insmod segfault

[Bruno Randolf <bruno.randolf@4g-systems.de>]

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hello!

i have problems with a kernel module: when i insmod it, i get a segmentation 
fault and "Unable to handle kernel paging request at virtual address 
00000004" oops, so as far as i understand it, it seems like relocation does 
not occur properly.

i can reproduce the problem with the attached simple test code. when i insmod 
only hello_module.o it works fine, but when i insmod the result of "ld" 
(mod.o) i get the error. so it seems the problem is with the linker. or am i 
using wrong compiler / linker flags or doing something stupid?

i compile with "gcc -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer 
- -fno-strict-aliasing -mno-abicalls -G 0 -fno-pic -mcpu=r4600 -mips2 
- -Wa,--trap -pipe -mlong-calls -I/usr/src/linux/include -O3 -D__KERNEL__ 
- -DLINUX -DMESSAGES"

and link with "ld -r -o mod.o hello_module.o b.o"

versions:
* au1500 CPU
* kernel version 2.4.21-pre4 from cvs
* gcc version 3.0.4 (also: gcc version 2.95.4)
* GNU ld version 2.12.90.0.1 20020307 Debian/GNU Linux
* insmod version 2.4.15

objdump -x mod.o says:

- ---

mod.o:     file format elf32-tradlittlemips
mod.o
architecture: mips:6000, flags 0x00000011:
HAS_RELOC, HAS_SYMS
start address 0x00000000
private flags = 10001001: [abi=O32] [mips2] [not 32bitmode]

Sections:
Idx Name          Size      VMA               LMA               File off  Algn
  0 .reginfo      00000018  00000000  00000000  00000034  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA, LINK_ONCE_SAME_SIZE
  1 .text         00000070  00000000  00000000  00000050  2**4
                  CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
  2 .rodata       00000030  00000000  00000000  000000c0  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  3 .modinfo      0000001c  00000000  00000000  000000f0  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  4 .data         00000000  00000000  00000000  00000110  2**4
                  CONTENTS, ALLOC, LOAD, DATA
  5 .sbss         00000000  00000000  00000000  00000110  2**0
                  ALLOC
  6 .bss          00000000  00000000  00000000  00000110  2**4
                  ALLOC
  7 .comment      00000024  00000000  00000000  00000110  2**0
                  CONTENTS, READONLY
  8 .pdr          00000040  00000000  00000000  00000134  2**2
                  CONTENTS, RELOC, READONLY
SYMBOL TABLE:
00000000 l    d  .reginfo       00000000
00000000 l    d  .text  00000000
00000000 l    d  *ABS*  00000000
00000000 l    d  *ABS*  00000000
00000000 l    d  .rodata        00000000
00000000 l    d  .modinfo       00000000
00000000 l    d  .data  00000000
00000000 l    d  .sbss  00000000
00000000 l    d  .bss   00000000
00000000 l    d  .comment       00000000
00000000 l    d  .pdr   00000000
00000000 l    d  *ABS*  00000000
00000000 l    d  *ABS*  00000000
00000000 l    d  *ABS*  00000000
00000000 l    d  *ABS*  00000000
00000000 l    d  *ABS*  00000000
00000000 l    df *ABS*  00000000 hello_module.c
00000000 l     O .modinfo       0000001b __module_kernel_version
00000000 l    df *ABS*  00000000 b.c
00000004 g     O .scommon       00000004 b
00000038 g     F .text  00000000 cleanup_module
00000000 g     F .text  00000000 init_module
00000000         *UND*  00000000 printk
00000004 g     O .scommon       00000004 glob_int


RELOCATION RECORDS FOR [.text]:
OFFSET   TYPE              VALUE
00000008 R_MIPS_HI16       .rodata
0000000c R_MIPS_LO16       .rodata
00000010 R_MIPS_HI16       printk
00000014 R_MIPS_LO16       printk
00000028 R_MIPS_HI16       glob_int
0000002c R_MIPS_LO16       glob_int
00000040 R_MIPS_HI16       .rodata
00000044 R_MIPS_LO16       .rodata
00000048 R_MIPS_HI16       printk
0000004c R_MIPS_LO16       printk


RELOCATION RECORDS FOR [.pdr]:
OFFSET   TYPE              VALUE
00000000 R_MIPS_32         init_module
00000020 R_MIPS_32         cleanup_module

- ---

thanks for any hints.

btw: this issue is not related to the one i posted about before ("au1500mm 
problems") - which is resolved already and was caused by a wrong 
initialization of the dual PHY ethernet hardware.

bruno
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[-- Attachment #2: b.c --]
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int b;

[-- Attachment #3: hello_module.c --]
[-- Type: text/x-csrc, Size: 205 bytes --]

#define MODULE
#include <linux/module.h>

int glob_int;

int init_module(void) {
	printk("<1>hello world\n");
	glob_int = 0;
	return 0;
}

void cleanup_module(void) {
	printk("<1>goodby cruel world\n");
}

[-- Attachment #4: Makefile --]
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CC := gcc
CFLAGS := -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -fno-strict-aliasing -mno-abicalls -G 0 -fno-pic -mcpu=r4600 -mips2 -Wa,--trap -pipe -mlong-calls -I/usr/src/linux/include -O3 -D__KERNEL__ -DLINUX -DMESSAGES

all: hello_module.o b.o

	ld -r -o mod.o hello_module.o b.o

clean:
	rm hello_module.o b.o