linux-kernel - Re: [RFC][PATCH] Make ftrace able to trace function return

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 30 Oct 2008 19:30:20 +0100
From:	"Frédéric Weisbecker" <fweisbec@...il.com>
To:	"Ingo Molnar" <mingo@...e.hu>
Cc:	"Steven Rostedt" <rostedt@...dmis.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] Make ftrace able to trace function return

2008/10/30 Ingo Molnar <mingo@...e.hu>:
> hm, are you aware of the -finstrument-functions feature of GCC?
>
> that feature generates such entry points at build time:
>
>                   void __cyg_profile_func_enter (void *this_fn,
>                                                  void *call_site);
>                   void __cyg_profile_func_exit  (void *this_fn,
>                                                  void *call_site);

Oh I didn't know it.
But wouldn't it conflict with the -pg used for mcount in ftrace?

> this might be faster/cleaner than using a trampoline approach IMO.

Yes, oubviously!

> OTOH, entry+exit profiling has about double the cost of just entry
> profiling - so maybe there should be some runtime flexibility there.
> Plus the same recordmcount trick should be used to patch up these
> entry points to NOP by default.

Yes that's right. Hm I don't know what to do since there is already mcount....
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/