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  • Dmitry Baryshkov Dmitry Baryshkov lumag
1 author
  1. Sep 28, 2022
  3. May 07, 2022
    • Masahiro Yamada's avatar
      kbuild: split the second line of *.mod into *.usyms · 9413e764
      Masahiro Yamada authored 
      
The *.mod files have two lines; the first line lists the member objects
of the module, and the second line, if CONFIG_TRIM_UNUSED_KSYMS=y, lists
the undefined symbols.

Currently, we generate *.mod after constructing composite modules,
otherwise, we cannot compute the second line. No prerequisite is
required to print the first line.

They are orthogonal. Splitting them into separate commands will ease
further cleanups.

This commit splits the list of undefined symbols out to *.usyms files.

Previously, the list of undefined symbols ended up with a very long
line, but now it has one symbol per line.

Use sed like we did before commit 7d32358b ("kbuild: avoid split
lines in .mod files").

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: default avatarNicolas Schier <nicolas@fjasle.eu>
      9413e764
  5. May 01, 2021
  7. Apr 24, 2021
    • Masahiro Yamada's avatar
      kbuild: generate Module.symvers only when vmlinux exists · 69bc8d38
      Masahiro Yamada authored 
      
The external module build shows the following warning if Module.symvers
is missing in the kernel tree.

  WARNING: Symbol version dump "Module.symvers" is missing.
           Modules may not have dependencies or modversions.

I think this is an important heads-up because the resulting modules may
not work as expected. This happens when you did not build the entire
kernel tree, for example, you might have prepared the minimal setups
for external modules by 'make defconfig && make modules_preapre'.

A problem is that 'make modules' creates Module.symvers even without
vmlinux. In this case, that warning is suppressed since Module.symvers
already exists in spite of its incomplete content.

The incomplete (i.e. invalid) Module.symvers should not be created.

This commit changes the second pass of modpost to dump symbols into
modules-only.symvers. The final Module.symvers is created by
concatenating vmlinux.symvers and modules-only.symvers if both exist.

Module.symvers is supposed to collect symbols from both vmlinux and
modules. It might be a bit confusing, and I am not quite sure if it
is an official interface, but presumably it is difficult to rename it
because some tools (e.g. kmod) parse it.

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
      69bc8d38
    • Rasmus Villemoes's avatar
      kbuild: add CONFIG_VMLINUX_MAP expert option · 5cc12472
      Rasmus Villemoes authored 
      
It can be quite useful to have ld emit a link map file, in order to
debug or verify that special sections end up where they are supposed
to, and to see what LD_DEAD_CODE_DATA_ELIMINATION manages to get rid
of.

The only reason I'm not just adding this unconditionally is that the
.map file can be rather large (several MB), and that's a waste of
space when one isn't interested in these things. Also make it depend
on CONFIG_EXPERT.

Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
      5cc12472
  9. Feb 04, 2021
  11. Jan 14, 2021
  13. Sep 10, 2020
  15. Jul 31, 2020
  17. Jul 05, 2020
  19. Jun 06, 2020
    • Masahiro Yamada's avatar
      modpost: generate vmlinux.symvers and reuse it for the second modpost · 269a535c
      Masahiro Yamada authored 
      
The full build runs modpost twice, first for vmlinux.o and second for
modules.

The first pass dumps all the vmlinux symbols into Module.symvers, but
the second pass parses vmlinux again instead of reusing the dump file,
presumably because it needs to avoid accumulating stale symbols.

Loading symbol info from a dump file is faster than parsing an ELF object.
Besides, modpost deals with various issues to parse vmlinux in the second
pass.

A solution is to make the first pass dumps symbols into a separate file,
vmlinux.symvers. The second pass reads it, and parses module .o files.
The merged symbol information is dumped into Module.symvers in the same
way as before.

This makes further modpost cleanups possible.

Also, it fixes the problem of 'make vmlinux', which previously overwrote
Module.symvers, throwing away module symbols.

I slightly touched scripts/link-vmlinux.sh so that vmlinux is re-linked
when you cross this commit. Otherwise, vmlinux.symvers would not be
generated.

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
      269a535c
  21. Mar 25, 2020
  23. Mar 02, 2020
  25. Feb 20, 2020
  27. Nov 11, 2019
  29. Sep 10, 2019
  31. Aug 21, 2019
  33. Jul 27, 2019
  35. Jul 17, 2019
    • Masahiro Yamada's avatar
      kbuild: create *.mod with full directory path and remove MODVERDIR · b7dca6dd
      Masahiro Yamada authored 
      While descending directories, Kbuild produces objects for modules,
but do not link final *.ko files; it is done in the modpost.

To keep track of modules, Kbuild creates a *.mod file in $(MODVERDIR)
for every module it is building. Some post-processing steps read the
necessary information from *.mod files. This avoids descending into
directories again. This mechanism was introduced in 2003 or so.

Later, commit 551559e1 ("kbuild: implement modules.order") added
modules.order. So, we can simply read it out to know all the modules
with directory paths. This is easier than parsing the first line of
*.mod files.

$(MODVERDIR) has a flat directory structure, that is, *.mod files
are named only with base names. This is based on the assumption that
the module name is unique across the tree. This assumption is really
fragile.

Stephen Rothwell reported a race condition caused by a module name
conflict:

  https://lkml.org/lkml/2019/5/13/991



In parallel building, two different threads could write to the same
$(MODVERDIR)/*.mod simultaneously.

Non-unique module names are the source of all kind of troubles, hence
commit 3a48a919 ("kbuild: check uniqueness of module names")
introduced a new checker script.

However, it is still fragile in the build system point of view because
this race happens before scripts/modules-check.sh is invoked. If it
happens again, the modpost will emit unclear error messages.

To fix this issue completely, create *.mod with full directory path
so that two threads never attempt to write to the same file.

$(MODVERDIR) is no longer needed.

Since modules with directory paths are listed in modules.order, Kbuild
is still able to find *.mod files without additional descending.

I also killed cmd_secanalysis; scripts/mod/sumversion.c computes MD4 hash
for modules with MODULE_VERSION(). When CONFIG_DEBUG_SECTION_MISMATCH=y,
it occurs not only in the modpost stage, but also during directory
descending, where sumversion.c may parse stale *.mod files. It would emit
'No such file or directory' warning when an object consisting a module is
renamed, or when a single-obj module is turned into a multi-obj module or
vice versa.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: default avatarNicolas Pitre <nico@fluxnic.net>
      b7dca6dd
  37. Jul 09, 2019
    • Masahiro Yamada's avatar
      kbuild: do not create wrappers for header-test-y · c93a0368
      Masahiro Yamada authored 
      
header-test-y does not work with headers in sub-directories.

For example, you may want to write a Makefile, like this:

include/linux/Kbuild:

  header-test-y += mtd/nand.h

This entry will create a wrapper include/linux/mtd/nand.hdrtest.c
with the following content:

  #include "mtd/nand.h"

To make this work, we need to add $(srctree)/include/linux to the
header search path. It would be tedious to add ccflags-y.

Instead, we could change the *.hdrtest.c rule to wrap:

  #include "nand.h"

This works for in-tree build since #include "..." searches in the
relative path from the header with this directive. For O=... build,
we need to add $(srctree)/include/linux/mtd to the header search path,
which will be even more tedious.

After all, I thought it would be handier to compile headers directly
without creating wrappers.

I added a new build rule to compile %.h into %.h.s

The target is %.h.s instead of %.h.o because it is slightly faster.
Also, as for GCC, an empty assembly is smaller than an empty object.

I wrote the build rule:

  $(CC) $(c_flags) -S -o $@ -x c /dev/null -include $<

instead of:

  $(CC) $(c_flags) -S -o $@ -x c $<

Both work fine with GCC, but the latter is bad for Clang.

This comes down to the difference in the -Wunused-function policy.
GCC does not warn about unused 'static inline' functions at all.
Clang does not warn about the ones in included headers, but does
about the ones in the source. So, we should handle headers as
headers, not as source files.

In fact, this has been hidden since commit abb2ea7d ("compiler,
clang: suppress warning for unused static inline functions"), but we
should not rely on that.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: default avatarJani Nikula <jani.nikula@intel.com>
Tested-by: default avatarJani Nikula <jani.nikula@intel.com>
      c93a0368
  39. Jun 15, 2019
  41. May 18, 2019
  43. May 08, 2019
  45. May 07, 2019
    • Alexey Gladkov's avatar
      moduleparam: Save information about built-in modules in separate file · 898490c0
      Alexey Gladkov authored 
      
Problem:

When a kernel module is compiled as a separate module, some important
information about the kernel module is available via .modinfo section of
the module.  In contrast, when the kernel module is compiled into the
kernel, that information is not available.

Information about built-in modules is necessary in the following cases:

1. When it is necessary to find out what additional parameters can be
passed to the kernel at boot time.

2. When you need to know which module names and their aliases are in
the kernel. This is very useful for creating an initrd image.

Proposal:

The proposed patch does not remove .modinfo section with module
information from the vmlinux at the build time and saves it into a
separate file after kernel linking. So, the kernel does not increase in
size and no additional information remains in it. Information is stored
in the same format as in the separate modules (null-terminated string
array). Because the .modinfo section is already exported with a separate
modules, we are not creating a new API.

It can be easily read in the userspace:

$ tr '\0' '\n' < modules.builtin.modinfo
ext4.softdep=pre: crc32c
ext4.license=GPL
ext4.description=Fourth Extended Filesystem
ext4.author=Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others
ext4.alias=fs-ext4
ext4.alias=ext3
ext4.alias=fs-ext3
ext4.alias=ext2
ext4.alias=fs-ext2
md_mod.alias=block-major-9-*
md_mod.alias=md
md_mod.description=MD RAID framework
md_mod.license=GPL
md_mod.parmtype=create_on_open:bool
md_mod.parmtype=start_dirty_degraded:int
...

Co-Developed-by: default avatarGleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: default avatarGleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: default avatarAlexey Gladkov <gladkov.alexey@gmail.com>
Acked-by: default avatarJessica Yu <jeyu@kernel.org>
Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      898490c0
    • Masahiro Yamada's avatar
      .gitignore: add leading and trailing slashes to generated directories · 1e35663e
      Masahiro Yamada authored 
      
Clarify these directory paths are relative to the top of the source
tree.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      1e35663e
  47. Dec 13, 2018
    • Rob Herring's avatar
      kbuild: Add support for DT binding schema checks · 4f0e3a57
      Rob Herring authored 
      
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: default avatarMasahiro 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: default avatarRob Herring <robh@kernel.org>
      4f0e3a57
  49. Apr 11, 2018
    • Miguel Ojeda's avatar
      clang-format: add configuration file · d4ef8d3f
      Miguel Ojeda authored 
      clang-format is a tool to format C/C++/...  code according to a set of
rules and heuristics.  Like most tools, it is not perfect nor covers
every single case, but it is good enough to be helpful.

In particular, it is useful for quickly re-formatting blocks of code
automatically, for reviewing full files in order to spot coding style
mistakes, typos and possible improvements.  It is also handy for sorting
``#includes``, for aligning variables and macros, for reflowing text and
other similar tasks.  It also serves as a teaching tool/guide for
newcomers.

The tool itself has been already included in the repositories of popular
Linux distributions for a long time.  The rules in this file are
intended for clang-format >= 4, which is easily available in most
distributions.

This commit adds the configuration file that contains the rules that the
tool uses to know how to format the code according to the kernel coding
style.  This gives us several advantages:

  * clang-format works out of the box with reasonable defaults;
    avoiding that everyone has to re-do the configuration.

  * Everyone agrees (eventually) on what is the most useful default
    configuration for most of the kernel.

  * If it becomes commonplace among kernel developers, clang-format
    may feel compelled to support us better. They already recognize
    the Linux kernel and its style in their documentation and in one
    of the style sub-options.

Some of clang-format's features relevant for the kernel are:

  * Uses clang's tooling support behind the scenes to parse and rewrite
    the code. It is not based on ad-hoc regexps.

  * Supports reasonably well the Linux kernel coding style.

  * Fast enough to be used at the press of a key.

  * There are already integrations (either built-in or third-party)
    for many common editors used by kernel developers (e.g. vim,
    emacs, Sublime, Atom...) that allow you to format an entire file
    or, more usefully, just your selection.

  * Able to parse unified diffs -- you can, for instance, reformat
    only the lines changed by a git commit.

  * Able to reflow text comments as well.

  * Widely supported and used by hundreds of developers in highly
    complex projects and organizations (e.g. the LLVM project itself,
    Chromium, WebKit, Google, Mozilla...). Therefore, it will be
    supported for a long time.

See more information about the tool at:

    https://clang.llvm.org/docs/ClangFormat.html
    https://clang.llvm.org/docs/ClangFormatStyleOptions.html

Link: http://lkml.kernel.org/r/20180318171632.qfkemw3mwbcukth6@gmail.com


Signed-off-by: default avatarMiguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d4ef8d3f
  51. Apr 07, 2018
  53. Mar 25, 2018
  55. Feb 14, 2018
  57. Dec 12, 2017
    • Paolo Pisati's avatar
      scripts/package: snap-pkg target · 5704d455
      Paolo Pisati authored 
      Following in footsteps of other targets like 'deb-pkg, 'rpm-pkg' and 'tar-pkg',
this patch adds a 'snap-pkg' target for the creation of a Linux kernel snap
package using the kbuild infrastructure.

A snap, in its general form, is a self contained, sandboxed, universal package
and it is intended to work across multiple distributions and/or devices. A snap
package is distributed as a single compressed squashfs filesystem.

A kernel snap is a snap package carrying the Linux kernel, kernel modules,
accessory files (DTBs, System.map, etc) and a manifesto file.  The purpose of a
kernel snap is to carry the Linux kernel during the creation of a system image,
eg. Ubuntu Core, and its subsequent upgrades.

For more information on snap packages: https://snapcraft.io/docs/



Signed-off-by: default avatarPaolo Pisati <paolo.pisati@canonical.com>
Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      5704d455
  59. Nov 14, 2017
  61. Nov 08, 2017
  63. Apr 24, 2017