174#endif
    175	if (testfunc() < 0) {
    176#ifdef DYNAMIC
    177		kfifo_free(&test);
    178#endif
    179		return -EIO;
    180	}
    181
    182	if (proc_create(PROC_FIFO, 0, NULL, &fifo_proc_ops) == NULL) {
    183#ifdef DYNAMIC
    184		kfifo_free(&test);
    185#endif
    186		return -ENOMEM;
    187	}
    188	return 0;
    189}
    190
    191static void __exit example_exit(void)
    192{
    193	remove_proc_entry(PROC_FIFO, NULL);
    194#ifdef DYNAMIC
    195	kfifo_free(&test);
    196#endif
    197}
    198
    199module_init(example_init);
    200module_exit(example_exit);
    201MODULE_LICENSE("GPL");
    202MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");