[PATCH bpf-next] bpf: Add config for skipping BTF enum64s

[Martin Reboredo <yakoyoku@gmail.com>]

From: Martin Rodriguez Reboredo <yakoyoku@gmail.com>

After the release of pahole 1.24 some people in the dwarves mailing list
notified issues related to building the kernel with the BTF_DEBUG_INFO
option toggled. They seem to be happenning due to the kernel and
resolve_btfids interpreting btf types erroneously. In the dwarves list
I've proposed a change to the scripts that I've written while testing
the Rust kernel, it simply passes the --skip_encoding_btf_enum64 to
pahole if it has version 1.24, but it might be desirable to have the
option to pass said flag.

Signed-off-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
---
 lib/Kconfig.debug       | 14 ++++++++++++++
 scripts/pahole-flags.sh |  7 +++++++
 2 files changed, 21 insertions(+)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 072e4b289c13..638a33cf9e57 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -356,6 +356,20 @@ 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_SKIP_ENCODING_BTF_ENUM64
+	def_bool PAHOLE_VERSION >= 124
+	help
+	  Encoding BTF enum64s can be skipped with the
+	  --skip_encoding_btf_enum64 pahole option.
+
+config DEBUG_INFO_BTF_SKIP_ENCODING_ENUM64
+	def_bool n
+	depends on DEBUG_INFO_BTF && PAHOLE_HAS_SKIP_ENCODING_BTF_ENUM64
+	help
+	  Omit the encoding of 64 bits enum values with pahole. With certain
+	  kernel configurations having ENUM64s enabled may result in malformed
+	  output binaries.
+
 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..e44bc2a947ce 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 +23,8 @@ fi
 if [ "${pahole_ver}" -ge "122" ]; then
 	extra_paholeopt="${extra_paholeopt} -j"
 fi
+if is_enabled DEBUG_INFO_BTF_SKIP_ENCODING_ENUM64; then
+	extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_enum64"
+fi
 
 echo ${extra_paholeopt}
-- 
2.37.2