CONFIG_X86_IOPL_IOPERM

This enables the ioperm() and iopl() syscalls which are necessary
for legacy applications.

Legacy IOPL support is an overbroad mechanism which allows user
space aside of accessing all 65536 I/O ports also to disable
interrupts. To gain this access the caller needs CAP_SYS_RAWIO
capabilities and permission from potentially active security
modules.

The emulation restricts the functionality of the syscall to
only allowing the full range I/O port access, but prevents the
ability to disable interrupts from user space which would be
granted if the hardware IOPL mechanism would be used.

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