update

new_device/.Module.symvers.cmd

@@ -0,0 +1 @@
+cmd_/home/kern/project_os/2020260_Assignment04/new_device/Module.symvers := sed 's/\.ko$$/\.o/' /home/kern/project_os/2020260_Assignment04/new_device/modules.order | scripts/mod/modpost  -a  -o /home/kern/project_os/2020260_Assignment04/new_device/Module.symvers -e -i Module.symvers  -N -T -

new_device/.modules.order.cmd

@@ -0,0 +1 @@
+cmd_/home/kern/project_os/2020260_Assignment04/new_device/modules.order := {   echo /home/kern/project_os/2020260_Assignment04/new_device/new_device.ko; :; } | awk '!x[$$0]++' - > /home/kern/project_os/2020260_Assignment04/new_device/modules.order

new_device/.new_device.ko.cmd

@@ -0,0 +1 @@
+cmd_/home/kern/project_os/2020260_Assignment04/new_device/new_device.ko := ld -r -m elf_x86_64 --build-id=sha1  -T scripts/module.lds -o /home/kern/project_os/2020260_Assignment04/new_device/new_device.ko /home/kern/project_os/2020260_Assignment04/new_device/new_device.o /home/kern/project_os/2020260_Assignment04/new_device/new_device.mod.o;  true

new_device/.new_device.mod.cmd

@@ -0,0 +1 @@
+cmd_/home/kern/project_os/2020260_Assignment04/new_device/new_device.mod := { echo  /home/kern/project_os/2020260_Assignment04/new_device/new_device.o;  echo; } > /home/kern/project_os/2020260_Assignment04/new_device/new_device.mod

new_device/Makefile

@@ -0,0 +1,9 @@
+obj-m = new_device.o
+
+KBUILD_CFLAGS += -w
+
+all:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules $(KBUILD_CFLAGS)
+	sudo insmod new_device.ko buffer_size=200
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

new_device/modules.order

@@ -0,0 +1 @@
+/home/kern/project_os/2020260_Assignment04/new_device/new_device.ko

new_device/new_device.c

@@ -0,0 +1,151 @@
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/rtc.h>
+#include <linux/sched.h>
+#include <asm/uaccess.h>
+#include <linux/slab.h>
+#include <linux/semaphore.h>
+#include <linux/init.h>
+#include <linux/miscdevice.h>
+#include <linux/platform_device.h>
+
+
+#define LICENSE "GPL"
+
+MODULE_LICENSE(LICENSE);
+
+static struct miscdevice my_device;
+static struct semaphore full;
+static struct semaphore empty;
+static struct semaphore _read;
+static struct semaphore _write;
+
+static int no_of_open_devices;
+static int buffer_size;
+static int bytes_string = 200;
+static int index_r = 0;
+static int index_w = 0;
+static int buf_clear;
+static struct semaphore full;
+static struct semaphore empty;
+static struct semaphore _read;
+static struct semaphore _write;
+char** buffer;
+
+module_param(buffer_size, int, 0000);
+
+static ssize_t dequeue_data(struct file*, char*, size_t, loff_t*);
+static ssize_t enqueue_data(struct file*, const char*, size_t, loff_t*);
+static int open_device(struct inode*, struct file*);
+static int close_device(struct inode*, struct file*);
+static struct file_operations my_device_fops = {
+	.open = &open_device,
+	.read = &dequeue_data,
+	.write = &enqueue_data,
+	.release = &close_device
+};
+
+int init_module(){
+	my_device.name = "new_device";
+	my_device.fops = &my_device_fops;
+	my_device.minor = MISC_DYNAMIC_MINOR;
+	int res;
+	if((res = misc_register(&my_device))){
+		printk(KERN_ERR "Device new_device cannot be registered\n");
+		return res;
+	}
+	printk(KERN_INFO "New Device Registered:\n");
+	printk(KERN_INFO "device name: new_device\n");
+	printk(KERN_INFO "buffer size: %d\n", buffer_size);
+    sema_init(&_read, 1);
+	sema_init(&_write, 1);
+    sema_init(&full, 0);
+	sema_init(&empty, buffer_size);
+	int data_allocated = 0;
+
+	buffer = (char**)kmalloc(buffer_size * sizeof(char*), GFP_KERNEL);
+
+	while(data_allocated < buffer_size)
+    {
+		buffer[data_allocated] = (char*)kmalloc((bytes_string + 1) * sizeof(char), GFP_KERNEL);
+		buffer[bytes_string] = '\0';
+		++data_allocated;
+	}
+    no_of_open_devices = 0;
+    buf_clear = buffer_size;
+	return 0;
+}
+
+static int open_device(struct inode* _inode, struct file* fp){
+	++no_of_open_devices;
+	return 0;
+}
+static int close_device(struct inode* _inode, struct file* fp){
+    --no_of_open_devices;
+	return 0;
+}
+static ssize_t dequeue_data(struct file* fp, char* user_buffer, size_t char_read_size, loff_t* pos){
+    int i = 0;
+	down_interruptible(&_read);
+	down_interruptible(&full);
+	index_r %= buffer_size;
+	for(i = 0; i < char_read_size; i++){
+		if(buf_clear >= buffer_size){
+			break;
+		}
+		copy_to_user(&user_buffer[i], &buffer[index_r][i], 1);
+	}
+	++buf_clear;
+    ++index_r;
+	up(&empty);
+	up(&_read);
+	return i;
+}
+
+static ssize_t enqueue_data(struct file* fp, const char* user_buffer, size_t char_write_size, loff_t* pos){
+	int i = 0;
+	down_interruptible(&_write);
+	down_interruptible(&empty);
+	index_w %= buffer_size;
+	for(i = 0; i < char_write_size; i++)
+    {
+		if(buf_clear <= 0)
+        {
+			break;
+		}
+		copy_from_user(&buffer[index_w][i], &user_buffer[i], 1);
+	}
+	--buf_clear;
+    ++index_w;
+    // while(1){
+    //     result = syscall(READER_SYSCALL_NO, random_str, BYTE_COUNT);
+    //     //result = read(fd1, random_str, sizeof(random_str));
+    //     if(result < 0){
+    //         perror("syscall");
+
+    //     }
+    //     if(result >= 0){
+    //         printf("%d\n", result);
+    //         printf("******************************************\n\nstring received: %d %s\n\n", cnt,random_str);
+    //         cnt++;
+    //         //memset(random_str, 0, 8);
+
+    //     }
+    //     sleep(2);
+    // }
+	up(&full);
+	up(&_write);
+	return i;
+}
+
+
+void cleanup_module(){
+	int free_space;
+	for(free_space = 0; free_space < buffer_size; free_space++){
+		kfree(buffer[free_space]);
+	}
+	misc_deregister(&my_device);
+	printk(KERN_INFO "Device Unregistered: new_device\n");
+}

new_device/new_device.mod

@@ -0,0 +1,2 @@
+/home/kern/project_os/2020260_Assignment04/new_device/new_device.o
+

new_device/new_device.mod.c

@@ -0,0 +1,31 @@
+#include <linux/module.h>
+#define INCLUDE_VERMAGIC
+#include <linux/build-salt.h>
+#include <linux/elfnote-lto.h>
+#include <linux/vermagic.h>
+#include <linux/compiler.h>
+
+BUILD_SALT;
+BUILD_LTO_INFO;
+
+MODULE_INFO(vermagic, VERMAGIC_STRING);
+MODULE_INFO(name, KBUILD_MODNAME);
+
+__visible struct module __this_module
+__section(".gnu.linkonce.this_module") = {
+	.name = KBUILD_MODNAME,
+	.init = init_module,
+#ifdef CONFIG_MODULE_UNLOAD
+	.exit = cleanup_module,
+#endif
+	.arch = MODULE_ARCH_INIT,
+};
+
+#ifdef CONFIG_RETPOLINE
+MODULE_INFO(retpoline, "Y");
+#endif
+
+MODULE_INFO(depends, "");
+
+
+MODULE_INFO(srcversion, "E7F873D52D59CFDD69475ED");

system calls/systemcall_kernelread

@@ -0,0 +1,28 @@
+SYSCALL_DEFINE2(kernel_device_reader, char __user *, read_buffer, int, len_buffer)
++{	
++	struct file * fp;
++	//mm_segment_t fs;     
++	loff_t pos;  
++	//char buf[8];
++	//int fd = ksys_open("/dev/new_device", O_RDWR);
++	fp = filp_open("/dev/new_device", O_RDWR , 0777);   
++	if (IS_ERR (fp)) {         
++		printk ("file error\n");         
++		return -EFAULT;     
++	}
++	pos = 0;
++	ssize_t result = vfs_read (fp, read_buffer, sizeof (read_buffer), & pos);     
++	//int result = ksys_read(fd, buf, len_buffer);
++	if(result < 0){
++		printk("read error");
++		return -EFAULT;
++	}
++	// long bytes_copied = copy_to_user(read_buffer, buf, len_buffer);
++	// if(bytes_copied < 0){
++	// 	printk("copy to user error");
++	// 	return -EFAULT;
++	// }
++	//ksys_close(fd);
++	filp_close (fp, NULL);     
++	return 0;
++}

system calls/systemcall_kernelwrite

@@ -0,0 +1,32 @@
++SYSCALL_DEFINE2(kernel_device_writer, char __user *, write_buffer, int, len_buffer)
++{
++	//char buf[8];
++	struct file * fp;     
++	//mm_segment_t fs;     
++	loff_t pos;   
++	// int fd = ksys_open("/dev/new_device", O_WRONLY);
++    // if(fd== -1){
++	// 	printk("writer open error");
++	// 	return -EFAULT;
++	// }
++	fp = filp_open("/dev/new_device", O_WRONLY , 0777);   
++	if (IS_ERR (fp)) {         
++		printk ("file error\n");         
++		return -EFAULT;     
++	}
++	// long bytes_copied = strncpy_from_user(buf, write_buffer, len_buffer);
++	// if(bytes_copied < 0){
++	// 	printk("strcpy writer error");
++	// 	return -EFAULT;
++	// }
++	pos = 0;     
++	ssize_t result = vfs_write (fp, write_buffer, sizeof (write_buffer), & pos);     
++	//int result = ksys_write(fd, buf, len_buffer);
++	if(result < 0){
++		printk("write error");
++		return -EFAULT;
++	}
++	//ksys_close(fd);
++	filp_close (fp, NULL);     
++	return 0;
++}

test/Makefile

@@ -0,0 +1,5 @@
+deafult:
+	gcc consumer.c -o c
+	gcc producer.c -o p
+clean:
+	rm c p

test/consumer.c

@@ -0,0 +1,25 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#define BYTE_COUNT 8
+#define READER_SYSCALL_NO 448
+int main(void){
+    char random_str[8];
+    int result = 0;
+    int cnt = 1;
+    while(1){
+        result = syscall(READER_SYSCALL_NO, random_str, BYTE_COUNT);
+        if(result < 0){
+            perror("syscall");
+        }
+        if(result >= 0){
+            printf("******************************************\n\nstring received: %d %s\n\n", cnt,random_str);
+            cnt++;
+        }
+        sleep(2);
+    }
+    return 0;
+}
+//buffer_size=20

test/producer.c

@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#define BYTE_COUNT 8
+#define WRITER_SYSCALL_NO 449
+int main(void){
+    int cnt = 1;
+    int fd = open("/dev/urandom", O_RDONLY);
+    if(fd== -1){
+        perror("open");
+        exit(1);
+    }
+    char random_str[8];
+    while(1){
+        ssize_t res = read(fd, random_str, 8);
+        if(res < 0){
+            perror("read");
+            exit(1);    
+        }
+        int result = syscall(WRITER_SYSCALL_NO, random_str, BYTE_COUNT);
+        if(result < 0){
+            perror("syscall");
+            exit(1);
+        }
+        if(result >= 0){
+            printf("******************************************\n\nstring sent:%d %s\n\n", cnt,random_str);
+            cnt++;
+        }
+        sleep(2);
+    }
+    close(fd);
+    return 0;
+}