Merge pull request torvalds#491 from danobi/disable_btf_rust

rust: bpf: Disable BTF generation for modules written in Rust

Author: ojeda

scripts/Makefile.modfinal

@@ -39,10 +39,12 @@ quiet_cmd_ld_ko_o = LD [M]  $@
 
 quiet_cmd_btf_ko = BTF [M] $@
       cmd_btf_ko = 							\
-	if [ -f vmlinux ]; then						\
-		LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J --btf_base vmlinux $@; \
-	else								\
+	if [ ! -f vmlinux ]; then					\
 		printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \
+	elif $(srctree)/scripts/is_rust_module.sh $@; then 		\
+		printf "Skipping BTF generation for %s because it's a Rust module\n" $@ 1>&2; \
+	else								\
+		LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J --btf_base vmlinux $@; \
 	fi;
 
 # Same as newer-prereqs, but allows to exclude specified extra dependencies

scripts/is_rust_module.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# is_rust_module.sh MOD.ko
+#
+# Returns 0 if MOD.ko is a rust module, 1 otherwise.
+
+set -e
+module="$*"
+
+while IFS= read -r line
+do
+  # Any symbol beginning with "_R" is a v0 mangled rust symbol
+  if [[ $line =~ ^[0-9a-fA-F]+[[:space:]]+[uUtTrR][[:space:]]+_R[^[:space:]]+$ ]]; then
+    exit 0
+  fi
+done < <(nm "$module")
+
+exit 1