Version 1.24 of pahole has the capability to exclude compilation units
(CUs) of specific languages. 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 (see
Rust-for-Linux/linux#735). So it's better for pahole to exclude Rust
CUs until support for it arrives.
Reviewed-by: Eric Curtin <ecurtin@xxxxxxxxxx>
Tested-by: Eric Curtin <ecurtin@xxxxxxxxxx>
Reviewed-by: Neal Gompa <neal@xxxxxxxxx>
Tested-by: Neal Gompa <neal@xxxxxxxxx>
Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@xxxxxxxxx>
---
init/Kconfig | 2 +-
lib/Kconfig.debug | 9 +++++++++
scripts/pahole-flags.sh | 8 ++++++++
3 files changed, 18 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..1071d2cd9b28 100755
--- a/scripts/pahole-flags.sh
+++ b/scripts/pahole-flags.sh
@@ -9,6 +9,10 @@ fi
pahole_ver=$($(dirname $0)/pahole-version.sh ${PAHOLE})
+is_enabled() {
+ grep -q "^$1=y" include/config/auto.conf
+}
+
if [ "${pahole_ver}" -ge "118" ] && [ "${pahole_ver}" -le "121" ]; then
# pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars
extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_vars"
@@ -19,5 +23,9 @@ fi
if [ "${pahole_ver}" -ge "122" ]; then
extra_paholeopt="${extra_paholeopt} -j"
fi
+if is_enabled CONFIG_RUST; then
+ # see PAHOLE_HAS_LANG_EXCLUDE
+ extra_paholeopt="${extra_paholeopt} --lang_exclude=rust"
+fi
echo ${extra_paholeopt}
--
2.39.0
