summaryrefslogtreecommitdiff
path: root/Documentation
diff options
context:
space:
mode:
authorAndrey Konovalov <andreyknvl@google.com>2021-04-30 09:00:12 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-04-30 21:20:41 +0300
commit96d7d1415ae8beb3f6ec62107a97ae73db611213 (patch)
tree12406990cc38946fbad7d96729a66f474f4e5f6c /Documentation
parentd57a964e09c22441e9fb497d1d7a5c1983a5d1fb (diff)
downloadlinux-96d7d1415ae8beb3f6ec62107a97ae73db611213.tar.xz
kasan: docs: clean up sections
Update KASAN documentation: - Give some sections clearer names. - Remove unneeded subsections in the "Tests" section. - Move the "For developers" section and split into subsections. Link: https://lkml.kernel.org/r/c2bbb56eaea80ad484f0ee85bb71959a3a63f1d7.1615559068.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/dev-tools/kasan.rst54
1 files changed, 27 insertions, 27 deletions
diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index 6f6ab3ed7b79..2e8dfb47eb49 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -177,24 +177,6 @@ particular KASAN features.
report or also panic the kernel (default: ``report``). Note, that tag
checking gets disabled after the first reported bug.
-For developers
-~~~~~~~~~~~~~~
-
-Software KASAN modes use compiler instrumentation to insert validity checks.
-Such instrumentation might be incompatible with some part of the kernel, and
-therefore needs to be disabled. To disable instrumentation for specific files
-or directories, add a line similar to the following to the respective kernel
-Makefile:
-
-- For a single file (e.g. main.o)::
-
- KASAN_SANITIZE_main.o := n
-
-- For all files in one directory::
-
- KASAN_SANITIZE := n
-
-
Implementation details
----------------------
@@ -308,8 +290,8 @@ support MTE (but supports TBI).
Hardware tag-based KASAN only reports the first found bug. After that MTE tag
checking gets disabled.
-What memory accesses are sanitised by KASAN?
---------------------------------------------
+Shadow memory
+-------------
The kernel maps memory in a number of different parts of the address
space. This poses something of a problem for KASAN, which requires
@@ -320,8 +302,8 @@ The range of kernel virtual addresses is large: there is not enough
real memory to support a real shadow region for every address that
could be accessed by the kernel.
-By default
-~~~~~~~~~~
+Default behaviour
+~~~~~~~~~~~~~~~~~
By default, architectures only map real memory over the shadow region
for the linear mapping (and potentially other small areas). For all
@@ -371,8 +353,29 @@ unmapped. This will require changes in arch-specific code.
This allows ``VMAP_STACK`` support on x86, and can simplify support of
architectures that do not have a fixed module region.
-CONFIG_KASAN_KUNIT_TEST and CONFIG_KASAN_MODULE_TEST
-----------------------------------------------------
+For developers
+--------------
+
+Ignoring accesses
+~~~~~~~~~~~~~~~~~
+
+Software KASAN modes use compiler instrumentation to insert validity checks.
+Such instrumentation might be incompatible with some part of the kernel, and
+therefore needs to be disabled. To disable instrumentation for specific files
+or directories, add a line similar to the following to the respective kernel
+Makefile:
+
+- For a single file (e.g. main.o)::
+
+ KASAN_SANITIZE_main.o := n
+
+- For all files in one directory::
+
+ KASAN_SANITIZE := n
+
+
+Tests
+~~~~~
KASAN tests consist of two parts:
@@ -418,21 +421,18 @@ Or, if one of the tests failed::
There are a few ways to run KUnit-compatible KASAN tests.
1. Loadable module
-~~~~~~~~~~~~~~~~~~
With ``CONFIG_KUNIT`` enabled, ``CONFIG_KASAN_KUNIT_TEST`` can be built as
a loadable module and run on any architecture that supports KASAN by loading
the module with insmod or modprobe. The module is called ``test_kasan``.
2. Built-In
-~~~~~~~~~~~
With ``CONFIG_KUNIT`` built-in, ``CONFIG_KASAN_KUNIT_TEST`` can be built-in
on any architecure that supports KASAN. These and any other KUnit tests enabled
will run and print the results at boot as a late-init call.
3. Using kunit_tool
-~~~~~~~~~~~~~~~~~~~
With ``CONFIG_KUNIT`` and ``CONFIG_KASAN_KUNIT_TEST`` built-in, it's also
possible use ``kunit_tool`` to see the results of these and other KUnit tests