Fix typos "plgins" -> "plugins".

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>

It is very rare to see versions of GCC prior to 4.8 being used to build
the mainline kernel. These old compilers are also know to have codegen
issues which can lead to silent miscompilation:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145

Raise the minimum GCC version for kernel build to 4.8 and remove some
tautological Kconfig dependencies as a consequence.

Cc: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Will Deacon <will@kernel.org>

Nobody was opposed to raising minimum GCC version to 4.8 [1]
So, we will drop GCC <= 4.7 support sooner or later.

We always use C++ compiler for building plugins for GCC >= 4.8.

This commit drops the plugin support for GCC <= 4.7 a bit earlier,
which allows us to dump lots of code.

[1] https://lkml.org/lkml/2020/1/23/545

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>

Information about GCC plugins is relevant to kernel building, so move this
document to the kbuild manual.

Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

I noticed that randconfig builds with gcc no longer produce a lot of
ccache hits, unlike with clang, and traced this back to plugins
now being enabled unconditionally if they are supported.

I am now working around this by adding

   export CCACHE_COMPILERCHECK=/usr/bin/size -A %compiler%

to my top-level Makefile. This changes the heuristic that ccache uses
to determine whether the plugins are the same after a 'make clean'.

However, it also seems that being able to just turn off the plugins is
generally useful, at least for build testing it adds noticeable overhead
but does not find a lot of bugs additional bugs, and may be easier for
ccache users than my workaround.

Fixes: 9f671e58159a ("security: Create "kernel hardening" config area")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20191211133951.401933-1-arnd@arndb.de
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

The gcc_plugins.txt file is already a ReST file. Move it
to the core-api book while renaming it.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>

Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves the stackleak plugin options to Kconfig.hardening's memory
initialization menu.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Alexander Popov <alex.popov@linux.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Right now kernel hardening options are scattered around various Kconfig
files. This can be a central place to collect these kinds of options
going forward. This is initially populated with the memory initialization
options from the gcc-plugins.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Pull gcc-plugins updates from Kees Cook:
 "This adds additional type coverage to the existing structleak plugin
  and adds a large set of selftests to help evaluate stack variable
  zero-initialization coverage.

  That can be used to test whatever instrumentation might be performing
  zero-initialization: either with the structleak plugin or with Clang's
  coming "-ftrivial-auto-var-init=zero" option.

  Summary:

   - Add scalar and array initialization coverage

   - Refactor Kconfig to make options more clear

   - Add self-test module for testing automatic initialization"

* tag 'gcc-plugins-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  lib: Introduce test_stackinit module
  gcc-plugins: structleak: Generalize to all variable types