It's easier to create in interposer library which will look somewhat
like this:
/*
* pthread_mutex_lock -- intercept pthread_mutex_lock
*/
int pthread_mutex_lock(pthread_mutex_t *mutex){
static void *actual_pthread_mutex_lock = NULL;
if (actual_pthread_mutex_lock == NULL) {
actual_pthread_mutex_lock = dlsym(RTLD_NEXT,
"pthread_mutex_lock");
assert(actual_pthread_mutex_lock != NULL);
}
return ((int (*)(pthread_mutex_t *))
actual_pthread_mutex_lock)(mutex);
}
This is nominally limited to user-space, but can happily
generate all the errors you'd ever want (;-))
You can do the same thing for kernel modules, by inserting
a module with the error injection code in front of a
hacked regular module.
--dave
Robert Milkowski <mi...@task.gda.pl> writes
> Hello Jonathan,
>
> Saturday, May 30, 2009, 12:11:58 AM, you wrote:
>
> JA> On Sat, May 30, 2009 at 12:04:50AM +0200, Pavel Filipensky wrote:
>>> Hi,
>>>
>>> is it somehow possible to use Dtrace for error injection in a kernel module?
>>>
>>> Something like changing:
>>> - function return value
>>> - value of a register
>>>
>>> If not, can it be implemented?
>
> JA> No; it violates the basic safety constraints of dtrace(1M).
>
> I don't know... it allows to change some things like n structure in
> user space which is filled in in kernel by syscall, but then doesn't
> allow to change an return code. What I'm trying to say is that it
> already allows to shoot yourself in foot or fix rather help you (like
> changing uname output being a classic example now) but doesn't allow
> you to do so with other cases...
>
> I think it would be very useful if it wuld allow to assign values to
> argN (args[N}).
>
--
David Collier-Brown | Always do right. This will gratify
Sun Microsystems, Toronto | some people and astonish the rest
dav...@sun.com | -- Mark Twain
cell: (647) 833-9377, home (416) 223-8968, bridge (877) 385-4099 code
506 9191#
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