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modpost: check for static EXPORT_SYMBOL* functions

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This patch adds a check to warn about static EXPORT_SYMBOL* functions
during the modpost. In most of the cases, a static symbol marked for
exporting is an odd combination that should be fixed either by deleting
the exporting mark or by removing the static attribute and adding the
appropriate declaration to headers.

This check could help to detect the following problems:
1. 550113d4e9 ("i2c: add newly exported functions to the header, too")
2. 54638c6eaf ("net: phy: make exported variables non-static")
3. 98ef2046f2 ("mm: remove the exporting of totalram_pages")
4. 73df167c81 ("s390/zcrypt: remove the exporting of ap_query_configuration")
5. a57caf8c52 ("sunrpc/cache: remove the exporting of cache_seq_next")
6. e4e4730698 ("crypto: skcipher - remove the exporting of skcipher_walk_next")
7. 14b4c48bb1 ("gve: Remove the exporting of gve_probe")
8. 9b79ee9773 ("scsi: libsas: remove the exporting of sas_wait_eh")
9. ...

The build time impact is very limited and is almost at the unnoticeable
level (< 1 sec).

Acked-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
This commit is contained in:
Denis Efremov 2019-08-01 09:06:57 +03:00 committed by Masahiro Yamada
parent d45331b00d
commit 15bfc2348d
1 changed files with 32 additions and 0 deletions
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32
scripts/mod/modpost.c
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@ -169,6 +169,7 @@ struct symbol {
unsigned int kernel:1; /* 1 if symbol is from kernel
* (only for external modules) **/
unsigned int preloaded:1; /* 1 if symbol from Module.symvers, or crc */
unsigned int is_static:1; /* 1 if symbol is not global */
enum export export; /* Type of export */
char name[0];
};
@ -201,6 +202,7 @@ static struct symbol *alloc_symbol(const char *name, unsigned int weak,
strcpy(s->name, name);
s->weak = weak;
s->next = next;
s->is_static = 1;
return s;
}
@ -1980,6 +1982,21 @@ static void read_symbols(const char *modname)
handle_modversions(mod, &info, sym, symname);
handle_moddevtable(mod, &info, sym, symname);
}
// check for static EXPORT_SYMBOL_* functions && global vars
for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
unsigned char bind = ELF_ST_BIND(sym->st_info);
if (bind == STB_GLOBAL || bind == STB_WEAK) {
struct symbol *s =
find_symbol(remove_dot(info.strtab +
sym->st_name));
if (s)
s->is_static = 0;
}
}
if (!is_vmlinux(modname) || vmlinux_section_warnings)
check_sec_ref(mod, modname, &info);
@ -2369,6 +2386,7 @@ static void read_dump(const char *fname, unsigned int kernel)
s = sym_add_exported(symname, mod, export_no(export));
s->kernel = kernel;
s->preloaded = 1;
s->is_static = 0;
sym_update_crc(symname, mod, crc, export_no(export));
}
release_file(file, size);
@ -2425,6 +2443,7 @@ int main(int argc, char **argv)
char *dump_write = NULL, *files_source = NULL;
int opt;
int err;
int n;
struct ext_sym_list *extsym_iter;
struct ext_sym_list *extsym_start = NULL;
@ -2520,6 +2539,19 @@ int main(int argc, char **argv)
if (sec_mismatch_count && sec_mismatch_fatal)
fatal("modpost: Section mismatches detected.\n"
"Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.\n");
for (n = 0; n < SYMBOL_HASH_SIZE; n++) {
struct symbol *s = symbolhash[n];
while (s) {
if (s->is_static)
warn("\"%s\" [%s] is a static %s\n",
s->name, s->module->name,
export_str(s->export));
s = s->next;
}
}
free(buf.p);
return err;