Hi Masahiro,
On Fri, Jan 10, 2025 at 6:26 PM Masahiro Yamada <masahi...@kernel.org> wrote:
>
> On Sat, Jan 4, 2025 at 2:37 AM Matthew Maurer <mmau...@google.com> wrote:
> >
> > From: Sami Tolvanen <samitolva...@google.com>
> >
> > Previously, two things stopped Rust from using MODVERSIONS:
> > 1. Rust symbols are occasionally too long to be represented in the
> > original versions table
> > 2. Rust types cannot be properly hashed by the existing genksyms
> > approach because:
> > * Looking up type definitions in Rust is more complex than C
> > * Type layout is potentially dependent on the compiler in Rust,
> > not just the source type declaration.
> >
> > CONFIG_EXTENDED_MODVERSIONS addresses the first point, and
> > CONFIG_GENDWARFKSYMS the second. If Rust wants to use MODVERSIONS, allow
> > it to do so by selecting both features.
> >
> > Signed-off-by: Sami Tolvanen <samitolva...@google.com>
> > Co-developed-by: Matthew Maurer <mmau...@google.com>
> > Signed-off-by: Matthew Maurer <mmau...@google.com>
> > ---
> > init/Kconfig | 3 ++-
> > rust/Makefile | 34 ++++++++++++++++++++++++++++++++--
> > 2 files changed, 34 insertions(+), 3 deletions(-)
> >
> > diff --git a/init/Kconfig b/init/Kconfig
> > index
> > c1f9eb3d5f2e892e977ba1425599502dc830f552..b60acfd9431e0ac2bf401ecb6523b5104ad31150
> > 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -1959,7 +1959,8 @@ config RUST
> > bool "Rust support"
> > depends on HAVE_RUST
> > depends on RUST_IS_AVAILABLE
> > - depends on !MODVERSIONS
> > + select EXTENDED_MODVERSIONS if MODVERSIONS
> > + depends on !MODVERSIONS || GENDWARFKSYMS
> > depends on !GCC_PLUGIN_RANDSTRUCT
> > depends on !RANDSTRUCT
> > depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
> > diff --git a/rust/Makefile b/rust/Makefile
> > index
> > a40a3936126d603836e0ec9b42a1285916b60e45..80f970ad81f7989afe5ff2b5f633f50feb7f6006
> > 100644
> > --- a/rust/Makefile
> > +++ b/rust/Makefile
> > @@ -329,10 +329,11 @@ $(obj)/bindings/bindings_helpers_generated.rs:
> > private bindgen_target_extra = ;
> > $(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers/helpers.c
> > FORCE
> > $(call if_changed_dep,bindgen)
> >
> > +rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ &&
> > $$3!~/__cfi/ { printf $(2),$(3) }'
> > +
> > quiet_cmd_exports = EXPORTS $@
> > cmd_exports = \
> > - $(NM) -p --defined-only $< \
> > - | awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ {printf
> > "EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3}' > $@
> > + $(call rust_exports,$<,"EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3) > $@
>
> I noticed a nit:
>
> Both of the two callsites of rust_exports pass
> '$$3' to the last parameter instead of hardcoding it.
>
> Is it a flexibility for future extensions?
>
> I cannot think of any other use except for printing
> the third column, i.e. symbol name.
Good catch, the last parameter isn't necessary anymore. It was used in
early versions of the series to also pass symbol addresses to
gendwarfksyms, but that's not needed since we read the symbol table
directly now.
Sami
