Changes between Version 2 and Version 3 of Dev/KernelHack/COINS/worklog/201110

Timestamp:

Oct 18, 2011 12:35:10 PM (13 years ago)

Author:

mitty

Comment:

--

Dev/KernelHack/COINS/worklog/201110

@@ -529 +529 @@
 
  * GDBによるステップ実行は、3000行ほど実行してみたがguest側で結果が出力されないので、断念
+
+ = 10/14 =
+ == getcpu system call ==
+ * http://www.kernel.org/doc/man-pages/online/pages/man2/getcpu.2.html
+ * http://www.linuxquestions.org/questions/programming-9/determine-what-cpu-my-thread-is-on-817697/
+
+ * getcpu system callはには存在しない
+  * arch/x86/include/asm/unistd_64.h
+{{{#!cc
+#define __IGNORE_getcpu         /* implemented as a vsyscall */
+}}}
+
+ * s0711489@ubuntu-lucid64:~/coursework/KernelHack/02$ cat > getcpu.c
+{{{#!cc
+#define _GNU_SOURCE         /* See feature_test_macros(7) */
+#include <linux/getcpu.h>
+#include <stdio.h>
+
+int main (void) {
+        int c, s;
+        s = getcpu(&c, NULL, NULL);
+        printf ("getcpu() -> %d\n", (s == -1) ? s : c);
+}
+}}}
+ * s0711489@ubuntu-lucid64:~/coursework/KernelHack/02$ gcc getcpu.c -o getcpu
+{{{
+getcpu.c:1:26: error: linux/getcpu.h: No such file or directory
+}}}
+
+ === i386 ===
+ * s0711489@ubuntu-lucid:~$ sudo /mnt/hgfs/tools/install.sh
+{{{
++ cat /mnt/hgfs/linux-2.6.35.14/include/config/kernel.release
++ VERSION=2.6.35.14
++ echo Install Linux Kernel version 2.6.35.14
+Install Linux Kernel version 2.6.35.14
++ cd /mnt/hgfs/linux-2.6.35.14/
++ make install
+sh /mnt/hgfs/linux-2.6.35.14/arch/x86/boot/install.sh 2.6.35.14 arch/x86/boot/bzImage \
+                System.map "/boot"
++ make modules_install
+  INSTALL arch/x86/kernel/test_nx.ko
+  INSTALL drivers/scsi/scsi_wait_scan.ko
+  INSTALL net/netfilter/xt_mark.ko
+  DEPMOD  2.6.35.14
++ mkinitramfs -o /boot/initrd.img-2.6.35.14 2.6.35.14
++ update-grub
+Generating grub.cfg ...
+Found linux image: /boot/vmlinuz-2.6.35.14
+Found initrd image: /boot/initrd.img-2.6.35.14
+Found linux image: /boot/vmlinuz-2.6.32-33-generic
+Found initrd image: /boot/initrd.img-2.6.32-33-generic
+Found memtest86+ image: /boot/memtest86+.bin
+done
++ echo Install Kernel Headers to /lib/modules/2.6.35.14/build
+Install Kernel Headers to /lib/modules/2.6.35.14/build
++ date +%Y%m%d
++ mv /lib/modules/2.6.35.14/build /lib/modules/2.6.35.14/build-20111014
++ cd /mnt/hgfs/
++ tar c --files-from -
++ tar x -C /lib/modules/2.6.35.14/
++ egrep -v vmlinu
++ egrep -v .o$
++ find linux-2.6.35.14 -type f
++ mv /lib/modules/2.6.35.14/linux-2.6.35.14 /lib/modules/2.6.35.14/build
++ uname -a
+Linux ubuntu-lucid 2.6.32-33-generic #72-Ubuntu SMP Fri Jul 29 21:08:37 UTC 2011 i686 GNU/Linux
+}}}
+ * s0711489@ubuntu-lucid:~$ sudo vmware-config-tools.pl --default
+
+ * s0711489@ubuntu-lucid:~$ cat > getcpu.c
+{{{#!cc
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+int main( void )
+{
+        int cpu = syscall(SYS_getcpu);
+        if (cpu < 0)
+        {
+                printf( "Error: errno = %d\n", errno ); fflush(stdout);
+                printf( "Error: errno: %s\n", strerror(errno) ); fflush(stdout);
+                return -1;
+        }
+        printf( "cpu = %d\n", cpu );
+
+        return 0;
+}
+}}}
+
+ * s0711489@ubuntu-lucid:~$ gcc getcpu.c -o getcpu
+ * s0711489@ubuntu-lucid:~$ ./getcpu
+{{{
+Error: errno = 14
+Error: errno: Bad address
+}}}
+
+ * うまく動かない
+
+ == getuid system call ==
+ * windell57:x86_64 s0711489$ gdb
+{{{
+(gdb) set logging file gdb.getuid.log
+(gdb) set logging on
+Copying output to gdb.getuid.log.
+(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) b sys_getuid
+Breakpoint 1 at 0xffffffff81048d17: file kernel/timer.c, line 1366.
+(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) c
+Continuing.
+
+Breakpoint 1, sys_getuid () at kernel/timer.c:1366
+1366    {
+(gdb) s
+1368            return current_uid();
+(gdb)
+get_current ()
+    at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/current.h:14
+14              return percpu_read_stable(current_task);
+(gdb)
+1368            return current_uid();
+(gdb)
+sys_getuid () at kernel/timer.c:1366
+1366    {
+(gdb)
+1368            return current_uid();
+(gdb)
+get_current () at kernel/timer.c:1368
+1368            return current_uid();
+(gdb)
+sys_getuid () at kernel/timer.c:1369
+1369    }
+(gdb)
+
+Program received signal SIGINT, Interrupt.
+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) detach
+Ending remote debugging.
+(gdb) quit
+}}}
+
+ * s0711489@ubuntu-lucid64:~/coursework/KernelHack/02$ ./getuid
+{{{
+getuid() -> 1000
+}}}
+
+ === trace log with source list and print data ===
+ * windell57:x86_64 s0711489$ 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) b sys_getuid
+Breakpoint 1 at 0xffffffff81048d17: file kernel/timer.c, line 1366.
+(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) c
+Continuing.
+
+Breakpoint 1, sys_getuid () at kernel/timer.c:1366
+1366    {
+(gdb) bt
+#0  sys_getuid () at kernel/timer.c:1366
+#1  0xffffffff810029eb in ?? ()
+#2  0x0000000000000206 in ?? ()
+#3  0x00007ffff56d6ad0 in ?? ()
+#4  0x00007f8671347210 in ?? ()
+#5  0x00007f8671333300 in ?? ()
+#6  0x0000000000000066 in ?? ()
+#7  0x0000000000000000 in ?? ()
+(gdb) l
+1361
+1362            return pid;
+1363    }
+1364
+1365    SYSCALL_DEFINE0(getuid)
+1366    {
+1367            /* Only we change this so SMP safe */
+1368            return current_uid();
+1369    }
+1370
+(gdb) s
+1368            return current_uid();
+(gdb)
+get_current ()
+    at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/current.h:14
+14              return percpu_read_stable(current_task);
+(gdb) bt
+#0  get_current ()
+    at /home/ugrad/07/s0711489/coursework/KernelHack/linux-2.6.35.14/x86_64/arch/x86/include/asm/current.h:14
+#1  sys_getuid () at kernel/timer.c:1368
+#2  0xffffffff810029eb in ?? ()
+#3  0x0000000000000206 in ?? ()
+#4  0x00007ffff56d6ad0 in ?? ()
+#5  0x00007f8671347210 in ?? ()
+#6  0x00007f8671333300 in ?? ()
+#7  0x0000000000000066 in ?? ()
+#8  0x0000000000000000 in ?? ()
+(gdb) l
+9
+10      DECLARE_PER_CPU(struct task_struct *, current_task);
+11
+12      static __always_inline struct task_struct *get_current(void)
+13      {
+14              return percpu_read_stable(current_task);
+15      }
+16
+17      #define current get_current()
+18
+(gdb) p current_task
+Cannot access memory at address 0xb540
+(gdb) ptype current_task
+type = struct task_struct {
+
+(snip
+
+---Type <return> to continue, or q <return> to quit---q
+Quit
+(gdb) s
+1368            return current_uid();
+(gdb)
+sys_getuid () at kernel/timer.c:1366
+1366    {
+(gdb) bt
+#0  sys_getuid () at kernel/timer.c:1366
+#1  0xffffffff810029eb in ?? ()
+#2  0x0000000000000206 in ?? ()
+#3  0x00007ffff56d6ad0 in ?? ()
+#4  0x00007f8671347210 in ?? ()
+#5  0x00007f8671333300 in ?? ()
+#6  0x0000000000000066 in ?? ()
+#7  0x0000000000000000 in ?? ()
+(gdb) s
+1368            return current_uid();
+(gdb)
+get_current () at kernel/timer.c:1368
+1368            return current_uid();
+(gdb) bt
+#0  get_current () at kernel/timer.c:1368
+#1  sys_getuid () at kernel/timer.c:1368
+#2  0xffffffff810029eb in ?? ()
+#3  0x0000000000000206 in ?? ()
+#4  0x00007ffff56d6ad0 in ?? ()
+#5  0x00007f8671347210 in ?? ()
+#6  0x00007f8671333300 in ?? ()
+#7  0x0000000000000066 in ?? ()
+#8  0x0000000000000000 in ?? ()
+(gdb) l
+1363    }
+1364
+1365    SYSCALL_DEFINE0(getuid)
+1366    {
+1367            /* Only we change this so SMP safe */
+1368            return current_uid();
+1369    }
+1370
+1371    SYSCALL_DEFINE0(geteuid)
+1372    {
+(gdb) s
+sys_getuid () at kernel/timer.c:1369
+1369    }
+(gdb) bt
+#0  sys_getuid () at kernel/timer.c:1369
+#1  0xffffffff810029eb in ?? ()
+#2  0x0000000000000206 in ?? ()
+#3  0x00007ffff56d6ad0 in ?? ()
+#4  0x00007f8671347210 in ?? ()
+#5  0x00007f8671333300 in ?? ()
+#6  0x0000000000000066 in ?? ()
+#7  0x0000000000000000 in ?? ()
+(gdb) l
+1364
+1365    SYSCALL_DEFINE0(getuid)
+1366    {
+1367            /* Only we change this so SMP safe */
+1368            return current_uid();
+1369    }
+1370
+1371    SYSCALL_DEFINE0(geteuid)
+1372    {
+1373            /* Only we change this so SMP safe */
+(gdb) p current_uid
+No symbol "current_uid" in current context.
+(gdb) ptype current_uid
+No symbol "current_uid" in current context.
+(gdb) s
+
+Breakpoint 1, sys_getuid () at kernel/timer.c:1366
+1366    {
+(gdb) detach
+Ending remote debugging.
+}}}
+
+ * include/linux/cred.h
+{{{#!cc
+#define current_cred_xxx(xxx)                   \
+({                                              \
+        current->cred->xxx;                     \
+})
+
+#define current_uid()           (current_cred_xxx(uid))
+#define current_gid()           (current_cred_xxx(gid))
+
+(snip)
+}}}
+
+ * ptype of current_task->cred
+{{{
+(gdb) ptype current_task->cred
+type = const struct cred {
+    atomic_t usage;
+    uid_t uid;
+    gid_t gid;
+    uid_t suid;
+    gid_t sgid;
+    uid_t euid;
+    gid_t egid;
+    uid_t fsuid;
+    gid_t fsgid;
+    unsigned int securebits;
+    kernel_cap_t cap_inheritable;
+    kernel_cap_t cap_permitted;
+    kernel_cap_t cap_effective;
+    kernel_cap_t cap_bset;
+    unsigned char jit_keyring;
+    struct key *thread_keyring;
+    struct key *request_key_auth;
+    struct thread_group_cred *tgcred;
+    void *security;
+    struct user_struct *user;
+    struct group_info *group_info;
+    struct rcu_head rcu;
+} *
+(gdb) ptype current_task->cred->uid
+type = unsigned int
+}}}