On Wed, Feb 26, 2003 at 05:31:51PM +0200, Muli Ben-Yehuda wrote:
>
> On Wed, Feb 26, 2003 at 03:47:43PM +0000, Dr William Bland wrote:
>
> > Hello all,
> > I wrote my first module just a few days ago, so I'm very new to
> > all this. I want to be able to perform a kernel symbol lookup from within
> > a module, i.e. to have a function of one argument, a char*, returning a
> > void* (or whatever) where the input is the name of the kernel symbol
> > (e.g. "printk") and the output is the address that the symbol refers to
> > (e.g. the address of the printk function).
>
> If you're using a late 2.5 version of the kernel, take a look at
> kernel/kallsyms.c, kallsyms_lookup().
>
I'm using 2.4 at the moment, but thanks for the pointer.
> > Someone pointed me towards query_module(NULL, ...), but as far as I can
> > see this is intended to be called from user space programs and won't work
> > from within a module. Is this correct?
>
> This is correct. However, by looking at the sys_query_module code in
> the kernel, you can find out how to accomplish what you want to
> do. Specifically, take a look at kernel/module.c, qm_symbols(), which
> is what whoever pointed you probably meant. This call is in 2.4, but
> doesn't exist in 2.5.
>
Thanks for the pointer. I took a look at the source and copied some of it
into my source. I ended up with:
static void* kernel_symbol_lookup( char* name ) {
struct module *mod;
mod = &kernel_module;
size_t i;
struct module_symbol *s;
s = mod->syms;
for (i=0; i < mod->nsyms; ++i, ++s) {
if( strcmp( s->name, name ) == 0 )
return( (void*)s->value );
}
return (void*)NULL;
}
which looks good to me, except that kernel_module is undefined. I copied
the definition of that into my module as well, and now it compiles but
when I try to insmod I have unresolved symbols like __start___ksymtab
(these symbols are used in the definition of kernel_module).
I don't know what to do about that since kernel/module.c defines the above
symbol as:
extern struct module_symbol __start___ksymtab[];
which is what I have done in my module but it doesn't work there.
Any ideas?
Cheers,
Bill.
--
Dr. William Bland. Computer Programmer, UK.
www.abstractnonsense.com
--
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