25 May, 2020
1 commit
-
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:struct foo {
int stuff;
struct boo array[];
};By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.Also, notice that, dynamic memory allocations won't be affected by
this change:"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")Signed-off-by: Gustavo A. R. Silva
Signed-off-by: Masahiro Yamada
02 Mar, 2020
2 commits
-
If *q is '\0', the condition (isalnum(*q) || *q == '_') is false anyway.
It is redundant to ensure non-zero *q.
Signed-off-by: Masahiro Yamada
-
This is probably stale code. In old days (~ Linux 2.5.59), Kbuild made
genksyms generate include/linux/modules/*.ver files.The currenct Kbuild does not generate *.ver files at all.
Signed-off-by: Masahiro Yamada
01 Jul, 2019
1 commit
-
When there is not enough space on your storage device, the build will
fail with 'No space left on device' error message.The reason is obvious from the message, so you will free up some disk
space, then you will resume the build.However, sometimes you may still see a mysterious error message:
unterminated call to function 'wildcard': missing ')'.
If you run out of the disk space, fixdep may end up with generating
incomplete .*.cmd files.For example, if the disk-full error occurs while fixdep is running
print_dep(), the .*.cmd might be truncated like this:$(wildcard include/config/
When you run 'make' next time, this broken .*.cmd will be included,
then Make will terminate parsing since it is a wrong syntax.Once this happens, you need to run 'make clean' or delete the broken
.*.cmd file manually.Even if you do not see any error message, the .*.cmd files after any
error could be potentially incomplete, and unreliable. You may miss
the re-compilation due to missing header dependency.If printf() cannot output the string for disk shortage or whatever
reason, it returns a negative value, but currently fixdep does not
check it at all. Consequently, fixdep *successfully* generates a
broken .*.cmd file. Make never notices that since fixdep exits with 0,
which means success.Given the intended usage of fixdep, it must respect the return value
of not only malloc(), but also printf() and putchar().This seems a long-standing issue since the introduction of fixdep.
In old days, Kbuild tried to provide an extra safety by letting fixdep
output to a temporary file and renaming it after everything is done:scripts/basic/fixdep $(depfile) $@ '$(make-cmd)' > $(dot-target).tmp;\
rm -f $(depfile); \
mv -f $(dot-target).tmp $(dot-target).cmd)It was no help to avoid the current issue; fixdep successfully created
a truncated tmp file, which would be renamed to a .*.cmd file.This problem should be fixed by propagating the error status to the
build system because:[1] Since commit 9c2af1c7377a ("kbuild: add .DELETE_ON_ERROR special
target"), Make will delete the target automatically on any failure
in the recipe.[2] Since commit 392885ee82d3 ("kbuild: let fixdep directly write to
.*.cmd files"), .*.cmd file is included only when the corresponding
target already exists.Signed-off-by: Masahiro Yamada
01 Dec, 2018
1 commit
-
My main motivation of this commit is to clean up scripts/Kbuild.include
and scripts/Makefile.build.Currently, CONFIG_TRIM_UNUSED_KSYMS works with a tricky gimmick;
possibly exported symbols are detected by letting $(CPP) replace
EXPORT_SYMBOL* with a special string '=== __KSYM_*===', which is
post-processed by sed, and passed to fixdep. The extra preprocessing
is costly, and hacking cmd_and_fixdep is ugly.I came up with a new way to find exported symbols; insert a dummy
symbol __ksym_marker_* to each potentially exported symbol. Those
dummy symbols are picked up by $(NM), post-processed by sed, then
appended to .*.cmd files. I collected the post-process part to a
new shell script scripts/gen_ksymdeps.sh for readability. The dummy
symbols are put into the .discard.* section so that the linker
script rips them off the final vmlinux or modules.A nice side-effect is building with CONFIG_TRIM_UNUSED_KSYMS will
be much faster.Signed-off-by: Masahiro Yamada
Reviewed-by: Nicolas Pitre
07 May, 2018
1 commit
-
Underscores in symbol names are translated into slashes for path names.
Filesystems treat consecutive slashes as if there was only one, so
let's do the same in the dependency list for easier grepping, etc.Signed-off-by: Nicolas Pitre
Signed-off-by: Masahiro Yamada
26 Mar, 2018
1 commit
-
The idea of using fixdep was inspired by Kconfig, but autoksyms
belongs to a different group. So, I want to move those touched
files under include/config/ksym/ to include/ksym/.The directory include/ksym/ can be removed by 'make clean' because
it is meaningless for the external module building.Signed-off-by: Masahiro Yamada
Acked-by: Nicolas Pitre
05 Mar, 2018
3 commits
-
kconfig.h was excluded from consideration by fixdep by
6a5be57f0f00 (fixdep: fix extraneous dependencies) to avoid some false
positive hits(1) include/config/.h
(2) include/config/h.h
(3) include/config/foo.h(1) occurred because kconfig.h contains the string CONFIG_ in a
comment. However, since dee81e988674 (fixdep: faster CONFIG_ search), we
have a check that the part after CONFIG_ is non-empty, so this does not
happen anymore (and CONFIG_ appears by itself elsewhere, so that check
is worthwhile).(2) comes from the include guard, __LINUX_KCONFIG_H. But with the
previous patch, we no longer match that either.That leaves (3), which amounts to one [1] false dependency (aka stat() call
done by make), which I think we can live with:We've already had one case [2] where the lack of include/linux/kconfig.h in
the .o.cmd file caused a missing rebuild, and while I originally thought
we should just put kconfig.h in the dependency list without parsing it
for the CONFIG_ pattern, we actually do have some real CONFIG_ symbols
mentioned in it, and one can imagine some translation unit that just
does '#ifdef __BIG_ENDIAN' but doesn't through some other header
actually depend on CONFIG_CPU_BIG_ENDIAN - so changing the target
endianness could end up rebuilding the world, minus that small
TU. Quoting Linus,... when missing dependencies cause a missed re-compile, the resulting
bugs can be _really_ subtle.[1] well, two, we now also have CONFIG_BOOGER/booger.h - we could change
that to FOO if we care[2] https://lkml.org/lkml/2018/2/22/838
Cc: Linus Torvalds
Signed-off-by: Rasmus Villemoes
Signed-off-by: Masahiro Yamada -
The string CONFIG_ quite often appears after other alphanumerics,
meaning that that instance cannot be referencing a Kconfig
symbol. Omitting these means make has fewer files to stat() when
deciding what needs to be rebuilt - for a defconfig build, this seems to
remove about 2% of the (wildcard ...) lines from the .o.cmd files.Signed-off-by: Rasmus Villemoes
Signed-off-by: Masahiro Yamada -
uml-config.h hasn't existed in this decade (87e299e5c750 - x86, um: get
rid of uml-config.h). The few remaining UML_CONFIG instances are defined
directly in terms of their real CONFIG symbol in common-offsets.h, so
unlike when the symbols got defined via a sed script, anything that uses
UML_CONFIG_FOO now should also automatically pick up a dependency on
CONFIG_FOO via the normal fixdep mechanism (since common-offsets.h
should at least recursively be a dependency). Hence I believe we should
actually be able to ignore the HELLO_CONFIG_BOOM cases.Cc: Al Viro
Cc: Richard Weinberger
Cc: user-mode-linux-devel@lists.sourceforge.net
Signed-off-by: Rasmus Villemoes
Signed-off-by: Masahiro Yamada
18 Jan, 2018
7 commits
-
str_ends_with() tests if the given token ends with a particular string.
Currently, it is used to check file paths without $(srctree).Actually, we have one more place where this helper is useful. Use it
to check if CONFIG option ends with _MODULE.Signed-off-by: Masahiro Yamada
-
parse_dep_file() has too much indentation, and puts the code far to
the right. This commit refactors the code and reduces the one level
of indentation.strrcmp() computes 'slen' by itself, but the caller already knows the
length of the token, so 'slen' can be passed via function argument.
With this, we can swap the order of strrcmp() and "*p = \0;"Also, strrcmp() is an ambiguous function name. Flip the logic and
rename it to str_ends_with().I added a new helper is_ignored_file() - this returns 1 if the token
represents a file that should be ignored.Signed-off-by: Masahiro Yamada
-
I do not mind global variables where they are useful enough. In this
case, I do not see a good reason to use global variables since they
are just referenced in shallow places. It is easy to pass them via
function arguments.I squashed print_cmdline() into main() since it is just one line code.
Signed-off-by: Masahiro Yamada
-
Each token in the depfile is copied to the temporary buffer 's' to
terminate the token with zero. We do not need to do this any more
because the parsed buffer is now writable. Insert '\0' directly in
the buffer without calling memcpy().is no longer necessary. (It was needed for PATH_MAX).
Signed-off-by: Masahiro Yamada
-
Now, do_config_files() and print_deps() are almost the same. Only
the difference is the parser function called (parse_config_file vs
parse_dep_file).We can reduce the code duplication by factoring out the common code
into read_file() - this function allocates a buffer and loads a file
to it. It returns the pointer to the allocated buffer. (As before,
it bails out by exit(2) for any error.) The caller must free the
buffer when done.Having empty source files is possible; fixdep should simply skip them.
I deleted the "st.st_size == 0" check, so read_file() allocates 1-byte
buffer for an empty file. strstr() will immediately return NULL, and
this is what we expect.On the other hand, an empty dep_file should be treated as an error.
In this case, parse_dep_file() will error out with "no targets found"
and it is a correct error message.Signed-off-by: Masahiro Yamada
-
Commit dee81e988674 ("fixdep: faster CONFIG_ search") changed how to
read files in which CONFIG options are searched. It used malloc()
and read() instead of mmap() because it needed to zero-terminate the
buffer in order to use strstr(). print_deps() was left untouched
since there was no reason to change it.Now, I have two motivations to change it in the same way.
- do_config_file() and print_deps() do quite similar things; they
open a file, load it onto memory, and pass it to a parser function.
If we use malloc() and read() for print_deps() too, we can factor
out the common code. (I will do this in the next commit.)- parse_dep_file() copies each token to a temporary buffer because
it needs to zero-terminate it to be passed to printf(). It is not
possible to modify the buffer directly because it is mmap'ed with
O_RDONLY. If we load the file content into a malloc'ed buffer, we
can insert '\0' after each token, and save memcpy(). (I will do
this in the commit after next.)Signed-off-by: Masahiro Yamada
-
was included for ntohl(), but it was removed by
commit dee81e988674 ("fixdep: faster CONFIG_ search").Signed-off-by: Masahiro Yamada
08 Jan, 2018
1 commit
-
do_config_file() should exit with an error code on internal run-time
errors, and not return if it fails as then the error in do_config_file()
would go unnoticed in the current code and allow the build to continue.
The exit with error code will make the build fail in those very
exceptional cases. If this occurs, this actually indicates a deeper
problem in the execution of the kernel build process.Now, in these error cases, we do not explicitly free memory and close
the file handlers in do_config_file(), as this is covered by exit().This issue in the fixdep script was introduced with its initial
implementation back in 2002 by the original author Kai Germaschewski with
this commit 04bd72170653 ("kbuild: Make dependencies at compile time")
in the linux history git tree, i.e.,
git://git.kernel.org/pub/scm/linux/kernel/git/history/history.git.This issue was identified during the review of a previous patch that
intended to address a memory leak detected by a static analysis tool.Link: https://lkml.org/lkml/2017/12/14/736
Suggested-by: Nicholas Mc Guire
Suggested-by: Masahiro Yamada
Signed-off-by: Lukas Bulwahn
Signed-off-by: Masahiro Yamada
10 Aug, 2017
1 commit
-
Signed-off-by: Cao jin
Signed-off-by: Masahiro Yamada
25 Aug, 2016
1 commit
-
Do you think kernel build is 100% dominated by gcc? You are wrong!
One small utility called "fixdep" consistently manages to sneak into
profile's first page (unless you have small monitor of course).The choke point is this clever code:
for (; m < end; m++) {
if (*m == INT_CONF) { p = (char *) m ; goto conf; }
if (*m == INT_ONFI) { p = (char *) m-1; goto conf; }
if (*m == INT_NFIG) { p = (char *) m-2; goto conf; }
if (*m == INT_FIG_) { p = (char *) m-3; goto conf; }4 branches per 4 characters is not fast.
Use strstr(3), so that SSE2 etc can be used.
With this patch, fixdep is so deep at the bottom, it is hard to find it.
Signed-off-by: Alexey Dobriyan
Signed-off-by: Michal Marek
30 Mar, 2016
2 commits
-
Like with kconfig options, we now have the ability to compile in and
out individual EXPORT_SYMBOL() declarations based on the content of
include/generated/autoksyms.h. However we don't want the entire
world to be rebuilt whenever that file is touched.Let's apply the same build dependency trick used for CONFIG_* symbols
where the time stamp of empty files whose paths matching those symbols
is used to trigger fine grained rebuilds. In our case the key is the
symbol name passed to EXPORT_SYMBOL().However, unlike config options, we cannot just use fixdep to parse
the source code for EXPORT_SYMBOL(ksym) because several variants exist
and parsing them all in a separate tool, and keeping it in synch, is
not trivially maintainable. Furthermore, there are variants such asEXPORT_SYMBOL_GPL(pci_user_read_config_##size);
that are instanciated via a macro for which we can't easily determine
the actual exported symbol name(s) short of actually running the
preprocessor on them.Storing the symbol name string in a special ELF section doesn't work
for targets that output assembly or preprocessed source.So the best way is really to leverage the preprocessor by having it
output actual symbol names anchored by a special sequence that can be
easily filtered out. Then the list of symbols is simply fed to fixdep
to be merged with the other dependencies.That implies the preprocessor is executed twice for each source file.
A previous attempt relied on a warning pragma for each EXPORT_SYMBOL()
instance that was filtered apart from stderr by the build system with
a sed script during the actual compilation pass. Unfortunately the
preprocessor/compiler diagnostic output isn't stable between versions
and this solution, although more efficient, was deemed too fragile.Because of the lowercasing performed by fixdep, there might be name
collisions triggering spurious rebuilds for similar symbols. But this
shouldn't be a big issue in practice. (This is the case for CONFIG_*
symbols and I didn't want to be different here, whatever the original
reason for doing so.)To avoid needless build overhead, the exported symbol name gathering is
performed only when CONFIG_TRIM_UNUSED_KSYMS is selected.Signed-off-by: Nicolas Pitre
Acked-by: Rusty Russell -
... and merge them in the list of parsed dependencies.
Signed-off-by: Nicolas Pitre
18 Feb, 2016
1 commit
-
Coverity has recently added a check that will find when we don't check
the return code from fstat(2). Copy/paste the checking logic that
print_deps() has with an appropriate re-wording of the perror() message.Signed-off-by: Tom Rini
Signed-off-by: Michal Marek
07 Dec, 2015
1 commit
-
strrcmp only performs read access to the memory addressed by its
arguments so make them const pointers.Signed-off-by: Nicolas Iooss
Signed-off-by: Michal Marek
24 Aug, 2015
2 commits
-
The clear_config() is called just once at the beginning of this
program, but the global variable hashtab[] is already zero-filled
at the start-up.Signed-off-by: Masahiro Yamada
Signed-off-by: Michal Marek -
If the target string matches "CONFIG_", move the pointer p
forward. This saves several 7-chars adjustments.Signed-off-by: Masahiro Yamada
Signed-off-by: Michal Marek
10 Jun, 2014
1 commit
-
Signed-off-by: Masahiro Yamada
Signed-off-by: Michal Marek
06 Apr, 2013
1 commit
-
The current use-case for fixdep is: a source file is run through a single
processing step, which creates a single dependency file as a side-effect,
which fixdep transforms into the file used by the kernel build process.In order to transparently run the C pre-processor on device-tree files,
we wish to run both gcc -E and dtc on a source file in a single rule.
This generates two dependency files, which must be transformed together
into the file used by the kernel build process. This change modifies
fixdep so it can process the concatenation of multiple separate input
dependency files, and produce a correct unified output.The code changes have the slight benefit of transforming the loop in
parse_dep_file() into more of a lexer/tokenizer, with the loop body being
more of a parser. Previously, some of this logic was mixed together
before the loop. I also added some comments, which I hope are useful.Benchmarking shows that on a cross-compiled ARM tegra_defconfig build,
there is less than 0.5 seconds speed decrease with this change, on top
of a build time of ~2m24s. This is probably within the noise.Signed-off-by: Stephen Warren
Acked-by: Rob Herring
09 Jan, 2013
1 commit
-
Correct spelling typo in printk within various drivers.
Signed-off-by: Masanari Iida
Signed-off-by: Jiri Kosina
09 Sep, 2011
1 commit
-
The introduction of include/linux/kconfig.h created 3 extraneous
dependencies:
include/config/.h
include/config/h.h
include/config/foo.hFix this by excluding kconfig.h from fixdep calculations.
Signed-off-by: Peter Foley
Signed-off-by: Michal Marek
14 Mar, 2011
1 commit
-
Recent change to fixdep:
commit b7bd182176960fdd139486cadb9962b39f8a2b50
Author: Michal Marek
Date: Thu Feb 17 15:13:54 2011 +0100fixdep: Do not record dependency on the source file itself
changed the format of the *.cmd files without realizing that it is also
used by modpost. Put the path to the source file to the file back, in a
special variable, so that modpost sees all source files when calculating
srcversion for modules.Reported-and-tested-by: Henrik Rydberg
Signed-off-by: Michal Marek
Signed-off-by: Linus Torvalds
21 Feb, 2011
1 commit
-
The dependency is already expressed by the Makefiles, storing it in the
.cmd file breaks build if a .c file is replaced by .S or vice versa,
because the .cmd file containsfoo/bar.o: foo/bar.c ...
foo/bar.c ... :
so the foo/bar.c -> foo/bar.o rule triggers even if there is no
foo/bar.c anymore.Acked-by: Stephen Rothwell
Signed-off-by: Michal Marek
23 Dec, 2010
1 commit
-
Also add missing error handling to fstat call
Signed-off-by: Ben Gamari
Signed-off-by: Michal Marek
12 Nov, 2010
1 commit
-
I noticed fixdep uses ~2% of cpu time in kernel build, in function
use_config()fixdep spends a lot of cpu cycles in linear searches in its internal
string array. With about 400 stored strings per dep file, this begins to
be noticeable.Convert fixdep to use a hash table.
kbuild results on my x86_64 allmodconfig
Before patch :
real 10m30.414s
user 61m51.456s
sys 8m28.200sreal 10m12.334s
user 61m50.236s
sys 8m30.448sreal 10m42.947s
user 61m50.028s
sys 8m32.380sAfter:
real 10m8.180s
user 61m22.506s
sys 8m32.384sreal 10m35.039s
user 61m21.654s
sys 8m32.212sreal 10m14.487s
user 61m23.498s
sys 8m32.312sSigned-off-by: Eric Dumazet
Signed-off-by: Michal Marek
12 Dec, 2009
1 commit
-
Signed-off-by: Sam Ravnborg
Signed-off-by: Michal Marek
24 Sep, 2009
1 commit
-
* git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild-next: (30 commits)
Use macros for .data.page_aligned section.
Use macros for .bss.page_aligned section.
Use new __init_task_data macro in arch init_task.c files.
kbuild: Don't define ALIGN and ENTRY when preprocessing linker scripts.
arm, cris, mips, sparc, powerpc, um, xtensa: fix build with bash 4.0
kbuild: add static to prototypes
kbuild: fail build if recordmcount.pl fails
kbuild: set -fconserve-stack option for gcc 4.5
kbuild: echo the record_mcount command
gconfig: disable "typeahead find" search in treeviews
kbuild: fix cc1 options check to ensure we do not use -fPIC when compiling
checkincludes.pl: add option to remove duplicates in place
markup_oops: use modinfo to avoid confusion with underscored module names
checkincludes.pl: provide usage helper
checkincludes.pl: close file as soon as we're done with it
ctags: usability fix
kernel hacking: move STRIP_ASM_SYMS from General
gitignore usr/initramfs_data.cpio.bz2 and usr/initramfs_data.cpio.lzma
kbuild: Check if linker supports the -X option
kbuild: introduce ld-option
...Fix trivial conflict in scripts/basic/fixdep.c
21 Sep, 2009
2 commits
-
Signed-off-by: Trevor Keith
Signed-off-by: Jiri Kosina -
Ignore drivers/staging/ since it is very likely that new drivers
introduce it again.Signed-off-by: Markus Heidelberg
Signed-off-by: Jiri Kosina
20 Sep, 2009
1 commit
-
Warnings found via gcc -Wmissing-prototypes.
Signed-off-by: Trevor Keith
Acked-by: WANG Cong
Signed-off-by: Andrew Morton
Signed-off-by: Sam Ravnborg
15 Jun, 2009
1 commit
-
gcc-4.4.1:
HOSTCC scripts/basic/fixdep
scripts/basic/fixdep.c: In function 'traps':
scripts/basic/fixdep.c:377: warning: dereferencing type-punned pointer will break strict-aliasing rules
scripts/basic/fixdep.c:379: warning: dereferencing type-punned pointer will break strict-aliasing rules(Apparently -fno-strict-aliasing will fix this too)
Signed-off-by: WANG Cong
Signed-off-by: Andrew Morton
Signed-off-by: Sam Ravnborg
