According to Arm documentation, the exception-handling routine
needs to zero the following bits in FPEXC:
DEX, IDF, IXF, UFF, OFF, DZF and IOF
In seL4, the user space fault handler should do this, as the kernel
doesn't know when user space is done handling the FPU trap.
In case of virtualisation, the guest kernel should clear these bits.
Now that the seL4 kernel doesn't handle FPU traps itself any more,
user space can handle asynchronous traps if it wants to.
Signed-off-by: Indan Zupancic <indan@nul.nu>
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