Re: [PATCH v5 04/38] kmsan: introduce __no_sanitize_memory and __SANITIZE_MEMORY__

From: Andrey Konovalov <andreyknvl@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	 Marco Elver <elver@google.com>,
	Linux Memory Management List <linux-mm@kvack.org>,
	 Alexander Viro <viro@zeniv.linux.org.uk>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	 Andrew Morton <akpm@linux-foundation.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	 Andy Lutomirski <luto@kernel.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	 Arnd Bergmann <arnd@arndb.de>,
	Christoph Hellwig <hch@infradead.org>,
	Christoph Hellwig <hch@lst.de>,
	 "Darrick J. Wong" <darrick.wong@oracle.com>,
	"David S. Miller" <davem@davemloft.net>,
	 Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Eric Biggers <ebiggers@google.com>,
	 Eric Dumazet <edumazet@google.com>,
	Eric Van Hensbergen <ericvh@gmail.com>,
	 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Harry Wentland <harry.wentland@amd.com>,
	 Herbert Xu <herbert@gondor.apana.org.au>,
	Ilya Leoshkevich <iii@linux.ibm.com>,
	 Ingo Molnar <mingo@elte.hu>, Jason Wang <jasowang@redhat.com>,
	Jens Axboe <axboe@kernel.dk>,
	 Marek Szyprowski <m.szyprowski@samsung.com>,
	Mark Rutland <mark.rutland@arm.com>,
	 "Martin K. Petersen" <martin.petersen@oracle.com>,
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	 Matthew Wilcox <willy@infradead.org>,
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	Michal Hocko <mhocko@suse.com>,  Michal Simek <monstr@monstr.eu>,
	Petr Mladek <pmladek@suse.com>, Qian Cai <cai@lca.pw>,
	 Randy Dunlap <rdunlap@infradead.org>,
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	 Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
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	 Takashi Iwai <tiwai@suse.com>, "Theodore Ts'o" <tytso@mit.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	 Vasily Gorbik <gor@linux.ibm.com>,
	Wolfram Sang <wsa@the-dreams.de>
Subject: Re: [PATCH v5 04/38] kmsan: introduce __no_sanitize_memory and __SANITIZE_MEMORY__
Date: Mon, 30 Mar 2020 15:37:28 +0200	[thread overview]
Message-ID: <CAAeHK+yyiV+3N0Bih60t=FFDuxHJ4P1Pav8DRwPtE33TxVKQag@mail.gmail.com> (raw)
In-Reply-To: <20200325161249.55095-5-glider@google.com>

On Wed, Mar 25, 2020 at 5:13 PM <glider@google.com> wrote:
>
> __no_sanitize_memory is a function attribute that makes KMSAN
> ignore the uninitialized values coming from the function's
> inputs, and initialize the function's outputs.
>
> Functions marked with this attribute can't be inlined into functions
> not marked with it, and vice versa.
>
> __SANITIZE_MEMORY__ is a macro that's defined iff the file is
> instrumented with KMSAN. This is not the same as CONFIG_KMSAN, which is
> defined for every file.
>
> Signed-off-by: Alexander Potapenko <glider@google.com>
> To: Alexander Potapenko <glider@google.com>
> Cc: Vegard Nossum <vegard.nossum@oracle.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Marco Elver <elver@google.com>
> Cc: Andrey Konovalov <andreyknvl@google.com>
> Cc: linux-mm@kvack.org
> Acked-by: Marco Elver <elver@google.com>

Reviewed-by: Andrey Konovalov <andreyknvl@google.com>

>
> ---
>
> v4:
>  - dropped an unnecessary comment as requested by Marco Elver
>
> Change-Id: I1f1672652c8392f15f7ca8ac26cd4e71f9cc1e4b
> ---
>  include/linux/compiler-clang.h | 7 +++++++
>  include/linux/compiler-gcc.h   | 5 +++++
>  2 files changed, 12 insertions(+)
>
> diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
> index 2cb42d8bdedc6..d4f929b4a6705 100644
> --- a/include/linux/compiler-clang.h
> +++ b/include/linux/compiler-clang.h
> @@ -33,6 +33,13 @@
>  #define __no_sanitize_thread
>  #endif
>
> +#if __has_feature(memory_sanitizer)
> +# define __SANITIZE_MEMORY__
> +# define __no_sanitize_memory __attribute__((no_sanitize("kernel-memory")))
> +#else
> +# define __no_sanitize_memory
> +#endif
> +
>  /*
>   * Not all versions of clang implement the the type-generic versions
>   * of the builtin overflow checkers. Fortunately, clang implements
> diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
> index cf294faec2f87..1121557252f88 100644
> --- a/include/linux/compiler-gcc.h
> +++ b/include/linux/compiler-gcc.h
> @@ -151,6 +151,11 @@
>  #define __no_sanitize_thread
>  #endif
>
> +/*
> + * GCC doesn't support KMSAN.
> + */
> +#define __no_sanitize_memory
> +
>  #if GCC_VERSION >= 50100
>  #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
>  #endif
> --
> 2.25.1.696.g5e7596f4ac-goog
>