Hi there. I'd like to know if there is a way to export the sys_call_table symbol in the kernel 2.6.28.7. i know it's a bad thing to do but I need to to this for a didactical purpose. Here follows what I've tried. First of all, I made the sys_call_table writable modifing the section definition in the following assembly file: *----- file: arch/x86/kernel/entry_32.S ----* -.section .rodata, "a" +.section .data, "aw" Then I exported the symbol: *---- file: kernel/kallsyms.c ----* +extern void *sys_call_table; +EXPORT_SYMBOL(sys_call_table); So, I built the kernel and tried to load a basic module that reads the address of the read sys_call and substitutes it with a dummy wrapper. The module compiles and loads without any complaint, but then I get this error: BUG: unable to handle kernel paging request at c022bd98 ... Oops: 0003 [#1]SMP ... I understood that this is due to this line: -> sys_call_table[__NR_read] = my_read; i.e. the istruction that tries to modify the sys_call_table. If I get rid of it and just leave the instruction that reads the address of the read system call: -> o_read = sys_call_table[__NR_read]; the module works without crashing. Can anyone explain this to me? What did I do wrong? Thanks, Donato -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
