Masahiro Yamada 5aadfdeb8d kcov: test compiler capability in Kconfig and correct dependency
As Documentation/kbuild/kconfig-language.txt notes, 'select' should be
be used with care - it forces a lower limit of another symbol, ignoring
the dependency.  Currently, KCOV can select GCC_PLUGINS even if arch
does not select HAVE_GCC_PLUGINS.  This could cause the unmet direct
dependency.

Now that Kconfig can test compiler capability, let's handle this in a
more sophisticated way.

There are two ways to enable KCOV; use the compiler that natively
supports -fsanitize-coverage=trace-pc, or build the SANCOV plugin if
the compiler has ability to build GCC plugins.  Hence, the correct
dependency for KCOV is:

  depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS

You do not need to build the SANCOV plugin if the compiler already
supports -fsanitize-coverage=trace-pc.  Hence, the select should be:

  select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC

With this, GCC_PLUGIN_SANCOV is selected only when necessary, so
scripts/Makefile.gcc-plugins can be cleaner.

I also cleaned up Kconfig and scripts/Makefile.kcov as well.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
2018-06-11 09:14:08 +09:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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