GCC 4.9 and newer have a new warning -Wdate-time, which warns on any use
of __DATE__, __TIME__, or __TIMESTAMP__, which would make the build
non-deterministic.  Now that the kernel does not use any of those
macros, turn on -Werror=date-time if available, to keep it that way.

The kernel already (optionally) records this information at build time
in a single place; other kernel code should not duplicate that.
Signed-off-by: NJosh Triplett <josh@joshtriplett.org>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Change the debuging info generation flag in KBUILD_AFLAGS from '-gdwarf-2' to
'-Wa,--gdwarf-2'.  This will properly generate the debugging info for .S files
when CONFIG_DEBUG_INFO=y.

It seems current gcc does not pass a '--gdwarf-2' option on to the assembler
when '-gdwarf-2' is on its command line (note the differece in the gcc and as
flags).  This change provides the correct assembler flag to gcc, and so does
not rely on gcc to emit a flag for the assembler.

Signed-off-by: Geoff Levand <geoff@infradead.org> for Huawei, Linaro
Signed-off-by: NMichal Marek <mmarek@suse.cz>

make-4 changed the way/order it presents the command line options
into MAKEFLAGS

In make-3.8x, '-s' would always be first into a group of options
with the '-'/hyphen removed

$ make -p -s 2>/dev/null | grep ^MAKEFLAGS
MAKEFLAGS = sp

In make-4, '-s' seems to always be last into a group of options
with the '-'/hyphen removed

$ make -s -p 2>/dev/null | grep ^MAKEFLAGS
MAKEFLAGS = ps
Signed-off-by: NEmil Medve <Emilian.Medve@Freescale.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Commit 1bf49dd4 ("./Makefile: export initial ramdisk compression
config option") started setting the INITRD_COMPRESS environment variable
depending on which decompression models the kernel had available.

That is completely broken.

For example, we by default have CONFIG_RD_LZ4 enabled, and are able to
decompress such an initrd, but the user tools to *create* such an initrd
may not be availble.  So trying to tell dracut to generate an
lz4-compressed image just because we can decode such an image is
completely inappropriate.

Cc: J P <ppandit@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Beulich <JBeulich@suse.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This changes the stack protector config option into a choice of
"None", "Regular", and "Strong":

   CONFIG_CC_STACKPROTECTOR_NONE
   CONFIG_CC_STACKPROTECTOR_REGULAR
   CONFIG_CC_STACKPROTECTOR_STRONG

"Regular" means the old CONFIG_CC_STACKPROTECTOR=y option.

"Strong" is a new mode introduced by this patch. With "Strong" the
kernel is built with -fstack-protector-strong (available in
gcc 4.9 and later). This option increases the coverage of the stack
protector without the heavy performance hit of -fstack-protector-all.

For reference, the stack protector options available in gcc are:

-fstack-protector-all:
  Adds the stack-canary saving prefix and stack-canary checking
  suffix to _all_ function entry and exit. Results in substantial
  use of stack space for saving the canary for deep stack users
  (e.g. historically xfs), and measurable (though shockingly still
  low) performance hit due to all the saving/checking. Really not
  suitable for sane systems, and was entirely removed as an option
  from the kernel many years ago.

-fstack-protector:
  Adds the canary save/check to functions that define an 8
  (--param=ssp-buffer-size=N, N=8 by default) or more byte local
  char array. Traditionally, stack overflows happened with
  string-based manipulations, so this was a way to find those
  functions. Very few total functions actually get the canary; no
  measurable performance or size overhead.

-fstack-protector-strong
  Adds the canary for a wider set of functions, since it's not
  just those with strings that have ultimately been vulnerable to
  stack-busting. With this superset, more functions end up with a
  canary, but it still remains small compared to all functions
  with only a small change in performance. Based on the original
  design document, a function gets the canary when it contains any
  of:

    - local variable's address used as part of the right hand side
      of an assignment or function argument
    - local variable is an array (or union containing an array),
      regardless of array type or length
    - uses register local variables

  https://docs.google.com/a/google.com/document/d/1xXBH6rRZue4f296vGt9YQcuLVQHeE516stHwt8M9xyU

Find below a comparison of "size" and "objdump" output when built with
gcc-4.9 in three configurations:

  - defconfig
	11430641 kernel text size
	36110 function bodies

  - defconfig + CONFIG_CC_STACKPROTECTOR_REGULAR
	11468490 kernel text size (+0.33%)
	1015 of 36110 functions are stack-protected (2.81%)

  - defconfig + CONFIG_CC_STACKPROTECTOR_STRONG via this patch
	11692790 kernel text size (+2.24%)
	7401 of 36110 functions are stack-protected (20.5%)

With -strong, ARM's compressed boot code now triggers stack
protection, so a static guard was added. Since this is only used
during decompression and was never used before, the exposure
here is very small. Once it switches to the full kernel, the
stack guard is back to normal.

Chrome OS has been using -fstack-protector-strong for its kernel
builds for the last 8 months with no problems.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@linux-mips.org
Cc: linux-arch@vger.kernel.org
Link: http://lkml.kernel.org/r/1387481759-14535-3-git-send-email-keescook@chromium.org
[ Improved the changelog and descriptions some more. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Instead of duplicating the CC_STACKPROTECTOR Kconfig and
Makefile logic in each architecture, switch to using
HAVE_CC_STACKPROTECTOR and keep everything in one place. This
retains the x86-specific bug verification scripts.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@linux-mips.org
Cc: linux-arch@vger.kernel.org
Link: http://lkml.kernel.org/r/1387481759-14535-2-git-send-email-keescook@chromium.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

According to Documentation/Changes, make 3.80 is still being supported
for building the kernel, hence make files must not make (unconditional)
use of features introduced only in newer versions.

Commit 1bf49dd4 ("./Makefile: export initial ramdisk compression
config option") however introduced "else ifeq" constructs which make
3.80 doesn't understand.  Replace the logic there with more conventional
(in the kernel build infrastructure) list constructs (except that the
list here is intentionally limited to exactly one element).
Signed-off-by: NJan Beulich <jbeulich@suse.com>
Cc: P J P <ppandit@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make menuconfig allows one to choose compression format of an initial
ramdisk image.  But this choice does not result in duly compressed ramdisk
image.  Because - $ make install - does not pass on the selected
compression choice to the dracut(8) tool, which creates the initramfs
file.  dracut(8) generates the image with the default compression, ie.
gzip(1).

This patch exports the selected compression option to a sub-shell
environment, so that it could be used by dracut(8) tool to generate
appropriately compressed initramfs images.

There isn't a straightforward way to pass on options to dracut(8) via
positional parameters.  Because it is indirectly invoked at the end of a $
make install sequence.

 # make install
   -> arch/$arch/boot/Makefile
    -> arch/$arch/boot/install.sh
     -> /sbing/installkernel ...
      -> /sbin/new-kernel-pkg ...
       -> /sbin/dracut ...
Signed-off-by: NP J P <ppandit@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When building the kernel in a shell which defines GREP_OPTIONS so that
grep behavior is modified, we can break the generation of the syscalls
table like so:

__SYSCALL_COMMON(^[[01;31m^[[K0^[[m^[[K, sys_read, sys_read)
__SYSCALL_COMMON(^[[01;31m^[[K1^[[m^[[K, sys_write, sys_write)
__SYSCALL_COMMON(^[[01;31m^[[K1^[[m^[[K0, sys_mprotect, sys_mprotect) ...

This is just the initial breakage, later we barf when generating
modules.

In this case, GREP_OPTIONS contains "--color=always" which adds the shell
colors markup and completely fudges the headers under ...generated/asm/.

Fix that by unexporting the GREP_OPTIONS variable for the whole kernel
build as we tend to use grep at a bunch of places.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

The common error found in forward-ported/backported patches is missing
headers.  One recent example (files and function names are mangled):

    void foo(){}
    EXPORT_SYMBOL(foo);

gave only warning

    foo.c:12345678:5: warning: function declaration isn't a prototype [-Wstrict-prototypes]
    void foo(){}
         ^

    foo.c:12345679:5: warning: data definition has no type or storage class [enabled by default]
    EXPORT_SYMBOL(foo);
    foo.c:12345679:5: warning: type defaults to 'int' in declaration of 'EXORT_SYMBOL' [-Werror=implicit-int]

Now it's a fatal error. Tested on x86_64 allyesconfig.

[akpm@linux-foundation.org: fix typos in comments]
Signed-off-by: NSergei Trofimovich <slyfox@gentoo.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

This reverts the Linux for Workgroups thing.  And no, before somebody
asks, we're not doing Linux95.  Not for a few years, at least.

Sure, the flag added some color to the logo, and could have remained as
a testament to my leet gimp skills.  But no.  And I'll do this early, to
avoid the chance of forgetting when I'm doing the actual rc1 release on
the road.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use filechk to detect if the content changed or not.
Signed-off-by: NMichal Marek <mmarek@suse.cz>

This reverts commit d2aae847.

It is completely and utterly broken.  Module install should not build
any files, and adding broken dependencies to "help" it build files is
complete and utter sh*t.

The kernel should not be built by root, and "make install" and "make
module_install" (that for obvious reasons need to be run as root)
absolutely must not build any files.  They should only ever copy the
already-built files over.

So having dependencies for the install targets is wrong, wrong, wrong.

If you try to install a kernel without building it first, you *should*
get errors. The build system shouldn't try to help root build the files.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make modules_install fails with -j option:

   DEPMOD
 Usage: .../.source/linux/scripts/depmod.sh /sbin/depmod <kernelrelease>
 make[1]: *** [_modinst_post] Error 1

Adding kernelrelease dependency to fix this.
Signed-off-by: NRobert Richter <robert.richter@calxeda.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NMichal Marek <mmarek@suse.cz>