On Fri, Mar 12, 2021 at 03:24PM +0100, Andrey Konovalov wrote: > Update KASAN documentation: > > - Give some sections clearer names. > - Remove unneeded subsections in the "Tests" section. > - Move the "For developers" section and split into subsections. > > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> > --- > > Changes v1->v2: > - Rename "By default" section to "Default behaviour". > --- > Documentation/dev-tools/kasan.rst | 54 +++++++++++++++---------------- > 1 file changed, 27 insertions(+), 27 deletions(-) > > diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst > index ddf4239a5890..b3b2c517db55 100644 > --- a/Documentation/dev-tools/kasan.rst > +++ b/Documentation/dev-tools/kasan.rst > @@ -168,24 +168,6 @@ 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 > ---------------------- > > @@ -299,8 +281,8 @@ 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 > @@ -311,8 +293,8 @@ 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 > @@ -362,8 +344,29 @@ 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: > > @@ -409,21 +412,18 @@ 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 > -- > 2.31.0.rc2.261.g7f71774620-goog >
