Beispiele und Screenshots 4.4.2022

20220321/Operating_system_placement-de.pdf

+../common/Operating_system_placement-de.pdf
\ No newline at end of file

20220404/Makefile

+Makefile-modules-1
\ No newline at end of file

20220404/Makefile-1

+philosophy: philosophy.o answer.o
+	gcc philosophy.o answer.o -o philosophy
+
+answer.o: answer.c answer.h
+	gcc -Wall -O answer.c -c
+
+philosophy.o: philosophy.c answer.h
+	gcc -Wall -O philosophy.c -c

20220404/Makefile-2

+TARGET = philosophy
+OBJECTS = philosophy.o answer.o
+HEADERS = answer.h
+CFLAGS = -Wall -O
+
+$(TARGET): $(OBJECTS)
+	gcc $(OBJECTS) -o $(TARGET)
+
+answer.o: answer.c $(HEADERS)
+	gcc $(CFLAGS) answer.c -c
+
+philosophy.o: philosophy.c $(HEADERS)
+	gcc $(CFLAGS) philosophy.c -c
+
+clean:
+	rm -f $(OBJECTS) $(TARGET)

20220404/Makefile-3

+TARGET = philosophy
+OBJECTS = philosophy.o answer.o
+HEADERS = answer.h
+CFLAGS = -Wall -O
+
+$(TARGET): $(OBJECTS)
+	gcc $(OBJECTS) -o $(TARGET)
+
+%.o: %.c $(HEADERS)
+	gcc $(CFLAGS) $< -c
+
+clean:
+	rm -f $(OBJECTS) $(TARGET)

20220404/Makefile-modules-1

+obj-m += hellomod-1.o
+obj-m += hellomod-2.o
+obj-m += chardev-1.o
+
+all:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

20220404/answer.c

+#include "answer.h"
+
+int answer (void)
+{
+  return ANSWER;
+}

20220404/answer.h

+extern int answer (void);
+
+#define ANSWER 42

20220404/chardev-1.c

+/*
+ *  chardev.c: Creates a read-only char device that says how many times
+ *  you've read from the dev file
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <asm/uaccess.h>	/* for put_user */
+
+/*  
+ *  Prototypes - this would normally go in a .h file
+ */
+int init_module(void);
+void cleanup_module(void);
+static int device_open(struct inode *, struct file *);
+static int device_release(struct inode *, struct file *);
+static ssize_t device_read(struct file *, char *, size_t, loff_t *);
+static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
+
+#define SUCCESS 0
+#define DEVICE_NAME "chardev"	/* Dev name as it appears in /proc/devices   */
+#define BUF_LEN 80		/* Max length of the message from the device */
+
+/* 
+ * Global variables are declared as static, so are global within the file. 
+ */
+
+static int Major;		/* Major number assigned to our device driver */
+static int Device_Open = 0;	/* Is device open?  
+				 * Used to prevent multiple access to device */
+static char msg[BUF_LEN];	/* The msg the device will give when asked */
+static char *msg_Ptr;
+
+static struct file_operations fops = {
+	.read = device_read,
+	.write = device_write,
+	.open = device_open,
+	.release = device_release
+};
+
+/*
+ * This function is called when the module is loaded
+ */
+int init_module(void)
+{
+        Major = register_chrdev(0, DEVICE_NAME, &fops);
+
+	if (Major < 0) {
+	  printk(KERN_ALERT "Registering char device failed with %d\n", Major);
+	  return Major;
+	}
+
+	printk(KERN_INFO "I was assigned major number %d. To talk to\n", Major);
+	printk(KERN_INFO "the driver, create a dev file with\n");
+	printk(KERN_INFO "'mknod /dev/%s c %d 0'.\n", DEVICE_NAME, Major);
+	printk(KERN_INFO "Try various minor numbers. Try to cat and echo to\n");
+	printk(KERN_INFO "the device file.\n");
+	printk(KERN_INFO "Remove the device file and module when done.\n");
+
+	return SUCCESS;
+}
+
+/*
+ * This function is called when the module is unloaded
+ */
+void cleanup_module(void)
+{
+	/* 
+	 * Unregister the device 
+	 */
+	unregister_chrdev(Major, DEVICE_NAME);
+}
+
+/*
+ * Methods
+ */
+
+/* 
+ * Called when a process tries to open the device file, like
+ * "cat /dev/mycharfile"
+ */
+static int device_open(struct inode *inode, struct file *file)
+{
+	static int counter = 0;
+
+	if (Device_Open)
+		return -EBUSY;
+
+	Device_Open++;
+	sprintf(msg, "I already told you %d times Hello world!\n", counter++);
+	msg_Ptr = msg;
+	try_module_get(THIS_MODULE);
+
+	return SUCCESS;
+}
+
+/* 
+ * Called when a process closes the device file.
+ */
+static int device_release(struct inode *inode, struct file *file)
+{
+	Device_Open--;		/* We're now ready for our next caller */
+
+	/* 
+	 * Decrement the usage count, or else once you opened the file, you'll
+	 * never get get rid of the module. 
+	 */
+	module_put(THIS_MODULE);
+
+	return 0;
+}
+
+/* 
+ * Called when a process, which already opened the dev file, attempts to
+ * read from it.
+ */
+static ssize_t device_read(struct file *filp,	/* see include/linux/fs.h   */
+			   char *buffer,	/* buffer to fill with data */
+			   size_t length,	/* length of the buffer     */
+			   loff_t * offset)
+{
+	/*
+	 * Number of bytes actually written to the buffer 
+	 */
+	int bytes_read = 0;
+
+	/*
+	 * If we're at the end of the message, 
+	 * return 0 signifying end of file 
+	 */
+	if (*msg_Ptr == 0)
+		return 0;
+
+	/* 
+	 * Actually put the data into the buffer 
+	 */
+	while (length && *msg_Ptr) {
+
+		/* 
+		 * The buffer is in the user data segment, not the kernel 
+		 * segment so "*" assignment won't work.  We have to use 
+		 * put_user which copies data from the kernel data segment to
+		 * the user data segment. 
+		 */
+		put_user(*(msg_Ptr++), buffer++);
+
+		length--;
+		bytes_read++;
+	}
+
+	/* 
+	 * Most read functions return the number of bytes put into the buffer
+	 */
+	return bytes_read;
+}
+
+/*  
+ * Called when a process writes to dev file: echo "hi" > /dev/hello 
+ */
+static ssize_t
+device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
+{
+	printk(KERN_ALERT "Sorry, this operation isn't supported.\n");
+	return -EINVAL;
+}

20220404/hellomod-1.c

+/*  
+ *  hello-1.c - The simplest kernel module.
+ */
+#include <linux/module.h>	/* Needed by all modules */
+#include <linux/kernel.h>	/* Needed for KERN_INFO */
+
+int init_module(void)
+{
+	printk(KERN_INFO "Hello world 1.\n");
+
+	/* 
+	 * A non 0 return means init_module failed; module can't be loaded. 
+	 */
+	return 0;
+}
+
+void cleanup_module(void)
+{
+	printk(KERN_INFO "Goodbye world 1.\n");
+}

20220404/hellomod-2.c

+/*  
+ *  hello-2.c - The simplest kernel module.
+ */
+#include <linux/module.h>	/* Needed by all modules */
+#include <linux/kernel.h>	/* Needed for KERN_INFO */
+
+MODULE_LICENSE("GPL");
+
+int init_module(void)
+{
+	printk(KERN_INFO "Hello world 2.\n");
+
+	/* 
+	 * A non 0 return means init_module failed; module can't be loaded. 
+	 */
+	return 0;
+}
+
+void cleanup_module(void)
+{
+	printk(KERN_INFO "Goodbye world 2.\n");
+}

20220404/make-1.txt

+cassini/home/peter/bo/2022ss/bs/20220404> cat philosophy.c
+#include <stdio.h>
+#include "answer.h"
+
+int main (void)
+{
+  printf ("The answer is %d.\n", answer ());
+  return 0;
+}
+cassini/home/peter/bo/2022ss/bs/20220404> cat answer.h
+extern int answer (void);
+
+#define ANSWER 42
+cassini/home/peter/bo/2022ss/bs/20220404> cat answer.c
+#include "answer.h"
+
+int answer (void)
+{
+  return ANSWER;
+}
+cassini/home/peter/bo/2022ss/bs/20220404> gcc -Wall -O philosophy.c -o philosophy
+/usr/bin/ld: /tmp/ccjJ8ZhE.o: in function `main':
+philosophy.c:(.text+0x5): undefined reference to `answer'
+collect2: error: ld returned 1 exit status
+cassini/home/peter/bo/2022ss/bs/20220404> gcc -Wall -O philosophy.c answer.c -o philosophy
+Sie haben neue Post in /var/mail/peter.
+cassini/home/peter/bo/2022ss/bs/20220404> ./philosophy
+The answer is 42.
+cassini/home/peter/bo/2022ss/bs/20220404> gcc -Wall -O philosophy.c -c
+cassini/home/peter/bo/2022ss/bs/20220404> gcc -Wall -O answer.c -c
+cassini/home/peter/bo/2022ss/bs/20220404> ls -l philosophy.[co] answer.[co]
+-rw-r--r-- 1 peter peter   60 Dez 13 13:46 answer.c
+-rw-r--r-- 1 peter peter 1208 Apr  4 13:57 answer.o
+-rw-r--r-- 1 peter peter  117 Jan  4  2021 philosophy.c
+-rw-r--r-- 1 peter peter 1632 Apr  4 13:57 philosophy.o
+cassini/home/peter/bo/2022ss/bs/20220404> gcc philosophy.o answer.o -o philosophy
+cassini/home/peter/bo/2022ss/bs/20220404> ./philosophy
+The answer is 42.
+cassini/home/peter/bo/2022ss/bs/20220404> gcc philosophy.o -o philosophy
+/usr/bin/ld: philosophy.o: in function `main':
+philosophy.c:(.text+0x5): undefined reference to `answer'
+collect2: error: ld returned 1 exit status
+cassini/home/peter/bo/2022ss/bs/20220404> cat Makefile-1
+philosophy: philosophy.o answer.o
+        gcc philosophy.o answer.o -o philosophy
+
+answer.o: answer.c answer.h
+        gcc -Wall -O answer.c -c
+
+philosophy.o: philosophy.c answer.h
+        gcc -Wall -O philosophy.c -c
+cassini/home/peter/bo/2022ss/bs/20220404> make
+make: *** Es wurden keine Ziele angegeben und keine „make“-Steuerdatei gefunden.  Schluss.
+cassini/home/peter/bo/2022ss/bs/20220404> make -f Makefile-1
+gcc philosophy.o answer.o -o philosophy
+cassini/home/peter/bo/2022ss/bs/20220404> rm *.o
+cassini/home/peter/bo/2022ss/bs/20220404> make -f Makefile-1
+gcc -Wall -O philosophy.c -c
+gcc -Wall -O answer.c -c
+gcc philosophy.o answer.o -o philosophy

20220404/make-2.txt

+/*
+ *  hello-1.c - The simplest kernel module.
+ */
+#include <linux/module.h>       /* Needed by all modules */
+#include <linux/kernel.h>       /* Needed for KERN_INFO */
+
+int init_module(void)
+{
+        printk(KERN_INFO "Hello world 1.\n");
+
+        /*
+         * A non 0 return means init_module failed; module can't be loaded.
+         */
+        return 0;
+}
+
+void cleanup_module(void)
+{
+        printk(KERN_INFO "Goodbye world 1.\n");
+}
+cassini/home/peter/bo/2022ss/bs/20220404> cat Makefile-modules-1
+obj-m += hellomod-1.o
+
+# obj-m += hellomod-2.o
+# obj-m += chardev-1.o
+
+all:
+        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
+cassini/home/peter/bo/2022ss/bs/20220404> ln -sf Makefile-modules-1 Makefile
+cassini/home/peter/bo/2022ss/bs/20220404> echo /lib/modules/$(shell uname -r)/build
+bash: shell: Kommando nicht gefunden.
+/lib/modules//build
+cassini/home/peter/bo/2022ss/bs/20220404> echo /lib/modules/$(uname -r)/build
+/lib/modules/4.19.0-12-amd64/build
+cassini/home/peter/bo/2022ss/bs/20220404> ls /lib/modules/4.19.0-12-amd64/build
+arch  include  Makefile  Module.symvers  scripts  tools
+cassini/home/peter/bo/2022ss/bs/20220404> uname
+Linux
+cassini/home/peter/bo/2022ss/bs/20220404> uname -r
+4.19.0-12-amd64
+cassini/home/peter/bo/2022ss/bs/20220404> pwd
+/home/peter/bo/2022ss/bs/20220404

20220404/modules-1.txt

+-rw-r--r-- 1 peter peter  270648 Apr  4 14:19  hellomod-1.ko
+cassini/home/peter/bo/2022ss/bs/20220404> ./hellomod-1.ko
+bash: ./hellomod-1.ko: Keine Berechtigung
+cassini/home/peter/bo/2022ss/bs/20220404> chmod +x hellomod-1.ko
+cassini/home/peter/bo/2022ss/bs/20220404> ./hellomod-1.ko
+bash: ./hellomod-1.ko: Kann die Binärdatei nicht ausführen: Fehler im Format der Programmdatei
+cassini/home/peter/bo/2022ss/bs/20220404> chmod -x hellomod-1.ko
+cassini/home/peter/bo/2022ss/bs/20220404> insmod hellomod-1.ko
+bash: insmod: Kommando nicht gefunden.
+cassini/home/peter/bo/2022ss/bs/20220404> sudo insmod hellomod-1.ko
+[sudo] Passwort für peter:
+cassini/home/peter/bo/2022ss/bs/20220404> sudo rmmod hellomod-1.ko
+cassini/home/peter/bo/2022ss/bs/20220404> cat hellomod-1.c
+/*
+ *  hello-1.c - The simplest kernel module.
+ */
+#include <linux/module.h>       /* Needed by all modules */
+#include <linux/kernel.h>       /* Needed for KERN_INFO */
+
+int init_module(void)
+{
+        printk(KERN_INFO "Hello world 1.\n");
+
+        /*
+         * A non 0 return means init_module failed; module can't be loaded.
+         */
+        return 0;
+}
+
+void cleanup_module(void)
+{
+        printk(KERN_INFO "Goodbye world 1.\n");
+}

20220404/modules-2.txt

+cassini/home/peter/bo/2022ss/bs/20220404> sudo dmesg
+[...]
+[1583119.050593] hellomod_1: loading out-of-tree module taints kernel.
+[1583119.050600] hellomod_1: module license 'unspecified' taints kernel.
+[1583119.050601] Disabling lock debugging due to kernel taint
+[1583119.050666] hellomod_1: module verification failed: signature and/or required key missing - tainting kernel
+[1583119.051455] Hello world 1.
+[1583136.476867] Goodbye world 1.

20220404/modules-3.txt

+cassini/home/peter/bo/2022ss/bs/20220404> sudo dmesg
+[...]
+[1583551.529893] Hello world 2.
+[1583557.018894] Goodbye world 2.

20220404/modules-4.txt

+[1584035.731938] I was assigned major number 241. To talk to
+[1584035.731939] the driver, create a dev file with
+[1584035.731940] 'mknod /dev/chardev c 241 0'.
+[1584035.731940] Try various minor numbers. Try to cat and echo to
+[1584035.731941] the device file.
+[1584035.731941] Remove the device file and module when done.

20220404/modules-5.txt

+cassini/home/peter/bo/2022ss/bs/20220404> mkdir dev
+cassini/home/peter/bo/2022ss/bs/20220404> mknod dev/chardev c 241 0
+mknod: dev/chardev: Die Operation ist nicht erlaubt
+cassini/home/peter/bo/2022ss/bs/20220404> sudo mknod dev/chardev c 241 0
+cassini/home/peter/bo/2022ss/bs/20220404> ls -l dev/
+insgesamt 0
+crw-r--r-- 1 root root 241, 0 Apr  4 14:39 chardev
+cassini/home/peter/bo/2022ss/bs/20220404> ls -l /dev/tty
+crw-rw-rw- 1 root tty 5, 0 Apr  4 14:22 /dev/tty
+cassini/home/peter/bo/2022ss/bs/20220404> cat dev/chardev
+I already told you 0 times Hello world!
+cassini/home/peter/bo/2022ss/bs/20220404> cat dev/chardev
+I already told you 1 times Hello world!
+cassini/home/peter/bo/2022ss/bs/20220404> cat dev/chardev
+I already told you 2 times Hello world!

20220404/nix-hello.c

+int main (void)
+{
+  char *p = (char *) 0xb8000000;
+  *p++ = 'H';
+  *p++ = 0x04;
+  *p++ = 'e';
+  *p++ = 0x02;
+  *p++ = 'l';
+  *p++ = 0x01;
+  *p++ = 'l';
+  *p++ = 0x06;
+  *p++ = 'o';
+  *p++ = 0x03;
+  return 0;
+}