docs: sphinxify ubsan.txt and move it to dev-tools

   kcov

   gcov

   kasan

   ubsan

Undefined Behavior Sanitizer - UBSAN

Overview

--------

The Undefined Behavior Sanitizer - UBSAN

========================================

UBSAN is a runtime undefined behaviour checker.

that may cause UB. If check fails (i.e. UB detected) __ubsan_handle_*

function called to print error message.

GCC has that feature since 4.9.x [1] (see -fsanitize=undefined option and

its suboptions). GCC 5.x has more checkers implemented [2].

GCC has that feature since 4.9.x [1_] (see ``-fsanitize=undefined`` option and

its suboptions). GCC 5.x has more checkers implemented [2_].

Report example

---------------

--------------

::

	 ================================================================================

	 UBSAN: Undefined behaviour in ../include/linux/bitops.h:110:33

Usage

-----

To enable UBSAN configure kernel with:

To enable UBSAN configure kernel with::

	CONFIG_UBSAN=y

and to check the entire kernel:

and to check the entire kernel::

        CONFIG_UBSAN_SANITIZE_ALL=y

To enable 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):

- For a single file (e.g. main.o)::

    UBSAN_SANITIZE_main.o := y

        For all files in one directory:

- For all files in one directory::

    UBSAN_SANITIZE := y

To exclude files from being instrumented even if

CONFIG_UBSAN_SANITIZE_ALL=y, use:

``CONFIG_UBSAN_SANITIZE_ALL=y``, use::

  UBSAN_SANITIZE_main.o := n

        and:

and::

  UBSAN_SANITIZE := n

Detection of unaligned accesses controlled through the separate option -

References

----------

[1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html

[2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html

.. _1: https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html

.. _2: https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html