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  1. 30 12月, 2022 1 次提交
    • S
      kbuild: Fix running modpost with musl libc · 63ffe00d
      由 Samuel Holland 提交于 
      commit 3d57e1b7 ("kbuild: refactor the prerequisites of the modpost
rule") moved 'vmlinux.o' inside modpost-args, possibly before some of
the other options. However, getopt() in musl libc follows POSIX and
stops looking for options upon reaching the first non-option argument.
As a result, the '-T' option is misinterpreted as a positional argument,
and the build fails:

  make -f ./scripts/Makefile.modpost
     scripts/mod/modpost   -E   -o Module.symvers vmlinux.o -T modules.order
  -T: No such file or directory
  make[1]: *** [scripts/Makefile.modpost:137: Module.symvers] Error 1
  make: *** [Makefile:1960: modpost] Error 2

The fix is to move all options before 'vmlinux.o' in modpost-args.

Fixes: 3d57e1b7 ("kbuild: refactor the prerequisites of the modpost rule")
Signed-off-by: NSamuel Holland <samuel@sholland.org>
Reviewed-by: NNathan Chancellor <nathan@kernel.org>
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
      63ffe00d
  3. 14 12月, 2022 2 次提交
  5. 22 11月, 2022 1 次提交
  7. 27 10月, 2022 1 次提交
  9. 14 10月, 2022 1 次提交
  11. 02 10月, 2022 1 次提交
  13. 29 9月, 2022 3 次提交
  15. 29 5月, 2022 1 次提交
    • M
      kbuild: do not create *.prelink.o for Clang LTO or IBT · c25e1c55
      由 Masahiro Yamada 提交于 
      When CONFIG_LTO_CLANG=y, additional intermediate *.prelink.o is created
for each module. Also, objtool is postponed until LLVM IR is converted
to ELF.

CONFIG_X86_KERNEL_IBT works in a similar way to postpone objtool until
objects are merged together.

This commit stops generating *.prelink.o, so the build flow will look
similar with/without LTO.

The following figures show how the LTO build currently works, and
how this commit is changing it.

Current build flow
==================

 [1] single-object module

                                      $(LD)
           $(CC)                     +objtool              $(LD)
    foo.c --------------------> foo.o -----> foo.prelink.o -----> foo.ko
                              (LLVM IR)          (ELF)       |    (ELF)
                                                             |
                                                 foo.mod.o --/
                                                 (LLVM IR)

 [2] multi-object module
                                      $(LD)
           $(CC)         $(AR)       +objtool               $(LD)
    foo1.c -----> foo1.o -----> foo.o -----> foo.prelink.o -----> foo.ko
                           |  (archive)          (ELF)       |    (ELF)
    foo2.c -----> foo2.o --/                                 |
                 (LLVM IR)                       foo.mod.o --/
                                                 (LLVM IR)

  One confusion is that foo.o in multi-object module is an archive
  despite of its suffix.

New build flow
==============

 [1] single-object module

  Since there is only one object, there is no need to keep the LLVM IR.
  Use $(CC)+$(LD) to generate an ELF object in one build rule. When LTO
  is disabled, $(LD) is unneeded because $(CC) produces an ELF object.

               $(CC)+$(LD)+objtool              $(LD)
    foo.c ----------------------------> foo.o ---------> foo.ko
                                        (ELF)     |      (ELF)
                                                  |
                                      foo.mod.o --/
                                      (LLVM IR)

 [2] multi-object module

  Previously, $(AR) was used to combine LLVM IR files into an archive,
  but there was no technical reason to do so. Use $(LD) to merge them
  into a single ELF object.

                               $(LD)
             $(CC)            +objtool          $(LD)
    foo1.c ---------> foo1.o ---------> foo.o ---------> foo.ko
                                 |      (ELF)     |      (ELF)
    foo2.c ---------> foo2.o ----/                |
                     (LLVM IR)        foo.mod.o --/
                                      (LLVM IR)
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: NNicolas Schier <nicolas@fjasle.eu>
Tested-by: NNathan Chancellor <nathan@kernel.org>
Reviewed-by: NSami Tolvanen <samitolvanen@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
Acked-by: NJosh Poimboeuf <jpoimboe@kernel.org>
      c25e1c55
  17. 27 5月, 2022 2 次提交
  19. 19 9月, 2021 1 次提交
  21. 03 9月, 2021 1 次提交
  23. 25 4月, 2021 3 次提交
    • M
      kbuild: fix false-positive modpost warning when all symbols are trimmed · 4475dff5
      由 Masahiro Yamada 提交于 
      Nathan reports that the mips defconfig emits the following warning:

  WARNING: modpost: Symbol info of vmlinux is missing. Unresolved symbol check will be entirely skipped.

This false-positive happens when CONFIG_TRIM_UNUSED_KSYMS is enabled,
but no CONFIG option is set to 'm'.

Commit a0590473 ("nfs: fix PNFS_FLEXFILE_LAYOUT Kconfig default")
turned the last 'm' into 'y' for the mips defconfig, and uncovered
this issue.

In this case, the module feature itself is enabled, but we have no
module to build. As a result, CONFIG_TRIM_UNUSED_KSYMS drops all the
instances of EXPORT_SYMBOL. Then, modpost wrongly assumes vmlinux is
missing because vmlinux.symvers is empty. (As another false-positive
case, you can create a module that does not use any symbol of vmlinux).

The current behavior is to entirely suppress the unresolved symbol
warnings when vmlinux is missing just because there are too many.
I found the origin of this code in the historical git tree. [1]

If this is a matter of noisiness, I think modpost can display the
first 10 warnings, and the number of suppressed warnings at the end.

You will get a bit noisier logs when you run 'make modules' without
vmlinux, but such warnings are better to show because you never know
the resulting modules are actually loadable or not.

This commit changes the following:

 - If any of input *.symver files is missing, pass -w option to let
   the module build keep going with warnings instead of errors.

 - If there are too many (10+) unresolved symbol warnings, show only
   the first 10, and also the number of suppressed warnings.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=1cc0e0529569bf6a94f6d49770aa6d4b599d2c46Reported-by: NNathan Chancellor <nathan@kernel.org>
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
      4475dff5
    • M
      kbuild: do not set -w for vmlinux.o modpost · 5ab70ff4
      由 Masahiro Yamada 提交于 
      The -w option is meaningless for the first pass of modpost (vmlinux.o).

We know there are unresolved symbols in vmlinux.o, hence we skip
check_exports() and other checks when mod->is_vmlinux is set.

See the following part in the for-loop.

    if (mod->is_vmlinux || mod->from_dump)
            continue;
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
      5ab70ff4
    • M
      kbuild: generate Module.symvers only when vmlinux exists · 69bc8d38
      由 Masahiro Yamada 提交于 
      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: NMasahiro Yamada <masahiroy@kernel.org>
      69bc8d38
  25. 15 3月, 2021 1 次提交
    • M
      kbuild: prefix $(srctree)/ to some included Makefiles · 3204a7fb
      由 Masahiro Yamada 提交于 
      VPATH is used in Kbuild to make pattern rules search for prerequisites
in both $(objtree) and $(srctree). Some of *.c, *.S files are not real
sources, but generated by tools such as flex, bison, perl.

In contrast, I doubt the benefit of --include-dir=$(abs_srctree) because
it is always clear which Makefiles are real sources, and which are not.

So, my hope is to add $(srctree)/ prefix to all check-in Makefiles,
then remove --include-dir=$(abs_srctree) flag in the future.

I am touching only some Kbuild core parts for now. Treewide fixes will
be needed to achieve this goal.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
      3204a7fb
  27. 15 1月, 2021 2 次提交
  29. 02 8月, 2020 1 次提交
  31. 06 6月, 2020 9 次提交
  33. 03 6月, 2020 3 次提交
    • M
      modpost: pass -N option only for modules modpost · 4e5ab74c
      由 Masahiro Yamada 提交于 
      The built-in only code is not required to have MODULE_IMPORT_NS() to
use symbols. So, the namespace is not checked for vmlinux(.o).

Do not pass the meaningless -N option to the first pass of modpost.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
      4e5ab74c
    • M
      modpost: move -T option close to the modpost command · 89d61176
      由 Masahiro Yamada 提交于 
      The '-T -' option reads the file list from stdin.

It is clearer to put it close to the piped command.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
      89d61176
    • M
      modpost: fix -i (--ignore-errors) MAKEFLAGS detection · 91e6ee58
      由 Masahiro Yamada 提交于 
      $(filter -i,$(MAKEFLAGS)) works only in limited use-cases.

The representation of $(MAKEFLAGS) depends on various factors:
  - GNU Make version (version 3.8x or version 4.x)
  - The presence of other flags like -j

In my experiments, $(MAKEFLAGS) is expanded as follows:

  * GNU Make 3.8x:

    * without -j option:
      --no-print-directory -Rri

    * with -j option:
      --no-print-directory -Rr --jobserver-fds=3,4 -j -i

  * GNU Make 4.x:

    * without -j option:
      irR --no-print-directory

    * with -j option:
      irR -j --jobserver-fds=3,4 --no-print-directory

For GNU Make 4.x, the flags are grouped as 'irR', which does not work.

For the single thread build with GNU Make 3.8x, the flags are grouped
as '-Rri', which does not work either.

To make it work for all cases, do likewise as commit 6f0fa58e
("kbuild: simplify silent build (-s) detection").

BTW, since commit ff9b45c5 ("kbuild: modpost: read modules.order
instead of $(MODVERDIR)/*.mod"), you also need to pass -k option to
build final *.ko files. 'make -i -k' ignores compile errors in modules,
and build as many remaining *.ko as possible.

Please note this feature is kind of dangerous if other modules depend
on the broken module because the generated modules will lack the correct
module dependency or CRC. Honestly, I am not a big fan of it, but I am
keeping this feature.

Fixes: eed380f3 ("modpost: Optionally ignore secondary errors seen if a single module build fails")
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
      91e6ee58
  35. 29 5月, 2020 1 次提交
    • M
      kbuild: disallow multi-word in M= or KBUILD_EXTMOD · e9e81b63
      由 Masahiro Yamada 提交于 
      $(firstword ...) in scripts/Makefile.modpost was added by commit
3f3fd3c0 ("[PATCH] kbuild: allow multi-word $M in Makefile.modpost")
to build multiple external module directories.

It was a solution to resolve symbol dependencies when an external
module depends on another external module.

Commit 0d96fb20 ("kbuild: Add new Kbuild variable
KBUILD_EXTRA_SYMBOLS") introduced another solution by passing symbol
info via KBUILD_EXTRA_SYMBOLS, then broke the multi-word M= support.

  include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
               $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)

... does not work if KBUILD_EXTMOD contains multiple words.

This feature has been broken for more than a decade. Remove the
bitrotten code, and stop parsing if M or KBUILD_EXTMOD contains
multiple words.

As Documentation/kbuild/modules.rst explains, if your module depends
on another one, there are two solutions:
  - add a common top-level Kbuild file
  - use KBUILD_EXTRA_SYMBOLS
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
      e9e81b63
  37. 13 3月, 2020 1 次提交
  39. 16 1月, 2020 1 次提交
  41. 11 11月, 2019 3 次提交