On Wed, 11 Jan 2023 at 15:21, Martin Rodriguez Reboredo <yakoyoku@xxxxxxxxx> wrote: > > Version 1.24 of pahole has the capability to exclude compilation units > (CUs) of specific languages [1] [2]. Rust, as of writing, is not > currently supported by pahole and if it's used with a build that has > BTF debugging enabled it results in malformed kernel and module > binaries [3]. So it's better for pahole to exclude Rust CUs until > support for it arrives. > > Link: https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=49358dfe2aaae4e90b072332c3e324019826783f [1] > Link: https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=8ee363790b7437283c53090a85a9fec2f0b0fbc4 [2] > Link: https://github.com/Rust-for-Linux/linux/issues/735 [3] > > Co-developed-by: Eric Curtin <ecurtin@xxxxxxxxxx> > Signed-off-by: Eric Curtin <ecurtin@xxxxxxxxxx> > Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@xxxxxxxxx> I think this should be able to cover all the quirky build techniques. Tested-by: Eric Curtin <ecurtin@xxxxxxxxxx> > --- > V2 -> V3: Enable pahole option upon comparing with version 1.24 > V1 -> V2: Removed dependency on auto.conf > > init/Kconfig | 2 +- > lib/Kconfig.debug | 9 +++++++++ > scripts/pahole-flags.sh | 4 ++++ > 3 files changed, 14 insertions(+), 1 deletion(-) > > diff --git a/init/Kconfig b/init/Kconfig > index 694f7c160c9c..360aef8d7292 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1913,7 +1913,7 @@ config RUST > depends on !MODVERSIONS > depends on !GCC_PLUGINS > depends on !RANDSTRUCT > - depends on !DEBUG_INFO_BTF > + depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE > select CONSTRUCTORS > help > Enables Rust support in the kernel. > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index ea4c903c9868..d473d491e709 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -364,6 +364,15 @@ config PAHOLE_HAS_BTF_TAG > btf_decl_tag) or not. Currently only clang compiler implements > these attributes, so make the config depend on CC_IS_CLANG. > > +config PAHOLE_HAS_LANG_EXCLUDE > + def_bool PAHOLE_VERSION >= 124 > + help > + Support for the --lang_exclude flag which makes pahole exclude > + compilation units from the supplied language. Used in Kbuild to > + omit Rust CUs which are not supported in version 1.24 of pahole, > + otherwise it would emit malformed kernel and module binaries when > + using DEBUG_INFO_BTF_MODULES. > + > config DEBUG_INFO_BTF_MODULES > def_bool y > depends on DEBUG_INFO_BTF && MODULES && PAHOLE_HAS_SPLIT_BTF > diff --git a/scripts/pahole-flags.sh b/scripts/pahole-flags.sh > index 0d99ef17e4a5..1f1f1d397c39 100755 > --- a/scripts/pahole-flags.sh > +++ b/scripts/pahole-flags.sh > @@ -19,5 +19,9 @@ fi > if [ "${pahole_ver}" -ge "122" ]; then > extra_paholeopt="${extra_paholeopt} -j" > fi > +if [ "${pahole_ver}" -ge "124" ]; then > + # see PAHOLE_HAS_LANG_EXCLUDE > + extra_paholeopt="${extra_paholeopt} --lang_exclude=rust" > +fi > > echo ${extra_paholeopt} > -- > 2.39.0 >
