| Message ID | 20190429090854.GU9023@dhcp129-178.brq.redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] moduleparam: Save information about built-in modules in separate file | expand |
+++ Alexey Gladkov [29/04/19 11:08 +0200]: >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' < kernel.builtin s/kernel.builtin/modules.builtin.modinfo/ Otherwise, for module.h and moduleparam.h: Acked-by: Jessica Yu <jeyu@kernel.org> And it would be great if Lucas can confirm if the file format and name would be OK for kmod. Thanks! Jessica
On Mon, Apr 29, 2019 at 6:09 PM Alexey Gladkov <gladkov.alexey@gmail.com> wrote: > > 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' < kernel.builtin > 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 > ... > > v2: > * Extract modinfo from vmlinux.o as suggested by Masahiro Yamada; > * Rename output file to kernel.builtin; > * Add MODULE_VERSION to modinfo that is saved to the kernel.builtin; > * Fix build warnings on powerpc. > > v3: > * Rename output file to modules.builtin.modinfo as suggested by Masahiro Yamada; > * Update Documentation/dontdiff, Documentation/kbuild/kbuild.txt. > > 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> > --- > .gitignore | 1 + > Documentation/dontdiff | 1 + > Documentation/kbuild/kbuild.txt | 5 +++++ > Makefile | 2 ++ > include/asm-generic/vmlinux.lds.h | 1 + > include/linux/module.h | 1 + > include/linux/moduleparam.h | 12 +++++------- > scripts/link-vmlinux.sh | 4 ++++ > 8 files changed, 20 insertions(+), 7 deletions(-) > > diff --git a/.gitignore b/.gitignore > index a20ac26aa2f5..8ef2c87703b3 100644 > --- a/.gitignore > +++ b/.gitignore > @@ -45,6 +45,7 @@ > *.xz > Module.symvers > modules.builtin > +modules.builtin.modinfo > > # > # Top-level generic files Let me repeat the same comments as in v2 (https://patchwork.kernel.org/patch/10888207/#22595563) as you ignored them. This file is generated only in the top of the tree. Please add '/' prefix and move it to the "# Top-level generic files" section. # # Top-level generic files # /tags /TAGS /linux /vmlinux /vmlinux.32 /vmlinux-gdb.py /vmlinuz /System.map /Module.markers /modules.builtin.modinfo > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > index c8cf45362bd6..41ef7cb043c1 100755 > --- a/scripts/link-vmlinux.sh > +++ b/scripts/link-vmlinux.sh > @@ -226,6 +226,10 @@ modpost_link vmlinux.o > # modpost vmlinux.o to check for section mismatches > ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o > > +info MODINFO modules.builtin.modinfo > +"${OBJCOPY}" -j .modinfo -O binary vmlinux.o modules.builtin.modinfo > +chmod 444 modules.builtin.modinfo Why is this 'chmod 444' necessary? > + > kallsymso="" > kallsyms_vmlinux="" > if [ -n "${CONFIG_KALLSYMS}" ]; then
On Tue, Apr 30, 2019 at 12:08:44AM +0900, Masahiro Yamada wrote: > > modules.builtin > > +modules.builtin.modinfo > > > > # > > # Top-level generic files > > > Let me repeat the same comments as in v2 > (https://patchwork.kernel.org/patch/10888207/#22595563) > as you ignored them. I miss it. Sorry about that. > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > index c8cf45362bd6..41ef7cb043c1 100755 > > --- a/scripts/link-vmlinux.sh > > +++ b/scripts/link-vmlinux.sh > > @@ -226,6 +226,10 @@ modpost_link vmlinux.o > > # 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 > > +chmod 444 modules.builtin.modinfo > > > Why is this 'chmod 444' necessary? I just wanted to show that this file will never change. I will remove this line.
diff --git a/.gitignore b/.gitignore index a20ac26aa2f5..8ef2c87703b3 100644 --- a/.gitignore +++ b/.gitignore @@ -45,6 +45,7 @@ *.xz Module.symvers modules.builtin +modules.builtin.modinfo # # Top-level generic files diff --git a/Documentation/dontdiff b/Documentation/dontdiff index 2228fcc8e29f..3d4d5a402b8b 100644 --- a/Documentation/dontdiff +++ b/Documentation/dontdiff @@ -179,6 +179,7 @@ mktables 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 c9e3d93e7a89..63e118c8c837 100644 --- a/Documentation/kbuild/kbuild.txt +++ b/Documentation/kbuild/kbuild.txt @@ -11,6 +11,11 @@ modules.builtin 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 d5713e7b1e50..5e6657fcf08c 100644 --- a/Makefile +++ b/Makefile @@ -1288,6 +1288,7 @@ _modinst_: 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 @@ -1328,6 +1329,7 @@ endif # CONFIG_MODULES # 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 3d7a6a9c2370..44c724bf7d3a 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 f5bc4c046461..1cae28b1172a 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -237,6 +237,7 @@ extern typeof(name) __mod_##type##__##name##_device_table \ #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 ba36506db4fb..5ba250d9172a 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 c8cf45362bd6..41ef7cb043c1 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -226,6 +226,10 @@ modpost_link vmlinux.o # modpost vmlinux.o to check for section mismatches ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o +info MODINFO modules.builtin.modinfo +"${OBJCOPY}" -j .modinfo -O binary vmlinux.o modules.builtin.modinfo +chmod 444 modules.builtin.modinfo + kallsymso="" kallsyms_vmlinux="" if [ -n "${CONFIG_KALLSYMS}" ]; then