This new struct composes the linker provided (vector,len) section,
and provides a place to add other __dyndbg[] state-data later:

  descs - the vector of descriptors in __dyndbg section.
  num_descs - length of the data/section.

Use it, in several different ways, as follows:

In lib/dynamic_debug.c:

ddebug_add_module(): Alter params-list, replacing 2 args (array,index)
with a struct _ddebug_info * containing them both, with room for
expansion.  This helps future-proof the function prototype against the
looming addition of class-map info into the dyndbg-state, by providing
a place to add more member fields later.

NB: later add static struct _ddebug_info builtins_state declaration,
not needed yet.

ddebug_add_module() is called in 2 contexts:

In dynamic_debug_init(), declare, init a struct _ddebug_info di
auto-var to use as a cursor.  Then iterate over the prdbg blocks of
the builtin modules, and update the di cursor before calling
_add_module for each.

Its called from kernel/module/main.c:load_info() for each loaded
module:

In internal.h, alter struct load_info, replacing the dyndbg array,len
fields with an embedded _ddebug_info containing them both; and
populate its members in find_module_sections().

The 2 calling contexts differ in that _init deals with contiguous
subranges of __dyndbgs[] section, packed together, while loadable
modules are added one at a time.

So rename ddebug_add_module() into outer/__inner fns, call __inner
from _init, and provide the offset into the builtin __dyndbgs[] where
the module's prdbgs reside.  The cursor provides start, len of the
subrange for each.  The offset will be used later to pack the results
of builtin __dyndbg_sites[] de-duplication, and is 0 and unneeded for
loadable modules,

Note:

kernel/module/main.c includes <dynamic_debug.h> for struct
_ddeubg_info.  This might be prone to include loops, since its also
included by printk.h.  Nothing has broken in robot-land on this.

cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-12-jim.cromie@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>