From: fche@redhat.com (Frank Ch. Eigler)
To: Kevin Stafford <kevinrs@us.ibm.com>
Cc: systemtap@sources.redhat.com
Subject: Re: probes that access userspace
Date: Fri, 14 Oct 2005 16:23:00 -0000 [thread overview]
Message-ID: <y0mzmpc2hkt.fsf@tooth.toronto.redhat.com> (raw)
In-Reply-To: <E55D.2090005__29732.3145241991$1129302467$gmane$org@us.ibm.com>
kevinrs wrote:
> Especially when considering syscall tapset there are times when it
> is useful to access the value referenced by a user space
> pointer. [...]
> Is dwarf able to provide enough information to accurately detect a
> user space pointer reference? [...]
No, there appears to be no such qualification data in the debuginfo at
all. IIRC, the preprocessor makes __user go away before the compiler
ever sees it.
> [...] If this is not possible, I think it would be useful to
> enhance the language such that a probe script could explicitly
> notify the translator of a user space pointer access [...]
Perhaps. Other than the system call interfaces, is this difficulty
likely to arise often elsewhere?
> This will be especially beneficial for scripts probing user-space
> apps. Eventually, when SystemTap supports user-space probes, the
> translator will need to know how to follow pointers in user space.
Not quite. For user-level probes, there is no ambiguity: every
pointer dereference is in user space.
- FChE
next parent reply other threads:[~2005-10-14 16:23 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <E55D.2090005__29732.3145241991$1129302467$gmane$org@us.ibm.com>
2005-10-14 16:23 ` Frank Ch. Eigler [this message]
2005-10-14 19:10 ` Kevin Stafford
2005-10-14 19:21 ` Frank Ch. Eigler
2005-10-14 21:09 ` Jim Keniston
2005-10-14 22:15 ` Roland McGrath
2005-10-14 21:12 Kevin Stafford
-- strict thread matches above, loose matches on Subject: below --
2005-10-14 15:05 Kevin Stafford
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=y0mzmpc2hkt.fsf@tooth.toronto.redhat.com \
--to=fche@redhat.com \
--cc=kevinrs@us.ibm.com \
--cc=systemtap@sources.redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).