linux-kernel - [PATCH 07/43] compiler_attributes.h: add __disable_sanitizer

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Date:   Tue, 14 Dec 2021 17:20:14 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     glider@...gle.com
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Christoph Hellwig <hch@....de>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Ingo Molnar <mingo@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Kees Cook <keescook@...omium.org>,
        Marco Elver <elver@...gle.com>,
        Matthew Wilcox <willy@...radead.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Pekka Enberg <penberg@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 07/43] compiler_attributes.h: add __disable_sanitizer_instrumentation

The new attribute maps to
__attribute__((disable_sanitizer_instrumentation)), which will be
supported by Clang >= 14.0. Future support in GCC is also possible.

This attribute disables compiler instrumentation for kernel sanitizer
tools, making it easier to implement noinstr. It is different from the
existing __no_sanitize* attributes, which may still allow certain types
of instrumentation to prevent false positives.

Signed-off-by: Alexander Potapenko <glider@...gle.com>
---
Link: https://linux-review.googlesource.com/id/Ic0123ce99b33ab7d5ed1ae90593425be8d3d774a
---
 include/linux/compiler_attributes.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
index b9121afd87331..37e2600202216 100644
--- a/include/linux/compiler_attributes.h
+++ b/include/linux/compiler_attributes.h
@@ -308,6 +308,24 @@
 # define __compiletime_warning(msg)
 #endif
 
+/*
+ * Optional: only supported since clang >= 14.0
+ *
+ * clang: https://clang.llvm.org/docs/AttributeReference.html#disable-sanitizer-instrumentation
+ *
+ * disable_sanitizer_instrumentation is not always similar to
+ * no_sanitize((<sanitizer-name>)): the latter may still let specific sanitizers
+ * insert code into functions to prevent false positives. Unlike that,
+ * disable_sanitizer_instrumentation prevents all kinds of instrumentation to
+ * functions with the attribute.
+ */
+#if __has_attribute(disable_sanitizer_instrumentation)
+# define __disable_sanitizer_instrumentation \
+	 __attribute__((disable_sanitizer_instrumentation))
+#else
+# define __disable_sanitizer_instrumentation
+#endif
+
 /*
  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute
  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute
-- 
2.34.1.173.g76aa8bc2d0-goog