Messages in this thread | | | Subject | Re: The disappearing sys_call_table export. | From | Terje Eggestad <> | Date | 08 May 2003 14:54:35 +0200 |
| |
What really gets to me is that *you* wrote in (http://www.kernel.org/pub/linux/kernel/v2.5/ChangeLog-2.5.41):
3. Intercept system calls OProfile (and intel's vtune which is similar in function) used to do this; however what they really need is a notification on certain events (exec() mostly). The way modules do this is store the original function pointer, install a new one that calls the old one after storing whatever info they need. This mechanism breaks badly in the light of multiple such modules doing this versus modules unloading/uninstalling their handlers (by restoring their saved pointer that may or may not point to a valid handler anymore). Eg the use of the export in this just a bandaid due to lack of a proper mechanism, and also incorrect and crash prone.
So what you're saying here is not that you object to having people doing syscall hooks, just that operating on the syscall_table symbol directly is error prone (to which I wholeheartedly agree).
Then you reject a "proper mechanism".....
TJ
On Thu, 2003-05-08 at 11:59, Arjan van de Ven wrote: > On Thu, May 08, 2003 at 11:58:33AM +0200, Terje Eggestad wrote: > > I guess something like this: > > > > typedef int (*syscall_hook_t)(void * arg1, void * arg2, void * arg3, > > void * arg4, void * arg5, void * arg6); > > > > #define HOOK_IN_FLAG 0x1 > > #define HOOK_OUT_FLAG 0x2 > > > > opaquehandle = int register_syscall_hook(int syscall_nr, syscall_hook_t > > hook_function, int flags); > > int unregister(int opaquehandle); > > > > I'd make a stab at it if I knew that it stood a chance of getting > > accepted. > > I dont think it has. -- _________________________________________________________________________
Terje Eggestad mailto:terje.eggestad@scali.no Scali Scalable Linux Systems http://www.scali.com
Olaf Helsets Vei 6 tel: +47 22 62 89 61 (OFFICE) P.O.Box 150, Oppsal +47 975 31 574 (MOBILE) N-0619 Oslo fax: +47 22 62 89 51 NORWAY _________________________________________________________________________
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |