Messages in this thread |  | | Date | Mon, 9 Oct 2000 02:09:49 +0100 | From | Kenn Humborg <> | Subject | Re: Calling current() from interrupt context |
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On Mon, Oct 09, 2000 at 02:20:27AM +0200, Andi Kleen wrote: > On Mon, Oct 09, 2000 at 12:30:17AM +0200, Jamie Lokier wrote: > > Kenn Humborg wrote: > > > My feeling is that interrupt code has no business calling current(), > > > but I don't know the kernel well enough to be sure. Is there any > > > interrupt-level code that calls current() or is it a design > > > principle that it cannot be called? ... > > So if you can make the machine crash utterly when calling "current" in > > irq context, or when dereferencing the result, that would probably be a > > good thing :-)
Easily done. Because I don't really know how big we need to make the stacks yet, I've put a non-accessible guard page just below the interrupt stack. I can arrange for (SP & ~8192) to hit this page.
> > 2.4 TCP code relies on current being valid in a softirq. > > The m68k port which has a interrupt stack solves the problem by > loading current into a global register variable on all kernel entries. > x86-64 will likely do the same.
How do you tell GCC to stay away from that register when compiling the kernel without also making it unusable in userland?
Later, Kenn
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