From c1177979af9c616661a126a80dd486ad0543b836 Mon Sep 17 00:00:00 2001
From: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Date: Wed, 11 Jan 2023 12:20:50 -0300
Subject: [PATCH] btf, scripts: Exclude Rust CUs with pahole
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.
Co-developed-by: Eric Curtin <ecurtin@redhat.com>
Signed-off-by: Eric Curtin <ecurtin@redhat.com>
Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Eric Curtin <ecurtin@redhat.com>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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]
Link: https://lore.kernel.org/bpf/20230111152050.559334-1-yakoyoku@gmail.com
---
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 7e5c3ddc341de..c93f19dd872e2 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1935,7 +1935,7 @@ 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 881c3f84e88a3..335411ebaa1e0 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -389,6 +389,15 @@ 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 0d99ef17e4a52..1f1f1d397c399 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}
--
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