Date:   Fri, 10 Dec 2021 13:45:27 +0100
From:   Marco Elver <elver@google.com>
To:     Peter Collingbourne <pcc@google.com>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>, Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andy Lutomirski <luto@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        YiFei Zhu <yifeifz2@illinois.edu>,
        Mark Rutland <mark.rutland@arm.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Gabriel Krisman Bertazi <krisman@collabora.com>,
        Chris Hyser <chris.hyser@oracle.com>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Chris Wilson <chris@chris-wilson.co.uk>,
        Arnd Bergmann <arnd@arndb.de>,
        Dmitry Vyukov <dvyukov@google.com>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Alexey Gladkov <legion@kernel.org>,
        Ran Xiaokai <ran.xiaokai@zte.com.cn>,
        David Hildenbrand <david@redhat.com>,
        Xiaofeng Cao <caoxiaofeng@yulong.com>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Thomas Cedeno <thomascedeno@google.com>,
        Alexander Potapenko <glider@google.com>,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Evgenii Stepanov <eugenis@google.com>
Subject: Re: [PATCH v4 1/7] include: split out uaccess instrumentation into a
 separate header
Message-ID: <YbNL579AHDIg3PH5@elver.google.com>
References: <20211209221545.2333249-1-pcc@google.com>
 <20211209221545.2333249-2-pcc@google.com>
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On Thu, Dec 09, 2021 at 02:15PM -0800, Peter Collingbourne wrote:
> In an upcoming change we are going to add uaccess instrumentation
> that uses inline access to struct task_struct from the
> instrumentation routines. Because instrumentation.h is included
> from many places including (recursively) from sched.h this would
> otherwise lead to a circular dependency. Break the dependency by
> moving uaccess instrumentation routines into a separate header,
> instrumentation-uaccess.h.
> 
> Link: https://linux-review.googlesource.com/id/I625728db0c8db374e13e4ebc54985ac5c79ace7d
> Signed-off-by: Peter Collingbourne <pcc@google.com>
> Acked-by: Dmitry Vyukov <dvyukov@google.com>

Reviewed-by: Marco Elver <elver@google.com>

> ---
>  include/linux/instrumented-uaccess.h | 49 ++++++++++++++++++++++++++++
>  include/linux/instrumented.h         | 34 -------------------
>  include/linux/uaccess.h              |  2 +-
>  lib/iov_iter.c                       |  2 +-
>  lib/usercopy.c                       |  2 +-
>  5 files changed, 52 insertions(+), 37 deletions(-)
>  create mode 100644 include/linux/instrumented-uaccess.h
> 
> diff --git a/include/linux/instrumented-uaccess.h b/include/linux/instrumented-uaccess.h
> new file mode 100644
> index 000000000000..ece549088e50
> --- /dev/null
> +++ b/include/linux/instrumented-uaccess.h
> @@ -0,0 +1,49 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +/*
> + * This header provides generic wrappers for memory access instrumentation for
> + * uaccess routines that the compiler cannot emit for: KASAN, KCSAN.
> + */
> +#ifndef _LINUX_INSTRUMENTED_UACCESS_H
> +#define _LINUX_INSTRUMENTED_UACCESS_H
> +
> +#include <linux/compiler.h>
> +#include <linux/kasan-checks.h>
> +#include <linux/kcsan-checks.h>
> +#include <linux/types.h>
> +
> +/**
> + * instrument_copy_to_user - instrument reads of copy_to_user
> + *
> + * Instrument reads from kernel memory, that are due to copy_to_user (and
> + * variants). The instrumentation must be inserted before the accesses.
> + *
> + * @to destination address
> + * @from source address
> + * @n number of bytes to copy
> + */
> +static __always_inline void
> +instrument_copy_to_user(void __user *to, const void *from, unsigned long n)
> +{
> +	kasan_check_read(from, n);
> +	kcsan_check_read(from, n);
> +}
> +
> +/**
> + * instrument_copy_from_user - instrument writes of copy_from_user
> + *
> + * Instrument writes to kernel memory, that are due to copy_from_user (and
> + * variants). The instrumentation should be inserted before the accesses.
> + *
> + * @to destination address
> + * @from source address
> + * @n number of bytes to copy
> + */
> +static __always_inline void
> +instrument_copy_from_user(const void *to, const void __user *from, unsigned long n)
> +{
> +	kasan_check_write(to, n);
> +	kcsan_check_write(to, n);
> +}
> +
> +#endif /* _LINUX_INSTRUMENTED_UACCESS_H */
> diff --git a/include/linux/instrumented.h b/include/linux/instrumented.h
> index 42faebbaa202..b68f415510c7 100644
> --- a/include/linux/instrumented.h
> +++ b/include/linux/instrumented.h
> @@ -102,38 +102,4 @@ static __always_inline void instrument_atomic_read_write(const volatile void *v,
>  	kcsan_check_atomic_read_write(v, size);
>  }
>  
> -/**
> - * instrument_copy_to_user - instrument reads of copy_to_user
> - *
> - * Instrument reads from kernel memory, that are due to copy_to_user (and
> - * variants). The instrumentation must be inserted before the accesses.
> - *
> - * @to destination address
> - * @from source address
> - * @n number of bytes to copy
> - */
> -static __always_inline void
> -instrument_copy_to_user(void __user *to, const void *from, unsigned long n)
> -{
> -	kasan_check_read(from, n);
> -	kcsan_check_read(from, n);
> -}
> -
> -/**
> - * instrument_copy_from_user - instrument writes of copy_from_user
> - *
> - * Instrument writes to kernel memory, that are due to copy_from_user (and
> - * variants). The instrumentation should be inserted before the accesses.
> - *
> - * @to destination address
> - * @from source address
> - * @n number of bytes to copy
> - */
> -static __always_inline void
> -instrument_copy_from_user(const void *to, const void __user *from, unsigned long n)
> -{
> -	kasan_check_write(to, n);
> -	kcsan_check_write(to, n);
> -}
> -
>  #endif /* _LINUX_INSTRUMENTED_H */
> diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
> index ac0394087f7d..c0c467e39657 100644
> --- a/include/linux/uaccess.h
> +++ b/include/linux/uaccess.h
> @@ -3,7 +3,7 @@
>  #define __LINUX_UACCESS_H__
>  
>  #include <linux/fault-inject-usercopy.h>
> -#include <linux/instrumented.h>
> +#include <linux/instrumented-uaccess.h>
>  #include <linux/minmax.h>
>  #include <linux/sched.h>
>  #include <linux/thread_info.h>
> diff --git a/lib/iov_iter.c b/lib/iov_iter.c
> index 66a740e6e153..3f9dc6df7102 100644
> --- a/lib/iov_iter.c
> +++ b/lib/iov_iter.c
> @@ -12,7 +12,7 @@
>  #include <linux/compat.h>
>  #include <net/checksum.h>
>  #include <linux/scatterlist.h>
> -#include <linux/instrumented.h>
> +#include <linux/instrumented-uaccess.h>
>  
>  #define PIPE_PARANOIA /* for now */
>  
> diff --git a/lib/usercopy.c b/lib/usercopy.c
> index 7413dd300516..1cd188e62d06 100644
> --- a/lib/usercopy.c
> +++ b/lib/usercopy.c
> @@ -1,7 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include <linux/bitops.h>
>  #include <linux/fault-inject-usercopy.h>
> -#include <linux/instrumented.h>
> +#include <linux/instrumented-uaccess.h>
>  #include <linux/uaccess.h>
>  
>  /* out-of-line parts */
> -- 
> 2.34.1.173.g76aa8bc2d0-goog
>