Commit a0f97e06 ("kbuild: enable 'make CFLAGS=...' to add
additional options to CC") renamed CFLAGS to KBUILD_CFLAGS.

Commit 222d394d ("kbuild: enable 'make AFLAGS=...' to add
additional options to AS") renamed AFLAGS to KBUILD_AFLAGS.

Commit 06c5040c ("kbuild: enable 'make CPPFLAGS=...' to add
additional options to CPP") renamed CPPFLAGS to KBUILD_CPPFLAGS.

For some reason, LDFLAGS was not renamed.

Using a well-known variable like LDFLAGS may result in accidental
override of the variable.

Kbuild generally uses KBUILD_ prefixed variables for the internally
appended options, so here is one more conversion to sanitize the
naming convention.

I did not touch Makefiles under tools/ since the tools build system
is a different world.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: NPalmer Dabbelt <palmer@sifive.com>

This config option should be enabled only when both the compiler and
the linker support necessary flags.  Add proper dependencies to Kconfig.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

As commit ebaad7d3 ("kbuild: rpm: prompt to use "rpm-pkg" if "rpm"
target is used") noticed, the "rpm" target is now removed.
I assume people have already migrated to "rpm-pkg".
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Currently, if the vDSO ends up containing an indirect branch or
call, GCC will emit the "external thunk" style of retpoline, and it
will fail to link.

Fix it by building the vDSO with inline retpoline thunks.

I haven't seen any reports of this triggering on an unpatched
kernel.

Fixes: commit 76b04384 ("x86/retpoline: Add initial retpoline support")
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NMatt Rickard <matt@softrans.com.au>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jason Vas Dias <jason.vas.dias@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/c76538cd3afbe19c6246c2d1715bc6a60bd63985.1534448381.git.luto@kernel.org

-mcount-nop gcc option generates the calls to the profiling functions
as nops which allows to avoid patching mcount jump with NOP instructions
initially.

-mcount-nop gcc option will be activated if platform selects
HAVE_NOP_MCOUNT and gcc actually supports it.
In addition to that CC_USING_NOP_MCOUNT is defined and could be used by
architectures to adapt ftrace patching behavior.

Link: http://lkml.kernel.org/r/patch-3.thread-aa7b8d.git-e02ed2dc082b.your-ad-here.call-01533557518-ext-9465@work.hoursSigned-off-by: NVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Currently if CONFIG_FTRACE_MCOUNT_RECORD is enabled -mrecord-mcount
compiler flag support is tested for every Makefile.

Top 4 cc-option usages:
    511 -mrecord-mcount
     11  -fno-stack-protector
      9 -Wno-override-init
      2 -fsched-pressure

To address that move cc-option from scripts/Makefile.build to top Makefile
and export CC_USING_RECORD_MCOUNT to be used in original place.

While doing that also add -mrecord-mcount to CC_FLAGS_FTRACE (if gcc
actually supports it).

Link: http://lkml.kernel.org/r/patch-2.thread-aa7b8d.git-de935bace15a.your-ad-here.call-01533557518-ext-9465@work.hoursAcked-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

CC_FLAGS_FTRACE is exported and later used to remove ftrace relevant
build flags from files which should be built without ftrace support.
For that reason add -mfentry to CC_FLAGS_FTRACE as well. That fixes
a problem with vdso32 build on s390, where -mfentry could not be used
together with -m31 flag.

At the same time flags like -pg and -mfentry are not relevant for asm
files, so avoid adding them to KBUILD_AFLAGS.

Introduce CC_FLAGS_USING instead of CC_USING_FENTRY to collect
-DCC_USING_FENTRY (and future alike) which are relevant for both
KBUILD_CFLAGS and KBUILD_AFLAGS.

Link: http://lkml.kernel.org/r/patch-1.thread-aa7b8d.git-42971afe87de.your-ad-here.call-01533557518-ext-9465@work.hoursSigned-off-by: NVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

Kernel headers must be installed into $(objtree)/usr/include to avoid
the build failure of samples.

Commit ddea05fa ("kbuild: make samples depend on headers_install")
addressed this, but "samples/" is only used for the single target build.

"make samples/" properly installs kernel headers, but it does not work
for general building because a phony target "sample" (no trailing slash)
is used.
Reported-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: NDavid Howells <dhowells@redhat.com>

asm-generic and uapi-asm-generic do not depend on the kernel
configuration.  In fact, uapi-asm-generic is the prerequisite of
headers_{install,check}, hence it should not require the .config file.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: NRandy Dunlap <rdunlap@infradead.org>
Acked-by: NRichard Weinberger <richard@nod.at>

Currently, filechk unconditionally opens the first prerequisite and
redirects it as the stdin of a filechk_* rule.  Hence, every target
using $(call filechk,...) must list something as the first prerequisite
even if it is unneeded.

'< $<' is actually unneeded in most cases.  Each rule can explicitly
adds it if necessary.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

The top-level Makefile adds include/config/auto.conf as
prerequisites of 'scripts', 'prepare1', etc.

They were needed to terminate the build when include/config/auto.conf
is missing.

Now that the inclusion of include/config/auto.conf is mandatory
in the top-level Makefile if dot-config is 1 (Note 'include' directive
is used instead of '-include').

Make terminates the build by itself if it fails to create or update
include/config/auto.conf so we are sure that include/config/auto.conf
exists in the very first stage of make.

I am still keeping include/config/auto.conf as the prerequisite of
%/modules.builtin because modules.builtin is a real file.  According
to commit a6c36632 ("kbuild: Do not unnecessarily regenerate
modules.builtin"), it is intentional to compare time-stamps between
%/modules.builtin and include/config/auto.conf .  I moved tristate.conf
here because it is only included from scripts/Makefile.modbuiltin.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

'make kernelrelease' depends on CONFIG_LOCALVERSION(_AUTO), but
for the same reason as install targets, we do not want to update
the configuration just for printing the kernelrelease string.

This is likely to happen when you compiled the kernel with
CROSS_COMPILE, but forget to pass it to 'make kernelrelease'.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

"make syncconfig" is automatically invoked when any of the following
happens:

 - .config is updated
 - any of Kconfig files is updated
 - any of environment variables referenced in Kconfig is changed

Then, it updates configuration files such as include/config/auto.conf
include/generated/autoconf.h, etc.

Even install targets (install, modules_install, etc.) are no exception.
However, they should never ever modify the source tree.  Install
targets are often run with root privileges.  Once those configuration
files are owned by root, "make mrproper" would end up with permission
error.

Install targets should just copy things blindly.  They should not care
whether the configuration is up-to-date or not.  This makes more sense
because we are interested in the configuration that was used in the
previous kernel building.

This issue has existed since before, but rarely happened.  I expect
more chance where people are hit by this; with the new Kconfig syntax
extension, the .config now contains the compiler information.  If you
cross-compile the kernel with CROSS_COMPILE, but forget to pass it
for "make install", you meet "any of environment variables referenced
in Kconfig is changed" because $(CC) is referenced in Kconfig.
Another scenario is the compiler upgrade before the installation.

Install targets need the configuration.  "make modules_install" refer
to CONFIG_MODULES etc.  "make dtbs_install" also needs CONFIG_ARCH_*
to decide which dtb files to install.  However, the auto-update of
the configuration files should be avoided.  We already do this for
external modules.

Now, Make targets are categorized into 3 groups:

[1] Do not need the kernel configuration at all

    help, coccicheck, headers_install etc.

[2] Need the latest kernel configuration

    If new config options are added, Kconfig will show prompt to
    ask user's selection.

    Build targets such as vmlinux, in-kernel modules are the cases.

[3] Need the kernel configuration, but do not want to update it

    Install targets except headers_install, and external modules
    are the cases.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

When you build targets that require the kernel configuration, dot-config
is set to 1, then the top-level Makefile includes auto.conf.  However,
Make considers its inclusion is optional because the '-include' directive
is used here.

If a necessary configuration file is missing for the external module
building, the following error message is displayed:

  ERROR: Kernel configuration is invalid.
         include/generated/autoconf.h or include/config/auto.conf are missing.
         Run 'make oldconfig && make prepare' on kernel src to fix it.

However, Make still continues building; /bin/false let the creation of
'include/config/auto.config' fail, but Make can ignore the error since
it is included by the '-include' directive.

I guess the reason of using '-include' directive was to suppress
the warning when you build the kernel from a pristine source tree:

  Makefile:605: include/config/auto.conf: No such file or directory

The previous commit made sure include/config/auto.conf exists after
the 'make *config' stage.  Now, we can use the 'include' directive
without showing the warning.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Now that we have the rename in place, reuse the HOST*FLAGS options as
something that can be set from the command line and included with the
rest of the flags.
Signed-off-by: NLaura Abbott <labbott@redhat.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

In preparation for enabling command line LDLIBS, re-name HOST_LOADLIBES
to KBUILD_HOSTLDLIBS as the internal use only flags. Also rename
existing usage to HOSTLDLIBS for consistency. This should not have any
visible effects.
Signed-off-by: NLaura Abbott <labbott@redhat.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

In preparation for enabling command line LDFLAGS, re-name HOSTLDFLAGS
to KBUILD_HOSTLDFLAGS as the internal use only flags. This should not
have any visible effects.
Signed-off-by: NLaura Abbott <labbott@redhat.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

In preparation for enabling command line CXXFLAGS, re-name HOSTCXXFLAGS
to KBUILD_HOSTCXXFLAGS as the internal use only flags. This should not
have any visible effects.
Signed-off-by: NLaura Abbott <labbott@redhat.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

In preparation for enabling command line CFLAGS, re-name HOSTCFLAGS to
KBUILD_HOSTCFLAGS as the internal use only flags. This should not have
any visible effects.
Signed-off-by: NLaura Abbott <labbott@redhat.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Suppress warnings for systems that do not recognize LFS_*.

 getconf: no such configuration parameter `LFS_CFLAGS'
 getconf: no such configuration parameter `LFS_LDFLAGS'
 getconf: no such configuration parameter `LFS_LIBS'

Fixes: d7f14c66 ("kbuild: Enable Large File Support for hostprogs")
Reported-by: NChen Feng <puck.chen@hisilicon.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>

.PHONY is a target, not a variable.
Signed-off-by: NUlf Magnusson <ulfalizer@gmail.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

With the brand-new syntax extension of Kconfig, we can directly
check the compiler capability in the configuration phase.

If the cc-can-link.sh fails, the BPFILTER_UMH is automatically
hidden by the dependency.

I also deleted 'default n', which is no-op.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The changes to automatically test for working stack protector compiler
support in the Kconfig files removed the special STACKPROTECTOR_AUTO
option that picked the strongest stack protector that the compiler
supported.

That was all a nice cleanup - it makes no sense to have the AUTO case
now that the Kconfig phase can just determine the compiler support
directly.

HOWEVER.

It also meant that doing "make oldconfig" would now _disable_ the strong
stackprotector if you had AUTO enabled, because in a legacy config file,
the sane stack protector configuration would look like

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  # CONFIG_CC_STACKPROTECTOR_NONE is not set
  # CONFIG_CC_STACKPROTECTOR_REGULAR is not set
  # CONFIG_CC_STACKPROTECTOR_STRONG is not set
  CONFIG_CC_STACKPROTECTOR_AUTO=y

and when you ran this through "make oldconfig" with the Kbuild changes,
it would ask you about the regular CONFIG_CC_STACKPROTECTOR (that had
been renamed from CONFIG_CC_STACKPROTECTOR_REGULAR to just
CONFIG_CC_STACKPROTECTOR), but it would think that the STRONG version
used to be disabled (because it was really enabled by AUTO), and would
disable it in the new config, resulting in:

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
  CONFIG_CC_STACKPROTECTOR=y
  # CONFIG_CC_STACKPROTECTOR_STRONG is not set
  CONFIG_CC_HAS_SANE_STACKPROTECTOR=y

That's dangerously subtle - people could suddenly find themselves with
the weaker stack protector setup without even realizing.

The solution here is to just rename not just the old RECULAR stack
protector option, but also the strong one.  This does that by just
removing the CC_ prefix entirely for the user choices, because it really
is not about the compiler support (the compiler support now instead
automatially impacts _visibility_ of the options to users).

This results in "make oldconfig" actually asking the user for their
choice, so that we don't have any silent subtle security model changes.
The end result would generally look like this:

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
  CONFIG_STACKPROTECTOR=y
  CONFIG_STACKPROTECTOR_STRONG=y
  CONFIG_CC_HAS_SANE_STACKPROTECTOR=y

where the "CC_" versions really are about internal compiler
infrastructure, not the user selections.
Acked-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NKees Cook <keescook@chromium.org>

Move the test for -fstack-protector(-strong) option to Kconfig.

If the compiler does not support the option, the corresponding menu
is automatically hidden.  If STRONG is not supported, it will fall
back to REGULAR.  If REGULAR is not supported, it will be disabled.
This means, AUTO is implicitly handled by the dependency solver of
Kconfig, hence removed.

I also turned the 'choice' into only two boolean symbols.  The use of
'choice' is not a good idea here, because all of all{yes,mod,no}config
would choose the first visible value, while we want allnoconfig to
disable as many features as possible.

X86 has additional shell scripts in case the compiler supports those
options, but generates broken code.  I added CC_HAS_SANE_STACKPROTECTOR
to test this.  I had to add -m32 to gcc-x86_32-has-stack-protector.sh
to make it work correctly.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NKees Cook <keescook@chromium.org>

Commit 21c54b77 ("kconfig: show compiler version text in the top
comment") was intended to detect the compiler upgrade, but Geert
reported a breakage on the m68k build.

The compiler upgrade is detected by the change of the environment
variable, CC_VERSION_TEXT, which contains the first line of the output
from $(CC) --version.  Currently, this works well when CROSS_COMPILE
is given via the environment variable or the Make command line.

However, some architectures such as m68k can specify CROSS_COMPILE
from arch/$(SRCARCH)/Makefile as well.  In this case, "make ARCH=m68k"
ends up with endless syncconfig loop.

  $ make ARCH=m68k defconfig
  *** Default configuration is based on 'multi_defconfig'
  #
  # configuration written to .config
  #
  $ make ARCH=m68k
  scripts/kconfig/conf  --syncconfig Kconfig
  scripts/kconfig/conf  --syncconfig Kconfig
  scripts/kconfig/conf  --syncconfig Kconfig
  scripts/kconfig/conf  --syncconfig Kconfig

Things are happening like this:

Because arch/$(SRCARCH)/Makefile is included after CC_VERSION_TEXT
is set, it contains the host compiler version in the defconfig phase.

To create or update auto.conf, the following line is triggered:

include/config/%.conf: $(KCONFIG_CONFIG) include/config/auto.conf.cmd
        $(Q)$(MAKE) -f $(srctree)/Makefile syncconfig

This recurses the top Makefile after arch/$(SRCARCH)/Makefile is
included.  CROSS_COMPILE is set to a m68k toolchain prefix and
exported to the recursed Make.  Then, syncconfig is invoked with
the target compiler version in CC_VERSION_TEXT.

The Make will restart because auto.conf and auto.conf.cmd have been
updated.  At this point, CROSS_COMPILE is reset, so CC_VERSION_TEXT
is set to the host compiler version again.  Then, syncconfig is
triggered due to the change of CC_VERSION_TEXT.  This loop continues
eternally.

To fix this problem, $(CC_VERSION_TEXT) must be evaluated only after
arch/$(SRCARCH)/Makefile.  Setting it earlier is OK as long as it is
defined by using the '=' operator instead of ':='.

For the defconfig phase, $(CC_VERSION_TEXT) is evaluated when Kbuild
descends into scripts/kconfig/, so it contains the target compiler
version correctly.

include/config/auto.conf.cmd references $(CC_VERSION_TEXT) as well,
so it must be included after arch/$(SRCARCH)/Makefile.

Fixes: 21c54b77 ("kconfig: show compiler version text in the top comment")
Reported-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: NGeert Uytterhoeven <geert@linux-m68k.org>

check that CC can build executables and use that compiler instead of HOSTCC
Suggested-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

By default, sparse assumes a 64bit machine when compiled on x86-64
and 32bit when compiled on anything else.

This can of course create all sort of problems for the other archs, like
issuing false warnings ('shift too big (32) for type unsigned long'), or
worse, failing to emit legitimate warnings.

Fix this by adding the -m32/-m64 flag, depending on CONFIG_64BIT,
to CHECKFLAGS in the main Makefile (and so for all archs).
Also, remove the now unneeded -m32/-m64 in arch specific Makefiles.
Signed-off-by: NLuc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

The kernel depends on macros like __BYTE_ORDER__,
__BIG_ENDIAN__ or __LITTLE_ENDIAN__.

OTOH, sparse doesn't know about the endianness of the kernel and
by default uses the same as the machine on which sparse was built.

Ensure that sparse can predefine the macros corresponding to
how the kernel was configured by adding -m{big,little}-endian
to CHECKFLAGS in the main Makefile (and so for all archs).
Also, remove the equivalent done in arch specific Makefiles.
Signed-off-by: NLuc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>