From: William Cohen <wcohen@redhat.com>
To: linux-kernel@vger.kernel.org
Subject: CONFIG_DEBUG_RODATA prevents kprobes from working on 2.6.22-rc2
Date: Wed, 23 May 2007 11:32:53 -0400 [thread overview]
Message-ID: <46545EA5.3020201@redhat.com> (raw)
The recent changes in the 2.6.22-rc2 kernel to the write protection of read only
data enable by CONFIG_DEBUG_RODATA prevents kprobes from working. At least on
the on i386 and x86_64 machine the mark_rodata_ro() function marks memory
starting from _text as read only. Thus, when kprobes attempts to write a break
point into a location in the kernel it faults.
There is a description of the problem at:
http://sources.redhat.com/bugzilla/show_bug.cgi?id=4531
Shouldn't mark_rodata_ro be less agressive when CONFIG_KPROBES is enabled? Or
should kprobes temporarily change the page to be writeable, set the break point,
and then return the page to read only?
-Will
next reply other threads:[~2007-05-23 15:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-23 15:32 William Cohen [this message]
2007-05-25 12:19 ` CONFIG_DEBUG_RODATA prevents kprobes from working on 2.6.22-rc2 Andi Kleen
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