Re: [1/2] 2.6.22-rc5: known regressions with patches

Dave Jones
2007-06-20T23:38:18Z

On Wed, Jun 20, 2007 at 04:15:53PM -0700, Arjan van de Ven wrote:
> On Wed, 2007-06-20 at 19:07 -0400, Dave Jones wrote:
> > On Wed, Jun 20, 2007 at 03:38:06PM -0700, Linus Torvalds wrote:
> >
> > > And yes, that patch already got merged. However, the patch to *allow*
> > > Kprobes with DEBUG_RODATA is not, and will not be. It's not a regression,
> > > and quite frankly, I don't think I would even want that patch.
> > >
> > > Kprobes fundamntally disagrees with DEBUG_RODATA, there's no point in
> > > "working around it". Better just admit it.
> >
> > Surely the fundamental disagreement is only due to DEBUG_RODATA
> > covering write-protection of both .text, and .rodata ?
> > I can see value in having a kernel that supports kprobes, whilst
> > at the same point, raising red flags if something writes into
> > a const string. With my distro kernel maintainer hat on, I always
> > hate these 'pick one' decisions, because I always get convincing
> > arguments from proponents of both sides.
> >
> > Was it always this way? I thought DEBUG_RODATA initially just
> > covered, well.. rodata. And kprobes only wants to change .text
> > doesn't it ?
>
> no this got "fixed" recently. It used to only cover data.
> Andi merged a patch to make it cover text too.. imo we should reverse
> that, or make the check better and not have it cover text if kprobes is
> active. I can do the later if people are ok with that, it's
> approximately 3 lines of code.

Having the text as a separate option makes sense to me.
(Or at the least we should rename DEBUG_RODATA, as it's now misleading).

Dave

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