linux.git/scripts/Makefile.build, branch v6.1.168

kbuild: rust: avoid creating temporary files

2024-05-17T09:56:10+00:00

[ Upstream commit df01b7cfcef08bf3fdcac2909d0e1910781d6bfd ]

`rustc` outputs by default the temporary files (i.e. the ones saved
by `-Csave-temps`, such as `*.rcgu*` files) in the current working
directory when `-o` and `--out-dir` are not given (even if
`--emit=x=path` is given, i.e. it does not use those for temporaries).

Since out-of-tree modules are compiled from the `linux` tree,
`rustc` then tries to create them there, which may not be accessible.

Thus pass `--out-dir` explicitly, even if it is just for the temporary
files.

Similarly, do so for Rust host programs too.

Reported-by: Raphael Nestler 
Closes: https://github.com/Rust-for-Linux/linux/issues/1015
Reported-by: Andrea Righi 
Tested-by: Raphael Nestler  # non-hostprogs
Tested-by: Andrea Righi  # non-hostprogs
Fixes: 295d8398c67e ("kbuild: specify output names separately for each emission type from rustc")
Cc: stable@vger.kernel.org
Signed-off-by: Miguel Ojeda 
Tested-by: Martin Rodriguez Reboredo 
Signed-off-by: Masahiro Yamada 
Signed-off-by: Sasha Levin

kbuild: specify output names separately for each emission type from rustc

2024-05-17T09:55:53+00:00

[ Upstream commit 295d8398c67e314d99bb070f38883f83fe94a97a ]

In Kbuild, two different rules must not write to the same file, but
it happens when compiling rust source files.

For example, set CONFIG_SAMPLE_RUST_MINIMAL=m and run the following:

  $ make -j$(nproc) samples/rust/rust_minimal.o samples/rust/rust_minimal.rsi \
                    samples/rust/rust_minimal.s samples/rust/rust_minimal.ll
    [snip]
    RUSTC [M] samples/rust/rust_minimal.o
    RUSTC [M] samples/rust/rust_minimal.rsi
    RUSTC [M] samples/rust/rust_minimal.s
    RUSTC [M] samples/rust/rust_minimal.ll
  mv: cannot stat 'samples/rust/rust_minimal.d': No such file or directory
  make[3]: *** [scripts/Makefile.build:334: samples/rust/rust_minimal.ll] Error 1
  make[3]: *** Waiting for unfinished jobs....
  mv: cannot stat 'samples/rust/rust_minimal.d': No such file or directory
  make[3]: *** [scripts/Makefile.build:309: samples/rust/rust_minimal.o] Error 1
  mv: cannot stat 'samples/rust/rust_minimal.d': No such file or directory
  make[3]: *** [scripts/Makefile.build:326: samples/rust/rust_minimal.s] Error 1
  make[2]: *** [scripts/Makefile.build:504: samples/rust] Error 2
  make[1]: *** [scripts/Makefile.build:504: samples] Error 2
  make: *** [Makefile:2008: .] Error 2

The reason for the error is that 4 threads running in parallel renames
the same file, samples/rust/rust_minimal.d.

This does not happen when compiling C or assembly files because
-Wp,-MMD,$(depfile) explicitly specifies the dependency filepath.
$(depfile) is a unique path for each target.

Currently, rustc is only given --out-dir and --emit=
So, all the rust build rules output the dep-info into the default
.d, which causes the path conflict.

Fortunately, the --emit option is able to specify the output path
individually, with the form --emit==.

Add --emit=dep-info=$(depfile) to the common part. Also, remove the
redundant --out-dir because the output path is specified for each type.

The code gets much cleaner because we do not need to rename *.d files.

Signed-off-by: Masahiro Yamada 
Reviewed-by: Miguel Ojeda 
Tested-by: Miguel Ojeda 
Reviewed-by: Vincenzo Palazzo 
Stable-dep-of: ded103c7eb23 ("kbuild: rust: force `alloc` extern to allow "empty" Rust files")
Signed-off-by: Sasha Levin

kbuild: add -fno-discard-value-names to cmd_cc_ll_c

2022-10-14T20:22:29+00:00

When debugging LLVM IR, it can be handy for clang to not discard value
names used for local variables and parameters. Compare the generated IR.

-fdiscard-value-names:
  define i32 @core_sys_select(i32 %0, ptr %1, ptr %2, ptr %3, ptr %4) {
    %6 = alloca i64
    %7 = alloca %struct.poll_wqueues
    %8 = alloca [64 x i32]

-fno-discard-value-names:
  define i32 @core_sys_select(i32 %n, ptr %inp, ptr %outp, ptr %exp,
                              ptr %end_time) {
    %expire.i = alloca i64
    %table.i = alloca %struct.poll_wqueues
    %stack_fds = alloca [64 x i32]

The rule for generating human readable LLVM IR (.ll) is only useful as a
debugging feature:

$ make LLVM=1 fs/select.ll

As Fangrui notes:
  A LLVM_ENABLE_ASSERTIONS=off build of Clang defaults to
  -fdiscard-value-names.

  A LLVM_ENABLE_ASSERTIONS=on build of Clang defaults to
  -fno-discard-value-names.

Explicitly enable -fno-discard-value-names so that the IR always contains
value names regardless of whether assertions were enabled or not.
Assertions generally are not enabled in releases of clang packaged by
distributions.

Link: https://github.com/ClangBuiltLinux/linux/issues/1467
Reviewed-by: Nathan Chancellor 
Reviewed-by: Fangrui Song 
Signed-off-by: Nick Desaulniers 
Signed-off-by: Masahiro Yamada

Merge tag 'kbuild-v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2022-10-10T19:00:45+00:00

Pull Kbuild updates from Masahiro Yamada:

- Remove potentially incomplete targets when Kbuid is interrupted by
SIGINT etc in case GNU Make may miss to do that when stderr is piped
to another program.

- Rewrite the single target build so it works more correctly.

- Fix rpm-pkg builds with V=1.

- List top-level subdirectories in ./Kbuild.

- Ignore auto-generated __kstrtab_* and __kstrtabns_* symbols in
kallsyms.

- Avoid two different modules in lib/zstd/ having shared code, which
potentially causes building the common code as build-in and modular
back-and-forth.

- Unify two modpost invocations to optimize the build process.

- Remove head-y syntax in favor of linker scripts for placing
particular sections in the head of vmlinux.

- Bump the minimal GNU Make version to 3.82.

- Clean up misc Makefiles and scripts.

* tag 'kbuild-v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (41 commits)
docs: bump minimal GNU Make version to 3.82
ia64: simplify esi object addition in Makefile
Revert "kbuild: Check if linker supports the -X option"
kbuild: rebuild .vmlinux.export.o when its prerequisite is updated
kbuild: move modules.builtin(.modinfo) rules to Makefile.vmlinux_o
zstd: Fixing mixed module-builtin objects
kallsyms: ignore __kstrtab_* and __kstrtabns_* symbols
kallsyms: take the input file instead of reading stdin
kallsyms: drop duplicated ignore patterns from kallsyms.c
kbuild: reuse mksysmap output for kallsyms
mksysmap: update comment about __crc_*
kbuild: remove head-y syntax
kbuild: use obj-y instead extra-y for objects placed at the head
kbuild: hide error checker logs for V=1 builds
kbuild: re-run modpost when it is updated
kbuild: unify two modpost invocations
kbuild: move vmlinux.o rule to the top Makefile
kbuild: move .vmlinux.objs rule to Makefile.modpost
kbuild: list sub-directories in ./Kbuild
Makefile.compiler: replace cc-ifversion with compiler-specific macros
...

kbuild: fix and refactor single target build

2022-09-28T19:40:15+00:00

The single target build has a subtle bug for the combination for
an individual file and a subdirectory.

[1] 'make kernel/fork.i' builds only kernel/fork.i

  $ make kernel/fork.i
    CALL    scripts/checksyscalls.sh
    DESCEND objtool
    CPP     kernel/fork.i

[2] 'make kernel/' builds only under the kernel/ directory.

  $ make kernel/
    CALL    scripts/checksyscalls.sh
    DESCEND objtool
    CC      kernel/fork.o
    CC      kernel/exec_domain.o
       [snip]
    CC      kernel/rseq.o
    AR      kernel/built-in.a

But, if you try to do [1] and [2] in a single command, you will get
only [1] with a weird log:

  $ make kernel/fork.i kernel/
    CALL    scripts/checksyscalls.sh
    DESCEND objtool
    CPP     kernel/fork.i
  make[2]: Nothing to be done for 'kernel/'.

With 'make kernel/fork.i kernel/', you should get both [1] and [2].

Rewrite the single target build.

Signed-off-by: Masahiro Yamada

kbuild: do not deduplicate modules.order

2022-09-28T19:40:14+00:00

The AWK code was added to deduplicate modules.order in case $(obj-m)
contains the same module multiple times, but it is actually unneeded
since commit b2c885549122 ("kbuild: update modules.order only when
contained modules are updated").

The list is already deduplicated before being processed by AWK because
$^ is the deduplicated list of prerequisites.
(Please note the real-prereqs macro uses $^)

Yet, modules.order will contain duplication if two different Makefiles
build the same module:

  foo/Makefile:

      obj-m += bar/baz.o

  foo/bar/Makefile:

      obj-m += baz.o

However, the parallel builds cannot properly handle this case in the
first place. So, it is better to let it fail (as already done by
scripts/modules-check.sh).

Signed-off-by: Masahiro Yamada

Kbuild: add Rust support

2022-09-28T07:02:20+00:00

Having most of the new files in place, we now enable Rust support
in the build system, including `Kconfig` entries related to Rust,
the Rust configuration printer and a few other bits.

Reviewed-by: Kees Cook 
Reviewed-by: Nick Desaulniers 
Tested-by: Nick Desaulniers 
Reviewed-by: Greg Kroah-Hartman 
Co-developed-by: Alex Gaynor 
Signed-off-by: Alex Gaynor 
Co-developed-by: Finn Behrens 
Signed-off-by: Finn Behrens 
Co-developed-by: Adam Bratschi-Kaye 
Signed-off-by: Adam Bratschi-Kaye 
Co-developed-by: Wedson Almeida Filho 
Signed-off-by: Wedson Almeida Filho 
Co-developed-by: Michael Ellerman 
Signed-off-by: Michael Ellerman 
Co-developed-by: Sven Van Asbroeck 
Signed-off-by: Sven Van Asbroeck 
Co-developed-by: Gary Guo 
Signed-off-by: Gary Guo 
Co-developed-by: Boris-Chengbiao Zhou 
Signed-off-by: Boris-Chengbiao Zhou 
Co-developed-by: Boqun Feng 
Signed-off-by: Boqun Feng 
Co-developed-by: Douglas Su 
Signed-off-by: Douglas Su 
Co-developed-by: Dariusz Sosnowski 
Signed-off-by: Dariusz Sosnowski 
Co-developed-by: Antonio Terceiro 
Signed-off-by: Antonio Terceiro 
Co-developed-by: Daniel Xu 
Signed-off-by: Daniel Xu 
Co-developed-by: Björn Roy Baron 
Signed-off-by: Björn Roy Baron 
Co-developed-by: Martin Rodriguez Reboredo 
Signed-off-by: Martin Rodriguez Reboredo 
Signed-off-by: Miguel Ojeda

kbuild: remove sed command from cmd_ar_builtin

2022-07-27T12:17:59+00:00

Replace a pipeline of echo and sed with printf to decrease process forks.

Signed-off-by: Masahiro Yamada 
Reviewed-by: Nick Desaulniers

kbuild: avoid regex RS for POSIX awk

2022-06-07T16:27:26+00:00

In 22f26f21774f8 awk was added to deduplicate *.mod files.  The awk
invocation passes -v RS='( |\n)' to match a space or newline character
as the record separator.  Unfortunately, POSIX states[1]

> If RS contains more than one character, the results are unspecified.

Some implementations (such as the One True Awk[2] used by the BSDs) do
not treat RS as a regular expression.  When awk does not support regex
RS, build failures such as the following are produced (first error using
allmodconfig):

      CC [M]  arch/x86/events/intel/uncore.o
      CC [M]  arch/x86/events/intel/uncore_nhmex.o
      CC [M]  arch/x86/events/intel/uncore_snb.o
      CC [M]  arch/x86/events/intel/uncore_snbep.o
      CC [M]  arch/x86/events/intel/uncore_discovery.o
      LD [M]  arch/x86/events/intel/intel-uncore.o
    ld: cannot find uncore_nhmex.o: No such file or directory
    ld: cannot find uncore_snb.o: No such file or directory
    ld: cannot find uncore_snbep.o: No such file or directory
    ld: cannot find uncore_discovery.o: No such file or directory
    make[3]: *** [scripts/Makefile.build:422: arch/x86/events/intel/intel-uncore.o] Error 1
    make[2]: *** [scripts/Makefile.build:487: arch/x86/events/intel] Error 2
    make[1]: *** [scripts/Makefile.build:487: arch/x86/events] Error 2
    make: *** [Makefile:1839: arch/x86] Error 2

To avoid this, use printf(1) to produce a newline between each object
path, instead of the space produced by echo(1), so that the default RS
can be used by awk.

[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/awk.html
[2]: https://github.com/onetrueawk/awk

Fixes: 22f26f21774f ("kbuild: get rid of duplication in *.mod files")
Signed-off-by: Kevin Locke 
Signed-off-by: Masahiro Yamada

kbuild: factor out the common objtool arguments

2022-06-04T21:20:57+00:00

scripts/Makefile.build and scripts/link-vmlinux.sh have similar setups
for the objtool arguments.

It was difficult to factor out them because all the vmlinux build rules
were written in a shell script. It is somewhat tedious to touch the two
files every time a new objtool option is supported.

To reduce the code duplication, move the objtool for vmlinux.o into
scripts/Makefile.vmlinux_o. Then, move the common macros to Makefile.lib
so they are shared between Makefile.build and Makefile.vmlinux_o.

Signed-off-by: Masahiro Yamada 
Tested-by: Sedat Dilek  # LLVM-14 (x86-64)