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From: bruce@cs.usyd.edu.au (Bruce Janson)
To: linux-kernel@vger.kernel.org
Subject: the fault address of a traced process
Date: Sun, 30 Sep 2001 22:47:06 +1100	[thread overview]
Message-ID: <20010930125931Z273463-760+18683@vger.kernel.org> (raw)

One process traces another.
When the traced process tries to read, write or execute an unmapped
address it is stopped with a SIGSEGV signal.
The tracer now wants to determine the traced process' faulted address.
According to the (2.2.19) kernel source

  .../arch/i386/mm/fault.c:do_page_fault()

such a fault in user mode causes the offending address and error code to
be saved in

  tsk->tss.cr2

and

  tsk->tss.error_code

respectively.  There do not appear to be ptrace() or /proc hooks
to extract this data directly.  In earlier unices extraction of this
data would have required grubbing around in /dev/kmem using the
kernel namelist as a guide.
How should a tracer extract this information under a current
(2.2.*, 2.4.*) Linux?

             reply	other threads:[~2001-09-30 12:59 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-09-30 11:47 Bruce Janson [this message]
2001-10-01  0:53 ` Jeff Dike

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