2011-05-02 09:11:41     Module Example, Null Pointer Access?

2011-05-02 09:11:41     Module Example, Null Pointer Access?

rifat tursen (UNITED STATES)

Message: 100340   

Hello,

I am learning about kernel modules. I have compiled the sample module example from the wiki but whenever I load the module I get a null pointer access. I must be missing something very basic. To make matters more confusing for me, I have tried loading an example module from the Linux Device Drivers and it run without problems.

My platform is BF537 Stamp and I am using the 2010R1-RC5 distribution. I attach the error log that I receive when I issue the command "insmod sample_module.ko"

thank you for your help

rifat

root:/home> insmod sample_module.ko

NULL pointer access                                                           

Kernel OOPS in progress                                                       

Deferred Exception context                                                    

CURRENT PROCESS:                                                              

COMM=insmod PID=178  CPU=0                                                    

TEXT = 0x02c00040-0x02c4d3c0        DATA = 0x02c4d3e0-0x02c60570              

BSS = 0x02c60570-0x02c61f30  USER-STACK = 0x02c6af5c                         

                                                                              

return address: [0x000ad9d6]; contents of:                                    

0x000ad9b0:  6000  0127  0010  e410  fffe  2fee  3209  05fc                   

0x000ad9c0:  3220  0167  6fa6  af4d  3210  6fc4  0c45  1825                   

0x000ad9d0:  0000  0000  0000 [9968] 0c00  181a  0000  0000                   

0x000ad9e0:  0000  e417  fffe  2005  6cc5  9968  0c00  1810                   

                                                                              

ADSP-BF537-0.2(Detected 0.3) 500(MHz CCLK) 125(MHz SCLK) (mpu off)            

Linux version 2.6.34.7-ADI-2010R1 (root@eight) (gcc version 4.3.5 (ADI-2010R1-R0

                                                                              

SEQUENCER STATUS:               Tainted: P                                    

SEQSTAT: 00002027  IPEND: 8008  IMASK: ffff  SYSCFG: 0006                    

  EXCAUSE   : 0x27                                                            

  physical IVG3 asserted : <0xffa007d8> { _trap + 0x0 }                       

  physical IVG15 asserted : <0xffa010bc> { _evt_system_call + 0x0 }           

  logical irq   6 mapped  : <0xffa003ec> { _bfin_coretmr_interrupt + 0x0 }    

  logical irq  10 mapped  : <0x000bdfc0> { _bfin_rtc_interrupt + 0x0 }        

  logical irq  18 mapped  : <0x000a99d4> { _bfin_serial_dma_rx_int + 0x0 }    

  logical irq  19 mapped  : <0x000a972c> { _bfin_serial_dma_tx_int + 0x0 }    

  logical irq  24 mapped  : <0x000b94f0> { _bfin_mac_interrupt + 0x0 }        

RETE: <0x00000000> /* Maybe null pointer? */                                 

RETN: <0x02b83de4> /* kernel dynamic memory (maybe user-space) */            

RETX: <0x00000480> /* Maybe fixed code section */                            

RETS: <0x000acb8c> { ___driver_attach + 0x14 }                               

PC  : <0x000ad9d6> { _platform_match + 0x1a }                                

DCPLB_FAULT_ADDR: <0x00000001> /* Maybe null pointer? */                      

ICPLB_FAULT_ADDR: <0x000ad9d6> { _platform_match + 0x1a }                     

PROCESSOR STATE:                                                              

R0 : 00185c04    R1 : 02ad6d00    R2 : 00000000    R3 : 00000180             

R4 : 02c1acb2    R5 : 02ad6d00    R6 : 02b83e28    R7 : 00000000             

P0 : 02940d80    P1 : 02ad6d00    P2 : 00185c04    P3 : 02ad6d00             

P4 : 00185bfc    P5 : 00000001    FP : 02938200    SP : 02b83d08             

LB0: ffa01808    LT0: ffa01808    LC0: 00000000                              

LB1: 000949e0    LT1: 000949d4    LC1: 00000000                              

B0 : 00000000    L0 : 00000000    M0 : 00000000    I0 : 02aeae34             

B1 : 00000000    L1 : 00000000    M1 : 00000000    I1 : 02abc8ec             

B2 : 00000000    L2 : 00000000    M2 : 00000000    I2 : 00000000             

B3 : 00000000    L3 : 00000000    M3 : 00000000    I3 : 00000000             

A0.w: 00000000   A0.x: 00000000   A1.w: 00000000   A1.x: 00000000             

USP : 02c6ae5c  ASTAT: 00003005                                               

                                                                              

Hardware Trace:                                                               

   0 Target : <0x00003efc> { _trap_c + 0x0 }                                  

     Source : <0xffa0076c> { _exception_to_level5 + 0xa4 } CALL pcrel         

   1 Target : <0xffa006c8> { _exception_to_level5 + 0x0 }                     

     Source : <0xffa0057c> { _bfin_return_from_exception + 0x20 } RTX         

   2 Target : <0xffa0055c> { _bfin_return_from_exception + 0x0 }              

     Source : <0xffa00620> { _ex_trap_c + 0x74 } JUMP.S                       

   3 Target : <0xffa005ac> { _ex_trap_c + 0x0 }                               

     Source : <0xffa00484> { _ex_workaround_261 + 0x1c } JUMP.S               

   4 Target : <0xffa00468> { _ex_workaround_261 + 0x0 }                       

     Source : <0xffa00840> { _trap + 0x68 } JUMP (P4)                         

   5 Target : <0xffa007f6> { _trap + 0x1e }                                   

     Source : <0xffa007f2> { _trap + 0x1a } IF CC JUMP pcrel                  

   6 Target : <0xffa007d8> { _trap + 0x0 }                                    

      FAULT : <0x000ad9d6> { _platform_match + 0x1a } R0 = B[P5] (X)          

     Source : <0xffa0057c> { _bfin_return_from_exception + 0x20 } RTX         

   7 Target : <0xffa0055c> { _bfin_return_from_exception + 0x0 }              

     Source : <0xffa0047a> { _ex_workaround_261 + 0x12 } IF !CC JUMP pcrel    

   8 Target : <0xffa00468> { _ex_workaround_261 + 0x0 }                       

     Source : <0xffa00840> { _trap + 0x68 } JUMP (P4)                         

   9 Target : <0xffa007f6> { _trap + 0x1e }                                   

     Source : <0xffa007f2> { _trap + 0x1a } IF CC JUMP pcrel                  

  10 Target : <0xffa007d8> { _trap + 0x0 }                                    

     Source : <0x000ad9d4> { _platform_match + 0x18 } NOP                     

  11 Target : <0x000ad9bc> { _platform_match + 0x0 }                          

     Source : <0x000acb8a> { ___driver_attach + 0x12 } CALL (P2)              

  12 Target : <0x000acb78> { ___driver_attach + 0x0 }                         

     Source : <0x000ac476> { _bus_for_each_dev + 0x42 } CALL (P5)             

  13 Target : <0x000ac468> { _bus_for_each_dev + 0x34 }                       

     Source : <0x000ac484> { _bus_for_each_dev + 0x50 } IF !CC JUMP pcrel (BP)

  14 Target : <0x000ac480> { _bus_for_each_dev + 0x4c }                       

     Source : <0x00114d02> { _klist_next + 0x62 } RTS                         

  15 Target : <0x00114cf8> { _klist_next + 0x58 }                             

     Source : <0x00114cf2> { _klist_next + 0x52 } IF CC JUMP pcrel            

Kernel Stack                                                                  

Stack info:                                                                   

SP: [0x02b83cc8] <0x02b83cc8> /* kernel dynamic memory (maybe user-space) */ 

Memory from 0x02b83cc0 to 02b84000                                           

02b83cc0: 02029060  0202908c [00000000] 02029620  020297a0  02029060  02b83d08

02b83ce0: 00000000  ffa00770  00176000  00008008  00002027  02ad6d00  02c1acb2

02b83d00: 00000001  00000480  00000480  00008008  00002027  00000000  02b83de4

02b83d20: 000ad9d6 <000acb8c> 00185c04  00003005  000949e0  ffa01808  000949d4

02b83d40: 00000000  00000000  00000000  00000000  00000000  00000000  00000000

02b83d60: 00000000  00000000  00000000  00000000  00000000  00000000  00000000

02b83d80: 00000000  00000000  00000000  00000000  02abc8ec  02aeae34  02c6ae5c

02b83da0: 00000001  00185bfc  02ad6d00  00185c04  02ad6d00  02940d80  00000000

02b83dc0: 02ad6d00  02c1acb2  00000180  00000000  02ad6d00  00185c04  00185c04

02b83de0: 00000006  00000000  0007a2c2  02938200 <000acb8c> 00185c04  02ad6d00

02b83e00: 02c1acb2  02b83e08  02938200 <000ac478> 000acb78  0018defc  00000000

02b83e20: 0018defc  00090e8e  020055d8  02037530  000ac96e  02ad6d34  02b90004

02b83e40: 00000000  000abe76  02b83e68  000abeb0  000acb78  000abece  00000000

02b83e60: 000002d0  001431ac  02ad6cf0  02070800  000ace10  02ad6d34  0017400c

02b83e80: 02b90004  00008e29  02c1acb2  00000280  02921720 <00001028> 02ad6d34

02b83ea0: 0017002e  02b90004  00008e29  00000000  00000000  000254a8  02ad6d34

02b83ec0: 02c6ae68  00030478  02ad6d34  00000080  0000002e  02b90004  00008e29

02b83ee0: 2938a066  000452ea  00000000  020b01c0  ffffe000 <ffa0097a> 000303d4

02b83f00: 00000000  ffffe000  00000104  02949ff3  02029620  00000001  00008e29

02b83f20: 00000104  02c02e0c  00008000  00002000  00000000  02b84000  02c02e0c

02b83f40: 02c1b52a  ffa01120  02001044  02991fcf  02c0ca05  02991fc4  02c0ca04

02b83f60: 00000000  00000000  00000000  00000000  00000000  00000000  00000000

02b83f80: 00000000  00000000  00000000  00000000  00000000  00000000  00000000

02b83fa0: 00000000  00000000  00000000  00000000  02c6af6c  02c6ae5c  02c6ae68

02b83fc0: 02c6af60  0000002e  02b98e2d  02b99ff4  00000080  02b90004  02c60110

02b83fe0: 02c1acb2  00008e29  02c60110  00008e29  02b90004  02b90004  00000080

Return addresses in stack:                                                    

    address : <0x000acb8c> { ___driver_attach + 0x14 }                        

    address : <0x000acb8c> { ___driver_attach + 0x14 }                        

    address : <0x000ac478> { _bus_for_each_dev + 0x44 }                       

    address : <0x00001028> { _do_one_initcall + 0x28 }                        

    address : <0xffa0097a> { _system_call + 0x6a }                            

Modules linked in: sample_module(+) [last unloaded: hello]                    

Kernel panic - not syncing: Kernel exception                                  

Hardware Trace:                                                               

Stack info:                                                                   

SP: [0x02b83c2c] <0x02b83c2c> /* kernel dynamic memory (maybe user-space) */ 

Memory from 0x02b83c20 to 02b84000                                           

02b83c20: 0000000b  02b83c2c  00000013 [00144ed0] 001162ea  02b83d08  00144ed0

02b83c40: 001793ce  001793ce  02b83c5c  00004334  02b83d08  00008008  02b83d08

02b83c60: 0000003f  ffffffff  00000044  0003000b  0000ce6c  00189620  02029620

02b83c80: 0202964c  00000000  00000001  001868fc  00000000  002625a0  02b83cc8

02b83ca0: 0202908c  00186928  02029094  02b83cd4  02b83cd8  0000ce08  001868fc

02b83cc0: 02029060  0202908c  00000000  02029620  020297a0  02029060  02b83d08

02b83ce0: 00000000  ffa00770  00176000  00008008  00002027  02ad6d00  02c1acb2

02b83d00: 00000001  00000480  00000480  00008008  00002027  00000000  02b83de4

02b83d20: 000ad9d6 <000acb8c> 00185c04  00003005  000949e0  ffa01808  000949d4

02b83d40: 00000000  00000000  00000000  00000000  00000000  00000000  00000000

02b83d60: 00000000  00000000  00000000  00000000  00000000  00000000  00000000

02b83d80: 00000000  00000000  00000000  00000000  02abc8ec  02aeae34  02c6ae5c

02b83da0: 00000001  00185bfc  02ad6d00  00185c04  02ad6d00  02940d80  00000000

02b83dc0: 02ad6d00  02c1acb2  00000180  00000000  02ad6d00  00185c04  00185c04

02b83de0: 00000006  00000000  0007a2c2  02938200 <000acb8c> 00185c04  02ad6d00

02b83e00: 02c1acb2  02b83e08  02938200 <000ac478> 000acb78  0018defc  00000000

02b83e20: 0018defc  00090e8e  020055d8  02037530  000ac96e  02ad6d34  02b90004

02b83e40: 00000000  000abe76  02b83e68  000abeb0  000acb78  000abece  00000000

02b83e60: 000002d0  001431ac  02ad6cf0  02070800  000ace10  02ad6d34  0017400c

02b83e80: 02b90004  00008e29  02c1acb2  00000280  02921720 <00001028> 02ad6d34

02b83ea0: 0017002e  02b90004  00008e29  00000000  00000000  000254a8  02ad6d34

02b83ec0: 02c6ae68  00030478  02ad6d34  00000080  0000002e  02b90004  00008e29

02b83ee0: 2938a066  000452ea  00000000  020b01c0  ffffe000 <ffa0097a> 000303d4

02b83f00: 00000000  ffffe000  00000104  02949ff3  02029620  00000001  00008e29

02b83f20: 00000104  02c02e0c  00008000  00002000  00000000  02b84000  02c02e0c

02b83f40: 02c1b52a  ffa01120  02001044  02991fcf  02c0ca05  02991fc4  02c0ca04

02b83f60: 00000000  00000000  00000000  00000000  00000000  00000000  00000000

02b83f80: 00000000  00000000  00000000  00000000  00000000  00000000  00000000

02b83fa0: 00000000  00000000  00000000  00000000  02c6af6c  02c6ae5c  02c6ae68

02b83fc0: 02c6af60  0000002e  02b98e2d  02b99ff4  00000080  02b90004  02c60110

02b83fe0: 02c1acb2  00008e29  02c60110  00008e29  02b90004  02b90004  00000080

Return addresses in stack:                                                    

    address : <0x000acb8c> { ___driver_attach + 0x14 }                        

    address : <0x000acb8c> { ___driver_attach + 0x14 }                        

    address : <0x000ac478> { _bus_for_each_dev + 0x44 }                       

    address : <0x00001028> { _do_one_initcall + 0x28 }                        

    address : <0xffa0097a> { _system_call + 0x6a }

QuoteReplyEditDelete

2011-05-02 12:55:34     Re: Module Example, Null Pointer Access?

Mike Frysinger (UNITED STATES)

Message: 100342   

post the actual code you're compiling and loading

QuoteReplyEditDelete

2011-05-02 14:30:36     Re: Module Example, Null Pointer Access?

rifat tursen (UNITED STATES)

Message: 100344   

Hello, the code is taken directly from the wiki

#include <linux/init.h>

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/device.h>

#include <linux/platform_device.h>

MODULE_DESCRIPTION("sample module");

MODULE_LICENSE("GPL");

static int sample_module_drv_probe(struct device *dev)

{

    printk(KERN_DEBUG "probe sample module device\n");

    return 0;

}

static int sample_module_drv_remove(struct device *dev)

{

    printk(KERN_DEBUG "remove sample module device\n");

    return 0;

}

static struct device_driver sample_module_driver = {

    .name           = "sample_module",

    .bus            = &platform_bus_type,

    .probe          = sample_module_drv_probe,

    .remove         = sample_module_drv_remove,

};

static int __init sample_module_init(void)

{

    printk(KERN_DEBUG "init sample module device\n");

    return driver_register(&sample_module_driver);

}

static void __exit sample_module_cleanup(void)

{

    printk(KERN_DEBUG "cleanup sample module device\n");

    driver_unregister(&sample_module_driver);

}

module_init(sample_module_init);

module_exit(sample_module_cleanup);

thanks a lot

QuoteReplyEditDelete

2011-05-02 14:40:35     Re: Module Example, Null Pointer Access?

Mike Frysinger (UNITED STATES)

Message: 100345   

that is the old way for registering a platform device driver.  look at drivers/watchdog/bfin_wdt.c as a simple way of registering a platform driver.

QuoteReplyEditDelete

2011-05-02 15:18:33     Re: Module Example, Null Pointer Access?

rifat tursen (UNITED STATES)

Message: 100346   

okey,

thanks a lot for the info. I will change the code according to this.

QuoteReplyEditDelete

2011-05-05 21:53:52     Re: Module Example, Null Pointer Access?

Sergio Morales (COLOMBIA)

Message: 100448   

hi Mike, could you upgrade the page to create modules with a smaller version of watchdog code please?, that would be really helpful and could prevent me from doing many stupid questions.

thanks in advance