linux-kernel - Re: System call instrumentation

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Mon, 5 May 2008 14:28:35 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
Cc:	linux-kernel@...r.kernel.org, systemtap@...rces.redhat.com,
	"Frank Ch. Eigler" <fche@...hat.com>
Subject: Re: System call instrumentation


* Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca> wrote:

> Ideally, I'd like to have this kind of high-level information :
> 
> event name : kernel syscall
> syscall name : open
> arg1 (%s) : "somefile"    <-----
> arg2 (%d) : flags
> arg3 (%d) : mode
> 
> However, "somefile" has to be read from userspace. With the protection 
> involved, it would cause a performance impact to read it a second time 
> rather than tracing the string once it's been copied to kernel-space.

performance is a secondary issue here, and copies are fast anyway _if_ 
someone wants to trace a syscall. (because the first copy brings the 
cacheline into the cache, subsequent copies are almost for free compared 
to the first copy)

	Ingo
--
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/