Commit graph

1779 commits

Author SHA1 Message Date
Linus Torvalds
2ef96a5bb1 Linux 5.7-rc5 2020-05-10 15:16:58 -07:00
Linus Torvalds
adc7192096 gcc-10: disable 'restrict' warning for now
gcc-10 now warns about passing aliasing pointers to functions that take
restricted pointers.

That's actually a great warning, and if we ever start using 'restrict'
in the kernel, it might be quite useful.  But right now we don't, and it
turns out that the only thing this warns about is an idiom where we have
declared a few functions to be "printf-like" (which seems to make gcc
pick up the restricted pointer thing), and then we print to the same
buffer that we also use as an input.

And people do that as an odd concatenation pattern, with code like this:

    #define sysfs_show_gen_prop(buffer, fmt, ...) \
        snprintf(buffer, PAGE_SIZE, "%s"fmt, buffer, __VA_ARGS__)

where we have 'buffer' as both the destination of the final result, and
as the initial argument.

Yes, it's a bit questionable.  And outside of the kernel, people do have
standard declarations like

    int snprintf( char *restrict buffer, size_t bufsz,
                  const char *restrict format, ... );

where that output buffer is marked as a restrict pointer that cannot
alias with any other arguments.

But in the context of the kernel, that 'use snprintf() to concatenate to
the end result' does work, and the pattern shows up in multiple places.
And we have not marked our own version of snprintf() as taking restrict
pointers, so the warning is incorrect for now, and gcc picks it up on
its own.

If we do start using 'restrict' in the kernel (and it might be a good
idea if people find places where it matters), we'll need to figure out
how to avoid this issue for snprintf and friends.  But in the meantime,
this warning is not useful.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-05-09 15:45:21 -07:00
Linus Torvalds
5a76021c2e gcc-10: disable 'stringop-overflow' warning for now
This is the final array bounds warning removal for gcc-10 for now.

Again, the warning is good, and we should re-enable all these warnings
when we have converted all the legacy array declaration cases to
flexible arrays. But in the meantime, it's just noise.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-05-09 15:40:52 -07:00
Linus Torvalds
44720996e2 gcc-10: disable 'array-bounds' warning for now
This is another fine warning, related to the 'zero-length-bounds' one,
but hitting the same historical code in the kernel.

Because C didn't historically support flexible array members, we have
code that instead uses a one-sized array, the same way we have cases of
zero-sized arrays.

The one-sized arrays come from either not wanting to use the gcc
zero-sized array extension, or from a slight convenience-feature, where
particularly for strings, the size of the structure now includes the
allocation for the final NUL character.

So with a "char name[1];" at the end of a structure, you can do things
like

       v = my_malloc(sizeof(struct vendor) + strlen(name));

and avoid the "+1" for the terminator.

Yes, the modern way to do that is with a flexible array, and using
'offsetof()' instead of 'sizeof()', and adding the "+1" by hand.  That
also technically gets the size "more correct" in that it avoids any
alignment (and thus padding) issues, but this is another long-term
cleanup thing that will not happen for 5.7.

So disable the warning for now, even though it's potentially quite
useful.  Having a slew of warnings that then hide more urgent new issues
is not an improvement.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-05-09 14:52:44 -07:00
Linus Torvalds
5c45de21a2 gcc-10: disable 'zero-length-bounds' warning for now
This is a fine warning, but we still have a number of zero-length arrays
in the kernel that come from the traditional gcc extension.  Yes, they
are getting converted to flexible arrays, but in the meantime the gcc-10
warning about zero-length bounds is very verbose, and is hiding other
issues.

I missed one actual build failure because it was hidden among hundreds
of lines of warning.  Thankfully I caught it on the second go before
pushing things out, but it convinced me that I really need to disable
the new warnings for now.

We'll hopefully be all done with our conversion to flexible arrays in
the not too distant future, and we can then re-enable this warning.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-05-09 14:30:29 -07:00
Linus Torvalds
78a5255ffb Stop the ad-hoc games with -Wno-maybe-initialized
We have some rather random rules about when we accept the
"maybe-initialized" warnings, and when we don't.

For example, we consider it unreliable for gcc versions < 4.9, but also
if -O3 is enabled, or if optimizing for size.  And then various kernel
config options disabled it, because they know that they trigger that
warning by confusing gcc sufficiently (ie PROFILE_ALL_BRANCHES).

And now gcc-10 seems to be introducing a lot of those warnings too, so
it falls under the same heading as 4.9 did.

At the same time, we have a very straightforward way to _enable_ that
warning when wanted: use "W=2" to enable more warnings.

So stop playing these ad-hoc games, and just disable that warning by
default, with the known and straight-forward "if you want to work on the
extra compiler warnings, use W=123".

Would it be great to have code that is always so obvious that it never
confuses the compiler whether a variable is used initialized or not?
Yes, it would.  In a perfect world, the compilers would be smarter, and
our source code would be simpler.

That's currently not the world we live in, though.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-05-09 13:57:10 -07:00
Linus Torvalds
0e698dfa28 Linux 5.7-rc4 2020-05-03 14:56:04 -07:00
Linus Torvalds
6a8b55ed40 Linux 5.7-rc3 2020-04-26 13:51:02 -07:00
Linus Torvalds
ae83d0b416 Linux 5.7-rc2 2020-04-19 14:35:30 -07:00
Linus Torvalds
8f3d9f3542 Linux 5.7-rc1 2020-04-12 12:35:55 -07:00
Masahiro Yamada
a0d1c951ef kbuild: support LLVM=1 to switch the default tools to Clang/LLVM
As Documentation/kbuild/llvm.rst implies, building the kernel with a
full set of LLVM tools gets very verbose and unwieldy.

Provide a single switch LLVM=1 to use Clang and LLVM tools instead
of GCC and Binutils. You can pass it from the command line or as an
environment variable.

Please note LLVM=1 does not turn on the integrated assembler. You need
to pass LLVM_IAS=1 to use it. When the upstream kernel is ready for the
integrated assembler, I think we can make it default.

We discussed what we need, and we agreed to go with a simple boolean
flag that switches both target and host tools:

  https://lkml.org/lkml/2020/3/28/494
  https://lkml.org/lkml/2020/4/3/43

Some items discussed, but not adopted:

- LLVM_DIR

  When multiple versions of LLVM are installed, I just thought supporting
  LLVM_DIR=/path/to/my/llvm/bin/ might be useful.

  CC      = $(LLVM_DIR)clang
  LD      = $(LLVM_DIR)ld.lld
    ...

  However, we can handle this by modifying PATH. So, we decided to not do
  this.

- LLVM_SUFFIX

  Some distributions (e.g. Debian) package specific versions of LLVM with
  naming conventions that use the version as a suffix.

  CC      = clang$(LLVM_SUFFIX)
  LD      = ld.lld(LLVM_SUFFIX)
    ...

  will allow a user to pass LLVM_SUFFIX=-11 to use clang-11 etc.,
  but the suffixed versions in /usr/bin/ are symlinks to binaries in
  /usr/lib/llvm-#/bin/, so this can also be handled by PATH.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com> # build
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2020-04-09 03:18:21 +09:00
Masahiro Yamada
7e20e47c70 kbuild: replace AS=clang with LLVM_IAS=1
The 'AS' variable is unused for building the kernel. Only the remaining
usage is to turn on the integrated assembler. A boolean flag is a better
fit for this purpose.

AS=clang was added for experts. So, I replaced it with LLVM_IAS=1,
breaking the backward compatibility.

Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2020-04-09 03:18:09 +09:00
Masahiro Yamada
7273ad2b08 kbuild: link lib-y objects to vmlinux forcibly when CONFIG_MODULES=y
Kbuild supports not only obj-y but also lib-y to list objects linked to
vmlinux.

The difference between them is that all the objects from obj-y are
forcibly linked to vmlinux, whereas the objects from lib-y are linked
as needed; if there is no user of a lib-y object, it is not linked.

lib-y is intended to list utility functions that may be called from all
over the place (and may be unused at all), but it is a problem for
EXPORT_SYMBOL(). Even if there is no call-site in the vmlinux, we need
to keep exported symbols for the use from loadable modules.

Commit 7f2084fa55 ("[kbuild] handle exports in lib-y objects reliably")
worked around it by linking a dummy object, lib-ksyms.o, which contains
references to all the symbols exported from lib.a in that directory.
It uses the linker script command, EXTERN. Unfortunately, the meaning of
EXTERN of ld.lld is different from that of ld.bfd. Therefore, this does
not work with LD=ld.lld (CBL issue #515).

Anyway, the build rule of lib-ksyms.o is somewhat tricky. So, I want to
get rid of it.

At first, I was thinking of accumulating lib-y objects into obj-y
(or even replacing lib-y with obj-y entirely), but the lib-y syntax
is used beyond the ordinary use in lib/ and arch/*/lib/.

Examples:

 - drivers/firmware/efi/libstub/Makefile builds lib.a, which is linked
   into vmlinux in the own way (arm64), or linked to the decompressor
   (arm, x86).

 - arch/alpha/lib/Makefile builds lib.a which is linked not only to
   vmlinux, but also to bootloaders in arch/alpha/boot/Makefile.

 - arch/xtensa/boot/lib/Makefile builds lib.a for use from
   arch/xtensa/boot/boot-redboot/Makefile.

One more thing, adding everything to obj-y would increase the vmlinux
size of allnoconfig (or tinyconfig).

For less impact, I tweaked the destination of lib.a at the top Makefile;
when CONFIG_MODULES=y, lib.a goes to KBUILD_VMLINUX_OBJS, which is
forcibly linked to vmlinux, otherwise lib.a goes to KBUILD_VMLINUX_LIBS
as before.

The size impact for normal usecases is quite small since at lease one
symbol in every lib-y object is eventually called by someone. In case
you are intrested, here are the figures.

x86_64_defconfig:

   text	   data	    bss	    dec	    hex	filename
19566602 5422072 1589328 26578002 1958c52 vmlinux.before
19566932 5422104 1589328 26578364 1958dbc vmlinux.after

The case with the biggest impact is allnoconfig + CONFIG_MODULES=y.

ARCH=x86 allnoconfig + CONFIG_MODULES=y:

   text	   data	    bss	    dec	    hex	filename
1175162	 254740	1220608	2650510	 28718e	vmlinux.before
1177974	 254836	1220608	2653418	 287cea	vmlinux.after

Hopefully this is still not a big deal. The per-file trimming with the
static library is not so effective after all.

If fine-grained optimization is desired, some architectures support
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION, which trims dead code per-symbol
basis. When LTO is supported in mainline, even better optimization will
be possible.

Link: https://github.com/ClangBuiltLinux/linux/issues/515
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reported-by: kbuild test robot <lkp@intel.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2020-04-09 00:13:45 +09:00
Nathan Chancellor
afe956c577 kbuild: Enable -Wtautological-compare
Currently, we disable -Wtautological-compare, which in turn disables a
bunch of more specific tautological comparison warnings that are useful
for the kernel such as -Wtautological-bitwise-compare. See clang's
documentation below for the other warnings that are suppressed by
-Wtautological-compare. Now that all of the major/noisy warnings have
been fixed, enable -Wtautological-compare so that more issues can be
caught at build time by various continuous integration setups.

-Wtautological-constant-out-of-range-compare is kept disabled under a
normal build but visible at W=1 because there are places in the kernel
where a constant or variable size can change based on the kernel
configuration. These are not fixed in a clean/concise way and the ones
I have audited so far appear to be harmless. It is not a subgroup but
rather just one warning so we do not lose out on much coverage by
default.

Link: https://github.com/ClangBuiltLinux/linux/issues/488
Link: http://releases.llvm.org/10.0.0/tools/clang/docs/DiagnosticsReference.html#wtautological-compare
Link: https://bugs.llvm.org/show_bug.cgi?id=42666
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-04-09 00:13:45 +09:00
Linus Torvalds
5b67fbfc32 Kbuild updates for v5.7
[Build system]
 
  - add CONFIG_UNUSED_KSYMS_WHITELIST, which will be useful to define
    a fixed set of export symbols for Generic Kernel Image (GKI)
 
  - allow to run 'make dt_binding_check' without .config
 
  - use full schema for checking DT examples in *.yaml files
 
  - make modpost fail for missing MODULE_IMPORT_NS(), which makes more
    sense because we know the produced modules are never loadable
 
  - Remove unused 'AS' variable
 
 [Kconfig]
 
  - sanitize DEFCONFIG_LIST, and remove ARCH_DEFCONFIG from Kconfig files
 
  - relax the 'imply' behavior so that symbols implied by y can become m
 
  - make 'imply' obey 'depends on' in order to make 'imply' really weak
 
 [Misc]
 
  - add documentation on building the kernel with Clang/LLVM
 
  - revive __HAVE_ARCH_STRLEN for 32bit sparc to use optimized strlen()
 
  - fix warning from deb-pkg builds when CONFIG_DEBUG_INFO=n
 
  - various script and Makefile cleanups
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Merge tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:
 "Build system:

   - add CONFIG_UNUSED_KSYMS_WHITELIST, which will be useful to define a
     fixed set of export symbols for Generic Kernel Image (GKI)

   - allow to run 'make dt_binding_check' without .config

   - use full schema for checking DT examples in *.yaml files

   - make modpost fail for missing MODULE_IMPORT_NS(), which makes more
     sense because we know the produced modules are never loadable

   - Remove unused 'AS' variable

  Kconfig:

   - sanitize DEFCONFIG_LIST, and remove ARCH_DEFCONFIG from Kconfig
     files

   - relax the 'imply' behavior so that symbols implied by 'y' can
     become 'm'

   - make 'imply' obey 'depends on' in order to make 'imply' really weak

  Misc:

   - add documentation on building the kernel with Clang/LLVM

   - revive __HAVE_ARCH_STRLEN for 32bit sparc to use optimized strlen()

   - fix warning from deb-pkg builds when CONFIG_DEBUG_INFO=n

   - various script and Makefile cleanups"

* tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
  Makefile: Update kselftest help information
  kbuild: deb-pkg: fix warning when CONFIG_DEBUG_INFO is unset
  kbuild: add outputmakefile to no-dot-config-targets
  kbuild: remove AS variable
  net: wan: wanxl: refactor the firmware rebuild rule
  net: wan: wanxl: use $(M68KCC) instead of $(M68KAS) for rebuilding firmware
  net: wan: wanxl: use allow to pass CROSS_COMPILE_M68k for rebuilding firmware
  kbuild: add comment about grouped target
  kbuild: add -Wall to KBUILD_HOSTCXXFLAGS
  kconfig: remove unused variable in qconf.cc
  sparc: revive __HAVE_ARCH_STRLEN for 32bit sparc
  kbuild: refactor Makefile.dtbinst more
  kbuild: compute the dtbs_install destination more simply
  Makefile: disallow data races on gcc-10 as well
  kconfig: make 'imply' obey the direct dependency
  kconfig: allow symbols implied by y to become m
  net: drop_monitor: use IS_REACHABLE() to guard net_dm_hw_report()
  modpost: return error if module is missing ns imports and MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n
  modpost: rework and consolidate logging interface
  kbuild: allow to run dt_binding_check without kernel configuration
  ...
2020-03-31 16:03:39 -07:00
Shuah Khan
e51d8dacf2 Makefile: Update kselftest help information
Update kselftest help information.

Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-04-01 01:05:04 +09:00
Linus Torvalds
7111951b8d Linux 5.6 2020-03-29 15:25:41 -07:00
David Engraf
4623980dea kbuild: add outputmakefile to no-dot-config-targets
The target outputmakefile is used to generate a Makefile
for out-of-tree builds and does not depend on the kernel
configuration.

Signed-off-by: David Engraf <david.engraf@sysgo.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-03-29 22:37:53 +09:00
Masahiro Yamada
aa824e0c96 kbuild: remove AS variable
As commit 5ef872636c ("kbuild: get rid of misleading $(AS) from
documents") noted, we rarely use $(AS) directly in the kernel build.

Now that the only/last user of $(AS) in drivers/net/wan/Makefile was
converted to $(CC), $(AS) is no longer used in the build process.

You can still pass in AS=clang, which is just a switch to turn on
the LLVM integrated assembler.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
2020-03-29 22:37:53 +09:00
Masahiro Yamada
f463c3510d kbuild: add comment about grouped target
GNU Make commit 8c888d95f618 ("[SV 8297] Implement "grouped targets"
for explicit rules.") added the '&:' syntax.

I think '&:' is a perfect fit here, but we cannot use it any time
soon. Just add a TODO comment.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-03-29 22:37:53 +09:00
Masahiro Yamada
735aab1e00 kbuild: add -Wall to KBUILD_HOSTCXXFLAGS
Add -Wall to catch more warnings for C++ host programs.

When I submitted the previous version, the 0-day bot reported
-Wc++11-compat warnings for old GCC:

  HOSTCXX -fPIC scripts/gcc-plugins/latent_entropy_plugin.o
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/tm.h:28:0,
                 from scripts/gcc-plugins/gcc-common.h:15,
                 from scripts/gcc-plugins/latent_entropy_plugin.c:78:
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/elfos.h:102:21: warning: C++11 requires a space between string literal and macro [-Wc++11-compat]
    fprintf ((FILE), "%s"HOST_WIDE_INT_PRINT_UNSIGNED"\n",\
                     ^
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/elfos.h:170:24: warning: C++11 requires a space between string literal and macro [-Wc++11-compat]
       fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n",  \
                        ^
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/tm.h:42:0,
                 from scripts/gcc-plugins/gcc-common.h:15,
                 from scripts/gcc-plugins/latent_entropy_plugin.c:78:
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/defaults.h:126:24: warning: C++11 requires a space between string literal and macro [-Wc++11-compat]
       fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n",  \
                        ^

The source of the warnings is in the plugin headers, so we have no
control of it. I just suppressed them by adding -Wno-c++11-compat to
scripts/gcc-plugins/Makefile.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
2020-03-29 22:37:53 +09:00
Masahiro Yamada
2431f22a91 kbuild: compute the dtbs_install destination more simply
The 'dtbinst_root' is used to remember the root of the in-kernel dts
directory (i.e. arch/*/boot/dts), but it looks clumsy.

I prefer using two variables 'obj' and 'dst' to track the in-kernel
directory and the install destination, respectively.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-03-25 10:19:43 +09:00
Linus Torvalds
16fbf79b0f Linux 5.6-rc7 2020-03-22 18:31:56 -07:00
Linus Torvalds
207f75c454 Kbuild fixes for v5.6 (3rd)
- fix __uint128_t capability test in Kconfig when GCC that defaults
    to 32-bit is used to build the 64-bit kernel
 
  - suppress new noisy Clang warnings -Wpointer-to-enum-cast
 
  - move the namespace field in Module.symvers for the backward
    compatibility reason for the depmod tool
 
  - use available compression for initramdisk when INTRAMFS_SOURCE
    is defined, which was the original behavior
 
  - fix modpost to handle correct large section numbers when it refers
    to modversion CRCs and module namespaces
 
  - fix comments and documents
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Merge tag 'kbuild-fixes-v5.6-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - fix __uint128_t capability test in Kconfig when GCC that defaults to
   32-bit is used to build the 64-bit kernel

 - suppress new noisy Clang warnings -Wpointer-to-enum-cast

 - move the namespace field in Module.symvers for the backward
   compatibility reason for the depmod tool

 - use available compression for initramdisk when INTRAMFS_SOURCE is
   defined, which was the original behavior

 - fix modpost to handle correct large section numbers when it refers to
   modversion CRCs and module namespaces

 - fix comments and documents

* tag 'kbuild-fixes-v5.6-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  scripts/kallsyms: fix wrong kallsyms_relative_base
  modpost: Get proper section index by get_secindex() instead of st_shndx
  initramfs: restore default compression behavior
  modpost: move the namespace field in Module.symvers last
  kbuild: Disable -Wpointer-to-enum-cast
  kbuild: doc: fix references to other documents
  int128: fix __uint128_t compiler test in Kconfig
  kconfig: introduce m32-flag and m64-flag
  kbuild: Fix inconsistent comment
2020-03-19 09:57:48 -07:00
Sergei Trofimovich
b1112139a1 Makefile: disallow data races on gcc-10 as well
gcc-10 will rename --param=allow-store-data-races=0
to -fno-allow-store-data-races.

The flag change happened at https://gcc.gnu.org/PR92046.

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-03-20 00:34:16 +09:00
Linus Torvalds
fb33c6510d Linux 5.6-rc6 2020-03-15 15:01:23 -07:00
Masahiro Yamada
9dffecc133 kbuild: allow to run dt_binding_check without kernel configuration
The dt_binding_check target is located outside of the
'ifneq ($(dtstree),) ... endif' block.

So, you can run 'make dt_binding_check' on any architecture.
This makes a perfect sense because the dt-schema is arch-agnostic.

The only one problem I see is that scripts/dtc/dtc is not always built.
For example, ARCH=x86 defconfig does not define CONFIG_DTC. Kbuild
descends into scripts/dtc/ with doing nothing. Then, it fails to build
*.example.dt.yaml files.

Let's build scripts/dtc/dtc forcibly when running dt_binding_check.

The dt-schema does not depend on any CONFIG option either, so you
should be able to run dt_binding_check without the .config file.

Going forward, you can directly run 'make dt_binding_check' in a
pristine source tree.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
2020-03-13 10:04:36 +09:00
Masahiro Yamada
e10c4321dc kbuild: allow to run dt_binding_check and dtbs_check in a single command
Since commit 93512dad33 ("dt-bindings: Improve validation build error
handling"), 'make dtbs_check' does not validate the schema fully.

If you want to check everything, you need to run two commands separately.

  $ make ARCH=arm dt_binding_check
  $ make ARCH=arm dtbs_check

They are exclusive each other, so you cannot do like this:

  $ make ARCH=arm dt_binding_check dtbs_check

In this case, dt-doc-validate and dt-extract-example are skipped
because CHECK_DTBS is set.

Let's make it possible to run these two targets in a single command.
It will be useful for schema writers.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
2020-03-13 10:04:36 +09:00
Masahiro Yamada
b5154bf63e kbuild: avoid concurrency issue in parallel building dtbs and dtbs_check
'make dtbs_check' checks the shecma in addition to building *.dtb files,
in other words, 'make dtbs_check' is a super-set of 'make dtbs'.
So, you do not have to do 'make dtbs dtbs_check', but I want to keep
the build system as robust as possible in any use.

Currently, 'dtbs' and 'dtbs_check' are independent of each other.
In parallel building, two threads descend into arch/*/boot/dts/,
one for dtbs and the other for dtbs_check, then end up with building
the same DTB simultaneously.

This commit fixes the concurrency issue. Otherwise, I see build errors
like follows:

$ make ARCH=arm64 defconfig
$ make -j16 ARCH=arm64 DT_SCHEMA_FILES=Documentation/devicetree/bindings/arm/psci.yaml dtbs dtbs_check
  <snip>
  DTC     arch/arm64/boot/dts/qcom/sdm845-cheza-r2.dtb
  DTC     arch/arm64/boot/dts/amlogic/meson-gxl-s905x-p212.dtb
  DTC     arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-lite2.dtb
  DTC     arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-lite2.dtb
  DTC     arch/arm64/boot/dts/freescale/imx8mn-evk.dtb
  DTC     arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-one-plus.dtb
  DTC     arch/arm64/boot/dts/zte/zx296718-pcbox.dtb
  DTC     arch/arm64/boot/dts/altera/socfpga_stratix10_socdk.dt.yaml
  DTC     arch/arm64/boot/dts/amlogic/meson-gxl-s905d-p230.dtb
  DTC     arch/arm64/boot/dts/xilinx/zynqmp-zc1254-revA.dtb
  DTC     arch/arm64/boot/dts/allwinner/sun50i-h6-pine-h64.dtb
  DTC     arch/arm64/boot/dts/rockchip/rk3399-gru-scarlet-inx.dtb
  DTC     arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-one-plus.dtb
  CHECK   arch/arm64/boot/dts/altera/socfpga_stratix10_socdk.dt.yaml
fixdep: error opening file: arch/arm64/boot/dts/allwinner/.sun50i-h6-orangepi-lite2.dtb.d: No such file or directory
make[2]: *** [scripts/Makefile.lib:296: arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-lite2.dtb] Error 2
make[2]: *** Deleting file 'arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-lite2.dtb'
make[2]: *** Waiting for unfinished jobs....
  DTC     arch/arm64/boot/dts/rockchip/rk3399-gru-scarlet-kd.dtb
  DTC     arch/arm64/boot/dts/amlogic/meson-gxl-s905d-p231.dtb
  DTC     arch/arm64/boot/dts/xilinx/zynqmp-zc1275-revA.dtb
  DTC     arch/arm64/boot/dts/freescale/imx8mn-ddr4-evk.dtb
fixdep: parse error; no targets found
make[2]: *** [scripts/Makefile.lib:296: arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-one-plus.dtb] Error 1
make[2]: *** Deleting file 'arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-one-plus.dtb'
make[1]: *** [scripts/Makefile.build:505: arch/arm64/boot/dts/allwinner] Error 2
make[1]: *** Waiting for unfinished jobs....
  DTC     arch/arm64/boot/dts/renesas/r8a77951-salvator-xs.dtb

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
2020-03-13 10:04:36 +09:00
SZ Lin (林上智)
46b7c49254 kbuild: Fix inconsistent comment
The commit 2042b5486b ("kbuild: unset variables in top Makefile
instead of setting 0") renamed the variable from "config-targets"
to "config-build", the comment should be consistent accordingly.

Signed-off-by: Kaiden PK Yu (余泊鎧) <KaidenPK.Yu@moxa.com>
Signed-off-by: SZ Lin (林上智) <sz.lin@moxa.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-03-12 07:39:30 +09:00
Linus Torvalds
2c523b344d Linux 5.6-rc5 2020-03-08 17:44:44 -07:00
Quentin Perret
88694cff49 kbuild: generate autoksyms.h early
When doing a cold build, autoksyms.h starts empty, and is updated late
in the build process to have visibility over the symbols used by in-tree
drivers. But since the symbol whitelist is known upfront, it can be used
to pre-populate autoksyms.h and maximize the amount of code that can be
compiled to its final state in a single pass, hence reducing build time.

Do this by using gen_autoksyms.sh to initialize autoksyms.h instead of
creating an empty file.

Acked-by: Nicolas Pitre <nico@fluxnic.net>
Tested-by: Matthias Maennich <maennich@google.com>
Reviewed-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-03-03 20:49:21 +09:00
Masahiro Yamada
2a86f66121 kbuild: use KBUILD_DEFCONFIG as the fallback for DEFCONFIG_LIST
Most of the Kconfig commands (except defconfig and all*config) read
the .config file as a base set of CONFIG options.

When it does not exist, the files in DEFCONFIG_LIST are searched in
this order and loaded if found.

I do not see much sense in the last two lines in DEFCONFIG_LIST.

[1] ARCH_DEFCONFIG

The entry for DEFCONFIG_LIST is guarded by 'depends on !UML'. So, the
ARCH_DEFCONFIG definition in arch/x86/um/Kconfig is meaningless.

arch/{sh,sparc,x86}/Kconfig define ARCH_DEFCONFIG depending on 32 or
64 bit variant symbols. This is a little bit strange; ARCH_DEFCONFIG
should be a fixed string because the base config file is loaded before
the symbol evaluation stage.

Using KBUILD_DEFCONFIG makes more sense because it is fixed before
Kconfig is invoked. Fortunately, arch/{sh,sparc,x86}/Makefile define it
in the same way, and it works as expected. Hence, replace ARCH_DEFCONFIG
with "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)".

[2] arch/$(ARCH)/defconfig

This file path is no longer valid. The defconfig files are always located
in the arch configs/ directories.

  $ find arch -name defconfig | sort
  arch/alpha/configs/defconfig
  arch/arm64/configs/defconfig
  arch/csky/configs/defconfig
  arch/nds32/configs/defconfig
  arch/riscv/configs/defconfig
  arch/s390/configs/defconfig
  arch/unicore32/configs/defconfig

The path arch/*/configs/defconfig is already covered by
"arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)". So, this file path is
not necessary.

I moved the default KBUILD_DEFCONFIG to the top Makefile. Otherwise,
the 7 architectures listed above would end up with endless loop of
syncconfig.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-03-03 20:49:21 +09:00
Masahiro Yamada
a83e4ca26a kbuild: remove cc-option switch from -Wframe-larger-than=
This CONFIG option was added by commit 35bb5b1e0e ("Add option to
enable -Wframe-larger-than= on gcc 4.4"). At that time, the cc-option
check was needed.

According to Documentation/process/changes.rst, the current minimal
supported version of GCC is 4.6, so you can assume GCC supports it.
Clang supports it as well.

Remove the cc-option switch and redundant comments.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
2020-03-02 21:18:19 +09:00
Linus Torvalds
98d54f81e3 Linux 5.6-rc4 2020-03-01 16:38:46 -06:00
Masahiro Yamada
c473a8d03e kbuild: add dt_binding_check to PHONY in a correct place
The dt_binding_check is added to PHONY, but it is invisible when
$(dtstree) is empty. So, it is not specified as phony for
ARCH=x86 etc.

Add it to PHONY outside the ifneq ... endif block.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
2020-02-27 02:28:15 +09:00
Masahiro Yamada
964a596db8 kbuild: add dtbs_check to PHONY
The dtbs_check should be a phony target, but currently it is not
specified so.

'make dtbs_check' works even if a file named 'dtbs_check' exists
because it depends on another phony target, scripts_dtc, but we
should not rely on it.

Add dtbs_check to PHONY.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
2020-02-27 02:26:01 +09:00
Randy Dunlap
505b12b386 kbuild: add comment for V=2 mode
Complete the comments for valid values of KBUILD_VERBOSE,
specifically for KBUILD_VERBOSE=2.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-27 02:19:07 +09:00
Linus Torvalds
f8788d86ab Linux 5.6-rc3 2020-02-23 16:17:42 -08:00
Linus Torvalds
11a48a5a18 Linux 5.6-rc2 2020-02-16 13:16:59 -08:00
Linus Torvalds
bb6d3fb354 Linux 5.6-rc1 2020-02-09 16:08:48 -08:00
Masahiro Yamada
f566e1fbad kbuild: make multiple directory targets work
Currently, the single-target build does not work when two
or more sub-directories are given:

  $ make fs/ kernel/ lib/
    CALL    scripts/checksyscalls.sh
    CALL    scripts/atomic/check-atomics.sh
    DESCEND  objtool
  make[2]: Nothing to be done for 'kernel/'.
  make[2]: Nothing to be done for 'fs/'.
  make[2]: Nothing to be done for 'lib/'.

Make it work properly.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-02-06 06:31:51 +09:00
Linus Torvalds
368d060bb4 Kbuild updates for v5.6
- detect missing include guard in UAPI headers
 
  - do not create orphan built-in.a or obj-y objects
 
  - generate modules.builtin more simply, and drop tristate.conf
 
  - simplify built-in initramfs creation
 
  - make linux-headers deb package thinner
 
  - optimize the deb package build script
 
  - misc cleanups
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Merge tag 'kbuild-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - detect missing include guard in UAPI headers

 - do not create orphan built-in.a or obj-y objects

 - generate modules.builtin more simply, and drop tristate.conf

 - simplify built-in initramfs creation

 - make linux-headers deb package thinner

 - optimize the deb package build script

 - misc cleanups

* tag 'kbuild-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
  builddeb: split libc headers deployment out into a function
  builddeb: split kernel headers deployment out into a function
  builddeb: remove redundant make for ARCH=um
  builddeb: avoid invoking sub-shells where possible
  builddeb: remove redundant $objtree/
  builddeb: match temporary directory name to the package name
  builddeb: remove unneeded files in hdrobjfiles for headers package
  kbuild: use -S instead of -E for precise cc-option test in Kconfig
  builddeb: allow selection of .deb compressor
  kbuild: remove 'Building modules, stage 2.' log
  kbuild: remove *.tmp file when filechk fails
  kbuild: remove PYTHON2 variable
  modpost: assume STT_SPARC_REGISTER is defined
  gen_initramfs.sh: remove intermediate cpio_list on errors
  initramfs: refactor the initramfs build rules
  gen_initramfs.sh: always output cpio even without -o option
  initramfs: add default_cpio_list, and delete -d option support
  initramfs: generate dependency list and cpio at the same time
  initramfs: specify $(src)/gen_initramfs.sh as a prerequisite in Makefile
  initramfs: make initramfs compression choice non-optional
  ...
2020-02-01 10:01:52 -08:00
Linus Torvalds
d5226fa6db Linux 5.5 2020-01-26 16:23:03 -08:00
Linus Torvalds
def9d27807 Linux 5.5-rc7 2020-01-19 16:02:49 -08:00
Masahiro Yamada
94f7345b71 kbuild: remove PYTHON2 variable
Python 2 has retired. There is no user of this variable.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-01-16 00:26:22 +09:00
Linus Torvalds
b3a987b026 Linux 5.5-rc6 2020-01-12 16:55:08 -08:00
Masahiro Yamada
8b41fc4454 kbuild: create modules.builtin without Makefile.modbuiltin or tristate.conf
Commit bc081dd6e9 ("kbuild: generate modules.builtin") added
infrastructure to generate modules.builtin, the list of all
builtin modules.

Basically, it works like this:

  - Kconfig generates include/config/tristate.conf, the list of
    tristate CONFIG options with a value in a capital letter.

  - scripts/Makefile.modbuiltin makes Kbuild descend into
    directories to collect the information of builtin modules.

I am not a big fan of it because Kbuild ends up with traversing
the source tree twice.

I am not sure how perfectly it should work, but this approach cannot
avoid false positives; even if the relevant CONFIG option is tristate,
some Makefiles forces obj-m to obj-y.

Some examples are:

  arch/powerpc/platforms/powermac/Makefile:
    obj-$(CONFIG_NVRAM:m=y)         += nvram.o

  net/ipv6/Makefile:
    obj-$(subst m,y,$(CONFIG_IPV6)) += inet6_hashtables.o

  net/netlabel/Makefile:
    obj-$(subst m,y,$(CONFIG_IPV6)) += netlabel_calipso.o

Nobody has complained about (or noticed) it, so it is probably fine to
have false positives in modules.builtin.

This commit simplifies the implementation. Let's exploit the fact
that every module has MODULE_LICENSE(). (modpost shows a warning if
MODULE_LICENSE is missing. If so, 0-day bot would already have blocked
such a module.)

I added MODULE_FILE to <linux/module.h>. When the code is being compiled
as builtin, it will be filled with the file path of the module, and
collected into modules.builtin.info. Then, scripts/link-vmlinux.sh
extracts the list of builtin modules out of it.

This new approach fixes the false-positives above, but adds another
type of false-positives; non-modular code may have MODULE_LICENSE()
by mistake. This is not a big deal, it is just the code is always
orphan. We can clean it up if we like. You can see cleanup examples by:

  $ git log --grep='make.* explicitly non-modular'

To sum up, this commits deletes lots of code, but still produces almost
equivalent results. Please note it does not increase the vmlinux size at
all. As you can see in include/asm-generic/vmlinux.lds.h, the .modinfo
section is discarded in the link stage.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-01-07 02:18:39 +09:00
Linus Torvalds
c79f46a282 Linux 5.5-rc5 2020-01-05 14:23:27 -08:00
Linus Torvalds
fd6988496e Linux 5.5-rc4 2019-12-29 15:29:16 -08:00