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From a779a482fb9b9f8fcdf8b2519c789b4b9bb5dd05 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@nbd.name>
Date: Fri, 7 Jul 2017 16:56:48 +0200
Subject: build: add a hack for removing non-essential module info
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
include/linux/module.h | 13 ++++++++-----
include/linux/moduleparam.h | 15 ++++++++++++---
init/Kconfig | 7 +++++++
kernel/module.c | 5 ++++-
scripts/mod/modpost.c | 12 ++++++++++++
5 files changed, 43 insertions(+), 9 deletions(-)
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -157,6 +157,7 @@ extern void cleanup_module(void);
/* Generic info of form tag = "info" */
#define MODULE_INFO(tag, info) __MODULE_INFO(tag, tag, info)
+#define MODULE_INFO_STRIP(tag, info) __MODULE_INFO_STRIP(tag, tag, info)
/* For userspace: you can also call me... */
#define MODULE_ALIAS(_alias) MODULE_INFO(alias, _alias)
@@ -216,12 +217,12 @@ extern void cleanup_module(void);
* Author(s), use "Name <email>" or just "Name", for multiple
* authors use multiple MODULE_AUTHOR() statements/lines.
*/
-#define MODULE_AUTHOR(_author) MODULE_INFO(author, _author)
+#define MODULE_AUTHOR(_author) MODULE_INFO_STRIP(author, _author)
/* What your module does. */
-#define MODULE_DESCRIPTION(_description) MODULE_INFO(description, _description)
+#define MODULE_DESCRIPTION(_description) MODULE_INFO_STRIP(description, _description)
-#ifdef MODULE
+#if defined(MODULE) && !defined(CONFIG_MODULE_STRIPPED)
/* Creates an alias so file2alias.c can find device table. */
#define MODULE_DEVICE_TABLE(type, name) \
extern typeof(name) __mod_##type##__##name##_device_table \
@@ -248,7 +249,9 @@ extern typeof(name) __mod_##type##__##na
*/
#if defined(MODULE) || !defined(CONFIG_SYSFS)
-#define MODULE_VERSION(_version) MODULE_INFO(version, _version)
+#define MODULE_VERSION(_version) MODULE_INFO_STRIP(version, _version)
+#elif defined(CONFIG_MODULE_STRIPPED)
+#define MODULE_VERSION(_version) __MODULE_INFO_DISABLED(version)
#else
#define MODULE_VERSION(_version) \
MODULE_INFO(version, _version); \
@@ -271,7 +274,7 @@ extern typeof(name) __mod_##type##__##na
/* Optional firmware file (or files) needed by the module
* format is simply firmware file name. Multiple firmware
* files require multiple MODULE_FIRMWARE() specifiers */
-#define MODULE_FIRMWARE(_firmware) MODULE_INFO(firmware, _firmware)
+#define MODULE_FIRMWARE(_firmware) MODULE_INFO_STRIP(firmware, _firmware)
#define MODULE_IMPORT_NS(ns) MODULE_INFO(import_ns, #ns)
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -20,10 +20,24 @@
/* Chosen so that structs with an unsigned long line up. */
#define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long))
+/* This struct is here for syntactic coherency, it is not used */
+#define __MODULE_INFO_DISABLED(name) \
+ struct __UNIQUE_ID(name) {}
+
+#ifdef CONFIG_MODULE_STRIPPED
+#define __MODULE_INFO_STRIP(tag, name, info) __MODULE_INFO_DISABLED(name)
+#else
+#define __MODULE_INFO_STRIP(tag, name, info) __MODULE_INFO(tag, name, info)
+#endif
+
+#ifdef MODULE
#define __MODULE_INFO(tag, name, info) \
static const char __UNIQUE_ID(name)[] \
__used __attribute__((section(".modinfo"), unused, aligned(1))) \
= __MODULE_INFO_PREFIX __stringify(tag) "=" info
+#else
+#define __MODULE_INFO(tag, name, info) __MODULE_INFO_DISABLED(name)
+#endif
#define __MODULE_PARM_TYPE(name, _type) \
__MODULE_INFO(parmtype, name##type, #name ":" _type)
@@ -31,7 +45,7 @@ static const char __UNIQUE_ID(name)[]
/* One for each parameter, describing how to use it. Some files do
multiple of these per line, so can't just use MODULE_INFO. */
#define MODULE_PARM_DESC(_parm, desc) \
- __MODULE_INFO(parm, _parm, #_parm ":" desc)
+ __MODULE_INFO_STRIP(parm, _parm, #_parm ":" desc)
struct kernel_param;
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -2198,6 +2198,13 @@ config TRIM_UNUSED_KSYMS
If unsure, or if you need to build out-of-tree modules, say N.
+config MODULE_STRIPPED
+ bool "Reduce module size"
+ depends on MODULES
+ help
+ Remove module parameter descriptions, author info, version, aliases,
+ device tables, etc.
+
endif # MODULES
config MODULES_TREE_LOOKUP
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1285,6 +1285,7 @@ static struct module_attribute *modinfo_
static const char vermagic[] = VERMAGIC_STRING;
+#if defined(CONFIG_MODVERSIONS) || !defined(CONFIG_MODULE_STRIPPED)
static int try_to_force_load(struct module *mod, const char *reason)
{
#ifdef CONFIG_MODULE_FORCE_LOAD
@@ -1296,6 +1297,7 @@ static int try_to_force_load(struct modu
return -ENOEXEC;
#endif
}
+#endif
#ifdef CONFIG_MODVERSIONS
@@ -3256,9 +3256,11 @@ static int setup_load_info(struct load_i
static int check_modinfo(struct module *mod, struct load_info *info, int flags)
{
- const char *modmagic = get_modinfo(info, "vermagic");
int err;
+#ifndef CONFIG_MODULE_STRIPPED
+ const char *modmagic = get_modinfo(info, "vermagic");
+
if (flags & MODULE_INIT_IGNORE_VERMAGIC)
modmagic = NULL;
@@ -3279,6 +3281,7 @@ static int check_modinfo(struct module *
mod->name);
add_taint_module(mod, TAINT_OOT_MODULE, LOCKDEP_STILL_OK);
}
+#endif
check_modinfo_retpoline(mod, info);
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2056,7 +2056,9 @@ static void read_symbols(const char *mod
symname = remove_dot(info.strtab + sym->st_name);
handle_modversions(mod, &info, sym, symname);
+#ifndef CONFIG_MODULE_STRIPPED
handle_moddevtable(mod, &info, sym, symname);
+#endif
}
/* Apply symbol namespaces from __kstrtabns_<symbol> entries. */
@@ -2270,8 +2272,10 @@ static void add_header(struct buffer *b,
buf_printf(b, "\n");
buf_printf(b, "BUILD_SALT;\n");
buf_printf(b, "\n");
+#ifndef CONFIG_MODULE_STRIPPED
buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n");
buf_printf(b, "MODULE_INFO(name, KBUILD_MODNAME);\n");
+#endif
buf_printf(b, "\n");
buf_printf(b, "__visible struct module __this_module\n");
buf_printf(b, "__section(.gnu.linkonce.this_module) = {\n");
@@ -2288,8 +2292,10 @@ static void add_header(struct buffer *b,
static void add_intree_flag(struct buffer *b, int is_intree)
{
+#ifndef CONFIG_MODULE_STRIPPED
if (is_intree)
buf_printf(b, "\nMODULE_INFO(intree, \"Y\");\n");
+#endif
}
/* Cannot check for assembler */
@@ -2302,8 +2308,10 @@ static void add_retpoline(struct buffer
static void add_staging_flag(struct buffer *b, const char *name)
{
+#ifndef CONFIG_MODULE_STRIPPED
if (strstarts(name, "drivers/staging"))
buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n");
+#endif
}
/**
@@ -2387,11 +2395,13 @@ static void add_depends(struct buffer *b
static void add_srcversion(struct buffer *b, struct module *mod)
{
+#ifndef CONFIG_MODULE_STRIPPED
if (mod->srcversion[0]) {
buf_printf(b, "\n");
buf_printf(b, "MODULE_INFO(srcversion, \"%s\");\n",
mod->srcversion);
}
+#endif
}
static void write_if_changed(struct buffer *b, const char *fname)
@@ -2661,7 +2671,9 @@ int main(int argc, char **argv)
add_staging_flag(&buf, mod->name);
err |= add_versions(&buf, mod);
add_depends(&buf, mod);
+#ifndef CONFIG_MODULE_STRIPPED
add_moddevtable(&buf, mod);
+#endif
add_srcversion(&buf, mod);
sprintf(fname, "%s.mod.c", mod->name);
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