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modpost: check static EXPORT_SYMBOL* by modpost again

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Commit 31cb50b559 ("kbuild: check static EXPORT_SYMBOL* by script
instead of modpost") moved the static EXPORT_SYMBOL* check from the
mostpost to a shell script because I thought it must be checked per
compilation unit to avoid false negatives.

I came up with an idea to do this in modpost, against combined ELF
files. The relocation entries in ELF will find the correct exported
symbol even if there exist symbols with the same name in different
compilation units.

Again, the same 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) {}

Then, modpost can catch it correctly.

    MODPOST Module.symvers
  ERROR: modpost: vmlinux: local symbol 'foo' was exported

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
This commit is contained in:
Masahiro Yamada
2023-06-12 00:50:54 +09:00
parent 7d59313f19
commit 6d62b1c46b
3 changed files with 7 additions and 74 deletions
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7
scripts/mod/modpost.c
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@@ -1210,6 +1210,13 @@ static void check_export_symbol(struct module *mod, struct elf_info *elf,
return;
}
if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL &&
ELF_ST_BIND(sym->st_info) != STB_WEAK) {
error("%s: local symbol '%s' was exported\n", mod->name,
label_name + strlen(prefix));
return;
}
name = sym_name(elf, sym);
if (strcmp(label_name + strlen(prefix), name)) {
error("%s: .export_symbol section references '%s', but it does not seem to be an export symbol\n",