Turning on this flag could prevent the compiler from optimising away
some "useless" checks for null pointers.  Such bugs can sometimes become
exploitable at compile time because of the -O2 optimisation.

See http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Optimize-Options.html



An example that clearly shows this 'problem' is commit 6bf67672.

 static void __devexit agnx_pci_remove(struct pci_dev *pdev)
 {
     struct ieee80211_hw *dev = pci_get_drvdata(pdev);
-    struct agnx_priv *priv = dev->priv;
+    struct agnx_priv *priv;
     AGNX_TRACE;

     if (!dev)
         return;
+    priv = dev->priv;

By reverting this patch, and compile it with and without
-fno-delete-null-pointer-checks flag, we can see that the check for dev
is compiled away.

    call    printk  #
-   testq   %r12, %r12  # dev
-   je  .L94    #,
    movq    %r12, %rdi  # dev,

Clearly the 'fix' is to stop using dev before it is tested, but building
with -fno-delete-null-pointer-checks flag at least makes it harder to
abuse.

Signed-off-by: Eugene Teo <eugeneteo@kernel.sg>
Acked-by: Eric Paris <eparis@redhat.com>
Acked-by: Wang Cong <amwang@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This causes kernel images that don't run init to completion with certain
broken gcc versions.

This fixes kernel bugzilla entry:
	http://bugzilla.kernel.org/show_bug.cgi?id=13012

I suspect the gcc problem is this:
	http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28230



Fix the problem by using the -fno-strict-overflow flag instead, which
not only does not exist in the known-to-be-broken versions of gcc (it
was introduced later than fwrapv), but seems to be much less disturbing
to gcc too: the difference in the generated code by -fno-strict-overflow
are smaller (compared to using neither flag) than when using -fwrapv.

Reported-by: Barry K. Nathan <barryn@pobox.com>
Pushed-by: Frans Pop <elendil@planet.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

TOPDIR is obsolete, it can be finally removed now.

Signed-off-by: WANG Cong <amwang@redhat.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Some distributions have enabled the gcc flag -Wformat-security by default.
This results in a number of warnings about format arguments to functions,
sometimes in cases where fixing the warning is not likely to actually fix a
bug.  Instead of hand patching a dozens of places (possibly more) that produce
warnings that get ignored anyway we just turn off the flag in the Makefile.

Signed-off-by: Floris Kraak <randakar@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Enable the use of GCC's coverage testing tool gcov [1] with the Linux
kernel.  gcov may be useful for:

 * debugging (has this code been reached at all?)
 * test improvement (how do I change my test to cover these lines?)
 * minimizing kernel configurations (do I need this option if the
   associated code is never run?)

The profiling patch incorporates the following changes:

 * change kbuild to include profiling flags
 * provide functions needed by profiling code
 * present profiling data as files in debugfs

Note that on some architectures, enabling gcc's profiling option
"-fprofile-arcs" for the entire kernel may trigger compile/link/
run-time problems, some of which are caused by toolchain bugs and
others which require adjustment of architecture code.

For this reason profiling the entire kernel is initially restricted
to those architectures for which it is known to work without changes.
This restriction can be lifted once an architecture has been tested
and found compatible with gcc's profiling. Profiling of single files
or directories is still available on all platforms (see config help
text).

[1] http://gcc.gnu.org/onlinedocs/gcc/Gcov.html



Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Li Wei <W.Li@Sun.COM>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The GNU make's origin function know undefined variable well,
so the outer ifdef/endif conditional checking is unneeded.

From `info make` documentation, origin will return

  `undefined'
     if VARIABLE was never defined.
  `command line'
     if VARIABLE was defined on the command line.
   ...

Therefore, $(origin V) will get a value anyway, killing ifdef/endif is
viable and safe.

Furthermore, I've checked the minimal requirements from
Documentation/Changes is GNU make 3.79.1, and that version of GNU make
has support of origin function well already, so now it's safe to kill
the outer conditional checking, without upgrading the minimal
requirements.

Signed-off-by: Cheng Renquan <crq@kernel.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

The checking of CONFIG_FRAME_WARN in the top level Makefile forgot to
actually derefence the variable thus leading to an always true check.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Correct the Makefile help text to read "make modules_prepare".

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Signed-off-by: Frédéric Brière <fbriere@fbriere.net>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

We need a location for generated files.
Today they are spread over several places and bringing them
together to a common place makes it obvious hat is generated
and what isreal files.

Al Viro originally suggested: include/gen
Linus suggested to spell it out.

This patch implement support for

    include/generated

All files in include/generated are ignored by git.
include/generated is removed during "make mrproper".

With this we are ready to implement support for include/generated
in the various architctures and in the base kernel.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>

Make it possible for the linker to discard local symbols from vmlinux as
they cause vmlinux to balloon when CONFIG_KALLSYMS=y and they cause
dump_stack() and get_wchan() to produce useless information under some
circumstances.

With this we add a config option (CONFIG_STRIP_ASM_SYMS) that will cause
the build to supply -X to the linker to tell it to strip temporary local
symbols.

This doesn't seem to cause gdb any problems.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru>
Acked-by: Dmitry Gryazin <gdu@mns.spb.ru>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

This adds in support for building with ARCH=sh64 using the sh SRCARCH.
This tidies up the randconfig generation somewhat to make sure that we
don't end up with impossible configurations, and without having to rely
on things like KCONFIG_ALLCONFIG to detect the proper CPU support subset.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

With a sufficiently new compiler and binutils, code which wasn't
previously generating .eh_frame sections has begun to.  Certain
architectures (powerpc, in this case) may generate unexpected relocation
formats in response to this, preventing modules from loading.

While the new relocation types should probably be handled, revert to the
previous behaviour with regards to generation of .eh_frame sections.

(This was reported against Fedora, which appears to be the only distro
doing any building against gcc-4.4 at present: RH bz#486545.)

Signed-off-by: Kyle McMartin <kyle@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Alexandre Oliva <aoliva@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Sam Ravnborg says:
 "We have several architectures that plays strange games with $(CC) and
  $(CROSS_COMPILE).

  So we need to postpone any use of $(call cc-option..) until we have
  included the arch specific Makefile so we try with the correct $(CC)
  version."

Requested-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This makes sure that gcc doesn't try to optimize away wrapping
arithmetic, which the kernel occasionally uses for overflow testing, ie
things like

	if (ptr + offset < ptr)

which technically is undefined for non-unsigned types. See

	http://bugzilla.kernel.org/show_bug.cgi?id=12597



for details.

Not all versions of gcc support it, so we need to make it conditional
(it looks like it was introduced in gcc-3.4).

Reminded-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Following a thread on busybox mailing list
depmod -r option is ignored by module-init-tools depmod
-r option break busybox depmod.

So the best solution look to remove -r from kernel Makefile

Signed-off-by: Gilles Espinasse <g.esp@free.fr>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Running 'make rpm' fails when CONFIG_LOCALVERSION_AUTO=y and using a kernel source
tree under SCM.  This is due to KERNELRELEASE being different when the initial make
is run and when make is run from rpmbuild.

mkspec creates kernel.spec using KERNELRELEASE:

<mkspec>
echo "%files"
echo '%defattr (-, root, root)'
echo "%dir /lib/modules"
echo "/lib/modules/$KERNELRELEASE"
echo "/lib/firmware"
echo "/boot/*"
echo ""
</mkspec>

When CONFIG_LOCALVERSION_AUTO=y scripts/setlocalversion is called and grabs any
additional version info from SCM.  Next, the srctree is tarred up and SCM
information is excluded.

rpmbuild reruns make and in the process generates a new include/config/kernel.release
and thus a new KERNELRELEASE.  However this time the SCM information is gone so
KERNELRELEASE no longer has the additional version information.  When "make modules_install"
runs, it uses the new KERNELRELEASE value to determine where to install the modules.
This conflicts with where the spec file assumes they are going because of the
mis-matching KERNELRELEASE versions.

<snippet>
+ INSTALL_MOD_PATH=/var/tmp/kernel-2.6.29rc4tip01479g5d85422-root
+ make -j16 modules_install
  INSTALL crypto/aead.ko
  INSTALL crypto/cbc.ko
  INSTALL crypto/chainiv.ko
  INSTALL crypto/crc32c.ko
  INSTALL crypto/crypto_algapi.ko
  INSTALL crypto/crypto_blkcipher.ko
  INSTALL crypto/crypto_hash.ko
  INSTALL crypto/cryptomgr.ko
  INSTALL crypto/ecb.ko
  INSTALL crypto/eseqiv.ko
  INSTALL crypto/krng.ko
  INSTALL crypto/md5.ko
  INSTALL crypto/pcbc.ko
  INSTALL crypto/rng.ko
  INSTALL drivers/block/cciss.ko
  INSTALL drivers/hid/hid-dummy.ko
  INSTALL drivers/scsi/iscsi_tcp.ko
  INSTALL drivers/scsi/libiscsi.ko
  INSTALL drivers/scsi/libiscsi_tcp.ko
  INSTALL drivers/scsi/scsi_transport_iscsi.ko
  INSTALL drivers/scsi/scsi_wait_scan.ko
  INSTALL fs/lockd/lockd.ko
  INSTALL fs/nfs/nfs.ko
  INSTALL fs/nfsd/nfsd.ko
  INSTALL lib/libcrc32c.ko
  INSTALL net/sunrpc/sunrpc.ko
  DEPMOD  2.6.29-rc4-tip
+ cp arch/x86/boot/bzImage
/var/tmp/kernel-2.6.29rc4tip01479g5d85422-root/boot/vmlinuz-2.6.29-rc4-tip-01479-g5d85422
+ cp System.map
/var/tmp/kernel-2.6.29rc4tip01479g5d85422-root/boot/System.map-2.6.29-rc4-tip-01479-g5d85422
+ cp .config
/var/tmp/kernel-2.6.29rc4tip01479g5d85422-root/boot/config-2.6.29-rc4-tip-01479-g5d85422
+ cp vmlinux vmlinux.orig
+ bzip2 -9 vmlinux
+ mv vmlinux.bz2
/var/tmp/kernel-2.6.29rc4tip01479g5d85422-root/boot/vmlinux-2.6.29-rc4-tip-01479-g5d85422.bz2
+ mv vmlinux.orig vmlinux
+ /usr/lib/rpm/brp-compress
Processing files: kernel-2.6.29rc4tip01479g5d85422-2
error: File not found:
/var/tmp/kernel-2.6.29rc4tip01479g5d85422-root/lib/modules/2.6.29-rc4-tip-01479-g5d85422

RPM build errors:
    File not found:
/var/tmp/kernel-2.6.29rc4tip01479g5d85422-root/lib/modules/2.6.29-rc4-tip-01479-g5d85422
make[1]: *** [rpm] Error 1
make: *** [rpm] Error 2
</snippet>

I have tested this patch on git -tip, Linus' git tree, and the kernel.org tar files, both
with and without CONFIG_LOCALVERSION_AUTO=y.

Signed-off-by: Josh Hunt <josh@scalex86.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
----