kbuild: improved modversioning support for external modules
With following patch a second option is enabled to obtain symbol information from a second external module when a external module is build. The recommended approach is to use a common kbuild file but that may be impractical in certain cases. With this patch one can copy over a Module.symvers from one external module to make symbols (and symbol versions) available for another external module. Updated documentation in Documentation/kbuild/modules.txt Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
This commit is contained in:
Sam Ravnborg
Родитель
5c3ead8c72
Коммит
040fcc819a
|
|
@ -23,7 +23,10 @@ In this document you will find information about:
|
|||
=== 6. Module installation
|
||||
--- 6.1 INSTALL_MOD_PATH
|
||||
--- 6.2 INSTALL_MOD_DIR
|
||||
=== 7. Module versioning
|
||||
=== 7. Module versioning & Module.symvers
|
||||
--- 7.1 Symbols fron the kernel (vmlinux + modules)
|
||||
--- 7.2 Symbols and external modules
|
||||
--- 7.3 Symbols from another external module
|
||||
=== 8. Tips & Tricks
|
||||
--- 8.1 Testing for CONFIG_FOO_BAR
|
||||
|
||||
|
|
@ -89,7 +92,8 @@ when building an external module.
|
|||
make -C $KDIR M=$PWD modules_install
|
||||
Install the external module(s).
|
||||
Installation default is in /lib/modules/<kernel-version>/extra,
|
||||
but may be prefixed with INSTALL_MOD_PATH - see separate chapter.
|
||||
but may be prefixed with INSTALL_MOD_PATH - see separate
|
||||
chapter.
|
||||
|
||||
make -C $KDIR M=$PWD clean
|
||||
Remove all generated files for the module - the kernel
|
||||
|
|
@ -433,7 +437,7 @@ External modules are installed in the directory:
|
|||
=> Install dir: /lib/modules/$(KERNELRELEASE)/gandalf
|
||||
|
||||
|
||||
=== 7. Module versioning
|
||||
=== 7. Module versioning & Module.symvers
|
||||
|
||||
Module versioning is enabled by the CONFIG_MODVERSIONS tag.
|
||||
|
||||
|
|
@ -443,11 +447,80 @@ when a module is loaded/used then the CRC values contained in the kernel are
|
|||
compared with similar values in the module. If they are not equal then the
|
||||
kernel refuses to load the module.
|
||||
|
||||
During a kernel build a file named Module.symvers will be generated. This
|
||||
file includes the symbol version of all symbols within the kernel. If the
|
||||
Module.symvers file is saved from the last full kernel compile one does not
|
||||
have to do a full kernel compile to build a module version's compatible module.
|
||||
Module.symvers contains a list of all exported symbols from a kernel build.
|
||||
|
||||
--- 7.1 Symbols fron the kernel (vmlinux + modules)
|
||||
|
||||
During a kernel build a file named Module.symvers will be generated.
|
||||
Module.symvers contains all exported symbols from the kernel and
|
||||
compiled modules. For each symbols the corresponding CRC value
|
||||
is stored too.
|
||||
|
||||
The syntax of the Module.symvers file is:
|
||||
<CRC> <Symbol> <module>
|
||||
Sample:
|
||||
0x2d036834 scsi_remove_host drivers/scsi/scsi_mod
|
||||
|
||||
For a kernel build without CONFIG_MODVERSIONING enabled the crc
|
||||
would read: 0x00000000
|
||||
|
||||
Module.symvers serve two purposes.
|
||||
1) It list all exported symbols both from vmlinux and all modules
|
||||
2) It list CRC if CONFIG_MODVERSION is enabled
|
||||
|
||||
--- 7.2 Symbols and external modules
|
||||
|
||||
When building an external module the build system needs access to
|
||||
the symbols from the kernel to check if all external symbols are
|
||||
defined. This is done in the MODPOST step and to obtain all
|
||||
symbols modpost reads Module.symvers from the kernel.
|
||||
If a Module.symvers file is present in the directory where
|
||||
the external module is being build this file will be read too.
|
||||
During the MODPOST step a new Module.symvers file will be written
|
||||
containing all exported symbols that was not defined in the kernel.
|
||||
|
||||
--- 7.3 Symbols from another external module
|
||||
|
||||
Sometimes one external module uses exported symbols from another
|
||||
external module. Kbuild needs to have full knowledge on all symbols
|
||||
to avoid spitting out warnings about undefined symbols.
|
||||
Two solutions exist to let kbuild know all symbols of more than
|
||||
one external module.
|
||||
The method with a top-level kbuild file is recommended but may be
|
||||
impractical in certain situations.
|
||||
|
||||
Use a top-level Kbuild file
|
||||
If you have two modules: 'foo', 'bar' and 'foo' needs symbols
|
||||
from 'bar' then one can use a common top-level kbuild file so
|
||||
both modules are compiled in same build.
|
||||
|
||||
Consider following directory layout:
|
||||
./foo/ <= contains the foo module
|
||||
./bar/ <= contains the bar module
|
||||
The top-level Kbuild file would then look like:
|
||||
|
||||
#./Kbuild: (this file may also be named Makefile)
|
||||
obj-y := foo/ bar/
|
||||
|
||||
Executing:
|
||||
make -C $KDIR M=`pwd`
|
||||
|
||||
will then do the expected and compile both modules with full
|
||||
knowledge on symbols from both modules.
|
||||
|
||||
Use an extra Module.symvers file
|
||||
When an external module is build a Module.symvers file is
|
||||
generated containing all exported symbols which are not
|
||||
defined in the kernel.
|
||||
To get access to symbols from module 'bar' one can copy the
|
||||
Module.symvers file from the compilation of the 'bar' module
|
||||
to the directory where the 'foo' module is build.
|
||||
During the module build kbuild will read the Module.symvers
|
||||
file in the directory of the external module and when the
|
||||
build is finished a new Module.symvers file is created
|
||||
containing the sum of all symbols defined and not part of the
|
||||
kernel.
|
||||
|
||||
=== 8. Tips & Tricks
|
||||
|
||||
--- 8.1 Testing for CONFIG_FOO_BAR
|
||||
|
|
|
|||
|
|
@ -39,7 +39,8 @@ include .config
|
|||
include scripts/Kbuild.include
|
||||
include scripts/Makefile.lib
|
||||
|
||||
symverfile := $(objtree)/Module.symvers
|
||||
kernelsymfile := $(objtree)/Module.symvers
|
||||
modulesymfile := $(KBUILD_EXTMOD)/Modules.symvers
|
||||
|
||||
# Step 1), find all modules listed in $(MODVERDIR)/
|
||||
__modules := $(sort $(shell grep -h '\.ko' /dev/null $(wildcard $(MODVERDIR)/*.mod)))
|
||||
|
|
@ -54,7 +55,9 @@ quiet_cmd_modpost = MODPOST
|
|||
cmd_modpost = scripts/mod/modpost \
|
||||
$(if $(CONFIG_MODVERSIONS),-m) \
|
||||
$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a,) \
|
||||
$(if $(KBUILD_EXTMOD),-i,-o) $(symverfile) \
|
||||
$(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
|
||||
$(if $(KBUILD_EXTMOD),-I $(modulesymfile)) \
|
||||
$(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
|
||||
$(filter-out FORCE,$^)
|
||||
|
||||
.PHONY: __modpost
|
||||
|
|
|
|||
|
|
@ -20,6 +20,8 @@ int modversions = 0;
|
|||
int have_vmlinux = 0;
|
||||
/* Is CONFIG_MODULE_SRCVERSION_ALL set? */
|
||||
static int all_versions = 0;
|
||||
/* If we are modposting external module set to 1 */
|
||||
static int external_module = 0;
|
||||
|
||||
void fatal(const char *fmt, ...)
|
||||
{
|
||||
|
|
@ -45,6 +47,18 @@ void warn(const char *fmt, ...)
|
|||
va_end(arglist);
|
||||
}
|
||||
|
||||
static int is_vmlinux(const char *modname)
|
||||
{
|
||||
const char *myname;
|
||||
|
||||
if ((myname = strrchr(modname, '/')))
|
||||
myname++;
|
||||
else
|
||||
myname = modname;
|
||||
|
||||
return strcmp(myname, "vmlinux") == 0;
|
||||
}
|
||||
|
||||
void *do_nofail(void *ptr, const char *expr)
|
||||
{
|
||||
if (!ptr) {
|
||||
|
|
@ -100,6 +114,9 @@ struct symbol {
|
|||
unsigned int crc;
|
||||
int crc_valid;
|
||||
unsigned int weak:1;
|
||||
unsigned int vmlinux:1; /* 1 if symbol is defined in vmlinux */
|
||||
unsigned int kernel:1; /* 1 if symbol is from kernel
|
||||
* (only for external modules) **/
|
||||
char name[0];
|
||||
};
|
||||
|
||||
|
|
@ -135,8 +152,7 @@ static struct symbol *alloc_symbol(const char *name, unsigned int weak,
|
|||
}
|
||||
|
||||
/* For the hash of exported symbols */
|
||||
static void new_symbol(const char *name, struct module *module,
|
||||
unsigned int *crc)
|
||||
static struct symbol *new_symbol(const char *name, struct module *module)
|
||||
{
|
||||
unsigned int hash;
|
||||
struct symbol *new;
|
||||
|
|
@ -144,10 +160,7 @@ static void new_symbol(const char *name, struct module *module,
|
|||
hash = tdb_hash(name) % SYMBOL_HASH_SIZE;
|
||||
new = symbolhash[hash] = alloc_symbol(name, 0, symbolhash[hash]);
|
||||
new->module = module;
|
||||
if (crc) {
|
||||
new->crc = *crc;
|
||||
new->crc_valid = 1;
|
||||
}
|
||||
return new;
|
||||
}
|
||||
|
||||
static struct symbol *find_symbol(const char *name)
|
||||
|
|
@ -169,19 +182,27 @@ static struct symbol *find_symbol(const char *name)
|
|||
* Add an exported symbol - it may have already been added without a
|
||||
* CRC, in this case just update the CRC
|
||||
**/
|
||||
static void add_exported_symbol(const char *name, struct module *module,
|
||||
unsigned int *crc)
|
||||
static struct symbol *sym_add_exported(const char *name, struct module *mod)
|
||||
{
|
||||
struct symbol *s = find_symbol(name);
|
||||
|
||||
if (!s) {
|
||||
new_symbol(name, module, crc);
|
||||
return;
|
||||
}
|
||||
if (crc) {
|
||||
s->crc = *crc;
|
||||
s->crc_valid = 1;
|
||||
}
|
||||
if (!s)
|
||||
s = new_symbol(name, mod);
|
||||
|
||||
s->vmlinux = is_vmlinux(mod->name);
|
||||
s->kernel = 0;
|
||||
return s;
|
||||
}
|
||||
|
||||
static void sym_update_crc(const char *name, struct module *mod,
|
||||
unsigned int crc)
|
||||
{
|
||||
struct symbol *s = find_symbol(name);
|
||||
|
||||
if (!s)
|
||||
s = new_symbol(name, mod);
|
||||
s->crc = crc;
|
||||
s->crc_valid = 1;
|
||||
}
|
||||
|
||||
void *grab_file(const char *filename, unsigned long *size)
|
||||
|
|
@ -332,8 +353,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
|
|||
/* CRC'd symbol */
|
||||
if (memcmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
|
||||
crc = (unsigned int) sym->st_value;
|
||||
add_exported_symbol(symname + strlen(CRC_PFX),
|
||||
mod, &crc);
|
||||
sym_update_crc(symname + strlen(CRC_PFX), mod, crc);
|
||||
}
|
||||
break;
|
||||
case SHN_UNDEF:
|
||||
|
|
@ -377,8 +397,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
|
|||
default:
|
||||
/* All exported symbols */
|
||||
if (memcmp(symname, KSYMTAB_PFX, strlen(KSYMTAB_PFX)) == 0) {
|
||||
add_exported_symbol(symname + strlen(KSYMTAB_PFX),
|
||||
mod, NULL);
|
||||
sym_add_exported(symname + strlen(KSYMTAB_PFX), mod);
|
||||
}
|
||||
if (strcmp(symname, MODULE_SYMBOL_PREFIX "init_module") == 0)
|
||||
mod->has_init = 1;
|
||||
|
|
@ -388,18 +407,6 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
|
|||
}
|
||||
}
|
||||
|
||||
static int is_vmlinux(const char *modname)
|
||||
{
|
||||
const char *myname;
|
||||
|
||||
if ((myname = strrchr(modname, '/')))
|
||||
myname++;
|
||||
else
|
||||
myname = modname;
|
||||
|
||||
return strcmp(myname, "vmlinux") == 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* Parse tag=value strings from .modinfo section
|
||||
**/
|
||||
|
|
@ -450,9 +457,7 @@ static void read_symbols(char *modname)
|
|||
/* When there's no vmlinux, don't print warnings about
|
||||
* unresolved symbols (since there'll be too many ;) */
|
||||
if (is_vmlinux(modname)) {
|
||||
unsigned int fake_crc = 0;
|
||||
have_vmlinux = 1;
|
||||
add_exported_symbol("struct_module", mod, &fake_crc);
|
||||
mod->skip = 1;
|
||||
}
|
||||
|
||||
|
|
@ -665,7 +670,7 @@ static void write_if_changed(struct buffer *b, const char *fname)
|
|||
fclose(file);
|
||||
}
|
||||
|
||||
static void read_dump(const char *fname)
|
||||
static void read_dump(const char *fname, unsigned int kernel)
|
||||
{
|
||||
unsigned long size, pos = 0;
|
||||
void *file = grab_file(fname, &size);
|
||||
|
|
@ -679,6 +684,7 @@ static void read_dump(const char *fname)
|
|||
char *symname, *modname, *d;
|
||||
unsigned int crc;
|
||||
struct module *mod;
|
||||
struct symbol *s;
|
||||
|
||||
if (!(symname = strchr(line, '\t')))
|
||||
goto fail;
|
||||
|
|
@ -699,13 +705,28 @@ static void read_dump(const char *fname)
|
|||
mod = new_module(NOFAIL(strdup(modname)));
|
||||
mod->skip = 1;
|
||||
}
|
||||
add_exported_symbol(symname, mod, &crc);
|
||||
s = sym_add_exported(symname, mod);
|
||||
s->kernel = kernel;
|
||||
sym_update_crc(symname, mod, crc);
|
||||
}
|
||||
return;
|
||||
fail:
|
||||
fatal("parse error in symbol dump file\n");
|
||||
}
|
||||
|
||||
/* For normal builds always dump all symbols.
|
||||
* For external modules only dump symbols
|
||||
* that are not read from kernel Module.symvers.
|
||||
**/
|
||||
static int dump_sym(struct symbol *sym)
|
||||
{
|
||||
if (!external_module)
|
||||
return 1;
|
||||
if (sym->vmlinux || sym->kernel)
|
||||
return 0;
|
||||
return 1;
|
||||
}
|
||||
|
||||
static void write_dump(const char *fname)
|
||||
{
|
||||
struct buffer buf = { };
|
||||
|
|
@ -715,15 +736,10 @@ static void write_dump(const char *fname)
|
|||
for (n = 0; n < SYMBOL_HASH_SIZE ; n++) {
|
||||
symbol = symbolhash[n];
|
||||
while (symbol) {
|
||||
symbol = symbol->next;
|
||||
}
|
||||
}
|
||||
|
||||
for (n = 0; n < SYMBOL_HASH_SIZE ; n++) {
|
||||
symbol = symbolhash[n];
|
||||
while (symbol) {
|
||||
buf_printf(&buf, "0x%08x\t%s\t%s\n", symbol->crc,
|
||||
symbol->name, symbol->module->name);
|
||||
if (dump_sym(symbol))
|
||||
buf_printf(&buf, "0x%08x\t%s\t%s\n",
|
||||
symbol->crc, symbol->name,
|
||||
symbol->module->name);
|
||||
symbol = symbol->next;
|
||||
}
|
||||
}
|
||||
|
|
@ -735,13 +751,18 @@ int main(int argc, char **argv)
|
|||
struct module *mod;
|
||||
struct buffer buf = { };
|
||||
char fname[SZ];
|
||||
char *dump_read = NULL, *dump_write = NULL;
|
||||
char *kernel_read = NULL, *module_read = NULL;
|
||||
char *dump_write = NULL;
|
||||
int opt;
|
||||
|
||||
while ((opt = getopt(argc, argv, "i:mo:a")) != -1) {
|
||||
while ((opt = getopt(argc, argv, "i:I:mo:a")) != -1) {
|
||||
switch(opt) {
|
||||
case 'i':
|
||||
dump_read = optarg;
|
||||
kernel_read = optarg;
|
||||
break;
|
||||
case 'I':
|
||||
module_read = optarg;
|
||||
external_module = 1;
|
||||
break;
|
||||
case 'm':
|
||||
modversions = 1;
|
||||
|
|
@ -757,8 +778,10 @@ int main(int argc, char **argv)
|
|||
}
|
||||
}
|
||||
|
||||
if (dump_read)
|
||||
read_dump(dump_read);
|
||||
if (kernel_read)
|
||||
read_dump(kernel_read, 1);
|
||||
if (module_read)
|
||||
read_dump(module_read, 0);
|
||||
|
||||
while (optind < argc) {
|
||||
read_symbols(argv[optind++]);
|
||||
|
|
|
|||
Загрузка…
Ссылка в новой задаче