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    SubjectRe: [Question] arch-independent way to differentiate between user and kernel

    * Steven Rostedt <rostedt@goodmis.org> wrote:

    > Hi all,
    >
    > I'm dealing with a problem where I want to know from __do_IRQ in
    > kernel/irq/handle.c if the interrupt occurred while the process was in
    > user space or kernel space. But the trick here is that it must work
    > on all architectures.
    >
    > Does anyone know of some way that that function can tell if it had
    > interrupted the kernel or user space? I know of serveral
    > arch-dependent ways, but that's not acceptable right now.

    i dont think there's any. user_mode(regs) gets the closest - it might
    make sense to generalize it over all arches.

    update_process_times() gets an arch-independent 'was the tick user-space
    or kernel-space' flag, so the best starting point would be to look at
    the output of:

    for N in `find . -name '*.c' | xargs grep update_process_times |
    grep arch`; do echo $N; done | grep update_process_times |
    sort | uniq -c

    which gives:

    2 update_process_times()
    1 update_process_times(CHOOSE_MODE(user_context(UPT_SP(regs)),
    6 update_process_times(user);
    1 update_process_times(user_mode(fp));
    33 update_process_times(user_mode(regs));
    2 update_process_times(user_mode_vm(regs));

    so ~33 calls use user_mode(regs), and the rest needs to be reviewed and
    possibly changed. Looks doable.

    Ingo
    -
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