From: Kevin Stafford <kevinrs@us.ibm.com>
To: systemtap@sources.redhat.com
Subject: Re: probes that access userspace
Date: Fri, 14 Oct 2005 21:12:00 -0000 [thread overview]
Message-ID: <43501F51.2090002@us.ibm.com> (raw)
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--
Kevin Stafford
DES 2 | MS 2M3
Beaverton - OR
Linux Technology Center
IBM Systems & Technology
Phone: 1-503-578-3039
Email: kevinrs@us.ibm.com
[-- Attachment #2: Re: probes that access userspace --]
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From: Kevin Stafford <kevinrs@us.ibm.com>
To: "Frank Ch. Eigler" <fche@redhat.com>
Subject: Re: probes that access userspace
Date: Fri, 14 Oct 2005 14:10:53 -0700
Message-ID: <43501EDD.2070003@us.ibm.com>
Frank Ch. Eigler wrote:
>Hi -
>
>[...]
>
>>Being that for user-level probes, every pointer dereference is in
>>user space, I believe it is certain that this difficulty will arise
>>elsewhere.
>>
>>
>
>Perhaps I was being unclear. The "difficulty" I was referring to was
>the ambiguity in whether an ordinary or special dereference operation
>is required for any given $var->field expression.
>
Understood. The "difficulty" I was referring to was the necessity to
write embedded
C auxiliary functions to access user-space pointer arguments.
>[...]It is this ambiguity that could be resolved by the user via a
>language extension, and it is this ambiguity that does not exist for
>variables that show up in user-level probes.
>
>
Agreed. A language extension would require the script writer to know
where the
pointer was looking, thus eliminating any ambiguity or difficulty. Do we
agree that
this would be a useful mechanism for user-level probes and the syscall
tapset, among
possible others?
>- FChE
>
>
>
--
Kevin Stafford
DES 2 | MS 2M3
Beaverton - OR
Linux Technology Center
IBM Systems & Technology
Phone: 1-503-578-3039
Email: kevinrs@us.ibm.com
next reply other threads:[~2005-10-14 21:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-14 21:12 Kevin Stafford [this message]
[not found] <E55D.2090005__29732.3145241991$1129302467$gmane$org@us.ibm.com>
2005-10-14 16:23 ` Frank Ch. Eigler
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
-- strict thread matches above, loose matches on Subject: below --
2005-10-14 15:05 Kevin Stafford
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