commit 3ce120b16cc548472f80cf8644f90eda958cf1b6 upstream.

It appears that hardened gentoo enables "-fstack-check" by default for
gcc.

That doesn't work _at_all_ for the kernel, because the kernel stack
doesn't act like a user stack at all: it's much smaller, and it doesn't
auto-expand on use.  So the extra "probe one page below the stack" code
generated by -fstack-check just breaks the kernel in horrible ways,
causing infinite double faults etc.

[ I have to say, that the particular code gcc generates looks very
  stupid even for user space where it works, but that's a separate
  issue.  ]

Reported-and-tested-by: Alexander Tsoy <alexander@tsoy.me>
Reported-and-tested-by: Toralf Förster <toralf.foerster@gmx.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 433dc2ebe7d17dd21cba7ad5c362d37323592236 ]

Some $(call cc-option,...) are invoked very early, even before
KBUILD_CFLAGS, etc. are initialized.

The returned string from $(call cc-option,...) depends on
KBUILD_CPPFLAGS, KBUILD_CFLAGS, and GCC_PLUGINS_CFLAGS.

Since they are exported, they are not empty when the top Makefile
is recursively invoked.

The recursion occurs in several places.  For example, the top
Makefile invokes itself for silentoldconfig.  "make tinyconfig",
"make rpm-pkg" are the cases, too.

In those cases, the second call of cc-option from the same line
runs a different shell command due to non-pristine KBUILD_CFLAGS.

To get the same result all the time, KBUILD_* and GCC_PLUGINS_CFLAGS
must be initialized before any call of cc-option.  This avoids
garbage data in the .cache.mk file.

Move all calls of cc-option below the config targets because target
compiler flags are unnecessary for Kconfig.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>