module: zstd: check we don't leak symbols; regenerate symbol map

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Rich Ercolani <rincebrain@gmail.com>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes openzfs#12988 
Closes openzfs#13209

Makefile.am

@@ -103,7 +103,7 @@ endif
 endif
 
 PHONY += codecheck
-codecheck: cstyle shellcheck checkbashisms flake8 mancheck testscheck vcscheck
+codecheck: cstyle shellcheck checkbashisms flake8 mancheck testscheck vcscheck zstdcheck
 
 PHONY += checkstyle
 checkstyle: codecheck commitcheck
@@ -125,6 +125,7 @@ cstyle:
 		-o -type f -name '*.[hc]' \
 		! -name 'zfs_config.*' ! -name '*.mod.c' \
 		! -name 'opt_global.h' ! -name '*_if*.h' \
+		! -name 'zstd_compat_wrapper.h' \
 		! -path './module/zstd/lib/*' \
 		! -path './include/sys/lua/*' \
 		! -path './module/lua/l*.[ch]' \
@@ -164,6 +165,10 @@ vcscheck:
 		awk '{c++; print} END {if(c>0) exit 1}' ; \
 	fi
 
+PHONY += zstdcheck
+zstdcheck:
+	@$(MAKE) -C module/zstd checksymbols
+
 PHONY += lint
 lint: cppcheck paxcheck
 

module/zstd/Makefile.in

@@ -62,3 +62,8 @@ $(MODULE)-objs += $(vanilla-objs)
 all:
 	mkdir -p lib/common lib/compress lib/decompress
 
+gensymbols:
+	for obj in $(vanilla-objs); do echo; echo "/* $$obj: */"; @OBJDUMP@ -t $$obj | awk '$$2 == "g" && !/ zfs_/ {print "#define\t" $$6 " zfs_" $$6}' | sort; done >> include/zstd_compat_wrapper.h
+
+checksymbols:
+	@OBJDUMP@ -t $(vanilla-objs) | awk '/file format/ {print}  $$2 == "g" && !/ zfs_/ {++ret; print}  END {exit ret}'