On 1/11/23 4:20 PM, Martin Rodriguez Reboredo 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>
---
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}
I presume Miguel will pick this up via rust tree? (Either way, would be nice to
also get an Ack from Arnaldo.)
Thanks,
Daniel
