* CONFIG_DEBUG_RODATA prevents kprobes from working on 2.6.22-rc2
@ 2007-05-23 15:32 William Cohen
2007-05-25 12:19 ` Andi Kleen
0 siblings, 1 reply; 2+ messages in thread
From: William Cohen @ 2007-05-23 15:32 UTC (permalink / raw)
To: linux-kernel
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
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: CONFIG_DEBUG_RODATA prevents kprobes from working on 2.6.22-rc2
2007-05-23 15:32 CONFIG_DEBUG_RODATA prevents kprobes from working on 2.6.22-rc2 William Cohen
@ 2007-05-25 12:19 ` Andi Kleen
0 siblings, 0 replies; 2+ messages in thread
From: Andi Kleen @ 2007-05-25 12:19 UTC (permalink / raw)
To: William Cohen; +Cc: linux-kernel
William Cohen <wcohen@redhat.com> writes:
>
> 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?
The later.
-Andi
^ permalink raw reply [flat|nested] 2+ messages in thread
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2007-05-23 15:32 CONFIG_DEBUG_RODATA prevents kprobes from working on 2.6.22-rc2 William Cohen
2007-05-25 12:19 ` Andi Kleen
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