diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 54504013c749..02a4adb4a999 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -1038,6 +1038,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG) *(.discard) \ *(.discard.*) \ *(.export_symbol) \ + *(.no_trim_symbol) \ *(.modinfo) \ /* ld.bfd warns about .gnu.version* even when not emitted */ \ *(.gnu.version*) \ diff --git a/include/linux/module.h b/include/linux/module.h index 23792d5d7b74..30e5b19bafa9 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -306,7 +306,10 @@ extern int modules_disabled; /* for sysctl */ /* Get/put a kernel symbol (calls must be symmetric) */ void *__symbol_get(const char *symbol); void *__symbol_get_gpl(const char *symbol); -#define symbol_get(x) ((typeof(&x))(__symbol_get(__stringify(x)))) +#define symbol_get(x) ({ \ + static const char __notrim[] \ + __used __section(".no_trim_symbol") = __stringify(x); \ + (typeof(&x))(__symbol_get(__stringify(x))); }) /* modules using other modules: kdb wants to see this. */ struct module_use { diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index e18ae7dc8140..36b28987a2f0 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -507,6 +507,9 @@ static int parse_elf(struct elf_info *info, const char *filename) info->modinfo_len = sechdrs[i].sh_size; } else if (!strcmp(secname, ".export_symbol")) { info->export_symbol_secndx = i; + } else if (!strcmp(secname, ".no_trim_symbol")) { + info->no_trim_symbol = (void *)hdr + sechdrs[i].sh_offset; + info->no_trim_symbol_len = sechdrs[i].sh_size; } if (sechdrs[i].sh_type == SHT_SYMTAB) { @@ -1566,6 +1569,14 @@ static void read_symbols(const char *modname) /* strip trailing .o */ mod = new_module(modname, strlen(modname) - strlen(".o")); + /* save .no_trim_symbol section for later use */ + if (info.no_trim_symbol_len) { + mod->no_trim_symbol = xmalloc(info.no_trim_symbol_len); + memcpy(mod->no_trim_symbol, info.no_trim_symbol, + info.no_trim_symbol_len); + mod->no_trim_symbol_len = info.no_trim_symbol_len; + } + if (!mod->is_vmlinux) { license = get_modinfo(&info, "license"); if (!license) @@ -1728,6 +1739,28 @@ static void handle_white_list_exports(const char *white_list) free(buf); } +/* + * Keep symbols recorded in the .no_trim_symbol section. This is necessary to + * prevent CONFIG_TRIM_UNUSED_KSYMS from dropping EXPORT_SYMBOL because + * symbol_get() relies on the symbol being present in the ksymtab for lookups. + */ +static void keep_no_trim_symbols(struct module *mod) +{ + unsigned long size = mod->no_trim_symbol_len; + + for (char *s = mod->no_trim_symbol; s; s = next_string(s , &size)) { + struct symbol *sym; + + /* + * If find_symbol() returns NULL, this symbol is not provided + * by any module, and symbol_get() will fail. + */ + sym = find_symbol(s); + if (sym) + sym->used = true; + } +} + static void check_modname_len(struct module *mod) { const char *mod_name; @@ -2254,6 +2287,8 @@ int main(int argc, char **argv) read_symbols_from_files(files_source); list_for_each_entry(mod, &modules, list) { + keep_no_trim_symbols(mod); + if (mod->dump_file || mod->is_vmlinux) continue; diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h index ffd0a52a606e..59366f456b76 100644 --- a/scripts/mod/modpost.h +++ b/scripts/mod/modpost.h @@ -111,6 +111,8 @@ struct module_alias { * * @dump_file: path to the .symvers file if loaded from a file * @aliases: list head for module_aliases + * @no_trim_symbol: .no_trim_symbol section data + * @no_trim_symbol_len: length of the .no_trim_symbol section */ struct module { struct list_head list; @@ -128,6 +130,8 @@ struct module { // Actual imported namespaces struct list_head imported_namespaces; struct list_head aliases; + char *no_trim_symbol; + unsigned int no_trim_symbol_len; char name[]; }; @@ -141,6 +145,8 @@ struct elf_info { char *strtab; char *modinfo; unsigned int modinfo_len; + char *no_trim_symbol; + unsigned int no_trim_symbol_len; /* support for 32bit section numbers */ diff --git a/scripts/module.lds.S b/scripts/module.lds.S index c2f80f9141d4..450f1088d5fd 100644 --- a/scripts/module.lds.S +++ b/scripts/module.lds.S @@ -16,6 +16,7 @@ SECTIONS { *(.discard) *(.discard.*) *(.export_symbol) + *(.no_trim_symbol) } __ksymtab 0 : ALIGN(8) { *(SORT(___ksymtab+*)) }