Re: [PATCH v4 04/17] context_tracking: Add ct_state and CT_WARN_ON

Borislav Petkov
2015-06-30T12:21:22Z

On Mon, Jun 29, 2015 at 12:33:36PM -0700, Andy Lutomirski wrote:
> This will let us sprinkle sanity checks around the kernel without
> making too much of a mess.
>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
> include/linux/context_tracking.h | 15 +++++++++++++++
> include/linux/context_tracking_state.h | 1 +
> 2 files changed, 16 insertions(+)
>
> diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
> index b96bd299966f..008fc67d0d96 100644
> --- a/include/linux/context_tracking.h
> +++ b/include/linux/context_tracking.h
> @@ -49,13 +49,28 @@ static inline void exception_exit(enum ctx_state prev_ctx)
> }
> }
>
> +
> +/**
> + * ct_state() - return the current context tracking state if known
> + *
> + * Returns the current cpu's context tracking state if context tracking

CPU's

> + * is enabled. If context tracking is disabled, returns
> + * CONTEXT_DISABLED. This should be used primarily for debugging.
> + */
> +static inline enum ctx_state ct_state(void)
> +{
> + return context_tracking_is_enabled() ?
> + this_cpu_read(context_tracking.state) : CONTEXT_DISABLED;
> +}
> #else
> static inline void user_enter(void) { }
> static inline void user_exit(void) { }
> static inline enum ctx_state exception_enter(void) { return 0; }
> static inline void exception_exit(enum ctx_state prev_ctx) { }
> +static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
> #endif /* !CONFIG_CONTEXT_TRACKING */
>
> +#define CT_WARN_ON(cond) WARN_ON(context_tracking_is_enabled() && (cond))

Btw, that "CT_" prefix makes this look like it is the software
controlling this thing:

https://upload.wikimedia.org/wikipedia/commons/thumb/2/27/UPMCEast_CTscan.jpg/1280px-UPMCEast_CTscan.jpg

:-)

Other kernel code uses "cxt" or "ctxt" abbreviations. Maybe

CTXT_WARN_ON(cond)

...

> #ifdef CONFIG_CONTEXT_TRACKING_FORCE
> extern void context_tracking_init(void);
> diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h
> index 678ecdf90cf6..ee956c528fab 100644
> --- a/include/linux/context_tracking_state.h
> +++ b/include/linux/context_tracking_state.h
> @@ -14,6 +14,7 @@ struct context_tracking {
> bool active;
> int recursion;
> enum ctx_state {
> + CONTEXT_DISABLED = -1, /* returned by ct_state() if unknown */
> CONTEXT_KERNEL = 0,
> CONTEXT_USER,
> CONTEXT_GUEST,

And those then CTXT_*

--
Regards/Gruss,
Boris.

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