• Max Filippov's avatar
    xtensa: add support for call0 ABI in userspace · 09f8a6db
    Max Filippov authored
    
    
    Provide a Kconfig choice to select whether only the default ABI, only
    call0 ABI or both are supported. The default for XEA2 is windowed, but
    it may change for XEA3. Call0 only runs userspace with PS.WOE disabled.
    Supporting both windowed and call0 ABIs is tricky, as there's no
    indication in the ELF binaries which ABI they use. So it is done by
    probing: each process is started with PS.WOE disabled, but the handler
    of an illegal instruction exception taken with PS.WOE retries faulting
    instruction after enabling PS.WOE. It must happen before any signal is
    delivered to the process, otherwise it may be delivered incorrectly.
    Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
    09f8a6db