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authorMasahiro Yamada <masahiroy@kernel.org>2022-05-27 19:01:51 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2022-06-01 23:07:02 +0900
commit31cb50b5590fe911077b8463ad01144fac8fa4f3 (patch)
tree25e8abcf85190d0c3c1714bfa9bc4b793cc04292 /scripts/mod
parent534671e0ef5b652d6a983bc1c85c339f7dbfe6ce (diff)
kbuild: check static EXPORT_SYMBOL* by script instead of modpost
The 'static' specifier and EXPORT_SYMBOL() are an odd combination. Commit 15bfc2348d54 ("modpost: check for static EXPORT_SYMBOL* functions") tried to detect it, but this check has false negatives. Here is the sample code. Makefile: obj-y += foo1.o foo2.o foo1.c: #include <linux/export.h> static void foo(void) {} EXPORT_SYMBOL(foo); foo2.c: void foo(void) {} foo1.c exports the static symbol 'foo', but modpost cannot catch it because it is fooled by foo2.c, which has a global symbol with the same name. s->is_static is cleared if a global symbol with the same name is found somewhere, but EXPORT_SYMBOL() and the global symbol do not necessarily belong to the same compilation unit. This check should be done per compilation unit, but I do not know how to do it in modpost. modpost runs against vmlinux.o or modules, which merges multiple objects, then forgets their origin. modpost cannot parse individual objects because they may not be ELF but LLVM IR when CONFIG_LTO_CLANG=y. Add a simple bash script to parse the output from ${NM}. This works for CONFIG_LTO_CLANG=y because llvm-nm can dump symbols of LLVM IR files. Revert 15bfc2348d54. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
Diffstat (limited to 'scripts/mod')
-rw-r--r--scripts/mod/modpost.c28
1 files changed, 1 insertions, 27 deletions
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index e74224a6a8e8..9269735f85c5 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -212,7 +212,6 @@ struct symbol {
unsigned int crc;
bool crc_valid;
bool weak;
- bool is_static; /* true if symbol is not global */
bool is_gpl_only; /* exported by EXPORT_SYMBOL_GPL */
char name[];
};
@@ -242,7 +241,7 @@ static struct symbol *alloc_symbol(const char *name)
memset(s, 0, sizeof(*s));
strcpy(s->name, name);
- s->is_static = true;
+
return s;
}
@@ -2064,20 +2063,6 @@ static void read_symbols(const char *modname)
sym_get_data(&info, sym));
}
- // 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 = false;
- }
- }
-
check_sec_ref(modname, &info);
if (!mod->is_vmlinux) {
@@ -2507,7 +2492,6 @@ static void read_dump(const char *fname)
mod->from_dump = true;
}
s = sym_add_exported(symname, mod, gpl_only);
- s->is_static = false;
sym_set_crc(s, crc);
sym_update_namespace(symname, namespace);
}
@@ -2572,7 +2556,6 @@ int main(int argc, char **argv)
char *missing_namespace_deps = NULL;
char *dump_write = NULL, *files_source = NULL;
int opt;
- int n;
LIST_HEAD(dump_lists);
struct dump_list *dl, *dl2;
@@ -2648,15 +2631,6 @@ int main(int argc, char **argv)
if (sec_mismatch_count && !sec_mismatch_warn_only)
error("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;
-
- for (s = symbolhash[n]; s; s = s->next) {
- if (s->is_static)
- error("\"%s\" [%s] is a static EXPORT_SYMBOL\n",
- s->name, s->module->name);
- }
- }
if (nr_unresolved > MAX_UNRESOLVED_REPORTS)
warn("suppressed %u unresolved symbol warnings because there were too many)\n",