The kbuild cache was introduced to remember the result of shell
commands, some of which are expensive to compute, such as
$(call cc-option,...).

However, this turned out not so clever as I had first expected.
Actually, it is problematic.  For example, "$(CC) -print-file-name"
is cached.  If the compiler is updated, the stale search path causes
build error, which is difficult to figure out.  Another problem
scenario is cache files could be touched while install targets are
running under the root permission.  We can patch them if desired,
but the build infrastructure is getting uglier and uglier.

Now, we are going to move compiler flag tests to the configuration
phase.  If this is completed, the result of compiler tests will be
naturally cached in the .config file.  We will not have performance
issues of incremental building since this testing only happens at
Kconfig time.

To start this work with a cleaner code base, remove the kbuild
cache first.

Revert the following commits:
Commit 9a234a2e ("kbuild: create directory for make cache only when necessary")
Commit e17c400a ("kbuild: shrink .cache.mk when it exceeds 1000 lines")
Commit 4e562071 ("kbuild: Cache a few more calls to the compiler")
Commit 3298b690 ("kbuild: Add a cache for generated variables")
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NKees Cook <keescook@chromium.org>

filechk displays two short logs; CHK for creating a temporary file,
and UPD for really updating the target.

IMHO, the build system can be quiet when the target file has not
been updated.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NSam Ravnborg <sam@ravnborg.org>

I tried building using a freshly built Make (4.2.1-69-g8a731d1), but
already the objtool build broke with

orc_dump.c: In function ‘orc_dump’:
orc_dump.c:106:2: error: ‘elf_getshnum’ is deprecated [-Werror=deprecated-declarations]
  if (elf_getshdrnum(elf, &nr_sections)) {

Turns out that with that new Make, the backslash was not removed, so cpp
didn't see a #include directive, grep found nothing, and
-DLIBELF_USE_DEPRECATED was wrongly put in CFLAGS.

Now, that new Make behaviour is documented in their NEWS file:

  * WARNING: Backward-incompatibility!
    Number signs (#) appearing inside a macro reference or function invocation
    no longer introduce comments and should not be escaped with backslashes:
    thus a call such as:
      foo := $(shell echo '#')
    is legal.  Previously the number sign needed to be escaped, for example:
      foo := $(shell echo '\#')
    Now this latter will resolve to "\#".  If you want to write makefiles
    portable to both versions, assign the number sign to a variable:
      C := \#
      foo := $(shell echo '$C')
    This was claimed to be fixed in 3.81, but wasn't, for some reason.
    To detect this change search for 'nocomment' in the .FEATURES variable.

This also fixes up the two make-cmd instances to replace # with $(pound)
rather than with \#. There might very well be other places that need
similar fixup in preparation for whatever future Make release contains
the above change, but at least this builds an x86_64 defconfig with the
new make.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=197847
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

The idea of using fixdep was inspired by Kconfig, but autoksyms
belongs to a different group.  So, I want to move those touched
files under include/config/ksym/ to include/ksym/.

The directory include/ksym/ can be removed by 'make clean' because
it is meaningless for the external module building.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NNicolas Pitre <nico@linaro.org>

Currently, linker options are tested by the coordination of $(CC) and
$(LD) because $(LD) needs some object to link.

As commit 86a9df59 ("kbuild: fix linker feature test macros when
cross compiling with Clang") addressed, we need to make sure $(CC)
and $(LD) agree the underlying architecture of the passed object.

This could be a bit complex when we combine tools from different groups.
For example, we can use clang for $(CC), but we still need to rely on
GCC toolchain for $(LD).

So, I was searching for a way of standalone testing of linker options.
A trick I found is to use '-v'; this not only prints the version string,
but also tests if the given option is recognized.

If a given option is supported,

  $ aarch64-linux-gnu-ld -v --fix-cortex-a53-843419
  GNU ld (Linaro_Binutils-2017.11) 2.28.2.20170706
  $ echo $?
  0

If unsupported,

  $ aarch64-linux-gnu-ld -v --fix-cortex-a53-843419
  GNU ld (crosstool-NG linaro-1.13.1-4.7-2013.04-20130415 - Linaro GCC 2013.04) 2.23.1
  aarch64-linux-gnu-ld: unrecognized option '--fix-cortex-a53-843419'
  aarch64-linux-gnu-ld: use the --help option for usage information
  $ echo $?
  1

Gold works likewise.

  $ aarch64-linux-gnu-ld.gold -v --fix-cortex-a53-843419
  GNU gold (Linaro_Binutils-2017.11 2.28.2.20170706) 1.14
  masahiro@pug:~/ref/linux$ echo $?
  0
  $ aarch64-linux-gnu-ld.gold -v --fix-cortex-a53-999999
  GNU gold (Linaro_Binutils-2017.11 2.28.2.20170706) 1.14
  aarch64-linux-gnu-ld.gold: --fix-cortex-a53-999999: unknown option
  aarch64-linux-gnu-ld.gold: use the --help option for usage information
  $ echo $?
  1

LLD too.

  $ ld.lld -v --gc-sections
  LLD 7.0.0 (http://llvm.org/git/lld.git 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers)
  $ echo $?
  0
  $ ld.lld -v --fix-cortex-a53-843419
  LLD 7.0.0 (http://llvm.org/git/lld.git 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers)
  $ echo $?
  0
  $ ld.lld -v --fix-cortex-a53-999999
  ld.lld: error: unknown argument: --fix-cortex-a53-999999
  LLD 7.0.0 (http://llvm.org/git/lld.git 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers)
  $ echo $?
  1
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: NNick Desaulniers <ndesaulniers@google.com>

* Use BREs where EREs aren't necessary.
* Pass -E instead of -r to use EREs. This will be standardized in the
  next POSIX revision[0]. GNU sed supports this since 4.2 (May 2009),
  and busybox since 1.22.0 (Jan 2014).
* Use the [:space:] character class instead of ` \t` in bracket
  expressions. In bracket expressions, POSIX says that <backslash> loses
  its special meaning, so a conforming implementation cannot expand \t
  to <tab>[1].
* In BREs, use interval expressions (\{n,m\}) instead of non-standard
  features like \+ and \?.
* Use a loop instead of -s flag.

There are still plenty of other cases of non-standard sed invocations
(use of ERE features in BREs, in-place editing), but this fixes some
core ones.

[0] http://austingroupbugs.net/view.php?id=528
[1] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03_05Signed-off-by: NMichael Forney <forney@google.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Currently, the existence of $(dir $(make-cache)) is always checked,
and created if it is missing.

We can avoid unnecessary system calls by some tricks.

[1] If KBUILD_SRC is unset, we are building in the source tree.
    The output directory checks can be entirely skipped.
[2] If at least one cache data is found, it means the cache file
    was included.  Obviously its directory exists.  Skip "mkdir -p".
[3] If Makefile does not contain any call of __run-and-store, it will
    not create a cache file.  No need to create its directory.
[4] The "mkdir -p" should be only invoked by the first call of
    __run-and-store
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NDouglas Anderson <dianders@chromium.org>

I was not seeing my linker flags getting added when using ld-option when
cross compiling with Clang. Upon investigation, this seems to be due to
a difference in how GCC vs Clang handle cross compilation.

GCC is configured at build time to support one backend, that is implicit
when compiling.  Clang is explicit via the use of `-target <triple>` and
ships with all supported backends by default.

GNU Make feature test macros that compile then link will always fail
when cross compiling with Clang unless Clang's triple is passed along to
the compiler. For example:

$ clang -x c /dev/null -c -o temp.o
$ aarch64-linux-android/bin/ld -E temp.o
aarch64-linux-android/bin/ld:
unknown architecture of input file `temp.o' is incompatible with
aarch64 output
aarch64-linux-android/bin/ld:
warning: cannot find entry symbol _start; defaulting to
0000000000400078
$ echo $?
1

$ clang -target aarch64-linux-android- -x c /dev/null -c -o temp.o
$ aarch64-linux-android/bin/ld -E temp.o
aarch64-linux-android/bin/ld:
warning: cannot find entry symbol _start; defaulting to 00000000004002e4
$ echo $?
0

This causes conditional checks that invoke $(CC) without the target
triple, then $(LD) on the result, to always fail.
Suggested-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NNick Desaulniers <ndesaulniers@google.com>
Reviewed-by: NMatthias Kaehlcke <mka@chromium.org>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

The cache files are only cleaned away by "make clean".  If you continue
incremental builds, the cache files will grow up little by little.
It is not a big deal in general use cases because compiler flags do not
change quite often.

However, if you do build-test for various architectures, compilers, and
kernel configurations, you will end up with huge cache files soon.

When the cache file exceeds 1000 lines, shrink it down to 500 by "tail".
The Least Recently Added lines are cut. (not Least Recently Used)
I hope it will work well enough.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NDouglas Anderson <dianders@chromium.org>

While timing a "no-op" build of the kernel (incrementally building the
kernel even though nothing changed) in the Chrome OS build system I
found that it was much slower than I expected.

Digging into things a bit, I found that quite a bit of the time was
spent invoking the C compiler even though we weren't actually building
anything.  Currently in the Chrome OS build system the C compiler is
called through a number of wrappers (one of which is written in
python!) and can take upwards of 100 ms to invoke even if we're not
doing anything difficult, so these invocations of the compiler were
taking a lot of time.  Worse the invocations couldn't seem to take
advantage of the multiple cores on my system.

Certainly it seems like we could make the compiler invocations in the
Chrome OS build system faster, but only to a point.  Inherently
invoking a program as big as a C compiler is a fairly heavy
operation.  Thus even if we can speed the compiler calls it made sense
to track down what was happening.

It turned out that all the compiler invocations were coming from
usages like this in the kernel's Makefile:

KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,)

Due to the way cc-option and similar statements work the above
contains an implicit call to the C compiler.  ...and due to the fact
that we're storing the result in KBUILD_CFLAGS, a simply expanded
variable, the call will happen every time the Makefile is parsed, even
if there are no users of KBUILD_CFLAGS.

Rather than redoing this computation every time, it makes a lot of
sense to cache the result of all of the Makefile's compiler calls just
like we do when we compile a ".c" file to a ".o" file.  Conceptually
this is quite a simple idea.  ...and since the calls to invoke the
compiler and similar tools are centrally located in the Kbuild.include
file this doesn't even need to be super invasive.

Implementing the cache in a simple-to-use and efficient way is not
quite as simple as it first sounds, though.  To get maximum speed we
really want the cache in a format that make can natively understand
and make doesn't really have an ability to load/parse files. ...but
make _can_ import other Makefiles, so the solution is to store the
cache in Makefile format.  This requires coming up with a valid/unique
Makefile variable name for each value to be cached, but that's
solvable with some cleverness.

After this change, we'll automatically create a ".cache.mk" file that
will contain our cached variables.  We'll load this on each invocation
of make and will avoid recomputing anything that's already in our
cache.  The cache is stored in a format that it shouldn't need any
invalidation since anything that might change should affect the "key"
and any old cached value won't be used.
Signed-off-by: NDouglas Anderson <dianders@chromium.org>
Tested-by: NIngo Molnar <mingo@kernel.org>
Tested-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

This is a bunch of trivial fixes and cleanups.
Signed-off-by: NCao jin <caoj.fnst@cn.fujitsu.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

cc-option uses KBUILD_CFLAGS and KBUILD_CPPFLAGS when it determines
whether an option is supported or not. This is fine for options used to
build the kernel itself, however some components like the x86 boot code
use a different set of flags.

Add the new macro __cc-option which is a more generic version of
cc-option with additional parameters. One parameter is the compiler
with which the check should be performed, the other the compiler options
to be used instead KBUILD_C*FLAGS.

Refactor cc-option and hostcc-option to use __cc-option and move
hostcc-option to scripts/Kbuild.include.
Suggested-by: NArnd Bergmann <arnd@arndb.de>
Suggested-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NMatthias Kaehlcke <mka@chromium.org>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NMichal Marek <mmarek@suse.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Documentation/kbuild/makefiles.txt says the change for align options
occurred at GCC 3.0, and Documentation/process/changes.rst says the
minimal supported GCC version is 3.2, so it should be safe to hard-code
-falign* options.

Fix the only user arch/x86/Makefile_32.cpu and remove cc-option-align.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NIngo Molnar <mingo@kernel.org>

Clang will warn about unknown warnings but will not return false
unless -Werror is set. GCC will return false if an unknown
warning is passed.

Adding -Werror make both compiler behave the same.

[arnd: it turns out we need the same patch for testing whether -ffunction-sections
       works right with gcc. I've build tested extensively with this patch
       applied, so let's just merge this one now.]
Signed-off-by: NMark Charlebois <charlebm@gmail.com>
Signed-off-by: NBehan Webster <behanw@converseincode.com>
Reviewed-by: NJan-Simon Möller <dl9pf@gmx.de>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

The GCC '-maccumulate-outgoing-args' flag is enabled for most configs,
mostly because of issues which are no longer relevant.  For most
configs, and with most recent versions of GCC, it's no longer needed.

Clarify which cases need it, and only enable it for those cases.  Also
produce a compile-time error for the ftrace graph + mcount + '-Os' case,
which will otherwise cause runtime failures.

The main benefit of '-maccumulate-outgoing-args' is that it prevents an
ugly prologue for functions which have aligned stacks.  But removing the
option also has some benefits: more readable argument saves, smaller
text size, and (presumably) slightly improved performance.

Here are the object size savings for 32-bit and 64-bit defconfig
kernels:

      text	   data	    bss	     dec	    hex	filename
  10006710	3543328	1773568	15323606	 e9d1d6	vmlinux.x86-32.before
   9706358	3547424	1773568	15027350	 e54c96	vmlinux.x86-32.after

      text	   data	    bss	     dec	    hex	filename
  10652105	4537576	 843776	16033457	 f4a6b1	vmlinux.x86-64.before
  10639629	4537576	 843776	16020981	 f475f5	vmlinux.x86-64.after

That comes out to a 3% text size improvement on x86-32 and a 0.1% text
size improvement on x86-64.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170316193133.zrj6gug53766m6nn@trebleSigned-off-by: NIngo Molnar <mingo@kernel.org>

Add a new command cpp_its_S introduced in commit cf2a5e0b ("MIPS:
Support generating Flattened Image Trees (.itb)") to ksym_dep_filter
handler - otherwise a warning is produced during the build of MIPS
platforms (when vmlinux.*.itb target is chosen).
Signed-off-by: NMarcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: Michal Marek <mmarek@suse.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15278/Signed-off-by: NJames Hogan <james.hogan@imgtec.com>

The gcc-plugins arguments should not be included when performing
cc-option tests.

Steps to reproduce:
1) make mrproper
2) make defconfig
3) enable GCC_PLUGINS, GCC_PLUGIN_CYC_COMPLEXITY
4) enable FUNCTION_TRACER (it will select other options as well)
5) make && make modules

Build errors:
MODPOST 18 modules
ERROR: "__fentry__" [net/netfilter/xt_nat.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_mark.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_addrtype.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_LOG.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_sip.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_irc.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_ftp.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat.ko] undefined!
Reported-by: NLaura Abbott <labbott@redhat.com>
Signed-off-by: NEmese Revfy <re.emese@gmail.com>
[kees: renamed variable, clarified commit message]
Signed-off-by: NKees Cook <keescook@chromium.org>

When building with separate object directories and driver specific
Makefiles that add additional header include paths, Kbuild adjusts
the gcc flags so that we include both the directory in the source
tree and in the object tree.

However, due to another bug I fixed earlier, this did not actually
include the correct directory in the object tree, so we know that
we only really need the source tree here. Also, including the
object tree sometimes causes warnings about nonexisting directories
when the include path only exists in the source.

This changes the logic to only emit the -I argument for the srctree,
not for objects. We still need both $(srctree)/$(src) and $(obj)
though, so I'm adding them manually.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NMichal Marek <mmarek@suse.com>

When we build with O=objdir and objdir is directly below the source tree,
$(srctree) becomes '..'.

When a Makefile adds a CFLAGS option like -Ipath/to/headers and
we are building with a separate object directory, Kbuild tries to
add two -I options, one for the source tree and one for the object
tree. An absolute path is treated as a special case, and don't add
this one twice. This also normally catches -I$(srctree)/$(src)
as $(srctree) usually is an absolute directory like /home/arnd/linux/.

The combination of the two behaviors however results in an invalid
path name to be included: we get both ../$(src) and ../../$(src),
the latter one pointing outside of the source tree, usually to a
nonexisting directory. Building with 'make W=1' makes this obvious:

cc1: error: ../../arch/arm/mach-s3c24xx/include: No such file or directory [-Werror=missing-include-dirs]

This adds another special case, treating path names starting with ../
like those starting with / so we don't try to prefix that with
$(srctree).
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NMichal Marek <mmarek@suse.com>

Currently, arg-check is implemented as follows:

  arg-check = $(strip $(filter-out $(cmd_$(1)), $(cmd_$@)) \
                      $(filter-out $(cmd_$@),   $(cmd_$(1))) )

This does not care about the order of arguments that appear in
$(cmd_$(1)) and $(cmd_$@).  So, if_changed and friends never rebuild
the target if only the argument order is changed.  This is a problem
when the link order is changed.

Apparently,

  obj-y += foo.o
  obj-y += bar.o

and

  obj-y += bar.o
  obj-y += foo.o

should be distinguished because the link order determines the probe
order of drivers.  So, built-in.o should be rebuilt when the order
of objects is changed.

This commit fixes arg-check to compare the old/current commands
including the argument order.

Of course, this change has a side effect; Kbuild will react to the
change of compile option order.  For example, "-DFOO -DBAR" and
"-DBAR -DFOO" should give no difference to the build result, but
false positive should be better than false negative.

I am moving space_escape to the top of Kbuild.include just for a
matter of preference.  In practical terms, space_escape can be
defined after arg-check because arg-check uses "=" flavor, not ":=".
Having said that, collecting convenient variables in one place makes
sense from the point of readability.

Chaining "%%%SPACE%%%" to "_-_SPACE_-_" is also a matter of taste
at this point.  Actually, it can be arbitrary as long as it is an
unlikely used string.  The only problem I see in "%%%SPACE%%%" is
that "%" is a special character in "$(patsubst ...)" context.  This
commit just uses "$(subst ...)" for arg-check, but I am fixing it now
in case we might want to use it in $(patsubst ...) context in the
future.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NMichal Marek <mmarek@suse.com>

In kernel/cgroup.c there is:

    #define SUBSYS(_x)                                             \
        DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key);    \
        DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key);     \
        EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key);         \
        EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);

The expansion of this macro causes multiple EXPORT_SYMBOL_GPL() instances
to appear on the same preprocessor line output, confusing the sed script
expecting only one of them per line.  Unfortunately this can't be fixed
nicely in the sed script as sed's regexp can't do non greedy matching.

Fix this by turning any semicolon into a line break before filtering.
Reported-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NMichal Marek <mmarek@suse.com>

The following renames occurred recently:

  cmd_cc_i_c --> cmd_cpp_i_c
  cmd_as_s_S --> cmd_cpp_s_S

The respective cc_*_c and as_*_S patterns no longer match the above
therefore additional patterns are needed.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NMichal Marek <mmarek@suse.com>

Like with kconfig options, we now have the ability to compile in and
out individual EXPORT_SYMBOL() declarations based on the content of
include/generated/autoksyms.h.  However we don't want the entire
world to be rebuilt whenever that file is touched.

Let's apply the same build dependency trick used for CONFIG_* symbols
where the time stamp of empty files whose paths matching those symbols
is used to trigger fine grained rebuilds. In our case the key is the
symbol name passed to EXPORT_SYMBOL().

However, unlike config options, we cannot just use fixdep to parse
the source code for EXPORT_SYMBOL(ksym) because several variants exist
and parsing them all in a separate tool, and keeping it in synch, is
not trivially maintainable.  Furthermore, there are variants such as

	EXPORT_SYMBOL_GPL(pci_user_read_config_##size);

that are instanciated via a macro for which we can't easily determine
the actual exported symbol name(s) short of actually running the
preprocessor on them.

Storing the symbol name string in a special ELF section doesn't work
for targets that output assembly or preprocessed source.

So the best way is really to leverage the preprocessor by having it
output actual symbol names anchored by a special sequence that can be
easily filtered out. Then the list of symbols is simply fed to fixdep
to be merged with the other dependencies.

That implies the preprocessor is executed twice for each source file.
A previous attempt relied on a warning pragma for each EXPORT_SYMBOL()
instance that was filtered apart from stderr by the build system with
a sed script during the actual compilation pass. Unfortunately the
preprocessor/compiler diagnostic output isn't stable between versions
and this solution, although more efficient, was deemed too fragile.

Because of the lowercasing performed by fixdep, there might be name
collisions triggering spurious rebuilds for similar symbols. But this
shouldn't be a big issue in practice. (This is the case for CONFIG_*
symbols and I didn't want to be different here, whatever the original
reason for doing so.)

To avoid needless build overhead, the exported symbol name gathering is
performed only when CONFIG_TRIM_UNUSED_KSYMS is selected.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>

The generation and postprocessing of automatic dependency rules is
duplicated in rule_cc_o_c, rule_as_o_S and if_changed_dep. Since
this is not a trivial one-liner action, it is now abstracted under
cmd_and_fixdep to simplify things and make future changes in this area
easier.

In the rule_cc_o_c and rule_as_o_S cases that means the order of some
commands has been altered, namely fixdep and related file manipulations
are executed earlier, but they didn't depend on those commands that now
execute later.
Signed-off-by: NNicolas Pitre <nico@linaro.org>

Under certain conditions, Kbuild shows "... is up to date" where
if_changed or friends are used.

For example, the incremental build of ARM64 Linux shows this message
when the kernel image has not been updated.

  $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-
    CHK     include/config/kernel.release
    CHK     include/generated/uapi/linux/version.h
    CHK     include/generated/utsrelease.h
    CHK     include/generated/bounds.h
    CHK     include/generated/timeconst.h
    CHK     include/generated/asm-offsets.h
    CALL    scripts/checksyscalls.sh
    CHK     include/generated/compile.h
    CHK     kernel/config_data.h
  make[1]: `arch/arm64/boot/Image.gz' is up to date.
    Building modules, stage 2.
    MODPOST 0 modules

The following is the build rule in arch/arm64/boot/Makefile:

  $(obj)/Image.gz: $(obj)/Image FORCE
          $(call if_changed,gzip)

If the Image.gz is newer than the Image and the command line has not
changed (i.e., $(any-prereq) and $(arg-check) are both empty), the
build rule $(call if_changed,gzip) is evaluated to be empty, then
GNU Make reports the target is up to date.  In order to make GNU Make
quiet, we need to give it something to do, for example, "@:".  This
should be fixed in the Kbuild core part rather than in each Makefile.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NMichal Marek <mmarek@suse.com>

We cannot detect clang before including the arch Makefile, because that
can set the default cross compiler. We also cannot detect clang after
including the arch Makefile, because powerpc wants to know about clang.
Solve this by using an deferred variable. This costs us a few shell
invocations, but this is only a constant number.
Reported-by: NBehan Webster <behanw@converseincode.com>
Reported-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NMichal Marek <mmarek@suse.com>

Since commit 1329e8cc ("modsign: Extract signing cert from
CONFIG_MODULE_SIG_KEY if needed"), the build system has carefully coped
with the signing key being specified as a relative path in either the
source or or the build trees.

However, the actual signing of modules has not worked if the filename
is relative to the source tree.

Fix that by moving the config_filename helper into scripts/Kbuild.include
so that it can be used from elsewhere, and then using it in the top-level
Makefile to find the signing key file.

Kill the intermediate $(MODPUBKEY) and $(MODSECKEY) variables too, while
we're at it. There's no need for them.
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

The macro "try-run" can have an argument for each of true and false
cases.  Having an argument for the false case of cc-ifversion (and
ld-ifversion) would be useful too.
Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

The macros cc-version, cc-fullversion and ld-version take no argument.
It is not necessary to add $(call ...) to invoke them.
Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Helge Deller <deller@gmx.de> [parisc]
Signed-off-by: NMichal Marek <mmarek@suse.cz>

The macro "cc-version" takes no argument.  Drop $(CC) from the
"cc-ifversion" definition.
Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Passing -rR for "make headers_install" is redundant because
the top Makefile has already set -rR to MAKEFLAGS.
Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

The shorthand "clean" is defined in both the top Makefile and
scripts/Makefile.clean.  Likewise, the "hdr-inst" is defined in
both the top Makefile and scripts/Makefile.headersinst.

To reduce code duplication, this commit collects them into
scripts/Kbuild.include like the "build" and "modbuiltin" shorthands.
It requires scripts/Makefile.clean to include scripts/Kbuild.include,
but its impact on the performance of "make clean" should be
negligible.
Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Move dtbs install rules to Makefile.dtbinst. This change is needed to
implement support for dts vendor subdirs. The change makes Makefiles
easier and smaller as no longer the dtbs_install rule needs to be
defined. Another advantage is that install goals are not encoded in
targets anymore (%.dtb_dtbinst_).
Signed-off-by: NRobert Richter <rrichter@cavium.com>

$(if $(KBUILD_SRC),$(srctree)/) was a useful strategy
to omit a long absolute path for in-source-tree build
prior to commit 890676c6
(kbuild: Use relative path when building in the source tree).

Now $(srctree) is "." when building in the source tree.
It would not be annoying to add "$(srctree)/" all the time.
Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Commit c353acba ("kbuild: make: fix if_changed when command contains
backslashes") attempted to handle backslashes in *.cmd files, but it
only handled double backslashes for some reason. Changing make-cmd to also
handle single backslashes fixes rebuilds with dash, but it breaks bash
again. The reason is that the two shells disagree about the
interpretation of backslash sequences in the echo builtin. The way out
of this is to print the command with printf '%s\n'. While at it,
document what the individual parts of make-cmd do and why.
Reported-and-tested-by: NKonstantin Khlebnikov <koct9i@gmail.com>
Reviewed-by: NSam Ravnborg <sam@ravnborg.org>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

To check the linker version. Used by the LTO makefile.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1391846481-31491-9-git-send-email-ak@linux.intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

The kbuild's ld-option function is broken because
the command
  $(CC) /dev/null -c -o "$$TMPO"
does not create object file!

I have used a relatively old mips gcc 3.4.6 cross-compiler
and a relatively new gcc 4.7.2 to check this fact
but the results are the same.

EXAMPLE:
  $ rm /tmp/1.o
  $ mips-linux-gcc /dev/null -c -o /tmp/1.o
  mips-linux-gcc: /dev/null: linker input file unused because linking not done
  $ ls -la /tmp/1.o
  ls: cannot access /tmp/1.o: No such file or directory

We can easily fix the problem by adding
the '-x c' compiler option.

EXAMPLE:
  $ rm /tmp/1.o
  $ mips-linux-gcc -x c /dev/null -c -o /tmp/1.o
  $ ls -la /tmp/1.o
  -rw-r--r-- 1 antony antony 778 Apr  2 20:40 /tmp/1.o

Also fix wrong ld-option example.
Signed-off-by: NAntony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

The call if_changed mechanism does not work when the command contains
backslashes.  This basically is an issue with lzo and bzip2 compressed
kernels.  The compressed binaries do not contain the uncompressed image
size, so these use size_append to append the size.  This results in
backslashes in the executed command.  With this if_changed always
detects a change in the command and rebuilds the compressed image even
if nothing has changed.

Fix this by escaping backslashes in make-cmd
Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: NJan Luebbe <jlu@pengutronix.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Bernhard Walle <bernhard@bwalle.de>
Cc: Michal Marek <mmarek@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The correct syntax for gcc -x is "gcc -x assembler", not
"gcc -xassembler". Even though the latter happens to work, the former
is what is documented in the manual page and thus what gcc wrappers
such as icecream do expect.

This isn't a cosmetic change. The missing space prevents icecream from
recognizing compilation tasks it can't handle, leading to silent kernel
miscompilations.

Besides me, credits go to Michael Matz and Dirk Mueller for
investigating the miscompilation issue and tracking it down to this
incorrect -x parameter syntax.
Signed-off-by: NJean Delvare <jdelvare@suse.de>
Acked-by: NIngo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Cc: Bernhard Walle <bernhard@bwalle.de>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: NMichal Marek <mmarek@suse.cz>