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    SubjectRe: [PATCH v4 07/17] x86/traps: Assert that we're in CONTEXT_KERNEL in exception entries
    On Mon, Jun 29, 2015 at 12:33:39PM -0700, Andy Lutomirski wrote:
    > Other than the super-atomic exception entries, all exception entries
    > are supposed to switch our context tracking state to CONTEXT_KERNEL.
    > Assert that they do. These assertions appear trivial at this point,
    > as exception_enter is the function responsible for switching
    > context, but I'm planning on reworking x86's exception context
    > tracking, and these assertions will help make sure that all of this
    > code keeps working.
    >
    > Signed-off-by: Andy Lutomirski <luto@kernel.org>
    > ---
    > arch/x86/kernel/traps.c | 9 +++++++++
    > 1 file changed, 9 insertions(+)
    >
    > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
    > index f5791927aa64..2a783c4fe0e9 100644
    > --- a/arch/x86/kernel/traps.c
    > +++ b/arch/x86/kernel/traps.c
    > @@ -292,6 +292,8 @@ static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
    > enum ctx_state prev_state = exception_enter();
    > siginfo_t info;
    >
    > + CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
    > +
    > if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
    > NOTIFY_STOP) {
    > conditional_sti(regs);
    > @@ -376,6 +378,7 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
    > siginfo_t *info;
    >
    > prev_state = exception_enter();
    > + CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
    > if (notify_die(DIE_TRAP, "bounds", regs, error_code,
    > X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
    > goto exit;
    > @@ -457,6 +460,7 @@ do_general_protection(struct pt_regs *regs, long error_code)
    > enum ctx_state prev_state;
    >
    > prev_state = exception_enter();
    > + CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
    > conditional_sti(regs);
    >
    > if (v8086_mode(regs)) {
    > @@ -514,6 +518,7 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
    > return;
    >
    > prev_state = ist_enter(regs);
    > + CT_WARN_ON(ct_state() != CONTEXT_KERNEL);

    Yeah, so any chance those assertions can be moved at the end of both
    ist_enter() and exception_enter()?

    Yeah, I read above that you're planning to rework it but it is cleaner
    to have them at the end of the _enter() functions instead in all those
    trap handlers, no...?

    --
    Regards/Gruss,
    Boris.

    ECO tip #101: Trim your mails when you reply.
    --


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