moduleparam: Save information about built-in modules in separate file
Problem:
When a kernel module is compiled as a separate module, some important
information about the kernel module is available via .modinfo section of
the module. In contrast, when the kernel module is compiled into the
kernel, that information is not available.
Information about built-in modules is necessary in the following cases:
1. When it is necessary to find out what additional parameters can be
passed to the kernel at boot time.
2. When you need to know which module names and their aliases are in
the kernel. This is very useful for creating an initrd image.
Proposal:
The proposed patch does not remove .modinfo section with module
information from the vmlinux at the build time and saves it into a
separate file after kernel linking. So, the kernel does not increase in
size and no additional information remains in it. Information is stored
in the same format as in the separate modules (null-terminated string
array). Because the .modinfo section is already exported with a separate
modules, we are not creating a new API.
It can be easily read in the userspace:
$ tr '\0' '\n' < modules.builtin.modinfo
ext4.softdep=pre: crc32c
ext4.license=GPL
ext4.description=Fourth Extended Filesystem
ext4.author=Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others
ext4.alias=fs-ext4
ext4.alias=ext3
ext4.alias=fs-ext3
ext4.alias=ext2
ext4.alias=fs-ext2
md_mod.alias=block-major-9-*
md_mod.alias=md
md_mod.description=MD RAID framework
md_mod.license=GPL
md_mod.parmtype=create_on_open:bool
md_mod.parmtype=start_dirty_degraded:int
...
Co-Developed-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
Acked-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/.gitignore b/.gitignore
index e7bb6c6..2fb1765 100644
--- a/.gitignore
+++ b/.gitignore
@@ -58,6 +58,7 @@
/vmlinuz
/System.map
/Module.markers
+/modules.builtin.modinfo
#
# RPM spec file (make rpm-pkg)
diff --git a/Documentation/dontdiff b/Documentation/dontdiff
index ef25a06..512fa02 100644
--- a/Documentation/dontdiff
+++ b/Documentation/dontdiff
@@ -178,6 +178,7 @@
mktree
modpost
modules.builtin
+modules.builtin.modinfo
modules.order
modversions.h*
nconf
diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index 8a3830b..9c230ea 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -11,6 +11,11 @@
This file lists all modules that are built into the kernel. This is used
by modprobe to not fail when trying to load something builtin.
+modules.builtin.modinfo
+--------------------------------------------------
+This file contains modinfo from all modules that are built into the kernel.
+Unlike modinfo of a separate module, all fields are prefixed with module name.
+
Environment variables
diff --git a/Makefile b/Makefile
index 85dd977..9a8b3f9 100644
--- a/Makefile
+++ b/Makefile
@@ -1308,6 +1308,7 @@
fi
@cp -f $(objtree)/modules.order $(MODLIB)/
@cp -f $(objtree)/modules.builtin $(MODLIB)/
+ @cp -f $(objtree)/modules.builtin.modinfo $(MODLIB)/
$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modinst
# This depmod is only for convenience to give the initial
@@ -1348,6 +1349,7 @@
# Directories & files removed with 'make clean'
CLEAN_DIRS += $(MODVERDIR) include/ksym
+CLEAN_FILES += modules.builtin.modinfo
# Directories & files removed with 'make mrproper'
MRPROPER_DIRS += include/config usr/include include/generated \
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index f8f6f04..bbb9e33 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -844,6 +844,7 @@
EXIT_CALL \
*(.discard) \
*(.discard.*) \
+ *(.modinfo) \
}
/**
diff --git a/include/linux/module.h b/include/linux/module.h
index 5bf5dcd..5f700743 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -253,6 +253,7 @@
#define MODULE_VERSION(_version) MODULE_INFO(version, _version)
#else
#define MODULE_VERSION(_version) \
+ MODULE_INFO(version, _version); \
static struct module_version_attribute ___modver_attr = { \
.mattr = { \
.attr = { \
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index ba36506..5ba250d 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -10,23 +10,21 @@
module name. */
#ifdef MODULE
#define MODULE_PARAM_PREFIX /* empty */
+#define __MODULE_INFO_PREFIX /* empty */
#else
#define MODULE_PARAM_PREFIX KBUILD_MODNAME "."
+/* We cannot use MODULE_PARAM_PREFIX because some modules override it. */
+#define __MODULE_INFO_PREFIX KBUILD_MODNAME "."
#endif
/* Chosen so that structs with an unsigned long line up. */
#define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long))
-#ifdef MODULE
#define __MODULE_INFO(tag, name, info) \
static const char __UNIQUE_ID(name)[] \
__used __attribute__((section(".modinfo"), unused, aligned(1))) \
- = __stringify(tag) "=" info
-#else /* !MODULE */
-/* This struct is here for syntactic coherency, it is not used */
-#define __MODULE_INFO(tag, name, info) \
- struct __UNIQUE_ID(name) {}
-#endif
+ = __MODULE_INFO_PREFIX __stringify(tag) "=" info
+
#define __MODULE_PARM_TYPE(name, _type) \
__MODULE_INFO(parmtype, name##type, #name ":" _type)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index dc0e8c5..e4383e0 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -193,6 +193,9 @@
# modpost vmlinux.o to check for section mismatches
${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
+info MODINFO modules.builtin.modinfo
+${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
+
kallsymso=""
kallsyms_vmlinux=""
if [ -n "${CONFIG_KALLSYMS}" ]; then
