linux-kernel - Re: [PATCH v2 2/5] preempt/dynamic: Introduce preempt mode accessors

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 11 Nov 2021 09:54:05 +0100
From:   Marco Elver <elver@...gle.com>
To:     Valentin Schneider <valentin.schneider@....com>
Cc:     linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com,
        linuxppc-dev@...ts.ozlabs.org, linux-kbuild@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Mike Galbraith <efault@....de>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: Re: [PATCH v2 2/5] preempt/dynamic: Introduce preempt mode accessors

On Wed, Nov 10, 2021 at 08:24PM +0000, Valentin Schneider wrote:
[...]
> +#ifdef CONFIG_PREEMPT_DYNAMIC
> +
> +extern bool is_preempt_none(void);
> +extern bool is_preempt_voluntary(void);
> +extern bool is_preempt_full(void);
> +
> +#else
> +
> +#define is_preempt_none() IS_ENABLED(CONFIG_PREEMPT_NONE)
> +#define is_preempt_voluntary() IS_ENABLED(CONFIG_PREEMPT_VOLUNTARY)
> +#define is_preempt_full() IS_ENABLED(CONFIG_PREEMPT)
> +
> +#endif
> +
> +#define is_preempt_rt() IS_ENABLED(CONFIG_PREEMPT_RT)
> +

Can these callables be real functions in all configs, making the
!DYNAMIC ones just static inline bool ones? That'd catch invalid use in
#if etc. in all configs.

>  /*
>   * Does a critical section need to be broken due to another
>   * task waiting?: (technically does not depend on CONFIG_PREEMPTION,
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 97047aa7b6c2..9db7f77e53c3 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -6638,6 +6638,17 @@ static void __init preempt_dynamic_init(void)
>  	}
>  }
>  
> +#define PREEMPT_MODE_ACCESSOR(mode) \
> +	bool is_preempt_##mode(void)						 \
> +	{									 \
> +		WARN_ON_ONCE(preempt_dynamic_mode == preempt_dynamic_undefined); \
> +		return preempt_dynamic_mode == preempt_dynamic_##mode;		 \
> +	}

This needs an EXPORT_SYMBOL, so it's usable from modules like the
kcsan_test module.