modpost: reduce visibility of symbols and constify r/o arrays

Internally used symbols of modpost don't need to be externally visible;
make them static. Also constify the string arrays so they resist in the
r/o section instead of being runtime writable.

Those changes lead to a small size reduction as can be seen below:

   text    data     bss     dec     hex filename
  51381    2640   12416   66437   10385 scripts/mod/modpost.old
  51765    2224   12416   66405   10365 scripts/mod/modpost.new
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

scripts/mod/modpost.c

@@ -24,9 +24,9 @@
 #include "../../include/linux/export.h"
 
 /* Are we using CONFIG_MODVERSIONS? */
-int modversions = 0;
+static int modversions = 0;
 /* Warn about undefined symbols? (do so if we have vmlinux) */
-int have_vmlinux = 0;
+static int have_vmlinux = 0;
 /* Is CONFIG_MODULE_SRCVERSION_ALL set? */
 static int all_versions = 0;
 /* If we are modposting external module set to 1 */
@@ -229,7 +229,7 @@ static struct symbol *find_symbol(const char *name)
 	return NULL;
 }
 
-static struct {
+static const struct {
 	const char *str;
 	enum export export;
 } export_list[] = {
@@ -805,7 +805,7 @@ static int match(const char *sym, const char * const pat[])
 }
 
 /* sections that we do not want to do full section mismatch check on */
-static const char *section_white_list[] =
+static const char *const section_white_list[] =
 {
 	".comment*",
 	".debug*",
@@ -882,17 +882,18 @@ static void check_section(const char *modname, struct elf_info *elf,
 #define MEM_EXIT_SECTIONS  ".memexit.*"
 
 /* init data sections */
-static const char *init_data_sections[] = { ALL_INIT_DATA_SECTIONS, NULL };
+static const char *const init_data_sections[] =
+	{ ALL_INIT_DATA_SECTIONS, NULL };
 
 /* all init sections */
-static const char *init_sections[] = { ALL_INIT_SECTIONS, NULL };
+static const char *const init_sections[] = { ALL_INIT_SECTIONS, NULL };
 
 /* All init and exit sections (code + data) */
-static const char *init_exit_sections[] =
+static const char *const init_exit_sections[] =
 	{ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS, NULL };
 
 /* data section */
-static const char *data_sections[] = { DATA_SECTIONS, NULL };
+static const char *const data_sections[] = { DATA_SECTIONS, NULL };
 
 
 /* symbols in .data that may refer to init/exit sections */
@@ -906,8 +907,8 @@ static const char *data_sections[] = { DATA_SECTIONS, NULL };
 	"*_probe_one",							\
 	"*_console"
 
-static const char *head_sections[] = { ".head.text*", NULL };
-static const char *linker_symbols[] =
+static const char *const head_sections[] = { ".head.text*", NULL };
+static const char *const linker_symbols[] =
 	{ "__init_begin", "_sinittext", "_einittext", NULL };
 
 enum mismatch {
@@ -929,7 +930,7 @@ struct sectioncheck {
 	const char *symbol_white_list[20];
 };
 
-const struct sectioncheck sectioncheck[] = {
+static const struct sectioncheck sectioncheck[] = {
 /* Do not reference init/exit code/data from
  * normal code and data
  */