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

Arjan van de Ven
2007-06-20T23:19:58Z

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.