1. 21 Feb, 2018 2 commits
  2. 16 Jan, 2018 1 commit
  3. 20 Nov, 2017 1 commit
    • Matthew Wilcox's avatar
      Add optional check for bad kernel-doc comments · 3a025e1d
      Matthew Wilcox authored
      Implement a '-none' output mode for kernel-doc which will only output
      warning messages, and suppresses the warning message about there being
      no kernel-doc in the file.
      If the build has requested additional warnings, automatically check all
      .c files.  This patch does not check .h files.  Enabling the warning
      by default would add about 1300 warnings, so it's default off for now.
      People who care can use this to check they didn't break the docs and
      maybe we'll get all the warnings fixed and be able to enable this check
      by default in the future.
      Signed-off-by: default avatarMatthew Wilcox <mawilcox@microsoft.com>
      Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
  4. 18 Nov, 2017 1 commit
    • Masahiro Yamada's avatar
      kbuild: create built-in.o automatically if parent directory wants it · f7adc312
      Masahiro Yamada authored
      "obj-y += foo/" syntax requires Kbuild to visit the "foo" subdirectory
      and link built-in.o from that directory.  This means foo/Makefile is
      responsible for creating built-in.o even if there is no object to
      link (in this case, built-in.o is an empty archive).
      We have had several fixups like commit 4b024242
       ("kbuild: Fix
      linking error built-in.o no such file or directory"), then ended up
      with a complex condition as follows:
        ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),)
        builtin-target := $(obj)/built-in.o
      We still have more cases not covered by the above, so we need to add
        obj- := dummy.o
      in several places just for creating empty built-in.o.
      A key point is, the parent Makefile knows whether built-in.o is needed
      or not.  If a subdirectory needs to create built-in.o, its parent can
      tell the fact when descending.
      If non-empty $(need-builtin) flag is passed from the parent, built-in.o
      should be created.  $(obj-y) should be still checked to support the
      single target "%/".  All of ugly tricks will go away.
      Signed-off-by: Masahiro Yamada's avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      Reviewed-by: default avatarSam Ravnborg <sam@ravnborg.org>
  5. 16 Nov, 2017 4 commits
  6. 02 Nov, 2017 2 commits
    • Linus Torvalds's avatar
      Kbuild: don't pass "-C" to preprocessor when processing linker scripts · 5cb0512c
      Linus Torvalds authored
      For some odd historical reason, we preprocessed the linker scripts with
      "-C", which keeps comments around.  That makes no sense, since the
      comments are not meaningful for the build anyway.
      And it actually breaks things, since linker scripts can't have C++ style
      "//" comments in them, so keeping comments after preprocessing now
      limits us in odd and surprising ways in our header files for no good
      The -C option goes back to pre-git and pre-bitkeeper times, but seems to
      have been historically used (along with "-traditional") for some
      odd-ball architectures (ia64, MIPS and SH).  It probably didn't matter
      back then either, but might possibly have been used to minimize the
      difference between the original file and the pre-processed result.
      The reason for this may be lost in time, but let's not perpetuate it
      only because we can't remember why we did this crazy thing.
      This was triggered by the recent addition of SPDX lines to the source
      tree, where people apparently were confused about why header files
      couldn't use the C++ comment format.
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    • Greg Kroah-Hartman's avatar
      License cleanup: add SPDX GPL-2.0 license identifier to files with no license · b2441318
      Greg Kroah-Hartman authored
      Many source files in the tree are missing licensing information, which
      makes it harder for compliance tools to determine the correct license.
      By default all files without license information are under the default
      license of the kernel, which is GPL version 2.
      Update the files which contain no license information with the 'GPL-2.0'
      SPDX license identifier.  The SPDX identifier is a legally binding
      shorthand, which can be used instead of the full boiler plate text.
      This patch is based on work done by Thomas Gleixner and Kate Stewart and
      Philippe Ombredanne.
      How this work was done:
      Patches were generated and checked against linux-4.14-rc6 for a subset of
      the use cases:
       - file had no licensing information it it.
       - file was a */uapi/* one with no licensing information in it,
       - file was a */uapi/* one with existing licensing information,
      Further patches will be generated in subsequent months to fix up cases
      where non-standard license headers were used, and references to license
      had to be inferred by heuristics based on keywords.
      The analysis to determine which SPDX License Identifier to be applied to
      a file was done in a spreadsheet of side by side results from of the
      output of two independent scanners (ScanCode & Windriver) producing SPDX
      tag:value files created by Philippe Ombredanne.  Philippe prepared the
      base worksheet, and did an initial spot review of a few 1000 files.
      The 4.13 kernel was the starting point of the analysis with 60,537 files
      assessed.  Kate Stewart did a file by file comparison of the scanner
      results in the spreadsheet to determine which SPDX license identifier(s)
      to be applied to the file. She confirmed any determination that was not
      immediately clear with lawyers working with the Linux Foundation.
      Criteria used to select files for SPDX license identifier tagging was:
       - Files considered eligible had to be source code files.
       - Make and config files were included as candidates if they contained >5
         lines of source
       - File already had some variant of a license header in it (even if <5
      All documentation files were explicitly excluded.
      The following heuristics were used to determine which SPDX license
      identifiers to apply.
       - when both scanners couldn't find any license traces, file was
         considered to have no license information in it, and the top level
         COPYING file license applied.
         For non */uapi/* files that summary was:
         SPDX license identifier                            # files
         GPL-2.0                                              11139
         and resulted in the first patch in this series.
         If that file was a */uapi/* path one, it was "GPL-2.0 WITH
         Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:
         SPDX license identifier                            # files
         GPL-2.0 WITH Linux-syscall-note                        930
         and resulted in the second patch in this series.
       - if a file had some form of licensing information in it, and was one
         of the */uapi/* ones, it was denoted with the Linux-syscall-note if
         any GPL family license was found in the file or had no licensing in
         it (per prior point).  Results summary:
         SPDX license identifier                            # files
         GPL-2.0 WITH Linux-syscall-note                       270
         GPL-2.0+ WITH Linux-syscall-note                      169
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
         LGPL-2.1+ WITH Linux-syscall-note                      15
         GPL-1.0+ WITH Linux-syscall-note                       14
         ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
         LGPL-2.0+ WITH Linux-syscall-note                       4
         LGPL-2.1 WITH Linux-syscall-note                        3
         ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
         ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1
         and that resulted in the third patch in this series.
       - when the two scanners agreed on the detected license(s), that became
         the concluded license(s).
       - when there was disagreement between the two scanners (one detected a
         license but the other didn't, or they both detected different
         licenses) a manual inspection of the file occurred.
       - In most cases a manual inspection of the information in the file
         resulted in a clear resolution of the license that should apply (and
         which scanner probably needed to revisit its heuristics).
       - When it was not immediately clear, the license identifier was
         confirmed with lawyers working with the Linux Foundation.
       - If there was any question as to the appropriate license identifier,
         the file was flagged for further research and to be revisited later
         in time.
      In total, over 70 hours of logged manual review was done on the
      spreadsheet to determine the SPDX license identifiers to apply to the
      source files by Kate, Philippe, Thomas and, in some cases, confirmation
      by lawyers working with the Linux Foundation.
      Kate also obtained a third independent scan of the 4.13 code base from
      FOSSology, and compared selected files where the other two scanners
      disagreed against that SPDX file, to see if there was new insights.  The
      Windriver scanner is based on an older version of FOSSology in part, so
      they are related.
      Thomas did random spot checks in about 500 files from the spreadsheets
      for the uapi headers and agreed with SPDX license identifier in the
      files he inspected. For the non-uapi files Thomas did random spot checks
      in about 15000 files.
      In initial set of patches against 4.14-rc6, 3 files were found to have
      copy/paste license identifier errors, and have been fixed to reflect the
      correct identifier.
      Additionally Philippe spent 10 hours this week doing a detailed manual
      inspection and review of the 12,461 patched files from the initial patch
      version early this week with:
       - a full scancode scan run, collecting the matched texts, detected
         license ids and scores
       - reviewing anything where there was a license detected (about 500+
         files) to ensure that the applied SPDX license was correct
       - reviewing anything where there was no detection but the patch license
         was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
         SPDX license was correct
      This produced a worksheet with 20 files needing minor correction.  This
      worksheet was then exported into 3 different .csv files for the
      different types of files to be modified.
      These .csv files were then reviewed by Greg.  Thomas wrote a script to
      parse the csv files and add the proper SPDX tag to the file, in the
      format that the file expected.  This script was further refined by Greg
      based on the output to detect more types of files automatically and to
      distinguish between header and source .c files (which need different
      comment types.)  Finally Greg ran the script using the .csv files to
      generate the patches.
      Reviewed-by: default avatarKate Stewart <kstewart@linuxfoundation.org>
      Reviewed-by: default avatarPhilippe Ombredanne <pombredanne@nexb.com>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
  7. 14 Oct, 2017 1 commit
  8. 28 Sep, 2017 1 commit
  9. 09 Aug, 2017 1 commit
  10. 26 Jul, 2017 1 commit
    • Josh Poimboeuf's avatar
      x86/unwind: Add the ORC unwinder · ee9f8fce
      Josh Poimboeuf authored
      Add the new ORC unwinder which is enabled by CONFIG_ORC_UNWINDER=y.
      It plugs into the existing x86 unwinder framework.
      It relies on objtool to generate the needed .orc_unwind and
      .orc_unwind_ip sections.
      For more details on why ORC is used instead of DWARF, see
      Documentation/x86/orc-unwinder.txt - but the short version is
      that it's a simplified, fundamentally more robust debugninfo
      data structure, which also allows up to two orders of magnitude
      faster lookups than the DWARF unwinder - which matters to
      profiling workloads like perf.
      Thanks to Andy Lutomirski for the performance improvement ideas:
      splitting the ORC unwind table into two parallel arrays and creating a
      fast lookup table to search a subset of the unwind table.
      Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Jiri Slaby...
  11. 25 Jul, 2017 1 commit
  12. 30 Jun, 2017 1 commit
  13. 03 May, 2017 1 commit
  14. 24 Apr, 2017 1 commit
  15. 03 Feb, 2017 1 commit
    • Ard Biesheuvel's avatar
      kbuild: modversions: add infrastructure for emitting relative CRCs · 56067812
      Ard Biesheuvel authored
      This add the kbuild infrastructure that will allow architectures to emit
      vmlinux symbol CRCs as 32-bit offsets to another location in the kernel
      where the actual value is stored. This works around problems with CRCs
      being mistaken for relocatable symbols on kernels that self relocate at
      runtime (i.e., powerpc with CONFIG_RELOCATABLE=y)
      For the kbuild side of things, this comes down to the following:
       - introducing a Kconfig symbol MODULE_REL_CRCS
       - adding a -R switch to genksyms to instruct it to emit the CRC symbols
         as references into the .rodata section
       - making modpost distinguish such references from absolute CRC symbols
         by the section index (SHN_ABS)
       - making kallsyms disregard non-absolute symbols with a __crc_ prefix
      Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
  16. 11 Dec, 2016 1 commit
  17. 29 Nov, 2016 2 commits
  18. 09 Nov, 2016 1 commit
  19. 01 Nov, 2016 1 commit
  20. 22 Oct, 2016 1 commit
  21. 09 Sep, 2016 1 commit
    • Stephen Rothwell's avatar
      kbuild: allow architectures to use thin archives instead of ld -r · a5967db9
      Stephen Rothwell authored
      ld -r is an incremental link used to create built-in.o files in build
      subdirectories. It produces relocatable object files containing all
      its input files, and these are are then pulled together and relocated
      in the final link. Aside from the bloat, this constrains the final
      link relocations, which has bitten large powerpc builds with
      unresolvable relocations in the final link.
      Alan Modra has recommended the kernel use thin archives for linking.
      This is an alternative and means that the linker has more information
      available to it when it links the kernel.
      This patch enables a config option architectures can select, which
      causes all built-in.o files to be built as thin archives. built-in.o
      files in subdirectories do not get symbol table or index attached,
      which improves speed and size. The final link pass creates a
      built-in.o archive in the root output directory which includes the
      symbol table and index. The linker then uses takes this file to link.
      The --whole-archive linker option is required, because the linker now
      has visibility to every individual object file, and it will otherwise
      just completely avoid including those without external references
      (consider a file with EXPORT_SYMBOL or initcall or hardware exceptions
      as its only entry points). The traditional built works "by luck" as
      built-in.o files are large enough that they're going to get external
      references. However this optimisation is unpredictable for the kernel
      (due to above external references), ineffective at culling unused, and
      costly because the .o files have to be searched for references.
      Superior alternatives for link-time culling should be used instead.
      Build characteristics for inclink vs thinarc, on a small powerpc64le
      pseries VM with a modest .config:
                                        inclink       thinarc
      vmlinux                        15 618 680    15 625 028
      sum of all built-in.o          56 091 808     1 054 334
      sum excluding root built-in.o                   151 430
      find -name built-in.o | xargs rm ; time make vmlinux
      real                              22.772s       21.143s
      user                              13.280s       13.430s
      sys                                4.310s        2.750s
      - Final kernel pulled in only about 6K more, which shows how
        ineffective the object file culling is.
      - Build performance looks improved due to less pagecache activity.
        On IO constrained systems it could be a bigger win.
      - Build size saving is significant.
      Side note, the toochain understands archives, so there's some tricks,
      $ ar t built-in.o          # list all files you linked with
      $ size built-in.o          # and their sizes
      $ objdump -d built-in.o    # disassembly (unrelocated) with filenames
      Implementation by sfr, minor tweaks by npiggin.
      Signed-off-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
      Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
      Signed-off-by: default avatarMichal Marek <mmarek@suse.com>
  22. 08 Aug, 2016 1 commit
    • Al Viro's avatar
      [kbuild] handle exports in lib-y objects reliably · 7f2084fa
      Al Viro authored
      Collect the symbols exported by anything that goes into lib.a and
      add an empty object (lib-exports.o) with explicit undefs for each
      of those to obj-y.
      That allows to relax the rules regarding the use of exports in
      lib-* objects - right now an object with export can be in lib-*
      only if we are guaranteed that there always will be users in
      built-in parts of the tree, otherwise it needs to be in obj-*.
      As the result, we have an unholy mix of lib- and obj- in lib/Makefile
      and (especially) in arch/*/lib/Makefile.  Moreover, a change in
      generic part of the kernel can lead to mysteriously missing exports
      on some configs.  With this change we don't have to worry about
      that anymore.
      One side effect is that built-in.o now pulls everything with exports
      from the corresponding lib.a (if such exists).  That's exactly what
      we want for linking vmlinux and fortunately it's almost the only thing
      built-in.o is used in.  arch/ia64/hp/sim/boot/bootloader is the only
      exception and it's easy to get rid of now - just turn everything in
      arch/ia64/lib into lib-* and don't bother with arch/ia64/lib/built-in.o
      [AV: stylistic fix from Michal folded in]
      Acked-by: default avatarMichal Marek <mmarek@suse.cz>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
  23. 07 Jun, 2016 1 commit
  24. 20 Apr, 2016 2 commits
  25. 29 Mar, 2016 2 commits
    • Nicolas Pitre's avatar
      kbuild: de-duplicate fixdep usage · e4aca459
      Nicolas Pitre authored
      The generation and postprocessing of automatic dependency rules is
      duplicated in rule_cc_o_c, rule_as_o_S and if_changed_dep. Since
      this is not a trivial one-liner action, it is now abstracted under
      cmd_and_fixdep to simplify things and make future changes in this area
      In the rule_cc_o_c and rule_as_o_S cases that means the order of some
      commands has been altered, namely fixdep and related file manipulations
      are executed earlier, but they didn't depend on those commands that now
      execute later.
      Signed-off-by: default avatarNicolas Pitre <nico@linaro.org>
    • Nicolas Pitre's avatar
      kbuild: record needed exported symbols for modules · 9895c03d
      Nicolas Pitre authored
      Kernel modules are partially linked object files with some undefined
      symbols that are expected to be matched with EXPORT_SYMBOL() entries
      from elsewhere.
      Each .tmp_versions/*.mod file currently contains two line of text
      separated by a newline character. The first line has the actual module
      file name while the second line has a list of object files constituting
      that module. Those files are parsed by modpost (scripts/mod/sumversion.c),
      scripts/Makefile.modpost, scripts/Makefile.modsign, etc.  Only the
      modpost utility cares about the second line while the others retrieve
      only the first line.
      Therefore we can add a third line to record the list of undefined symbols
      aka required EXPORT_SYMBOL() entries for each module into that file
      without breaking anything. Like for the second line, symbols are separated
      by a blank and the list is terminated with a newline character.
      To avoid needless build overhead, the undefined symbols extraction is
      performed only when CONFIG_TRIM_UNUSED_KSYMS is selected.
      Signed-off-by: default avatarNicolas Pitre <nico@linaro.org>
      Acked-by: default avatarRusty Russell <rusty@rustcorp.com.au>
  26. 05 Mar, 2016 1 commit
  27. 29 Feb, 2016 1 commit
  28. 25 Nov, 2015 1 commit
    • Michal Marek's avatar
      kbuild: Allow to specify composite modules with modname-m · cf4f2193
      Michal Marek authored
      This allows to write
        drm-$(CONFIG_AGP) += drm_agpsupport.o
      without having to handle CONFIG_AGP=y vs. CONFIG_AGP=m. Only support
      this syntax for modules, since built-in code depending on something
      modular cannot work and init/Makefile actually relies on the current
      semantics. There are a few drivers which adapted to the current
      semantics out of necessity; these are fixed to also work when the
      respective subsystem is modular.
      Acked-by: Peter Chen <peter.chen@freescale.com> [chipidea]
      Signed-off-by: default avatarMichal Marek <mmarek@suse.com>
  29. 29 Jan, 2015 1 commit
  30. 02 Oct, 2014 1 commit
  31. 19 Aug, 2014 1 commit
    • Masahiro Yamada's avatar
      kbuild: handle multi-objs dependency appropriately · c8589d1e
      Masahiro Yamada authored
      The comment in scripts/Makefile.build says as follows:
        We would rather have a list of rules like
              foo.o: $(foo-objs)
        but that's not so easy, so we rather make all composite objects depend
        on the set of all their parts
      This commit makes it possible!
      For example, assume a Makefile like this
        obj-m = foo.o bar.o
        foo-objs := foo1.o foo2.o
        bar-objs := bar1.o bar2.o
      Without this patch, foo.o depends on all of
      foo1.o foo2.o bar1.o bar2.o.
      It looks funny that foo.o is regenerated when bar1.c is updated.
      Now we can handle the dependency of foo.o and bar.o separately.
      Signed-off-by: default avatarMasahiro Yamada <yamada.m@jp.panasonic.com>
      Signed-off-by: default avatarMichal Marek <mmarek@suse.cz>
  32. 30 Apr, 2014 1 commit