On Thu, 2005-08-18 at 16:07 +0200, Arjan van de Ven wrote:
> > Whilst there's no normal legitimite usage for it, it is useful for
> > debugging.
> > One thing I often do is create a circular log buffer, then fish it back
> > out by mmaping /dev/mem or /dev/kmem, and going by system.map offsets.
>
> Whilst there's no normal legitimite usage for it, it is useful for debugging.
> One thing I often do is create a circular log buffer, then fish it back
> out by mmaping /dev/mem or /dev/kmem, and going by system.map offsets.
> No, nobody could claim it was clean or elegant, but it *is* useful.
--Arjan van de Ven <[EMAIL PROTECTED]> wrote (on Saturday, August 13, 2005
18:50:10 +0200):
> On Fri, 2005-08-12 at 09:35 -0700, Linus Torvalds wrote:
>>
>> On Thu, 11 Aug 2005, Steven Rostedt wrote:
>> >
>> > Found the problem. It is a bug with mmap_kmem. The order of checks is
>> > wrong, s
On Wed, 2005-08-17 at 00:33 +0100, Alan Cox wrote:
>
> If you use /dev/mem you should know what you are doing. Even with
> "checks" dd if=/dev/zero of=/dev/mem will do bad things. Trapping
> obviously bad cases is fine, but complete sanity checking may actually
> be counter productive.
>
Sometim
On Maw, 2005-08-16 at 17:12 -0500, Greg Edwards wrote:
> mmap_mem suffers from a lack of proper checks as well. For example, on
> Altix page 0 of each node is reserved for prom and a read or write to it
> will cause an MCA. mmaping /dev/mem with offset 0 will nicely explode.
> Would adding a pfn_
On Sat, Aug 13, 2005 at 08:18:07PM +0200, Arjan van de Ven wrote:
| On Sat, 2005-08-13 at 10:37 -0700, Linus Torvalds wrote:
| > Actually, the more I looked at that mmap_kmem() function, the less I liked
| > it. Let's get that sucker fixed better first. It's still not wonderful,
| > but at least
On Mon, 15 Aug 2005, Steven Rostedt wrote:
> On Mon, 2005-08-15 at 21:16 -0400, Steven Rostedt wrote:
>
> > Sorry for the late reply, my wife's Grandmother just passed away a few
> > days ago (at 98 years old) and if I went within 6 feet of the computer
> > she would have killed me!
>
> Just t
On Mon, 2005-08-15 at 21:16 -0400, Steven Rostedt wrote:
> Sorry for the late reply, my wife's Grandmother just passed away a few
> days ago (at 98 years old) and if I went within 6 feet of the computer
> she would have killed me!
Just to clearify, "she" as in my wife would have killed me. Not he
On Sat, 2005-08-13 at 10:37 -0700, Linus Torvalds wrote:
>
> On Sat, 13 Aug 2005, Arjan van de Ven wrote:
> >
> > attached is the same patch but now with Steven's change made as well
>
> Actually, the more I looked at that mmap_kmem() function, the less I liked
> it. Let's get that sucker fixe
On Mon, 15 Aug 2005, Olaf Hering wrote:
>
> ARCH=um doesnt like your version, but mine.
Yours is broken. As is arch-um.
The fix would _seem_ to be something like the appended. Can you verify?
Linus
diff --git a/include/asm-um/page.h b/include/asm-um/page.h
--- a/include/a
On Mon, Aug 15, Jeff Dike wrote:
> On Mon, Aug 15, 2005 at 09:33:07PM +0200, Olaf Hering wrote:
> > ARCH=um doesnt like your version, but mine.
> >
> > drivers/char/mem.c:267: error: invalid operands to binary <<
> >
> > pfn = (__pa((u64)vma->vm_pgoff) << PAGE_SHIFT) >> PAGE_SHIFT;
>
>
On Mon, Aug 15, 2005 at 09:33:07PM +0200, Olaf Hering wrote:
> ARCH=um doesnt like your version, but mine.
>
> drivers/char/mem.c:267: error: invalid operands to binary <<
>
> pfn = (__pa((u64)vma->vm_pgoff) << PAGE_SHIFT) >> PAGE_SHIFT;
My page.h was missing some parens. Try the patch
On Sat, Aug 13, 2005 at 10:37:03AM -0700, Linus Torvalds wrote:
>
>
> On Sat, 13 Aug 2005, Arjan van de Ven wrote:
> >
> > attached is the same patch but now with Steven's change made as well
>
> Actually, the more I looked at that mmap_kmem() function, the less I liked
> it. Let's get that s
On Sat, 2005-08-13 at 10:37 -0700, Linus Torvalds wrote:
>
> On Sat, 13 Aug 2005, Arjan van de Ven wrote:
> >
> > attached is the same patch but now with Steven's change made as well
>
> Actually, the more I looked at that mmap_kmem() function, the less I liked
> it. Let's get that sucker fixe
On Sat, 13 Aug 2005, Arjan van de Ven wrote:
>
> attached is the same patch but now with Steven's change made as well
Actually, the more I looked at that mmap_kmem() function, the less I liked
it. Let's get that sucker fixed better first. It's still not wonderful,
but at least now it tries t
> I believe rootkit detectors, as well as some versions of ps (wchan
> field) use kmem.
ps doesn't use kmem, and besides, in 2.6 we export that directly in
proc. poking in /dev/mem or /dev/kmem is NOT something you "just do".
THere are lots of pitfalls, things like PCI space, memory sizes/holes,
On Sat, 2005-08-13 at 09:56 -0700, Linus Torvalds wrote:
>
> On Sat, 13 Aug 2005, Arjan van de Ven wrote:
> > >
> > > So I'd be perfectly happy to fix this, but I'd be even happier if we made
> > > the whole kmem thing a config variable (maybe even default it to "off").
> >
> > attached is a si
On 8/13/05, Arjan van de Ven <[EMAIL PROTECTED]> wrote:
> On Fri, 2005-08-12 at 09:35 -0700, Linus Torvalds wrote:
> >
> > On Thu, 11 Aug 2005, Steven Rostedt wrote:
> > >
> > > Found the problem. It is a bug with mmap_kmem. The order of checks is
> > > wrong, so here's the patch. Attached is a
On Sat, 13 Aug 2005, Arjan van de Ven wrote:
> >
> > So I'd be perfectly happy to fix this, but I'd be even happier if we made
> > the whole kmem thing a config variable (maybe even default it to "off").
>
> attached is a simple patch that does exactly this...
Well, you should have fixed the
On Fri, 2005-08-12 at 09:35 -0700, Linus Torvalds wrote:
>
> On Thu, 11 Aug 2005, Steven Rostedt wrote:
> >
> > Found the problem. It is a bug with mmap_kmem. The order of checks is
> > wrong, so here's the patch. Attached is a little program that reads the
> > System map looking for the varia
> Perfect! So it should be under CONFIG_DEBUG_KERNEL and default to off.
>
> So you can still debug and we raise the bar higher for rootkits,
> if they are the only other user.
>
> Too simple?
If you wanted to recompile your kernel to debug you could as well
add printks. But the whole point of
Hi Andi,
On Friday 12 August 2005 18:54, Andi Kleen wrote:
> Acessing vmalloc in /dev/mem would be pretty awkward. Yes it doesn't
> also work in mmap of /dev/kmem, but at least in read/write.
> There are quite a lot of scripts that use it for kernel debugging
> like dumping variables. And for that
On Fri, Aug 12, 2005 at 07:56:26PM +0200, Arjan van de Ven wrote:
> On Fri, 2005-08-12 at 18:54 +0200, Andi Kleen wrote:
> > Linus Torvalds <[EMAIL PROTECTED]> writes:
> > >
> > > I'm actually more inclined to try to deprecate /dev/kmem.. I don't think
> > > anybody has ever really used it except
On Fri, 2005-08-12 at 18:54 +0200, Andi Kleen wrote:
> Linus Torvalds <[EMAIL PROTECTED]> writes:
> >
> > I'm actually more inclined to try to deprecate /dev/kmem.. I don't think
> > anybody has ever really used it except for some rootkits.
>
> I don't think that's true.
got any examples ?
>
On Fri, 12 Aug 2005, Arjan van de Ven wrote:
> > Again, I'm asking to have it turned into a config option. Even default to
> > off. I understand that /dev/kmem shouldn't be in a production machine.
> > There's no reason for it. But it is nice to have when debugging the
> > kernel. I'll make the c
On Fri, 2005-08-12 at 13:07 -0400, Steven Rostedt wrote:
>
> On Fri, 12 Aug 2005, Dave Jones wrote:
> >
> > The above patches were in -mm for a while, though they didn't
> > have a config option, they just 'did it', and some of the
> > changes were a bit unclean, but I can polish that up if you're
On Fri, 12 Aug 2005, Dave Jones wrote:
>
> The above patches were in -mm for a while, though they didn't
> have a config option, they just 'did it', and some of the
> changes were a bit unclean, but I can polish that up if you're
> interested.
Again, I'm asking to have it turned into a config op
On Fri, 12 Aug 2005, Linus Torvalds wrote:
>
> I'm actually more inclined to try to deprecate /dev/kmem.. I don't think
> anybody has ever really used it except for some rootkits. It only exists
> in the first place because it's historical.
>
> We do need to support /dev/mem for X, but even that m
On Fri, Aug 12, 2005 at 09:35:03AM -0700, Linus Torvalds wrote:
> On Thu, 11 Aug 2005, Steven Rostedt wrote:
> >
> > Found the problem. It is a bug with mmap_kmem. The order of checks is
> > wrong, so here's the patch. Attached is a little program that reads the
> > System map looking for
Linus Torvalds <[EMAIL PROTECTED]> writes:
>
> I'm actually more inclined to try to deprecate /dev/kmem.. I don't think
> anybody has ever really used it except for some rootkits.
I don't think that's true.
> So I'd be perfectly happy to fix this, but I'd be even happier if we made
> the who
On Thu, 11 Aug 2005, Steven Rostedt wrote:
>
> Found the problem. It is a bug with mmap_kmem. The order of checks is
> wrong, so here's the patch. Attached is a little program that reads the
> System map looking for the variable modprobe_path. If it finds it, then
> it opens /dev/kmem for re
On Thu, 11 Aug 2005, Steven Rostedt wrote:
>
> Found the problem. It is a bug with mmap_kmem. The order of checks is
> wrong, so here's the patch.
> - if (!pfn_valid(vma->vm_pgoff))
> - return -EIO;
> val = (u64)vma->vm_pgoff << PAGE_SHIFT;
> vma->vm_pgoff = __pa(val)
On Thu, 2005-08-11 at 17:36 -0400, Steven Rostedt wrote:
> OK, I thought I use to know this. But what is the difference
> between /dev/kmem and /dev/mem. I thought that with /dev/kmem you could
> use the actual kernel addresses to read from.
>
> For example, if I wanted to read the current varia
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