Pull documentation fixes from Jonathan Corbet:
"A handful of fixes for reasonably obnoxious documentation issues"
* tag 'docs-fixes' of git://git.lwn.net/linux:
scripts: documentation-file-ref-check: Add line break before exit
scripts/kernel-doc: Add missing close-paren in c:function directives
docs: admin-guide: merge sections for the kernel.modprobe sysctl
docs: timekeeping: Use correct prototype for deprecated functions
If you run 'make dtbs_check' without installing the libyaml package,
the error message "dtc needs libyaml ..." is shown.
This should be checked also for 'make dt_binding_check' because dtc
needs to validate *.example.dts extracted from *.yaml files.
It is missing since commit 4f0e3a57d6 ("kbuild: Add support for DT
binding schema checks"), but this fix-up is applicable only after commit
e10c4321dc ("kbuild: allow to run dt_binding_check and dtbs_check
in a single command").
I gave the Fixes tag to the latter in case somebody is interested in
back-porting this.
Fixes: e10c4321dc ("kbuild: allow to run dt_binding_check and dtbs_check in a single command")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
If execute ./scripts/documentation-file-ref-check in a directory which is
not a git tree, it will exit without a line break, fix it.
Without this patch:
[loongson@localhost linux-5.7-rc1]$ ./scripts/documentation-file-ref-check
Warning: can't check if file exists, as this is not a git tree[loongson@localhost linux-5.7-rc1]$
With this patch:
[loongson@localhost linux-5.7-rc1]$ ./scripts/documentation-file-ref-check
Warning: can't check if file exists, as this is not a git tree
[loongson@localhost linux-5.7-rc1]$
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/1586857308-2040-1-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
When kernel-doc generates a 'c:function' directive for a function
one of whose arguments is a function pointer, it fails to print
the close-paren after the argument list of the function pointer
argument. For instance:
long work_on_cpu(int cpu, long (*fn) (void *, void * arg)
in driver-api/basics.html is missing a ')' separating the
"void *" of the 'fn' arguments from the ", void * arg" which
is an argument to work_on_cpu().
Add the missing close-paren, so that we render the prototype
correctly:
long work_on_cpu(int cpu, long (*fn)(void *), void * arg)
(Note that Sphinx stops rendering a space between the '(fn*)' and the
'(void *)' once it gets something that's syntactically valid.)
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Link: https://lore.kernel.org/r/20200414143743.32677-1-peter.maydell@linaro.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Staring v4.18, Kconfig evaluates compiler capabilities, and hides CONFIG
options your compiler does not support. This works well if you configure
and build the kernel on the same host machine.
It is inconvenient if you prepare the .config that is carried to a
different build environment (typically this happens when you package
the kernel for distros) because using a different compiler potentially
produces different CONFIG options than the real build environment.
So, you probably want to make as many options visible as possible.
In other words, you need to create a super-set of CONFIG options that
cover any build environment. If some of the CONFIG options turned out
to be unsupported on the build machine, they are automatically disabled
by the nature of Kconfig.
However, it is not feasible to get a full-featured compiler for every
arch.
This issue was discussed here:
https://lkml.org/lkml/2019/12/9/620
Other than distros, savedefconfig is also a problem. Some arch sub-systems
periodically resync defconfig files. If you use a less-capable compiler
for savedefconfig, options that do not meet 'depends on $(cc-option,...)'
will be forcibly disabled. So, 'make defconfig && make savedefconfig'
may silently change the behavior.
This commit adds a set of dummy toolchains that pretend to support any
feature.
Most of compiler features are tested by cc-option, which simply checks
the exit code of $(CC). The dummy tools are shell scripts that always
exit with 0. So, $(cc-option, ...) is evaluated as 'y'.
There are more complicated checks such as:
scripts/gcc-x86_{32,64}-has-stack-protector.sh
scripts/gcc-plugin.sh
scripts/tools-support-relr.sh
scripts/dummy-tools/gcc passes all checks.
From the top directory of the source tree, you can do:
$ make CROSS_COMPILE=scripts/dummy-tools/ oldconfig
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Tested-by: Jeremy Cline <jcline@redhat.com>
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>
I do not like to add an extra include path for every tool with no
good reason. This should be specified per file.
This line was added by commit 6520fe5564 ("x86, realmode: 16-bit
real-mode code support for relocs tool"), which did not touch
anything else in scripts/. I see no reason to add this.
Also, remove the comment about kallsyms because we do not have any
for the rest of programs.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The items described on those TODOs are already solved. So,
remove the comments.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
At least on my tests (building against Qt5.13), it seems to
me that, since Kernel 3.14, the split view mode is broken.
Maybe it was not a top priority during the conversion time.
Anyway, this patch changes the logic in order to properly
support the split view mode and the single view mode.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The port to Qt5 tried to preserve the same way as it used
to work with Qt3 and Qt4. However, at least with newer
versions of Qt5 (5.13), this doesn't work properly.
Change the schema by adding a vertical layout, in order
for it to start working properly again.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Both main config window and the item window have "Option"
name. That sounds weird, and makes harder to debug issues
of a window appearing at the wrong place.
So, change the title to reflect the contents of each
window.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The recommended way to initialize a null string is with
QString(). This is there at least since Qt5.5, with is
when qconf was ported to Qt5.
Fix those warnings:
scripts/kconfig/qconf.cc: In member function ‘void ConfigItem::updateMenu()’:
scripts/kconfig/qconf.cc:158:31: warning: ‘QString::null’ is deprecated: use QString() [-Wdeprecated-declarations]
158 | setText(noColIdx, QString::null);
| ^~~~
In file included from /usr/include/qt5/QtCore/qobject.h:47,
from /usr/include/qt5/QtWidgets/qwidget.h:45,
from /usr/include/qt5/QtWidgets/qmainwindow.h:44,
from /usr/include/qt5/QtWidgets/QMainWindow:1,
from scripts/kconfig/qconf.cc:9:
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Nobody was opposed to raising minimum GCC version to 4.8 [1]
So, we will drop GCC <= 4.7 support sooner or later.
We always use C++ compiler for building plugins for GCC >= 4.8.
This commit drops the plugin support for GCC <= 4.7 a bit earlier,
which allows us to dump lots of code.
[1] https://lkml.org/lkml/2020/1/23/545
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
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>
In order to do kernel builds with the bounds checker individually
available, introduce CONFIG_UBSAN_BOUNDS, with the remaining options under
CONFIG_UBSAN_MISC.
For example, using this, we can start to expand the coverage syzkaller is
providing. Right now, all of UBSan is disabled for syzbot builds because
taken as a whole, it is too noisy. This will let us focus on one feature
at a time.
For the bounds checker specifically, this provides a mechanism to
eliminate an entire class of array overflows with close to zero
performance overhead (I cannot measure a difference). In my (mostly)
defconfig, enabling bounds checking adds ~4200 checks to the kernel.
Performance changes are in the noise, likely due to the branch predictors
optimizing for the non-fail path.
Some notes on the bounds checker:
- it does not instrument {mem,str}*()-family functions, it only
instruments direct indexed accesses (e.g. "foo[i]"). Dealing with
the {mem,str}*()-family functions is a work-in-progress around
CONFIG_FORTIFY_SOURCE[1].
- it ignores flexible array members, including the very old single
byte (e.g. "int foo[1];") declarations. (Note that GCC's
implementation appears to ignore _all_ trailing arrays, but Clang only
ignores empty, 0, and 1 byte arrays[2].)
[1] https://github.com/KSPP/linux/issues/6
[2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92589
Suggested-by: Elena Petrova <lenaptr@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Link: http://lkml.kernel.org/r/20200227193516.32566-3-keescook@chromium.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "ubsan: Split out bounds checker", v5.
This splits out the bounds checker so it can be individually used. This
is enabled in Android and hopefully for syzbot. Includes LKDTM tests for
behavioral corner-cases (beyond just the bounds checker), and adjusts
ubsan and kasan slightly for correct panic handling.
This patch (of 6):
The Undefined Behavior Sanitizer can operate in two modes: warning
reporting mode via lib/ubsan.c handler calls, or trap mode, which uses
__builtin_trap() as the handler. Using lib/ubsan.c means the kernel image
is about 5% larger (due to all the debugging text and reporting structures
to capture details about the warning conditions). Using the trap mode,
the image size changes are much smaller, though at the loss of the
"warning only" mode.
In order to give greater flexibility to system builders that want minimal
changes to image size and are prepared to deal with kernel code being
aborted and potentially destabilizing the system, this introduces
CONFIG_UBSAN_TRAP. The resulting image sizes comparison:
text data bss dec hex filename
19533663 6183037 18554956 44271656 2a38828 vmlinux.stock
19991849 7618513 18874448 46484810 2c54d4a vmlinux.ubsan
19712181 6284181 18366540 44362902 2a4ec96 vmlinux.ubsan-trap
CONFIG_UBSAN=y: image +4.8% (text +2.3%, data +18.9%)
CONFIG_UBSAN_TRAP=y: image +0.2% (text +0.9%, data +1.6%)
Additionally adjusts the CONFIG_UBSAN Kconfig help for clarity and removes
the mention of non-existing boot param "ubsan_handle".
Suggested-by: Elena Petrova <lenaptr@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Link: http://lkml.kernel.org/r/20200227193516.32566-2-keescook@chromium.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 1574a29f8e ("checkpatch: allow multiple const * types") claims to
support repetition of pattern "const *", but it actually allows only one
extra instance.
Check the following lines
int a(char const * const x[]);
int b(char const * const *x);
int c(char const * const * const x[]);
int d(char const * const * const *x);
with command
./scripts/checkpatch.pl --show-types -f filename
to find that only the first line passes the test, while a warning
is triggered by the other 3 lines:
WARNING:FUNCTION_ARGUMENTS: function definition argument
'char const * const' should also have an identifier name
The reason is that the pattern match halts at the second asterisk in the
line, thus the remaining text starting with asterisk fails to match a
valid name for a variable.
Fixed by replacing "?" (Match 1 or 0 times) with "{0,4}" (Match no more
than 4 times) in the regular expression. Fix also the similar test for
types in unusual order.
Fixes: 1574a29f8e ("checkpatch: allow multiple const * types")
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joe Perches <joe@perches.com>
Link: http://lkml.kernel.org/r/20200122163852.124417-1-borneo.antonio@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
