From: Andrey Konovalov <andreyknvl@google.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Alexander Potapenko <glider@google.com>,
Marco Elver <elver@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>,
Dmitry Vyukov <dvyukov@google.com>,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH 02/11] kasan: docs: update overview section
Date: Thu, 11 Mar 2021 22:37:14 +0100 [thread overview]
Message-ID: <da296c4fe645f724922b691019e9e578e1834557.1615498565.git.andreyknvl@google.com> (raw)
In-Reply-To: <f6efb2f36fc1f40eb22df027e6bc956cac71745e.1615498565.git.andreyknvl@google.com>
Update the "Overview" section in KASAN documentation:
- Outline main use cases for each mode.
- Mention that HW_TAGS mode need compiler support too.
- Move the part about SLUB/SLAB support from "Usage" to "Overview".
- Punctuation, readability, and other minor clean-ups.
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
Documentation/dev-tools/kasan.rst | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index c9484f34da2a..343a683d0520 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -11,17 +11,31 @@ designed to find out-of-bound and use-after-free bugs. KASAN has three modes:
2. software tag-based KASAN (similar to userspace HWASan),
3. hardware tag-based KASAN (based on hardware memory tagging).
-Software KASAN modes (1 and 2) use compile-time instrumentation to insert
-validity checks before every memory access, and therefore require a compiler
+Generic KASAN is mainly used for debugging due to a large memory overhead.
+Software tag-based KASAN can be used for dogfood testing as it has a lower
+memory overhead that allows using it with real workloads. Hardware tag-based
+KASAN comes with low memory and performance overheads and, therefore, can be
+used in production. Either as an in-field memory bug detector or as a security
+mitigation.
+
+Software KASAN modes (#1 and #2) use compile-time instrumentation to insert
+validity checks before every memory access and, therefore, require a compiler
version that supports that.
-Generic KASAN is supported in both GCC and Clang. With GCC it requires version
+Generic KASAN is supported in GCC and Clang. With GCC, it requires version
8.3.0 or later. Any supported Clang version is compatible, but detection of
out-of-bounds accesses for global variables is only supported since Clang 11.
-Tag-based KASAN is only supported in Clang.
+Software tag-based KASAN mode is only supported in Clang.
-Currently generic KASAN is supported for the x86_64, arm, arm64, xtensa, s390
+The hardware KASAN mode (#3) relies on hardware to perform the checks but
+still requires a compiler version that supports memory tagging instructions.
+This mode is supported in Clang 11+.
+
+Both software KASAN modes work with SLUB and SLAB memory allocators,
+while the hardware tag-based KASAN currently only supports SLUB.
+
+Currently, generic KASAN is supported for the x86_64, arm, arm64, xtensa, s390,
and riscv architectures, and tag-based KASAN modes are supported only for arm64.
Usage
@@ -39,9 +53,6 @@ For software modes, you also need to choose between CONFIG_KASAN_OUTLINE and
CONFIG_KASAN_INLINE. Outline and inline are compiler instrumentation types.
The former produces smaller binary while the latter is 1.1 - 2 times faster.
-Both software KASAN modes work with both SLUB and SLAB memory allocators,
-while the hardware tag-based KASAN currently only support SLUB.
-
For better error reports that include stack traces, enable CONFIG_STACKTRACE.
To augment reports with last allocation and freeing stack of the physical page,
--
2.31.0.rc2.261.g7f71774620-goog
next prev parent reply other threads:[~2021-03-11 21:37 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-11 21:37 [PATCH 01/11] kasan: docs: clean up sections Andrey Konovalov
2021-03-11 21:37 ` Andrey Konovalov [this message]
2021-03-12 10:17 ` [PATCH 02/11] kasan: docs: update overview section Marco Elver
2021-03-12 13:51 ` Andrey Konovalov
2021-03-11 21:37 ` [PATCH 03/11] kasan: docs: update usage section Andrey Konovalov
2021-03-11 21:37 ` [PATCH 04/11] kasan: docs: update error reports section Andrey Konovalov
2021-03-11 21:37 ` [PATCH 05/11] kasan: docs: update boot parameters section Andrey Konovalov
2021-03-11 21:37 ` [PATCH 06/11] kasan: docs: update GENERIC implementation details section Andrey Konovalov
2021-03-11 21:37 ` [PATCH 07/11] kasan: docs: update SW_TAGS " Andrey Konovalov
2021-03-11 21:37 ` [PATCH 08/11] kasan: docs: update HW_TAGS " Andrey Konovalov
2021-03-11 21:37 ` [PATCH 09/11] kasan: docs: update shadow memory section Andrey Konovalov
2021-03-12 10:52 ` Marco Elver
2021-03-12 13:52 ` Andrey Konovalov
2021-03-11 21:37 ` [PATCH 10/11] kasan: docs: update ignoring accesses section Andrey Konovalov
2021-03-12 11:02 ` Marco Elver
2021-03-12 14:07 ` Andrey Konovalov
2021-03-11 21:37 ` [PATCH 11/11] kasan: docs: update tests section Andrey Konovalov
2021-03-12 10:47 ` Marco Elver
2021-03-12 13:53 ` Andrey Konovalov
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