linux-toradex.git/scripts/mod/modpost.h, branch v6.11-rc5

kbuild: move some helper headers from scripts/kconfig/ to scripts/include/

2024-07-21T14:10:43+00:00

Move array_size.h, hashtable.h, list.h, list_types.h from scripts/kconfig/
to scripts/include/.

These headers will be useful for other host programs.

Remove scripts/mod/list.h.

Signed-off-by: Masahiro Yamada

modpost: avoid using the alias attribute

2024-01-31T14:24:27+00:00

Aiden Leong reported modpost fails to build on macOS since commit
16a473f60edc ("modpost: inform compilers that fatal() never returns"):

  scripts/mod/modpost.c:93:21: error: aliases are not supported on darwin

Nathan's research indicates that Darwin seems to support weak aliases
at least [1]. Although the situation might be improved in future Clang
versions, we can achieve a similar outcome without relying on it.

This commit makes fatal() a macro of error() + exit(1) in modpost.h, as
compilers recognize that exit() never returns.

[1]: https://github.com/llvm/llvm-project/issues/71001

Fixes: 16a473f60edc ("modpost: inform compilers that fatal() never returns")
Reported-by: Aiden Leong 
Closes: https://lore.kernel.org/all/d9ac2960-6644-4a87-b5e4-4bfb6e0364a8@aibsd.com/
Signed-off-by: Masahiro Yamada

modpost: inform compilers that fatal() never returns

2023-12-10T06:34:37+00:00

The function fatal() never returns because modpost_log() calls exit(1)
when LOG_FATAL is passed.

Inform compilers of this fact so that unreachable code flow can be
identified at compile time.

Signed-off-by: Masahiro Yamada 
Reviewed-by: Nathan Chancellor

modpost: move attribute((format(printf, 2, 3))) to modpost.h

2023-12-10T06:34:37+00:00

This attribute must be added to the function declaration in a header
for comprehensive checking of all the callsites.

Fixes: 6d9a89ea4b06 ("kbuild: declare the modpost error functions as printf like")
Signed-off-by: Masahiro Yamada 
Reviewed-by: Nathan Chancellor

Merge tag 'kbuild-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2023-11-04T18:07:19+00:00

Pull Kbuild updates from Masahiro Yamada:

 - Implement the binary search in modpost for faster symbol lookup

 - Respect HOSTCC when linking host programs written in Rust

 - Change the binrpm-pkg target to generate kernel-devel RPM package

 - Fix endianness issues for tee and ishtp MODULE_DEVICE_TABLE

 - Unify vdso_install rules

 - Remove unused __memexit* annotations

 - Eliminate stale whitelisting for __devinit/__devexit from modpost

 - Enable dummy-tools to handle the -fpatchable-function-entry flag

 - Add 'userldlibs' syntax

* tag 'kbuild-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits)
  kbuild: support 'userldlibs' syntax
  kbuild: dummy-tools: pretend we understand -fpatchable-function-entry
  kbuild: Correct missing architecture-specific hyphens
  modpost: squash ALL_{INIT,EXIT}_TEXT_SECTIONS to ALL_TEXT_SECTIONS
  modpost: merge sectioncheck table entries regarding init/exit sections
  modpost: use ALL_INIT_SECTIONS for the section check from DATA_SECTIONS
  modpost: disallow the combination of EXPORT_SYMBOL and __meminit*
  modpost: remove EXIT_SECTIONS macro
  modpost: remove MEM_INIT_SECTIONS macro
  modpost: remove more symbol patterns from the section check whitelist
  modpost: disallow *driver to reference .meminit* sections
  linux/init: remove __memexit* annotations
  modpost: remove ALL_EXIT_DATA_SECTIONS macro
  kbuild: simplify cmd_ld_multi_m
  kbuild: avoid too many execution of scripts/pahole-flags.sh
  kbuild: remove ARCH_POSTLINK from module builds
  kbuild: unify no-compiler-targets and no-sync-config-targets
  kbuild: unify vdso_install rules
  docs: kbuild: add INSTALL_DTBS_PATH
  UML: remove unused cmd_vdso_install
  ...

modpost: define TO_NATIVE() using bswap_* functions

2023-10-18T08:16:09+00:00

The current TO_NATIVE() has some limitations:

 1) You cannot cast the argument.

 2) You cannot pass a variable marked as 'const'.

 3) Passing an array is a bug, but it is not detected.

Impelement TO_NATIVE() using bswap_*() functions. These are GNU
extensions. If we face portability issues, we can port the code from
include/uapi/linux/swab.h.

With this change, get_rel_type_and_sym() can be simplified by casting
the arguments directly.

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

modpost: Optimize symbol search from linear to binary search

2023-10-03T11:25:59+00:00

Modify modpost to use binary search for converting addresses back
into symbol references.  Previously it used linear search.

This change saves a few seconds of wall time for defconfig builds,
but can save several minutes on allyesconfigs.

Before:
$ make LLVM=1 -j128 allyesconfig vmlinux -s KCFLAGS="-Wno-error"
$ time scripts/mod/modpost -M -m -a -N -o vmlinux.symvers vmlinux.o
198.38user 1.27system 3:19.71elapsed

After:
$ make LLVM=1 -j128 allyesconfig vmlinux -s KCFLAGS="-Wno-error"
$ time scripts/mod/modpost -M -m -a -N -o vmlinux.symvers vmlinux.o
11.91user 0.85system 0:12.78elapsed

Signed-off-by: Jack Brennen 
Tested-by: Nick Desaulniers 
Signed-off-by: Masahiro Yamada

modpost: clean up MIPS64 little endian relocation code

2023-07-31T14:42:14+00:00

MIPS64 little endian target has an odd encoding of r_info.

This commit makes the special handling less ugly. It is still ugly,
but #if conditionals will go away, at least.

Signed-off-by: Masahiro Yamada

kbuild: generate KSYMTAB entries by modpost

2023-06-22T12:17:10+00:00

Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing
CONFIG_MODULE_REL_CRCS") made modpost output CRCs in the same way
whether the EXPORT_SYMBOL() is placed in *.c or *.S.

For further cleanups, this commit applies a similar approach to the
entire data structure of EXPORT_SYMBOL().

The EXPORT_SYMBOL() compilation is split into two stages.

When a source file is compiled, EXPORT_SYMBOL() will be converted into
a dummy symbol in the .export_symbol section.

For example,

    EXPORT_SYMBOL(foo);
    EXPORT_SYMBOL_NS_GPL(bar, BAR_NAMESPACE);

will be encoded into the following assembly code:

    .section ".export_symbol","a"
    __export_symbol_foo:
            .asciz ""                      /* license */
            .asciz ""                      /* name space */
            .balign 8
            .quad foo                      /* symbol reference */
    .previous

    .section ".export_symbol","a"
    __export_symbol_bar:
            .asciz "GPL"                   /* license */
            .asciz "BAR_NAMESPACE"         /* name space */
            .balign 8
            .quad bar                      /* symbol reference */
    .previous

They are mere markers to tell modpost the name, license, and namespace
of the symbols. They will be dropped from the final vmlinux and modules
because the *(.export_symbol) will go into /DISCARD/ in the linker script.

Then, modpost extracts all the information about EXPORT_SYMBOL() from the
.export_symbol section, and generates the final C code:

    KSYMTAB_FUNC(foo, "", "");
    KSYMTAB_FUNC(bar, "_gpl", "BAR_NAMESPACE");

KSYMTAB_FUNC() (or KSYMTAB_DATA() if it is data) is expanded to struct
kernel_symbol that will be linked to the vmlinux or a module.

With this change, EXPORT_SYMBOL() works in the same way for *.c and *.S
files, providing the following benefits.

[1] Deprecate EXPORT_DATA_SYMBOL()

In the old days, EXPORT_SYMBOL() was only available in C files. To export
a symbol in *.S, EXPORT_SYMBOL() was placed in a separate *.c file.
arch/arm/kernel/armksyms.c is one example written in the classic manner.

Commit 22823ab419d8 ("EXPORT_SYMBOL() for asm") removed this limitation.
Since then, EXPORT_SYMBOL() can be placed close to the symbol definition
in *.S files. It was a nice improvement.

However, as that commit mentioned, you need to use EXPORT_DATA_SYMBOL()
for data objects on some architectures.

In the new approach, modpost checks symbol's type (STT_FUNC or not),
and outputs KSYMTAB_FUNC() or KSYMTAB_DATA() accordingly.

There are only two users of EXPORT_DATA_SYMBOL:

  EXPORT_DATA_SYMBOL_GPL(empty_zero_page)    (arch/ia64/kernel/head.S)
  EXPORT_DATA_SYMBOL(ia64_ivt)               (arch/ia64/kernel/ivt.S)

They are transformed as follows and output into .vmlinux.export.c

  KSYMTAB_DATA(empty_zero_page, "_gpl", "");
  KSYMTAB_DATA(ia64_ivt, "", "");

The other EXPORT_SYMBOL users in ia64 assembly are output as
KSYMTAB_FUNC().

EXPORT_DATA_SYMBOL() is now deprecated.

[2] merge  and 

There are two similar header implementations:

  include/linux/export.h        for .c files
  include/asm-generic/export.h  for .S files

Ideally, the functionality should be consistent between them, but they
tend to diverge.

Commit 8651ec01daed ("module: add support for symbol namespaces.") did
not support the namespace for *.S files.

This commit shifts the essential implementation part to C, which supports
EXPORT_SYMBOL_NS() for *.S files.

 and  will remain as a wrapper of
 for a while.

They will be removed after #include  directives are all
replaced with #include .

[3] Implement CONFIG_TRIM_UNUSED_KSYMS in one-pass algorithm (by a later commit)

When CONFIG_TRIM_UNUSED_KSYMS is enabled, Kbuild recursively traverses
the directory tree to determine which EXPORT_SYMBOL to trim. If an
EXPORT_SYMBOL turns out to be unused by anyone, Kbuild begins the
second traverse, where some source files are recompiled with their
EXPORT_SYMBOL() tuned into a no-op.

We can do this better now; modpost can selectively emit KSYMTAB entries
that are really used by modules.

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

modpost: remove is_shndx_special() check from section_rel(a)

2023-05-28T11:35:16+00:00

This check is unneeded. Without it, sec_name() will returns the null
string "", then section_mismatch() will return immediately.

Anyway, special section indices rarely appear in these loops.

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