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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild fix from Masahiro Yamada:
"Fix false positive warning/error about missing library for objtool"
* tag 'kbuild-fixes-v4.20-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: fix false positive warning/error about missing libelf
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For the same reason as commit 25896d073d8a ("x86/build: Fix compiler
support check for CONFIG_RETPOLINE"), you cannot put this $(error ...)
into the parse stage of the top Makefile.
Perhaps I'd propose a more sophisticated solution later, but this is
the best I can do for now.
Link: https://lkml.org/lkml/2017/12/25/211
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Reported-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reported-by: Qian Cai <cai@lca.pw>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Qian Cai <cai@lca.pw>
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work around asm() related GCC inlining bugs"
This reverts commit 77b0bf55bc675233d22cd5df97605d516d64525e.
See this commit for details about the revert:
e769742d3584 ("Revert "x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs"")
Conflicts:
arch/x86/Makefile
Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Borislav Petkov <bp@alien8.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: Richard Biener <rguenther@suse.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This flag is documented in the GCC 4.6 manual, and recognized by
Clang as well. Let's rip off the cc-option switch.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
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-Wstrict-prototypes is added to KBUILD_CFLAGS first, then overridden
by -Werror=strict-prototypes later.
Let's add -Werror=strict-prototypes unconditionally because it is
supported by GCC 4.6, and also by Clang.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
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This flag is documented in the GCC 4.6 manual, and recognized by
Clang as well. Let's rip off the cc-option switch.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
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- Use conventional $(MAKE) $(asm-generic)=<dir> style
for directory descending
- Remove unneeded FORCE since "all" is a phony target
- Remove unneeded "_dummy :=" assignment
- Skip $(shell mkdir ...) when headers exist in the directory
- Misc cleanups
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
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This adds the build infrastructure for checking DT binding schema
documents and validating dts files using the binding schema.
Check DT binding schema documents:
make dt_binding_check
Build dts files and check using DT binding schema:
make dtbs_check
Optionally, DT_SCHEMA_FILES can be passed in with a schema file(s) to
use for validation. This makes it easier to find and fix errors
generated by a specific schema.
Currently, the validation targets are separate from a normal build to
avoid a hard dependency on the external DT schema project and because
there are lots of warnings generated.
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: linux-doc@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-kbuild@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
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When CONFIG_HEADERS_CHECK is enabled, the headers_check is executed
as a serialized task in the vmlinux recipe.
Make it independent of vmlinux so that parallel building can process
the headers_check and other build targets simultaneously.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Currently, fixdep writes dependencies to .*.tmp, which is renamed to
.*.cmd after everything succeeds. This is a very safe way to avoid
corrupted .*.cmd files. The if_changed_dep has carried this safety
mechanism since it was added in 2002.
If fixdep fails for some reasons or a user terminates the build while
fixdep is running, the incomplete output from the fixdep could be
troublesome.
This is my insight about some bad scenarios:
[1] If the compiler succeeds to generate *.o file, but fixdep fails
to write necessary dependencies to .*.cmd file, Make will miss
to rebuild the object when headers or CONFIG options are changed.
In this case, fixdep should not generate .*.cmd file at all so
that 'arg-check' will surely trigger the rebuild of the object.
[2] A partially constructed .*.cmd file may not be a syntactically
correct makefile. The next time Make runs, it would include it,
then fail to parse it. Once this happens, 'make clean' is be the
only way to fix it.
In fact, [1] is no longer a problem since commit 9c2af1c7377a ("kbuild:
add .DELETE_ON_ERROR special target"). Make deletes a target file on
any failure in its recipe. Because fixdep is a part of the recipe of
*.o target, if it fails, the *.o is deleted anyway. However, I am a
bit worried about the slight possibility of [2].
So, here is a solution. Let fixdep directly write to a .*.cmd file,
but allow makefiles to include it only when its corresponding target
exists.
This effectively reverts commit 2982c953570b ("kbuild: remove redundant
$(wildcard ...) for cmd_files calculation"), and commit 00d78ab2ba75
("kbuild: remove dead code in cmd_files calculation in top Makefile")
because now we must check the presence of targets.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Now that 'archprepare' depends on 'scripts', Kbuild can descend into
scripts/gcc-plugins in a more standard way.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
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Before start descending, Kbuild needs to run 'prepare' and 'scripts',
which has been orthogonal to each other.
Going forward, let's consider 'scripts' is a part of the preparation.
This will allow more cleanups.
Move 'scripts' to the prerequisite of 'archprepare', where UML starts
compiling target *.c files.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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I am eagar to build under the scripts/ directory only with $(HOSTCC),
but scripts/mod/ highly depends on the $(CC) and target arch headers.
That it why the 'scripts' target must depend on 'asm-generic',
'gcc-plugins', and $(autoksyms_h).
Move it to the 'prepare0' stage. I know this is a cheesy workaround,
but better than the current situation.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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UML fails to build with CONFIG_GCC_PLUGINS=y.
$ make -s ARCH=um mrproper
$ make -s ARCH=um allmodconfig
$ make ARCH=um
UPD include/generated/uapi/linux/version.h
WRAP arch/x86/include/generated/uapi/asm/bpf_perf_event.h
WRAP arch/x86/include/generated/uapi/asm/poll.h
WRAP arch/x86/include/generated/asm/dma-contiguous.h
WRAP arch/x86/include/generated/asm/early_ioremap.h
WRAP arch/x86/include/generated/asm/export.h
WRAP arch/x86/include/generated/asm/mcs_spinlock.h
WRAP arch/x86/include/generated/asm/mm-arch-hooks.h
SYSTBL arch/x86/include/generated/asm/syscalls_32.h
SYSHDR arch/x86/include/generated/asm/unistd_32_ia32.h
SYSHDR arch/x86/include/generated/asm/unistd_64_x32.h
SYSTBL arch/x86/include/generated/asm/syscalls_64.h
SYSHDR arch/x86/include/generated/uapi/asm/unistd_32.h
SYSHDR arch/x86/include/generated/uapi/asm/unistd_64.h
SYSHDR arch/x86/include/generated/uapi/asm/unistd_x32.h
HOSTCC scripts/unifdef
CC arch/x86/um/user-offsets.s
cc1: error: cannot load plugin ./scripts/gcc-plugins/cyc_complexity_plugin.so
./scripts/gcc-plugins/cyc_complexity_plugin.so: cannot open shared object file: No such file or directory
cc1: error: cannot load plugin ./scripts/gcc-plugins/structleak_plugin.so
./scripts/gcc-plugins/structleak_plugin.so: cannot open shared object file: No such file or directory
cc1: error: cannot load plugin ./scripts/gcc-plugins/latent_entropy_plugin.so
./scripts/gcc-plugins/latent_entropy_plugin.so: cannot open shared object file: No such file or directory
cc1: error: cannot load plugin ./scripts/gcc-plugins/randomize_layout_plugin.so
./scripts/gcc-plugins/randomize_layout_plugin.so: cannot open shared object file: No such file or directory
make[1]: *** [scripts/Makefile.build;119: arch/x86/um/user-offsets.s] Error 1
make: *** [arch/um/Makefile;152: arch/x86/um/user-offsets.s] Error 2
Reorder the preparation stage (with cleanups) to make sure gcc-plugins
is built before descending to arch/x86/um/.
Fixes: 6b90bd4ba40b ("GCC plugin infrastructure")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Building a single target in an external module fails due to missing
.tmp_versions directory.
For example,
$ make -C /lib/modules/$(uname -r)/build M=$PWD foo.o
will fail in the following way:
CC [M] /home/masahiro/foo/foo.o
/bin/sh: 1: cannot create /home/masahiro/foo/.tmp_versions/foo.mod: Directory nonexistent
This is because $(cmd_crmodverdir) is executed only before building
/, %/, %.ko single targets of external modules. Create .tmp_versions
in the 'prepare' target.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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SUBDIRS has been kept as a backward compatibility since
commit ("[PATCH] kbuild: external module support") in 2002.
We do not need multiple ways to do the same thing, so I will remove
SUBDIRS after the Linux 5.3 release. I cleaned up in-tree code, and
updated the document so that nobody would try to use it.
Meanwhile, display the following warning if SUBDIRS is used.
Makefile:189: ================= WARNING ================
Makefile:190: 'SUBDIRS' will be removed after Linux 5.3
Makefile:191: Please use 'M=' or 'KBUILD_EXTMOD' instead
Makefile:192: ==========================================
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Boris Brezillon <boris.brezillon@bootlin.com> # for scx200_docflash.c
Acked-by: Guenter Roeck <linux@roeck-us.net> # for scx200_wdt.c
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The powerpc makefile will use these in it's boot wrapper.
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Collect basic Clang options such as --target, --prefix, --gcc-toolchain,
-no-integrated-as into a single variable CLANG_FLAGS so that it can be
easily reused in other parts of Makefile.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Greg Hackmann <ghackmann@google.com>
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We are still a way off the Clang's integrated assembler support for
the kernel. Hence, -no-integrated-as is mandatory to build the kernel
with Clang. If you had an ancient version of Clang that does not
recognize this option, you would not be able to compile the kernel
anyway.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
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There is one more user of $(cc-name) in the top Makefile. It is supposed
to detect Clang before invoking Kconfig, so it should still be there
in the $(shell ...) form. All the other users of $(cc-name) have been
replaced with $(CONFIG_CC_IS_CLANG). Hence, scripts/Kbuild.include does
not need to define cc-name any more.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Evaluating cc-name invokes the compiler every time even when you are
not compiling anything, like 'make help'. This is not efficient.
The compiler type has been already detected in the Kconfig stage.
Use CONFIG_CC_IS_CLANG, instead.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Paul Burton <paul.burton@mips.com> (MIPS)
Acked-by: Joel Stanley <joel@jms.id.au>
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git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull VLA removal from Kees Cook:
"Globally warn on VLA use.
This turns on "-Wvla" globally now that the last few trees with their
VLA removals have landed (crypto, block, net, and powerpc).
Arnd mentioned that there may be a couple more VLAs hiding in
hard-to-find randconfigs, but nothing big has shaken out in the last
month or so in linux-next.
We should be basically VLA-free now! Wheee. :)
Summary:
- Remove unused fallback for BUILD_BUG_ON (which technically contains
a VLA)
- Lift -Wvla to the top-level Makefile"
* tag 'vla-v4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
Makefile: Globally enable VLA warning
compiler.h: give up __compiletime_assert_fallback()
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- optimize kallsyms slightly
- remove check for old CFLAGS usage
- add some compiler flags unconditionally instead of evaluating
$(call cc-option,...)
- fix variable shadowing in host tools
- refactor scripts/mkmakefile
- refactor various makefiles
* tag 'kbuild-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
modpost: Create macro to avoid variable shadowing
ASN.1: Remove unnecessary shadowed local variable
kbuild: use 'else ifeq' for checksrc to improve readability
kbuild: remove unneeded link_multi_deps
kbuild: add -Wno-unused-but-set-variable flag unconditionally
kbuild: add -Wdeclaration-after-statement flag unconditionally
kbuild: add -Wno-pointer-sign flag unconditionally
modpost: remove leftover symbol prefix handling for module device table
kbuild: simplify command line creation in scripts/mkmakefile
kbuild: do not pass $(objtree) to scripts/mkmakefile
kbuild: remove user ID check in scripts/mkmakefile
kbuild: remove VERSION and PATCHLEVEL from $(objtree)/Makefile
kbuild: add --include-dir flag only for out-of-tree build
kbuild: remove dead code in cmd_files calculation in top Makefile
kbuild: hide most of targets when running config or mixed targets
kbuild: remove old check for CFLAGS use
kbuild: prefix Makefile.dtbinst path with $(srctree) unconditionally
kallsyms: remove left-over Blackfin code
kallsyms: reduce size a little on 64-bit
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git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
Pull Devicetree updates from Rob Herring:
"A bit bigger than normal as I've been busy this cycle.
There's a few things with dependencies and a few things subsystem
maintainers didn't pick up, so I'm taking them thru my tree.
The fixes from Johan didn't get into linux-next, but they've been
waiting for some time now and they are what's left of what subsystem
maintainers didn't pick up.
Summary:
- Sync dtc with upstream version v1.4.7-14-gc86da84d30e4
- Work to get rid of direct accesses to struct device_node name and
type pointers in preparation for removing them. New helpers for
parsing DT cpu nodes and conversions to use the helpers. printk
conversions to %pOFn for printing DT node names. Most went thru
subystem trees, so this is the remainder.
- Fixes to DT child node lookups to actually be restricted to child
nodes instead of treewide.
- Refactoring of dtb targets out of arch code. This makes the support
more uniform and enables building all dtbs on c6x, microblaze, and
powerpc.
- Various DT binding updates for Renesas r8a7744 SoC
- Vendor prefixes for Facebook, OLPC
- Restructuring of some ARM binding docs moving some peripheral
bindings out of board/SoC binding files
- New "secure-chosen" binding for secure world settings on ARM
- Dual licensing of 2 DT IRQ binding headers"
* tag 'devicetree-for-4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux: (78 commits)
ARM: dt: relicense two DT binding IRQ headers
power: supply: twl4030-charger: fix OF sibling-node lookup
NFC: nfcmrvl_uart: fix OF child-node lookup
net: stmmac: dwmac-sun8i: fix OF child-node lookup
net: bcmgenet: fix OF child-node lookup
drm/msm: fix OF child-node lookup
drm/mediatek: fix OF sibling-node lookup
of: Add missing exports of node name compare functions
dt-bindings: Add OLPC vendor prefix
dt-bindings: misc: bk4: Add device tree binding for Liebherr's BK4 SPI bus
dt-bindings: thermal: samsung: Add SPDX license identifier
dt-bindings: clock: samsung: Add SPDX license identifiers
dt-bindings: timer: ostm: Add R7S9210 support
dt-bindings: phy: rcar-gen2: Add r8a7744 support
dt-bindings: can: rcar_can: Add r8a7744 support
dt-bindings: timer: renesas, cmt: Document r8a7744 CMT support
dt-bindings: watchdog: renesas-wdt: Document r8a7744 support
dt-bindings: thermal: rcar: Add device tree support for r8a7744
Documentation: dt: Add binding for /secure-chosen/stdout-path
dt-bindings: arm: zte: Move sysctrl bindings to their own doc
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking and misc x86 updates from Ingo Molnar:
"Lots of changes in this cycle - in part because locking/core attracted
a number of related x86 low level work which was easier to handle in a
single tree:
- Linux Kernel Memory Consistency Model updates (Alan Stern, Paul E.
McKenney, Andrea Parri)
- lockdep scalability improvements and micro-optimizations (Waiman
Long)
- rwsem improvements (Waiman Long)
- spinlock micro-optimization (Matthew Wilcox)
- qspinlocks: Provide a liveness guarantee (more fairness) on x86.
(Peter Zijlstra)
- Add support for relative references in jump tables on arm64, x86
and s390 to optimize jump labels (Ard Biesheuvel, Heiko Carstens)
- Be a lot less permissive on weird (kernel address) uaccess faults
on x86: BUG() when uaccess helpers fault on kernel addresses (Jann
Horn)
- macrofy x86 asm statements to un-confuse the GCC inliner. (Nadav
Amit)
- ... and a handful of other smaller changes as well"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (57 commits)
locking/lockdep: Make global debug_locks* variables read-mostly
locking/lockdep: Fix debug_locks off performance problem
locking/pvqspinlock: Extend node size when pvqspinlock is configured
locking/qspinlock_stat: Count instances of nested lock slowpaths
locking/qspinlock, x86: Provide liveness guarantee
x86/asm: 'Simplify' GEN_*_RMWcc() macros
locking/qspinlock: Rework some comments
locking/qspinlock: Re-order code
locking/lockdep: Remove duplicated 'lock_class_ops' percpu array
x86/defconfig: Enable CONFIG_USB_XHCI_HCD=y
futex: Replace spin_is_locked() with lockdep
locking/lockdep: Make class->ops a percpu counter and move it under CONFIG_DEBUG_LOCKDEP=y
x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs
x86/cpufeature: Macrofy inline assembly code to work around GCC inlining bugs
x86/extable: Macrofy inline assembly code to work around GCC inlining bugs
x86/paravirt: Work around GCC inlining bugs when compiling paravirt ops
x86/bug: Macrofy the BUG table section handling, to work around GCC inlining bugs
x86/alternatives: Macrofy lock prefixes to work around GCC inlining bugs
x86/refcount: Work around GCC inlining bug
x86/objtool: Use asm macros to work around GCC inlining bugs
...
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We have raised the compiler requirement from time to time.
With commit cafa0010cd51 ("Raise the minimum required gcc version
to 4.6"), the minimum for GCC is 4.6 now.
This flag was added by GCC 4.6, and it is recognized by ICC as well.
It is true that Clang does not support this flag but this commit is
just touching the else part of the "ifeq ($(cc-name),clang)" check.
Hence, Clang build is not affected.
Let's rip off the cc-disable-warning switch, and see if somebody
complains about it.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
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We have raised the compiler requirement from time to time.
With commit cafa0010cd51 ("Raise the minimum required gcc version
to 4.6"), the minimum for GCC is 4.6 now.
This flag has been here since the pre-git era. It is documented in
the GCC 4.6 manual, and it is recognized by Clang and ICC as well.
Let's rip off the cc-option switch, and see if somebody complains
about it.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
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We have raised the compiler requirement from time to time.
With commit cafa0010cd51 ("Raise the minimum required gcc version
to 4.6"), the minimum for GCC is 4.6 now.
The -Wno-pointer-sign has been here since the pre-git era. It is
documented in the GCC 4.6 manual, and it is recognized by Clang
and ICC as well.
Let's rip off the cc-disable-warning switch, and see if somebody
complains about it.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Masahiro writes:
"Kbuild fixes for v4.19 (2nd)
- Fix warnings from recordmcount.pl when building with Clang
- Allow Clang to use GNU toolchains correctly
- Disable CONFIG_SAMPLES for UML to avoid build error"
* tag 'kbuild-fixes-v4.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
samples: disable CONFIG_SAMPLES for UML
kbuild: allow to use GCC toolchain not in Clang search path
ftrace: Build with CPPFLAGS to get -Qunused-arguments
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Now that Variable Length Arrays (VLAs) have been entirely removed[1]
from the kernel, enable the VLA warning globally. The only exceptions
to this are the KASan an UBSan tests which are explicitly checking that
VLAs trigger their respective tests.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Airlie <airlied@linux.ie>
Cc: linux-kbuild@vger.kernel.org
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Kees Cook <keescook@chromium.org>
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Since $(objtree) is always '.', it is not useful to pass it to
scripts/mkmakefile. I assume nobody wants to run this script directly.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Neither VERSION nor PATCHLEVEL is used in any useful way.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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The --include-dir flag is used to include check-in Makefiles from
$(objtree) without $(srctree)/ prefix. Obviously, this is unneeded
for in-tree build. Add the flag just before changing the working
directory.
This becomes effective after invoking sub-make. Add a little bit
comments about it.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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around asm() related GCC inlining bugs
Using macros in inline assembly allows us to work around bugs
in GCC's inlining decisions.
Compile macros.S and use it to assemble all C files.
Currently only x86 will use it.
Background:
The inlining pass of GCC doesn't include an assembler, so it's not aware
of basic properties of the generated code, such as its size in bytes,
or that there are such things as discontiuous blocks of code and data
due to the newfangled linker feature called 'sections' ...
Instead GCC uses a lazy and fragile heuristic: it does a linear count of
certain syntactic and whitespace elements in inlined assembly block source
code, such as a count of new-lines and semicolons (!), as a poor substitute
for "code size and complexity".
Unsurprisingly this heuristic falls over and breaks its neck whith certain
common types of kernel code that use inline assembly, such as the frequent
practice of putting useful information into alternative sections.
As a result of this fresh, 20+ years old GCC bug, GCC's inlining decisions
are effectively disabled for inlined functions that make use of such asm()
blocks, because GCC thinks those sections of code are "large" - when in
reality they are often result in just a very low number of machine
instructions.
This absolute lack of inlining provess when GCC comes across such asm()
blocks both increases generated kernel code size and causes performance
overhead, which is particularly noticeable on paravirt kernels, which make
frequent use of these inlining facilities in attempt to stay out of the
way when running on baremetal hardware.
Instead of fixing the compiler we use a workaround: we set an assembly macro
and call it from the inlined assembly block. As a result GCC considers the
inline assembly block as a single instruction. (Which it often isn't but I digress.)
This uglifies and bloats the source code - for example just the refcount
related changes have this impact:
Makefile | 9 +++++++--
arch/x86/Makefile | 7 +++++++
arch/x86/kernel/macros.S | 7 +++++++
scripts/Kbuild.include | 4 +++-
scripts/mod/Makefile | 2 ++
5 files changed, 26 insertions(+), 3 deletions(-)
Yay readability and maintainability, it's not like assembly code is hard to read
and maintain ...
We also hope that GCC will eventually get fixed, but we are not holding
our breath for that. Yet we are optimistic, it might still happen, any decade now.
[ mingo: Wrote new changelog describing the background. ]
Tested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.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: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kbuild@vger.kernel.org
Link: http://lkml.kernel.org/r/20181003213100.189959-3-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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There is nothing arch specific about building dtb files other than their
location under /arch/*/boot/dts/. Keeping each arch aligned is a pain.
The dependencies and supported targets are all slightly different.
Also, a cross-compiler for each arch is needed, but really the host
compiler preprocessor is perfectly fine for building dtbs. Move the
build rules to a common location and remove the arch specific ones. This
is done in a single step to avoid warnings about overriding rules.
The build dependencies had been a mixture of 'scripts' and/or 'prepare'.
These pull in several dependencies some of which need a target compiler
(specifically devicetable-offsets.h) and aren't needed to build dtbs.
All that is really needed is dtc, so adjust the dependencies to only be
dtc.
This change enables support 'dtbs_install' on some arches which were
missing the target.
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Paul Burton <paul.burton@mips.com>
Acked-by: Ley Foon Tan <ley.foon.tan@intel.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: linux-kbuild@vger.kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: linux-mips@linux-mips.org
Cc: nios2-dev@lists.rocketboards.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-xtensa@linux-xtensa.org
Signed-off-by: Rob Herring <robh@kernel.org>
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When using a GCC cross toolchain which is not in a compiled in
Clang search path, Clang reverts to the system assembler and
linker. This leads to assembler or linker errors, depending on
which tool is first used for a given architecture.
It seems that Clang is not searching $PATH for a matching
assembler or linker.
Make sure that Clang picks up the correct assembler or linker by
passing the cross compilers bin directory as search path.
This allows to use Clang provided by distributions with GCC
toolchains not in /usr/bin.
Link: https://github.com/ClangBuiltLinux/linux/issues/78
Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-and-tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
Pulled kselftest fixes from Shuah:
"This Kselftest fixes update for 4.9-rc5 consists of:
-- fixes to build failures
-- fixes to add missing config files to increase test coverage
-- fixes to cgroup test and a new cgroup test for memory.oom.group"
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