Messages in this thread | | | Date | Sun, 20 Sep 2009 09:15:50 +0100 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH 1/2] ARM: Pass IFSR register to do_PrefetchAbort() |
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On Sat, Sep 19, 2009 at 12:03:16PM +0100, Russell King - ARM Linux wrote: > On Fri, Sep 18, 2009 at 11:55:42PM +0300, Kirill A. Shutemov wrote: > > It needed for proper prefetch abort handling on ARMv7. > > I think the only thing which is missing is an explaination about why > this is desirable given that only later CPUs can give this additional > information.
So you've posted it to the patch system, without further discussion here.
I think the solution is wrong - it makes instruction permission faults unnecessarily noisy, which is not what the decoding table is supposed to be doing. The decoding table's bad entries are there to catch those _unexpected_ cases.
Instead, I suggest that you have a look at this:
if (fsr & (1 << 11)) /* write? */ mask = VM_WRITE; else mask = VM_READ|VM_EXEC|VM_WRITE;
fault = VM_FAULT_BADACCESS; if (!(vma->vm_flags & mask)) goto out;
in __do_page_fault - if we are handling a prefetch abort, we really only want to check that the VMA has VM_EXEC permission, not that it can be read and written as well.
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