module version magic and arches with symbol prefixes

From: Mike Frysinger
Date: Thu Jun 18 2009 - 11:25:18 EST

the current check_modstruct_version() does this:
const unsigned long *crc;

if (!find_symbol("module_layout", NULL, &crc, true, false))
return check_version(sechdrs, versindex, "module_layout", mod, crc);
the trouble here is that it looks for a literal "module_layout" symbol
and for ports that have symbol prefixes (a quick check shows Blackfin
& h8300), this aint going to work.

i tried to hack it in the Blackfin port by add this to the linker script:
module_layout = _module_layout
but that didnt seem to work. maybe kallsysms couldnt find it or i
need to hack a different name ...

we could add a new function to asm-generic/sections.h:
#ifndef arch_symbol_name
#define arch_symbol_name(sym) sym
and in the case of Blackfin systems, we'd do:
#define arch_symbol_name(sym) "_" sym

no other consumer of find_symbol() has a problem because they're all
dynamic -- they scan the modules for required symbols and then scan
the kernel for those, so all the symbol prefixes line up.

that would fix the find_symbol() invocation, and check_version()
wouldnt need changing because in that case, it's look for the literal
symbol that scripts/mod/modpost.c is adding -- "module_layout" in this

also, using BUG() here seems pretty damn harsh. wouldnt it make more
sense to do something like:
if (WARN_ON(!find_symbol("module_layout", NULL, &crc, true, false)))
return 0;
this way the module is simply not loaded rather than killing the kernel
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