04 basic struct

04_basic_struct/Log_struct.txt

@@ -0,0 +1,29 @@
+# insmod struct4.ko
+struct4: loading out-of-tree module taints kernel.
+struct4: module load
+# echo '1' > /sys/kernel/hello/list
+struct4: adding report size: 2 to the list: '1
+'
+# echo -n "2" > /sys/kernel/hello/list
+struct4: adding report size: 1 to the list: '2'
+# echo -n "45" > /sys/kernel/hello/list
+struct4: adding report size: 2 to the list: '45'
+# echo -n "27" > /sys/kernel/hello/list
+struct4: adding report size: 2 to the list: '27'
+# cat /sys/kernel/hello/list
+struct4: report #0 size: 2 '1
+'
+struct4: report #1 size: 1 '2'
+struct4: report #2 size: 2 '45'
+struct4: report #3 size: 2 '27'
+1
+24527# 
+# 
+# rmmod struct4.ko
+struct4: freeing log size: 2 from the list: '27'
+struct4: freeing log size: 2 from the list: '45'
+struct4: freeing log size: 1 from the list: '2'
+struct4: freeing log size: 2 from the list: '1
+'
+struct4: list is empty: 1
+struct4: module exited

04_basic_struct/Makefile

@@ -0,0 +1,10 @@
+KERNELDIR ?= ../output/build/linux-5.10.7/ #WARNING relative path
+
+obj-m := struct4.o
+
+
+all: 
+	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
+
+clean:
+	$(MAKE) -C $(KERNELDIR) M=$(PWD) clean

04_basic_struct/struct4.c

@@ -0,0 +1,116 @@
+#define pr_fmt(fmt) "%s: " fmt,  KBUILD_MODNAME
+
+#include <linux/module.h> // Core header for loading LKMs into the kernel
+#include <linux/kobject.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+
+struct m_item {
+        struct list_head list;
+        char *m;
+        size_t m_len;
+};
+static LIST_HEAD(m_list_head);
+
+static ssize_t hello_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+    struct m_item *pos = NULL;
+    size_t item_number = 0;
+    size_t count = 0;
+    char *p_buff = buf;
+
+    list_for_each_entry_reverse(pos, &m_list_head, list) 
+    {
+        pr_info("report #%lu size: %lu '%.*s'\n",
+            item_number, pos->m_len, (int)pos->m_len, (char *)pos->m);
+
+        memcpy(p_buff, (char *)pos->m, pos->m_len);
+        p_buff += pos->m_len;
+        count += pos->m_len;
+        item_number += 1;
+    }
+    return count;
+}
+
+static ssize_t hello_store(struct kobject *kobj, struct kobj_attribute *attr,
+	const char *buf, size_t count)
+{
+    char *p_msg = NULL;
+    struct m_item *p_item = NULL;
+
+    p_msg = kmalloc(count, GFP_KERNEL);
+    if (!p_msg) 
+    {
+        pr_err("could not allocate report: %lu\n", count);
+        return -ENOMEM;
+    }
+    p_item = kmalloc(sizeof(struct m_item), GFP_KERNEL);
+    if (!p_item) 
+    {
+        pr_err("could not allocate m_item\n");
+        return -ENOMEM;
+    }
+    memcpy(p_msg, buf, count);
+    p_item->m = p_msg;
+    p_item->m_len = count;
+
+    pr_info("adding report size: %lu to the list: '%.*s'\n",
+            p_item->m_len, (int)p_item->m_len, (char *)p_item->m);
+    list_add(&p_item->list, &m_list_head);  
+    return count;
+}
+
+static struct kobj_attribute list_attribute =
+	__ATTR(list, 0664, hello_show, hello_store);
+
+static struct kobject *hello_kobj;
+
+
+static int hello_init(void)
+{
+	int res = 0;
+
+    pr_info("module load\n");
+
+	hello_kobj = kobject_create_and_add("hello", kernel_kobj);
+
+	if (!hello_kobj)
+		return -ENOMEM;
+	res = sysfs_create_file(hello_kobj, &list_attribute.attr);
+
+	if (res)
+		kobject_put(hello_kobj);
+	return res;
+}
+
+static void hello_exit(void)
+{
+	struct list_head *pos = NULL;
+    struct list_head *n = NULL;
+    struct m_item *p_item = NULL;
+
+    list_for_each_safe(pos, n, &m_list_head) 
+    {
+        p_item = list_entry(pos, struct m_item, list);
+        pr_info("freeing log size: %lu from the list: '%.*s'\n",
+                 p_item->m_len, (int)p_item->m_len, (char *)p_item->m);
+        list_del(pos);
+        kfree(p_item->m);
+        kfree(p_item);
+    }
+    pr_info("list is empty: %d\n", list_empty_careful(&m_list_head));
+    kobject_put(hello_kobj);
+	pr_info("module exited\n");
+}
+
+module_init(hello_init);
+module_exit(hello_exit);
+
+MODULE_AUTHOR("Serhii Siedin <serhii.siedin@globallogic.com>");
+MODULE_DESCRIPTION("Basic data structures module Homework");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("0.1");