module: make MODULE_SYMBOL_PREFIX into a CONFIG option

The next commit will require the use of MODULE_SYMBOL_PREFIX in
.tmp_exports-asm.S.  Currently it is mixed in with C structure
definitions in "asm/module.h".  Move the definition of this arch option
into Kconfig, so it can be easily accessed by any code.

This also lets modpost.c use the same definition.  Previously modpost
relied on a hardcoded list of architectures in mk_elfconfig.c.

A build test for blackfin, one of the two MODULE_SYMBOL_PREFIX archs,
showed the generated code was unchanged.  vmlinux was identical save
for build ids, and an apparently randomized suffix on a single "__key"
symbol in the kallsyms data).

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Acked-by: Mike Frysinger <vapier@gentoo.org> (blackfin)
CC: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

4 files changed, 15 insertions, 10 deletions

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index ffdafb26f539..224d85e72ef1 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -127,6 +127,11 @@ _c_flags += $(if $(patsubst n%,, \
                 $(CFLAGS_GCOV))
 endif
 
+ifdef CONFIG_SYMBOL_PREFIX
+_cpp_flags += -DSYMBOL_PREFIX=$(patsubst "%",%,$(CONFIG_SYMBOL_PREFIX))
+endif
+
+
 # If building the kernel in a separate objtree expand all occurrences
 # of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/').
 
diff --git a/scripts/mod/Makefile b/scripts/mod/Makefile
index 11d69c35e5b4..ff954f8168c1 100644
--- a/scripts/mod/Makefile
+++ b/scripts/mod/Makefile
@@ -8,7 +8,7 @@ modpost-objs	:= modpost.o file2alias.o sumversion.o
 $(obj)/modpost.o $(obj)/file2alias.o $(obj)/sumversion.o: $(obj)/elfconfig.h
 
 quiet_cmd_elfconfig = MKELF   $@
-      cmd_elfconfig = $(obj)/mk_elfconfig $(ARCH) < $< > $@
+      cmd_elfconfig = $(obj)/mk_elfconfig < $< > $@
 
 $(obj)/elfconfig.h: $(obj)/empty.o $(obj)/mk_elfconfig FORCE
         $(call if_changed,elfconfig)
diff --git a/scripts/mod/mk_elfconfig.c b/scripts/mod/mk_elfconfig.c
index 6a96d47bd1e6..639bca7ba559 100644
--- a/scripts/mod/mk_elfconfig.c
+++ b/scripts/mod/mk_elfconfig.c
@@ -9,9 +9,6 @@ main(int argc, char **argv)
         unsigned char ei[EI_NIDENT];
         union { short s; char c[2]; } endian_test;
 
-        if (argc != 2) {
-                fprintf(stderr, "Error: no arch\n");
-        }
         if (fread(ei, 1, EI_NIDENT, stdin) != EI_NIDENT) {
                 fprintf(stderr, "Error: input truncated\n");
                 return 1;
@@ -55,12 +52,6 @@ main(int argc, char **argv)
         else
                 exit(1);
 
-        if ((strcmp(argv[1], "h8300") == 0)
-            || (strcmp(argv[1], "blackfin") == 0))
-                printf("#define MODULE_SYMBOL_PREFIX \"_\"\n");
-        else
-                printf("#define MODULE_SYMBOL_PREFIX \"\"\n");
-
         return 0;
 }
 
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 801a16a17545..fb0f9b711af3 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -15,8 +15,17 @@
 #include <stdio.h>
 #include <ctype.h>
 #include "modpost.h"
+#include "../../include/linux/autoconf.h"
 #include "../../include/linux/license.h"
 
+/* Some toolchains use a `_' prefix for all user symbols. */
+#ifdef CONFIG_SYMBOL_PREFIX
+#define MODULE_SYMBOL_PREFIX CONFIG_SYMBOL_PREFIX
+#else
+#define MODULE_SYMBOL_PREFIX ""
+#endif
+
+
 /* Are we using CONFIG_MODVERSIONS? */
 int modversions = 0;
 /* Warn about undefined symbols? (do so if we have vmlinux) */