Re: linux segment
On Tue, 30 Oct 2012, Fan Yang wrote: 2012/10/29 Mulyadi Santosa mulyadi.sant...@gmail.com Hi Fan... On Sun, Oct 28, 2012 at 9:02 PM, Fan Yang lljyang...@gmail.com wrote: [root@shell--box kernel_mod]# dmesg -c ** cs 60 96 ds 7b 123 ss 68 104 es 7b 123 fs d8 216 gs e0 224 ** The cs and ds in the kernel space is 60 and 7b. But the kernel define the KERNEL_CS as 60 and the KERNEL_DS as 7b. Where am I wrong? you print CS and DS twice, once during init and once during exit of your kernel module. So, which one do you want to confirm? All in all, I have a guess that you see such number (DS belongs to user space in kernel module) because IIRC kernel module loading is done using syscall and with the help of modprobe helper. Thus, it is important to access user space during that stage, hence DS still using user space data segment. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com Hi Mulyadi Santosa I get the same result during the kernel module init and exit. Then I try to add a syscall to print these registers, and nothing changed. It is strange. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies (Weird, this is the third time, I have to send this. If anybody gets this message multiple times, I apologise but my mail is not in the archives.) If Mulyadi is right and we need DS to be USER_DS to access user space (I really don't know, sorry, but maybe there is something in your uaccess.h?) then your attempt to try with a syscall couldn't yield other values because one trait of syscalls is that they can access user space. This means you would get DS = USER_DS precisely _because_ you are in a syscall. Module init and exit are, too, just some stack frames above one and thus fall into this category as well. But shouldn't it be possible to register a timer and then print the segment registers? Timers are fired in softirq context and, hence, have no connection to user space. Regards, Tobi ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: linux segment
On Tue, Oct 30, 2012 at 7:44 AM, Fan Yang lljyang...@gmail.com wrote: Hi Mulyadi Santosa I get the same result during the kernel module init and exit. Then I try to add a syscall to print these registers, and nothing changed. It is strange. I think you need to observe deeper, something change this. BTW, are you running this inside a virtualization? and which kernel version do you use? -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: linux segment
Hi Fan... On Sun, Oct 28, 2012 at 9:02 PM, Fan Yang lljyang...@gmail.com wrote: [root@shell--box kernel_mod]# dmesg -c ** cs 60 96 ds 7b 123 ss 68 104 es 7b 123 fs d8 216 gs e0 224 ** The cs and ds in the kernel space is 60 and 7b. But the kernel define the KERNEL_CS as 60 and the KERNEL_DS as 7b. Where am I wrong? you print CS and DS twice, once during init and once during exit of your kernel module. So, which one do you want to confirm? All in all, I have a guess that you see such number (DS belongs to user space in kernel module) because IIRC kernel module loading is done using syscall and with the help of modprobe helper. Thus, it is important to access user space during that stage, hence DS still using user space data segment. -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: linux segment
2012/10/27 Jun Hu duanshui...@hotmail.com
Can you post out your codes ?
*From:* Fan Yang lljyang...@gmail.com
*Sent:* Wednesday, October 24, 2012 8:04 PM
*To:* kernelnewbies@kernelnewbies.org
*Subject:* linux segment
Hi all:
I print the cs ds and ss register in the user space, and it is same as
the __USER_CS and __USER_DS which defined in kernel as 73 and 7b. In the
kernel __KERNEL_CS and __KERNEL_DS defined as 60 and 68, but when I print
this two value in my kernel module, I get 60 and 7b. Why ? It should be 60
and 68, shouldn't it?
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Hi Jun Hu
There is my code which run at the user space:
1 #includestdio.h
2 main()
3 {
4 unsigned long cs, ds, ss, es, fs, gs;
5 asm volatile(movl %%CS,%0\n\t:=r(cs));
6 asm volatile(movl %%DS,%0\n\t:=r(ds));
7 asm volatile(movl %%SS,%0\n\t:=r(ss));
8 asm volatile(movl %%ES,%0\n\t:=r(es));
9 asm volatile(movl %%FS,%0\n\t:=r(fs));
10 asm volatile(movl %%GS,%0\n\t:=r(gs));
11 printf (**\n);
12 printf (cs %lx\t%ld\n, cs, cs);
13 printf (ds %lx\t%ld\n, ds, ds);
14 printf (ss %lx\t%ld\n, ss, ss);
15 printf (es %lx\t%ld\n, es, es);
16 printf (fs %lx\t%ld\n, fs, fs);
17 printf (gs %lx\t%ld\n, gs, gs);
18 printf (**\n);
19 }
and the result of the progress in my machine is
**
cs 73 115
ds 7b 123
ss 7b 123
es 7b 123
fs 0 0
gs 33 51
**
so, you can see the cs and ds register is 73 and 7b which are same as the
kernel defined. And the code of the kernel module is
1 #includelinux/init.h
2 #includelinux/kernel.h
3 #includelinux/module.h
4
5 static void __init print_init (void)
6 {
7 unsigned long cs, ds, ss, es, fs, gs,currenttime;
8 asm volatile(movl %%CS,%0\n\t:=r(cs));
9 asm volatile(movl %%DS,%0\n\t:=r(ds));
10 asm volatile(movl %%SS,%0\n\t:=r(ss));
11 asm volatile(movl %%ES,%0\n\t:=r(es));
12 asm volatile(movl %%FS,%0\n\t:=r(fs));
13 asm volatile(movl %%GS,%0\n\t:=r(gs));
14 printk (**\n);
15 printk (cs %lx\t%ld\n, cs, cs);
16 printk (ds %lx\t%ld\n, ds, ds);
17 printk (ss %lx\t%ld\n, ss, ss);
18 printk (es %lx\t%ld\n, es, es);
19 printk (fs %lx\t%ld\n, fs, fs);
20 printk (gs %lx\t%ld\n, gs, gs);
21 printk (**\n);
22
23 }
24
25 static void __exit print_exit (void)
26 {
27 unsigned long cs, ds, ss;
28 asm volatile(movl %%cs,%0\n\t:=r(cs));
29 asm volatile(movl %%ds,%0\n\t:=r(ds));
30 asm volatile(movl %%ss,%0\n\t:=r(ss));
31
32 printk (**\n);
33 printk (cs %lx\t%ld\n, cs, cs);
34 printk (ds %lx\t%ld\n, ds, ds);
35 printk (ss %lx\t%ld\n, ss, ss);
36 printk (**\n);
37 printk (*bye***\n);
38 }
39
40 module_init (print_init);
41 module_exit (print_exit);
42 MODULE_LICENSE (GPL);
the result of the running this module is
[root@shell--box kernel_mod]# dmesg -c
**
cs 60 96
ds 7b 123
ss 68 104
es 7b 123
fs d8 216
gs e0 224
**
The cs and ds in the kernel space is 60 and 7b. But the kernel define the
KERNEL_CS as 60 and the KERNEL_DS as 7b. Where am I wrong?
Thanks
Fan
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Re: linux segment
2012/10/28 Fan Yang lljyang...@gmail.com
2012/10/27 Jun Hu duanshui...@hotmail.com
Can you post out your codes ?
*From:* Fan Yang lljyang...@gmail.com
*Sent:* Wednesday, October 24, 2012 8:04 PM
*To:* kernelnewbies@kernelnewbies.org
*Subject:* linux segment
Hi all:
I print the cs ds and ss register in the user space, and it is same
as the __USER_CS and __USER_DS which defined in kernel as 73 and 7b. In the
kernel __KERNEL_CS and __KERNEL_DS defined as 60 and 68, but when I print
this two value in my kernel module, I get 60 and 7b. Why ? It should be 60
and 68, shouldn't it?
--
___
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Kernelnewbies@kernelnewbies.org
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Hi Jun Hu
There is my code which run at the user space:
1 #includestdio.h
2 main()
3 {
4 unsigned long cs, ds, ss, es, fs, gs;
5 asm volatile(movl %%CS,%0\n\t:=r(cs));
6 asm volatile(movl %%DS,%0\n\t:=r(ds));
7 asm volatile(movl %%SS,%0\n\t:=r(ss));
8 asm volatile(movl %%ES,%0\n\t:=r(es));
9 asm volatile(movl %%FS,%0\n\t:=r(fs));
10 asm volatile(movl %%GS,%0\n\t:=r(gs));
11 printf (**\n);
12 printf (cs %lx\t%ld\n, cs, cs);
13 printf (ds %lx\t%ld\n, ds, ds);
14 printf (ss %lx\t%ld\n, ss, ss);
15 printf (es %lx\t%ld\n, es, es);
16 printf (fs %lx\t%ld\n, fs, fs);
17 printf (gs %lx\t%ld\n, gs, gs);
18 printf (**\n);
19 }
and the result of the progress in my machine is
**
cs 73 115
ds 7b 123
ss 7b 123
es 7b 123
fs 0 0
gs 33 51
**
so, you can see the cs and ds register is 73 and 7b which are same as the
kernel defined. And the code of the kernel module is
1 #includelinux/init.h
2 #includelinux/kernel.h
3 #includelinux/module.h
4
5 static void __init print_init (void)
6 {
7 unsigned long cs, ds, ss, es, fs, gs,currenttime;
8 asm volatile(movl %%CS,%0\n\t:=r(cs));
9 asm volatile(movl %%DS,%0\n\t:=r(ds));
10 asm volatile(movl %%SS,%0\n\t:=r(ss));
11 asm volatile(movl %%ES,%0\n\t:=r(es));
12 asm volatile(movl %%FS,%0\n\t:=r(fs));
13 asm volatile(movl %%GS,%0\n\t:=r(gs));
14 printk (**\n);
15 printk (cs %lx\t%ld\n, cs, cs);
16 printk (ds %lx\t%ld\n, ds, ds);
17 printk (ss %lx\t%ld\n, ss, ss);
18 printk (es %lx\t%ld\n, es, es);
19 printk (fs %lx\t%ld\n, fs, fs);
20 printk (gs %lx\t%ld\n, gs, gs);
21 printk (**\n);
22
23 }
24
25 static void __exit print_exit (void)
26 {
27 unsigned long cs, ds, ss;
28 asm volatile(movl %%cs,%0\n\t:=r(cs));
29 asm volatile(movl %%ds,%0\n\t:=r(ds));
30 asm volatile(movl %%ss,%0\n\t:=r(ss));
31
32 printk (**\n);
33 printk (cs %lx\t%ld\n, cs, cs);
34 printk (ds %lx\t%ld\n, ds, ds);
35 printk (ss %lx\t%ld\n, ss, ss);
36 printk (**\n);
37 printk (*bye***\n);
38 }
39
40 module_init (print_init);
41 module_exit (print_exit);
42 MODULE_LICENSE (GPL);
the result of the running this module is
[root@shell--box kernel_mod]# dmesg -c
**
cs 60 96
ds 7b 123
ss 68 104
es 7b 123
fs d8 216
gs e0 224
**
The cs and ds in the kernel space is 60 and 7b. But the kernel define the
KERNEL_CS as 60 and the KERNEL_DS as 7b. Where am I wrong?
Thanks
Fan
sorry, the kernel define the KERNEL_DS as 68, but I get 7b in my machine.
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Re: linux segment
Can you post out your codes ? From: Fan Yang Sent: Wednesday, October 24, 2012 8:04 PM To: kernelnewbies@kernelnewbies.org Subject: linux segment Hi all: I print the cs ds and ss register in the user space, and it is same as the __USER_CS and __USER_DS which defined in kernel as 73 and 7b. In the kernel __KERNEL_CS and __KERNEL_DS defined as 60 and 68, but when I print this two value in my kernel module, I get 60 and 7b. Why ? It should be 60 and 68, shouldn't it? ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: linux segment
On Wed, Oct 24, 2012 at 7:04 PM, Fan Yang lljyang...@gmail.com wrote: Hi all: I print the cs ds and ss register in the user space, and it is same as the __USER_CS and __USER_DS which defined in kernel as 73 and 7b. In the kernel __KERNEL_CS and __KERNEL_DS defined as 60 and 68, but when I print this two value in my kernel module, I get 60 and 7b. Why ? It should be 60 and 68, shouldn't it? you're not manually switch the data segment, aren't you? -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
linux segment
Hi all: I print the cs ds and ss register in the user space, and it is same as the __USER_CS and __USER_DS which defined in kernel as 73 and 7b. In the kernel __KERNEL_CS and __KERNEL_DS defined as 60 and 68, but when I print this two value in my kernel module, I get 60 and 7b. Why ? It should be 60 and 68, shouldn't it? ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
