kbuild: generate Module.symvers only when vmlinux exists

The external module build shows the following warning if Module.symvers
is missing in the kernel tree.

  WARNING: Symbol version dump "Module.symvers" is missing.
           Modules may not have dependencies or modversions.

I think this is an important heads-up because the resulting modules may
not work as expected. This happens when you did not build the entire
kernel tree, for example, you might have prepared the minimal setups
for external modules by 'make defconfig && make modules_preapre'.

A problem is that 'make modules' creates Module.symvers even without
vmlinux. In this case, that warning is suppressed since Module.symvers
already exists in spite of its incomplete content.

The incomplete (i.e. invalid) Module.symvers should not be created.

This commit changes the second pass of modpost to dump symbols into
modules-only.symvers. The final Module.symvers is created by
concatenating vmlinux.symvers and modules-only.symvers if both exist.

Module.symvers is supposed to collect symbols from both vmlinux and
modules. It might be a bit confusing, and I am not quite sure if it
is an official interface, but presumably it is difficult to rename it
because some tools (e.g. kmod) parse it.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

diff --git a/.gitignore b/.gitignore
index 3adea59847ce7e07facdc3c781cb223612d575ed..df8d3146a43fefae40f62384a9ce2d31d0690021 100644 (file)
--- a/.gitignore
+++ b/.gitignore
@@ -57,6 +57,7 @@ modules.order
 /tags
 /TAGS
 /linux
+/modules-only.symvers
 /vmlinux
 /vmlinux.32
 /vmlinux.map

diff --git a/Documentation/dontdiff b/Documentation/dontdiff
index ac42ad8d430d1239f8469254639bcd557555ee9b..910b30a2a7d98b89ce3b9bc6afb7a88aa7c8025c 100644 (file)
--- a/Documentation/dontdiff
+++ b/Documentation/dontdiff
@@ -178,6 +178,7 @@ mktables
 mktree
 mkutf8data
 modpost
+modules-only.symvers
 modules.builtin
 modules.builtin.modinfo
 modules.nsdeps

diff --git a/Makefile b/Makefile
index 2b161f5a5a66243429299818a4aa7c8c6e915921..ed8bd815e8a32ac14f4cbd5c8fbb78560b9c14cb 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -1532,7 +1532,7 @@ endif # CONFIG_MODULES
 # make distclean Remove editor backup files, patch leftover files and the like
 
 # Directories & files removed with 'make clean'
-CLEAN_FILES += include/ksym vmlinux.symvers \
+CLEAN_FILES += include/ksym vmlinux.symvers modules-only.symvers \
               modules.builtin modules.builtin.modinfo modules.nsdeps \
               compile_commands.json .thinlto-cache
 

diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index df57e259fac30e47663716bea95fe07c76213c25..3f5b09a09aef4066b6f0cabe7271113b4269f23a 100644 (file)
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -68,7 +68,20 @@ else
 ifeq ($(KBUILD_EXTMOD),)
 
 input-symdump := vmlinux.symvers
-output-symdump := Module.symvers
+output-symdump := modules-only.symvers
+
+quiet_cmd_cat = GEN     $@
+      cmd_cat = cat $(real-prereqs) > $@
+
+ifneq ($(wildcard vmlinux.symvers),)
+
+__modpost: Module.symvers
+Module.symvers: vmlinux.symvers modules-only.symvers FORCE
+       $(call if_changed,cat)
+
+targets += Module.symvers
+
+endif
 
 else
 

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 24725e50c7b4b181f2b5bce1c9e9fd4ca18774f1..10c3fba26f03a34a34cf140d90f8f7f0623a1eb3 100644 (file)
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2423,19 +2423,6 @@ fail:
        fatal("parse error in symbol dump file\n");
 }
 
-/* For normal builds always dump all symbols.
- * For external modules only dump symbols
- * that are not read from kernel Module.symvers.
- **/
-static int dump_sym(struct symbol *sym)
-{
-       if (!external_module)
-               return 1;
-       if (sym->module->from_dump)
-               return 0;
-       return 1;
-}
-
 static void write_dump(const char *fname)
 {
        struct buffer buf = { };
@@ -2446,7 +2433,7 @@ static void write_dump(const char *fname)
        for (n = 0; n < SYMBOL_HASH_SIZE ; n++) {
                symbol = symbolhash[n];
                while (symbol) {
-                       if (dump_sym(symbol)) {
+                       if (!symbol->module->from_dump) {
                                namespace = symbol->namespace;
                                buf_printf(&buf, "0x%08x\t%s\t%s\t%s\t%s\n",
                                           symbol->crc, symbol->name,