Changes between Version 7 and Version 8 of Dev/KernelHack/COINS/worklog/201111

Timestamp:

Nov 25, 2011 1:42:57 AM (13 years ago)

Author:

mitty

Comment:

--

Dev/KernelHack/COINS/worklog/201111

@@ -1688 +1688 @@
 Nov 20 17:52:58 ubuntu-lucid64 kernel: [ 4419.365281] stackmod is released
 }}}
+
+ == /proc read skeleton ==
+ * [http://www.ibm.com/developerworks/jp/linux/library/l-proc/ /procファイルシステムを使用したLinuxカーネルへのアクセス]
+ * [http://homepage3.nifty.com/rio_i/lab/driver24/007proc.html /proc インタフェースを使う]
+ * [http://d.hatena.ne.jp/masami256/20100315/1268662409 procfs経由でデータの読み書き - linuxとかテストとか]
+
+ * 参考
+  * sound/core/info.c -> create_proc_entry
+  * arch/h8300/kernel/gpio.c -> create_proc_entry
+  * arch/arm/mach-bcmring/dma.c -> create_proc_read_entry
+  * drivers/nubus/nubus.c -> create_proc_read_entry
+  * include/linux/proc_fs.h -> static inline struct proc_dir_entry *create_proc_read_entry
+
+ * s0711489@ubuntu-lucid64:~$ sudo insmod stackmod.ko
+{{{
+Nov 21 00:33:28 ubuntu-lucid64 kernel: [   41.547601] stackmod is loaded
+Nov 21 00:33:28 ubuntu-lucid64 kernel: [   41.547606] stackmod: 128 entry, major is 251, minor is 0
+Nov 21 00:33:28 ubuntu-lucid64 kernel: [   41.547615] stackmod: create /proc/stackmod
+Nov 21 00:33:28 ubuntu-lucid64 kernel: [   41.547617] stackmod is added successfully
+}}}
+
+ * s0711489@ubuntu-lucid64:~$ ls -l /proc/ | grep stack
+{{{
+-r--r--r--  1 root     root                   0 2011-11-21 00:34 stackmod
+}}}
+
+ * s0711489@ubuntu-lucid64:~$ cat /proc/stackmod
+{{{
+Nov 21 00:34:21 ubuntu-lucid64 kernel: [   94.446963] /proc/stackmod is read
+}}}
+
+ * s0711489@ubuntu-lucid64:~$ sudo rmmod stackmod.ko
+{{{
+Nov 21 00:35:43 ubuntu-lucid64 kernel: [  177.060782] stackmod is unloaded
+}}}
+
+ === implement stackmod_proc_read as proc_dir_entry->read_proc ===
+ * fs/proc/generic.c -> __proc_file_read
+{{{
+ * How to be a proc read function
+}}}
+
+ * s0711489@ubuntu-lucid64:~$ sudo insmod stackmod.ko
+ * s0711489@ubuntu-lucid64:~$ cat /proc/stackmod
+{{{
+0 stacks
+}}}
+{{{
+Nov 21 02:30:23 ubuntu-lucid64 kernel: [ 7055.042732] /proc/stackmod is read
+Nov 21 02:30:23 ubuntu-lucid64 kernel: [ 7055.042747] /proc/stackmod is read
+}}}
+
+ == kmalloc/kfree -> stack.buffer ==
+ === research kmalloc ===
+ * [http://tiki.is.os-omicron.org/tiki.cgi?c=v&p=Linux%2FLKM%2FGDB%A4%F2%BB%C8%A4%C3%A4%C6%A5%B3%A1%BC%A5%C9%A4%F2%C4%C9%A4%C3%A4%AB%A4%B1%A4%EB Omicron Linux/LKM/GDBを使ってコードを追っかける]
+ * [http://www.denx.de/wiki/DULG/DebuggingLinuxKernel DebuggingLinuxKernel < DULG < DENX]
+
+ ==== without memset ====
+ * s0711489@ubuntu-lucid64:~$ sudo insmod stackmod.ko
+ * s0711489@ubuntu-lucid64:~$ cat /sys/module/stackmod/sections/.text
+{{{
+0xffffffffa0056000
+}}}
+ * s0711489@ubuntu-lucid64:~$ cat /sys/module/stackmod/sections/.data
+{{{
+0xffffffffa0056458
+}}}
+ * s0711489@ubuntu-lucid64:~$ cat /sys/module/stackmod/sections/.bss
+{{{
+0xffffffffa0056690
+}}}
+
+ * gdb
+{{{
+(gdb) file vmlinux
+Reading symbols from /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/vmlinux...(no debugging symbols found)...done.
+(gdb) add-symbol-file ../../04/stackmod/stackmod.o 0xffffffffa0056000 -s .data 0xffffffffa0056458 -s .bss 0xffffffffa0056690
+add symbol table from file "../../04/stackmod/stackmod.o" at
+        .text_addr = 0xffffffffa0056000
+        .data_addr = 0xffffffffa0056458
+        .bss_addr = 0xffffffffa0056690
+(y or n) y
+Reading symbols from /home/ugrad/07/s0711489/coursework/KernelHack/04/stackmod/stackmod.o...done.
+(gdb) l stackmod.c:145
+
+140             stack.buffer = (char **) kmalloc(entry * sizeof(char *), GFP_KERNEL);
+141             if (stack.buffer == NULL) {
+142                     printk(KERN_WARNING MODNAME ": (char **) kmalloc failed\n");
+143                     ret = -ENOMEM;
+144                     goto error_cdev;
+145             }
+146     //        memset(stack.buffer, NULL, entry * sizeof(char *));
+147
+148             printk(KERN_INFO MODNAME " is added successfully\n");
+149
+(gdb) p stack
+Cannot access memory at address 0xffffffffa0056690
+(gdb) target remote localhost:8864
+Remote debugging using localhost:8864
+0xffffffff810097a9 in native_safe_halt ()
+    at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/irqflags.h:49
+49              asm volatile("sti; hlt": : :"memory");
+(gdb) p stack
+$1 = {buffer = 0xffff88001b740800, depth = 0, errno = 0}
+(gdb) ptype stack
+type = struct kernel_module_stack {
+    char **buffer;
+    int depth;
+    int errno;
+}
+(gdb) p stack.buffer
+$2 = (char **) 0xffff88001b740800
+(gdb) p stack.buffer[0]
+$3 = 0xffff88001b744c00 ""
+(gdb) p stack.buffer[1]
+$4 = 0x1000 <Address 0x1000 out of bounds>
+(gdb) p stack.buffer[2]
+$5 = 0xffffea00005f0148 ","
+(gdb) p stack.buffer[3]
+$6 = 0x1000 <Address 0x1000 out of bounds>
+(gdb) p stack.buffer[4]
+$7 = 0xffffea00005f0110 ","
+(gdb) p stack.buffer[5]
+$8 = 0x1000 <Address 0x1000 out of bounds>
+(gdb) p stack.buffer[6]
+$9 = 0xffffea00005f4048 ","
+(gdb) p stack.depth
+$10 = 0
+(gdb) p/c stack.depth
+$11 = 0 '\000'
+(gdb) p stack.buffer
+$12 = (char **) 0xffff88001b740800
+(gdb) p/x stack.buffer
+$13 = 0xffff88001b740800
+(gdb) p/x stack.buffer[0]
+$14 = 0xffff88001b744c00
+(gdb) p/x stack.buffer[1]
+$15 = 0x1000
+(gdb) p/x stack.buffer[2]
+$16 = 0xffffea00005f0148
+(gdb) p/x stack.buffer[3]
+$17 = 0x1000
+(gdb) p/x stack.buffer[4]
+$18 = 0xffffea00005f0110
+}}}
+
+ ==== with memset ====
+ * s0711489@ubuntu-lucid64:~$ sudo insmod stackmod.ko
+ * s0711489@ubuntu-lucid64:~$ cat /sys/module/stackmod/sections/.text
+{{{
+0xffffffffa0056000
+}}}
+ * s0711489@ubuntu-lucid64:~$ cat /sys/module/stackmod/sections/.data
+{{{
+0xffffffffa0056458
+}}}
+ * s0711489@ubuntu-lucid64:~$ cat /sys/module/stackmod/sections/.bss
+{{{
+0xffffffffa0056690
+}}}
+
+ * gdb
+{{{
+(gdb) file vmlinux
+Reading symbols from /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/vmlinux...(no debugging symbols found)...done.
+(gdb) add-symbol-file ../../04/stackmod/stackmod.o 0xffffffffa0056000 -s .data 0xffffffffa0056458 -s .bss 0xffffffffa0056690
+add symbol table from file "../../04/stackmod/stackmod.o" at
+        .text_addr = 0xffffffffa0056000
+        .data_addr = 0xffffffffa0056458
+        .bss_addr = 0xffffffffa0056690
+(y or n) y
+Reading symbols from /home/ugrad/07/s0711489/coursework/KernelHack/04/stackmod/stackmod.o...done.
+(gdb) l stackmod.c:145
+
+140             stack.buffer = (char **) kmalloc(entry * sizeof(char *), GFP_KERNEL);
+141             if (stack.buffer == NULL) {
+142                     printk(KERN_WARNING MODNAME ": (char **) kmalloc failed\n");
+143                     ret = -ENOMEM;
+144                     goto error_cdev;
+145             }
+146             memset(stack.buffer, (int) NULL, entry * sizeof(char *));
+147
+148             printk(KERN_INFO MODNAME " is added successfully\n");
+149
+(gdb) target remote localhost:8864
+Remote debugging using localhost:8864
+0xffffffff810097a9 in native_safe_halt ()
+    at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/irqflags.h:49
+49              asm volatile("sti; hlt": : :"memory");
+(gdb) p stack
+$1 = {buffer = 0xffff88001b5cb400, depth = 0, errno = 0}
+(gdb) p stack.buffer
+$2 = (char **) 0xffff88001b5cb400
+(gdb) p/c stack.buffer
+$3 = 0 '\000'
+(gdb) p/x stack.buffer
+$4 = 0xffff88001b5cb400
+(gdb) p/x stack.buffer[0]
+$5 = 0x0
+(gdb) p/x stack.buffer[1]
+$6 = 0x0
+(gdb) p/x stack.buffer[2]
+$7 = 0x0
+(gdb) p/x stack.buffer[3]
+$8 = 0x0
+(gdb) p/x stack.buffer[4]
+$9 = 0x0
+(gdb) p/x stack.buffer[5]
+$10 = 0x0
+(gdb) p/x stack.buffer[127]
+$11 = 0x0
+(gdb) p/x stack.buffer[128]
+$12 = 0xffff88001b5cb000
+(gdb) p/x stack.buffer[129]
+$13 = 0x0
+(gdb) p/x stack.buffer[130]
+$14 = 0xffffffff00000000
+(gdb) p/x stack.buffer[126]
+$15 = 0x0
+(gdb) p/x stack.buffer[125]
+$16 = 0x0
+}}}
+
+ ===== much more entry with memset =====
+ * s0711489@ubuntu-lucid64:~$ sudo rmmod stackmod.ko
+ * s0711489@ubuntu-lucid64:~$ sudo insmod stackmod.ko entry=1024
+ * s0711489@ubuntu-lucid64:~$ cat /sys/module/stackmod/sections/.text
+{{{
+0xffffffffa005c000
+}}}
+ * s0711489@ubuntu-lucid64:~$ cat /sys/module/stackmod/sections/.data
+{{{
+0xffffffffa005c458
+}}}
+ * s0711489@ubuntu-lucid64:~$ cat /sys/module/stackmod/sections/.bss
+{{{
+0xffffffffa005c690
+}}}
+
+ * gdb
+{{{
+(gdb) file vmlinux
+Reading symbols from /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/vmlinux...(no debugging symbols found)...done.
+(gdb) add-symbol-file ../../04/stackmod/stackmod.o 0xffffffffa005c000 -s .data 0xffffffffa005c458 -s .bss 0xffffffffa005c690
+add symbol table from file "../../04/stackmod/stackmod.o" at
+        .text_addr = 0xffffffffa005c000
+        .data_addr = 0xffffffffa005c458
+        .bss_addr = 0xffffffffa005c690
+(y or n) y
+Reading symbols from /home/ugrad/07/s0711489/coursework/KernelHack/04/stackmod/stackmod.o...done.
+(gdb) target remote localhost:8864
+Remote debugging using localhost:8864
+0xffffffff810097a9 in native_safe_halt ()
+    at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/irqflags.h:49
+49              asm volatile("sti; hlt": : :"memory");
+(gdb) p stack
+$1 = {buffer = 0xffff88001af16000, depth = 0, errno = 0}
+(gdb) p entry
+$2 = 1024
+(gdb) p stack.buffer
+$3 = (char **) 0xffff88001af16000
+(gdb) p/x stack.buffer
+$4 = 0xffff88001af16000
+(gdb) p/x stack.buffer[0]
+$5 = 0x0
+(gdb) p/x stack.buffer[127]
+$6 = 0x0
+(gdb) p/x stack.buffer[128]
+$7 = 0x0
+(gdb) p/x stack.buffer[1020]
+$8 = 0x0
+(gdb) p/x stack.buffer[1021]
+$9 = 0x0
+(gdb) p/x stack.buffer[1022]
+$10 = 0x0
+(gdb) p/x stack.buffer[1023]
+$11 = 0x0
+(gdb) p/x stack.buffer[1024]
+$12 = 0xc7c7485500c3c9a0
+(gdb) p/x stack.buffer[1025]
+$13 = 0xe8e58948a001a000
+(gdb) p/x stack.buffer[1026]
+$14 = 0x4855c3c9e11ca49c
+}}}