[PATCH] Treat ISI faults as read faults on classic 32-bit PowerPC

[Segher Boessenkool]

>> Should you really be testing VM_READ|VM_WRITE, or should it just
>> be VM_READ?
>
> We test VM_READ | VM_WRITE | VM_EXEC in the read case below, and that
> is because we have no HPTE encoding to say "writable but not readable"
> or "executable but not readable".  Similarly we have no encoding to
> say "writable but not executable" on classic processors, so if you
> have just VM_WRITE set, you get a page that is readable, writable and
> executable.

Ah yes.  I thought "executable requires readable", but
that is with the CPU its flags, not the Linux flags.

Would it be a good idea to map Linux flags to CPU flags
somewhere early in this function?  It might simplify some
code, and things certainly would become more readable.


Segher