gcc-6 started warning by default about variables that are not
used anywhere and that are marked 'const', generating many
false positives in an allmodconfig build, e.g.:

arch/arm/mach-davinci/board-da830-evm.c:282:20: warning: 'da830_evm_emif25_pins' defined but not used [-Wunused-const-variable=]
arch/arm/plat-omap/dmtimer.c:958:34: warning: 'omap_timer_match' defined but not used [-Wunused-const-variable=]
drivers/bluetooth/hci_bcm.c:625:39: warning: 'acpi_bcm_default_gpios' defined but not used [-Wunused-const-variable=]
drivers/char/hw_random/omap-rng.c:92:18: warning: 'reg_map_omap4' defined but not used [-Wunused-const-variable=]
drivers/devfreq/exynos/exynos5_bus.c:381:32: warning: 'exynos5_busfreq_int_pm' defined but not used [-Wunused-const-variable=]
drivers/dma/mv_xor.c:1139:34: warning: 'mv_xor_dt_ids' defined but not used [-Wunused-const-variable=]

This is similar to the existing -Wunused-but-set-variable warning
that was added in an earlier release and that we disable by default
now and only enable when W=1 is set, so it makes sense to do
the same here. Once we have eliminated the majority of the
warnings for both, we can put them back into the default list.

We probably want this in backport kernels as well, to allow building
them with gcc-6 without introducing extra warnings.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NOlof Johansson <olof@lixom.net>
Acked-by: NLee Jones <lee.jones@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: NMichal Marek <mmarek@suse.com>

When gcov profiling is enabled, we see a lot of spurious warnings about
possibly uninitialized variables being used:

arch/arm/mm/dma-mapping.c: In function 'arm_coherent_iommu_map_page':
arch/arm/mm/dma-mapping.c:1085:16: warning: 'start' may be used uninitialized in this function [-Wmaybe-uninitialized]
drivers/clk/st/clk-flexgen.c: In function 'st_of_flexgen_setup':
drivers/clk/st/clk-flexgen.c:323:9: warning: 'num_parents' may be used uninitialized in this function [-Wmaybe-uninitialized]
kernel/cgroup.c: In function 'cgroup_mount':
kernel/cgroup.c:2119:11: warning: 'root' may be used uninitialized in this function [-Wmaybe-uninitialized]

All of these are false positives, so it seems better to just disable
the warnings whenever GCOV is enabled. Most users don't enable GCOV,
and based on a prior patch, it is now also disabled for 'allmodconfig'
builds, so there should be no downsides of doing this.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NPeter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: NMichal Marek <mmarek@suse.com>

Enabling CONFIG_GCOV_PROFILE_ALL produces us a lot of warnings like

lib/lz4/lz4hc_compress.c: In function 'lz4_compresshcctx':
lib/lz4/lz4hc_compress.c:514:1: warning: the frame size of 1504 bytes is larger than 1024 bytes [-Wframe-larger-than=]

After some investigation, I found that this behavior started with gcc-4.9,
and opened https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69702.
A suggested workaround for it is to use the -fno-tree-loop-im
flag that turns off one of the optimization stages in gcc, so the
code runs a little slower but does not use excessive amounts
of stack.

We could make this conditional on the gcc version, but I could not
find an easy way to do this in Kbuild and the benefit would be
fairly small, given that most of the gcc version in production are
affected now.

I'm marking this for 'stable' backports because it addresses a bug
with code generation in gcc that exists in all kernel versions
with the affected gcc releases.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NPeter Oberparleiter <oberpar@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: NMichal Marek <mmarek@suse.com>

CONFIG_PROFILE_ALL_BRANCHES confuses gcc-5.x to the degree that it prints
incorrect warnings about a lot of variables that it thinks can be used
uninitialized, e.g.:

i2c/busses/i2c-diolan-u2c.c: In function 'diolan_usb_xfer':
i2c/busses/i2c-diolan-u2c.c:391:16: warning: 'byte' may be used uninitialized in this function
iio/gyro/itg3200_core.c: In function 'itg3200_probe':
iio/gyro/itg3200_core.c:213:6: warning: 'val' may be used uninitialized in this function
leds/leds-lp55xx-common.c: In function 'lp55xx_update_bits':
leds/leds-lp55xx-common.c:350:6: warning: 'tmp' may be used uninitialized in this function
misc/bmp085.c: In function 'show_pressure':
misc/bmp085.c:363:10: warning: 'pressure' may be used uninitialized in this function
power/ds2782_battery.c: In function 'ds2786_get_capacity':
power/ds2782_battery.c:214:17: warning: 'raw' may be used uninitialized in this function

These are all false positives that either rob someone's time when trying
to figure out whether they are real, or they get people to send wrong
patches to shut up the warnings.

Nobody normally wants to run a CONFIG_PROFILE_ALL_BRANCHES kernel in
production, so disabling the whole class of warnings for this configuration
has no serious downsides either.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: Steven Rostedt <rostedtgoodmis.org>
Signed-off-by: NMichal Marek <mmarek@suse.com>

When the kernel path contains a space or a colon somewhere in the path
name, the modules_install target doesn't work anymore, as the path names
are not enclosed in double quotes. It is also supposed that and O= build
will suffer from the same weakness as modules_install.

Instead of checking and improving kbuild to resist to directories
including these characters, error out early to prevent any build if the
kernel's main directory contains a space.
Signed-off-by: NRobert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: NMichal Marek <mmarek@suse.com>

The if_changed directive is useless against phony targets.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Fixes: 2441e78b ("kbuild: better abstract vmlinux sequential prerequisites")
Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

When CONFIG_TRIM_UNUSED_KSYMS=y and CONFIG_BUILD_DOCSRC=y it is possible
to get the following error:

ERROR: "cn_del_callback" [Documentation/connector/cn_test.ko] undefined!
ERROR: "cn_add_callback" [Documentation/connector/cn_test.ko] undefined!
ERROR: "cn_netlink_send" [Documentation/connector/cn_test.ko] undefined!
../scripts/Makefile.modpost:91: recipe for target '__modpost' failed

It is not sufficient to do "vmlinux-dirs += Documentation" as this also
depends on the headers_check target, and all of this needs to be done
before adjust_autoksyms.sh is executed.

Let's sort this out by gathering those sequential prerequisites in a make
target of their own, separate from the vmlinux target. And by doing so,
the special autoksyms_recursive target is no longer needed.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Acked-by: NRandy Dunlap <rdunlap@infradead.org>
Tested-by: NRandy Dunlap <rdunlap@infradead.org>

When a different output directory is specified during the build process (with
O= or KBUILD_OUTPUT), the call to adjust_autoksyms.sh script fails with the
following error:
/bin/sh scripts/adjust_autoksyms.sh \
	  "make KBUILD_MODULES=1 -f ../Makefile autoksyms_recursive"
	  /bin/sh: scripts/adjust_autoksyms.sh: No such file or directory
	  make[2]: *** [vmlinux] Error 127
	  make[1]: *** [sub-make] Error 2
	  make: *** [__sub-make] Error 2

Using the absolute path with $(srctree) variable solves the problem.

This is in case the CONFIG_TRIM_UNUSED_KSYMS option is specified.
Signed-off-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Fixes: 23121ca2 ("kbuild: create/adjust generated/autoksyms.h")
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NMichal Marek <mmarek@suse.com>

When doing a make allmodconfig, I hit the following compile error:

  In file included from builtin-check.c:32:0:
  elf.h:22:18: fatal error: gelf.h: No such file or directory
  compilation terminated.
  ...

Digging into it, it appears that the $(shell ..) command in the Makefile does
not give the proper result when it fails to find -lelf, and continues to
compile objtool.

Instead, use the "try-run" makefile macro to perform the test. This gives a
proper result for both cases.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Acked-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Fixes: 442f04c3 ("objtool: Add tool to perform compile-time stack metadata validation")
Link: http://lkml.kernel.org/r/20160420153234.GA24032@home.goodmis.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

Obviously, the "help" should be a PHONY target.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NMichal Marek <mmarek@suse.com>

As in other places, PHONY is a better fit for "modules" and
"modules_install".
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NMichal Marek <mmarek@suse.com>

These targets are marked as PHONY.  No need to add FORCE to their
dependency.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NMichal Marek <mmarek@suse.com>

Make sample modules in parallel with the rest of the kernel rather
than having them built from the vmlinux target. This makes the build
slightly faster, and those modules are properly considered when
adjust_autoksyms.sh is executed.
Signed-off-by: NNicolas Pitre <nico@linaro.org>

Given the list of exported symbols needed by all modules, we can create
a header file containing preprocessor defines for each of those symbols.
Also, when some symbols are added and/or removed from the list, we can
update the time on the corresponding files used as build dependencies for
those symbols. And finally, if any symbol did change state, the
corresponding source files must be rebuilt.

The insertion or removal of an EXPORT_SYMBOL() entry within a module may
create or remove the need for another exported symbol.  This is why this
operation has to be repeated until the list of needed exported symbols
becomes stable. Only then the final kernel and modules link take place.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>

Similar to include/generated/autoconf.h, include/generated/autoksyms.h
will contain a list of defines for each EXPORT_SYMBOL() that we want
active. The format is:

  #define __KSYM_<symbol_name> 1

This list will be auto-generated with another patch.  For now we only
include the preprocessor magic to automatically create or omit the
corresponding struct kernel_symbol declaration.

Given the content of include/generated/autoksyms.h may not be known in
advance, an empty file is created early on to let the build proceed.
Signed-off-by: NNicolas Pitre <nico@linaro.org>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>

kcov provides code coverage collection for coverage-guided fuzzing
(randomized testing).  Coverage-guided fuzzing is a testing technique
that uses coverage feedback to determine new interesting inputs to a
system.  A notable user-space example is AFL
(http://lcamtuf.coredump.cx/afl/).  However, this technique is not
widely used for kernel testing due to missing compiler and kernel
support.

kcov does not aim to collect as much coverage as possible.  It aims to
collect more or less stable coverage that is function of syscall inputs.
To achieve this goal it does not collect coverage in soft/hard
interrupts and instrumentation of some inherently non-deterministic or
non-interesting parts of kernel is disbled (e.g.  scheduler, locking).

Currently there is a single coverage collection mode (tracing), but the
API anticipates additional collection modes.  Initially I also
implemented a second mode which exposes coverage in a fixed-size hash
table of counters (what Quentin used in his original patch).  I've
dropped the second mode for simplicity.

This patch adds the necessary support on kernel side.  The complimentary
compiler support was added in gcc revision 231296.

We've used this support to build syzkaller system call fuzzer, which has
found 90 kernel bugs in just 2 months:

  https://github.com/google/syzkaller/wiki/Found-Bugs

We've also found 30+ bugs in our internal systems with syzkaller.
Another (yet unexplored) direction where kcov coverage would greatly
help is more traditional "blob mutation".  For example, mounting a
random blob as a filesystem, or receiving a random blob over wire.

Why not gcov.  Typical fuzzing loop looks as follows: (1) reset
coverage, (2) execute a bit of code, (3) collect coverage, repeat.  A
typical coverage can be just a dozen of basic blocks (e.g.  an invalid
input).  In such context gcov becomes prohibitively expensive as
reset/collect coverage steps depend on total number of basic
blocks/edges in program (in case of kernel it is about 2M).  Cost of
kcov depends only on number of executed basic blocks/edges.  On top of
that, kernel requires per-thread coverage because there are always
background threads and unrelated processes that also produce coverage.
With inlined gcov instrumentation per-thread coverage is not possible.

kcov exposes kernel PCs and control flow to user-space which is
insecure.  But debugfs should not be mapped as user accessible.

Based on a patch by Quentin Casasnovas.

[akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode']
[akpm@linux-foundation.org: unbreak allmodconfig]
[akpm@linux-foundation.org: follow x86 Makefile layout standards]
Signed-off-by: NDmitry Vyukov <dvyukov@google.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Cc: syzkaller <syzkaller@googlegroups.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Tavis Ormandy <taviso@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Kees Cook <keescook@google.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: David Drysdale <drysdale@google.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

With the introduction of the simple wait API we have two very
similar APIs in the kernel. For example wake_up() and swake_up()
is only one character away. Although the compiler will warn
happily the wrong usage it keeps on going an even links the kernel.
Thomas and Peter would rather like to see early missuses reported
as error early on.

In a first attempt we tried to wrap all swait and wait calls
into a macro which has an compile time type assertion. The result
was pretty ugly and wasn't able to catch all wrong usages.
woken_wake_function(), autoremove_wake_function() and wake_bit_function()
are assigned as function pointers. Wrapping them with a macro around is
not possible. Prefixing them with '_' was also not a real option
because there some users in the kernel which do use them as well.
All in all this attempt looked to intrusive and too ugly.

An alternative is to turn the pointer type check into an error which
catches wrong type uses. Obviously not only the swait/wait ones. That
isn't a bad thing either.
Signed-off-by: NDaniel Wagner <daniel.wagner@bmw-carit.de>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NMichal Marek <mmarek@suse.com>

This reverts commit ef50c046.

So adding -Werror=incompatible-pointer-types wasn't a bad idea, but it
should really not be done in the scheduler tree: it exposes us to a
number of pre-existing warnings (most of them harmless), now upgraded
to build failures...

This should be done via the kbuild tree.

Cc: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-rt-users@vger.kernel.org
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org

With CONFIG_STACK_VALIDATION enabled, if the host system doesn't have
a development version of libelf installed, the build fails with errors
like:

  elf.h:22:18: fatal error: gelf.h: No such file or directory compilation terminated.

Instead of failing to build, instead just print a warning and disable
stack validation.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-next@vger.kernel.org
Cc: linux@roeck-us.net
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/8c27fe00face60f42e888ddb3142c97e45223165.1457026550.git.jpoimboe@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Running "make O=foo" (with a relative directory path) fails with:

  scripts/Makefile.include:3: *** O=foo does not exist.  Stop.
  /home/jpoimboe/git/linux/Makefile:1547: recipe for target 'tools/objtool' failed

The tools Makefile gets confused by the relative path and tries to build
objtool in tools/foo.  Convert the output directory to an absolute path
before passing it to the tools Makefile.
Reported-by: NSudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-next@vger.kernel.org
Cc: linux@roeck-us.net
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/94a078c6c998fac9f01a14f574008bf7dff40191.1457016803.git.jpoimboe@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Add a CONFIG_STACK_VALIDATION option which will run "objtool check" for
each .o file to ensure the validity of its stack metadata.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/92baab69a6bf9bc7043af0bfca9fb964a1d45546.1456719558.git.jpoimboe@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Add kselftest-merge to enable the dependencies of kernel config
for all the kselftest testcases. User should call it after create
the kernel configuration(.config), eg:

$ make kselftest-merge
Signed-off-by: NBamvor Jian Zhang <bamvor.zhangjian@linaro.org>
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>

With the introduction of the simple wait API we have two very
similar APIs in the kernel. For example wake_up() and swake_up()
is only one character away. Although the compiler will warn
happily the wrong usage it keeps on going an even links the kernel.
Thomas and Peter would rather like to see early missuses reported
as error early on.

In a first attempt we tried to wrap all swait and wait calls
into a macro which has an compile time type assertion. The result
was pretty ugly and wasn't able to catch all wrong usages.
woken_wake_function(), autoremove_wake_function() and wake_bit_function()
are assigned as function pointers. Wrapping them with a macro around is
not possible. Prefixing them with '_' was also not a real option
because there some users in the kernel which do use them as well.
All in all this attempt looked to intrusive and too ugly.

An alternative is to turn the pointer type check into an error which
catches wrong type uses. Obviously not only the swait/wait ones. That
isn't a bad thing either.
Signed-off-by: NDaniel Wagner <daniel.wagner@bmw-carit.de>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-rt-users@vger.kernel.org
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1455871601-27484-3-git-send-email-wagi@monom.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>