2012/10/28 Fan Yang <lljyangfan@xxxxxxxxx>
Hi Jun Hu2012/10/27 Jun Hu <duanshuidao@xxxxxxxxxxx>Can you post out your codes ?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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There is my code which run at the user space:1 #include<stdio.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 115ds 7b 123ss 7b 123es 7b 123fs 0 0gs 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 is1 #include<linux/init.h>2 #include<linux/kernel.h>3 #include<linux/module.h>45 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");2223 }2425 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));3132 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 }3940 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 96ds 7b 123ss 68 104es 7b 123fs d8 216gs 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?
ThanksFan
sorry, the kernel define the KERNEL_DS as 68, but I get 7b in my machine.
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