gcc-4.7 and higher add a lot of false positive warnings about
potential uses of uninitialized warnings, but only when optimizing
for size (-Os). This is the default when building allyesconfig,
which turns on CONFIG_CC_OPTIMIZE_FOR_SIZE.
In order to avoid getting a lot of patches that initialize such
variables and accidentally hide real errors along the way, let's
just turn off this warning on the respective gcc versions
when building with size optimizations. The -Wmaybe-uninitialized
option was introduced in the same gcc version (4.7) that is now
causing the false positives, so there is no effect on older compilers.
A side effect is that when building with CONFIG_CC_OPTIMIZE_FOR_SIZE,
we might now see /fewer/ warnings about possibly uninitialized
warnings than with -O2, but that is still much better than seeing
warnings known to be bogus.
Change-Id: I5a863923ad347526e6dc58c0bbbc259eb20bfe5c
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Git-commit: e74fc973b6
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Bryan Huntsman <bryanh@codeaurora.org>
commit 2062afb4f8 upstream.
Michel Dänzer and a couple of other people reported inexplicable random
oopses in the scheduler, and the cause turns out to be gcc mis-compiling
the load_balance() function when debugging is enabled. The gcc bug
apparently goes back to gcc-4.5, but slight optimization changes means
that it now showed up as a problem in 4.9.0 and 4.9.1.
The instruction scheduling problem causes gcc to schedule a spill
operation to before the stack frame has been created, which in turn can
corrupt the spilled value if an interrupt comes in. There may be other
effects of this bug too, but that's the code generation problem seen in
Michel's case.
This is fixed in current gcc HEAD, but the workaround as suggested by
Markus Trippelsdorf is pretty simple: use -fno-var-tracking-assignments
when compiling the kernel, which disables the gcc code that causes the
problem. This can result in slightly worse debug information for
variable accesses, but that is infinitely preferable to actual code
generation problems.
Doing this unconditionally (not just for CONFIG_DEBUG_INFO) also allows
non-debug builds to verify that the debug build would be identical: we
can do
export GCC_COMPARE_DEBUG=1
to make gcc internally verify that the result of the build is
independent of the "-g" flag (it will make the compiler build everything
twice, toggling the debug flag, and compare the results).
Without the "-fno-var-tracking-assignments" option, the build would fail
(even with 4.8.3 that didn't show the actual stack frame bug) with a gcc
compare failure.
See also gcc bugzilla:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61801
Reported-by: Michel Dänzer <michel@daenzer.net>
Suggested-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Jakub Jelinek <jakub@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Rather than telling gcc to make warnings as errors, and then hunting
down make rules to disable this, leave them as warnings, but invoke
gcc through a wrapper that checks the warnings against a whitelist.
The initial whitelist comes from the warnings in the current build,
all of which have been allowed through Make overrides.
Change-Id: Ifc9952e03d1a5dbcd90819dc7aa0ec7e50328e20
Signed-off-by: David Brown <davidb@codeaurora.org>
(cherry picked from commit d21ced2f0dda815cac69c693cd81e2e75d8f0007)
A new option is added to the relocs tool called '--realmode'.
This option causes the generation of 16-bit segment relocations
and 32-bit linear relocations for the real-mode code. When
the real-mode code is moved to the low-memory during kernel
initialization, these relocation entries can be used to
relocate the code properly.
In the assembly code 16-bit segment relocations must be relative
to the 'real_mode_seg' absolute symbol. Linear relocations must be
relative to a symbol prefixed with 'pa_'.
16-bit segment relocation is used to load cs:ip in 16-bit code.
Linear relocations are used in the 32-bit code for relocatable
data references. They are declared in the linker script of the
real-mode code.
The relocs tool is moved to arch/x86/tools/relocs.c, and added new
target archscripts that can be used to build scripts needed building
an architecture. be compiled before building the arch/x86 tree.
[ hpa: accelerating this because it detects invalid absolute
relocations, a serious bug in binutils 2.22.52.0.x which currently
produces bad kernels. ]
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-2-git-send-email-jarkko.sakkinen@intel.com
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org>
Pull kbuild changes from Michal Marek:
- Unification of cmd_uimage among archs that use it
- make headers_check tries harder before reporting a missing
<linux/types.h> include
- kbuild portability fix for shells that do not support echo -e
- make clean descends into samples/
- setlocalversion grep fix
- modpost typo fix
- dtc warnings fix
* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
setlocalversion: Use "grep -q" instead of piping output to "read dummy"
modpost: fix ALL_INIT_DATA_SECTIONS
Kbuild: centralize MKIMAGE and cmd_uimage definitions
headers_check: recursively search for linux/types.h inclusion
scripts/Kbuild.include: Fix portability problem of "echo -e"
scripts: dtc: fix compile warnings
kbuild: clean up samples directory
kbuild: disable -Wmissing-field-initializers for W=1
Playing around with make randconfig I ended up with CONFIG_SAMPLES
set. After cleaning up the build I noticed that git status was
showing samples/hidraw/hid-example as an untracked file.
Adding samples to clean-dirs seems to solve the problem, but
I don't know if that is the correct way to solve the issue.
Signed-off-by: Gerard Snitselaar <dev@snitselaar.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>
* 'x86-syscall-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86: Move <asm/asm-offsets.h> from trace_syscalls.c to asm/syscall.h
x86, um: Fix typo in 32-bit system call modifications
um: Use $(srctree) not $(KBUILD_SRC)
x86, um: Mark system call tables readonly
x86, um: Use the same style generated syscall tables as native
um: Generate headers before generating user-offsets.s
um: Run host archheaders, allow use of host generated headers
kbuild, headers.sh: Don't make archheaders explicitly
x86, syscall: Allow syscall offset to be symbolic
x86, syscall: Re-fix typo in comment
x86: Simplify syscallhdr.sh
x86: Generate system call tables and unistd_*.h from tables
checksyscalls: Use arch/x86/syscalls/syscall_32.tbl as source
x86: Machine-readable syscall tables and scripts to process them
trace: Include <asm/asm-offsets.h> in trace_syscalls.c
x86-64, ia32: Move compat_ni_syscall into C and its own file
x86-64, syscall: Adjust comment spacing and remove typo
kbuild: Add support for an "archheaders" target
kbuild: Add support for installing generated asm headers
* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
Kbuild: Use dtc's -d (dependency) option
dtc: Implement -d option to write out a dependency file
kbuild: Fix comment in Makefile.lib
scripts/genksyms: clean lex/yacc generated files
kbuild: Correctly deal with make options which contain an "s"
When using remake, which is based on gnumake, if you invoke
an example build as shown below, the build will become silent
due to the top level make file incorrectly guessing that
the end user wants a silent build because an argument that
contained an "s" was used. Here are two examples one with remake
and one with straight gnumake.
remake --no-extended-errors
make --warn-undefined-variables
Fix up the top level Makefile to use filter to parse the options
that mean silent instead of findstring catching other random
arguments containing an "s".
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
CC: Michal Marek <mmarek@suse.cz>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: linux-kbuild@vger.kernel.org
Signed-off-by: Michal Marek <mmarek@suse.cz>
Add support for an "archheaders" target. This target can generate
files that need to be installed for user space by "make
headers_install" or "make headers_install_all".
In order to support "make headers_install_all", it must be able to run
without the tree having to be configured first.
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
.. with new name. Because nothing says "really solid kernel release"
like naming it after an extinct animal that just happened to be in the
news lately.
* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
Kbuild: append missing-syscalls to the default target list
genksyms: Regenerate lexer and parser
genksyms: Do not expand internal types
genksyms: Minor parser cleanup
Makefile: remove a duplicated line
fixdep: fix extraneous dependencies
scripts/Makefile.build: do not reference EXTRA_CFLAGS as CFLAGS replacement
kbuild: prevent make from deleting _shipped files
kbuild: Do not delete empty files in make distclean
There are two duplicated lines for 'make RECORDMCOUNT_WARN=1 [targets]'
in 'make help', remove the second one.
Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
Commit 3d64b44 introduced an empty file under
arch/arm/mach-zynq/board_dt.c. While this was not intended and the file
was removed from the tree by a later commit, we really should only match
junk files by known name patterns and not their size.
Reported-by: David Howells <dhowells@redhat.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
* 'kconfig' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6: (25 commits)
kconfig: Introduce IS_ENABLED(), IS_BUILTIN() and IS_MODULE()
xconfig: Abort close if configuration cannot be saved
kconfig: fix missing "0x" prefix from S_HEX symbol in autoconf.h
kconfig/nconf: remove useless conditionnal
kconfig/nconf: prevent segfault on empty menu
kconfig/nconf: use the generic menu_get_ext_help()
nconfig: Avoid Wunused-but-set warning
kconfig/conf: mark xfgets() private
kconfig: remove pending prototypes for kconfig_load()
kconfig/conf: add command line options' description
kconfig/conf: reduce the scope of `defconfig_file'
kconfig: use calloc() for expr allocation
kconfig: introduce specialized printer
kconfig: do not overwrite symbol direct dependency in assignment
kconfig/gconf: silent missing prototype warnings
kconfig/gconf: kill deadcode
kconfig: nuke LKC_DIRECT_LINK cruft
kconfig: nuke reference to SWIG
kconfig: add missing <stdlib.h> inclusion
kconfig: add missing <ctype.h> inclusion
...
Fix up conflicts in scripts/kconfig/Makefile
