kbuild/modules: Record versions for unresolved symbols

In the case of CONFIG_MODVERSIONING, the build step will only
generate preliminary <module>.o objects, and an additional
postprocessing step is necessary to record the versions of the unresolved
symbols and add them into the final <module>.ko
  
The version information for unresolved symbols is again recorded into
a special section, "__versions", which contains an array of symbol
name strings and checksum (struct modversion_info). Size is here not
an issue, since this section will not be stored permanently in kernel
memory.
  
Makefile.modver takes care of the following steps:
o Collect the version information for all exported symbols from vmlinux
  and all modules which export symbols.
o For each module, generate a C file which contains the modversion
  information for all unresolved symbols in that module.
o For each module, compile that C file to an object file
o Finally, link the <module>.ko using the preliminary <module.o> + the
  version information above.
  
The first two steps are currently done by not very efficient scripting,
so there's room for performance improvement using some helper C code.

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/module.h b/include/linux/module.h
index af4272910b27..e8726d9909d7 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -33,12 +33,19 @@
 #endif
 
 #define MODULE_NAME_LEN (64 - sizeof(unsigned long))
+
 struct kernel_symbol
 {
 	unsigned long value;
 	const char *name;
 };
 
+struct modversion_info
+{
+	unsigned long crc;
+	char name[MODULE_NAME_LEN];
+};
+
 /* These are either module local, or the kernel's dummy ones. */
 extern int init_module(void);
 extern void cleanup_module(void);