• Michael Neuling's avatar
    powerpc: Add isync to copy_and_flush · 29ce3c50
    Michael Neuling authored
    In __after_prom_start we copy the kernel down to zero in two calls to
    copy_and_flush.  After the first call (copy from 0 to copy_to_here:)
    we jump to the newly copied code soon after.
    Unfortunately there's no isync between the copy of this code and the
    jump to it.  Hence it's possible that stale instructions could still be
    in the icache or pipeline before we branch to it.
    We've seen this on real machines and it's results in no console output
      calling quiesce...
      returning from prom_init
    The below adds an isync to ensure that the copy and flushing has
    completed before any branching to the new instructions occurs.
    Signed-off-by: default avatarMichael Neuling <mikey@neuling.org>
    CC: <stable@vger.kernel.org>
    Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>