Recent changes to kernel/module.c caused the following compile
error:

  kernel/module.c: In function ‘show_taint’:
  kernel/module.c:1024:2: error: implicit declaration of function ‘module_flags_taint’ [-Werror=implicit-function-declaration]
  cc1: some warnings being treated as errors

Correct this error by moving the definition of module_flags_taint
outside of the #ifdef CONFIG_MODULE_UNLOAD section.
Signed-off-by: NKevin Winchester <kjwinchester@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Recent tools do not want to use /proc to retrieve module information. A few
values are currently missing from sysfs to replace the information available
in /proc/modules.

This adds /sys/module/*/{coresize,initsize,taint} attributes.

TAINT_PROPRIETARY_MODULE (P) and TAINT_OOT_MODULE (O) flags are both always
shown now, and do no longer exclude each other, also in /proc/modules.

Replace the open-coded sysfs attribute initializers with the __ATTR() macro.

Add the new attributes to Documentation/ABI.

Cc: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Signed-off-by: NKay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Use more flexible pr_debug.  This allows:

  echo "module module +p" > /dbg/dynamic_debug/control

to turn on debug messages when needed.
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

module_ref contains two "unsigned int" fields.

Thats now too small, since some machines can open more than 2^32 files.

Check commit 518de9b3 (fs: allow for more than 2^31 files) for
reference.

We can add an aligned(2 * sizeof(unsigned long)) attribute to force
alloc_percpu() allocating module_ref areas in single cache lines.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: Tejun Heo <tj@kernel.org>
CC: Robin Holt <holt@sgi.com>
CC: David Miller <davem@davemloft.net>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Looking at /proc/kallsyms, one starts to ponder whether all of the extra
strtab-related complexity in module.c is worth the memory savings.

Instead of making the add_kallsyms() loop even more complex, I tried the
other route of deleting the strmap logic and naively copying each string
into core_strtab with no consideration for consolidating duplicates.

Performance on an "already exists" insmod of nvidia.ko (runs
add_kallsyms() but does not actually initialize the module):

	Original scheme: 1.230s
	With naive copying: 0.058s

Extra space used: 35k (of a 408k module).
Signed-off-by: NKevin Cernekee <cernekee@gmail.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <73defb5e4bca04a6431392cc341112b1@localhost>

Signed-off-by: NKevin Cernekee <cernekee@gmail.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Use of the GPL or a compatible licence doesn't necessarily make the code
any good.  We already consider staging modules to be suspect, and this
should also be true for out-of-tree modules which may receive very
little review.
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Reviewed-by: NDave Jones <davej@redhat.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (patched oops-tracing.txt)

Dynamic debugging is currently disabled for tainted modules, except
for TAINT_CRAP.  This prevents use of dynamic debugging for
out-of-tree modules once the next patch is applied.

This condition was apparently intended to avoid a crash if a force-
loaded module has an incompatible definition of dynamic debug
structures.  However, a administrator that forces us to load a module
is claiming that it *is* compatible even though it fails our version
checks.  If they are mistaken, there are any number of ways the module
could crash the system.

As a side-effect, proprietary and other tainted modules can now use
dynamic_debug.
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Acked-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

The changed files were only including linux/module.h for the
EXPORT_SYMBOL infrastructure, and nothing else.  Revector them
onto the isolated export header for faster compile times.

Nothing to see here but a whole lot of instances of:

  -#include <linux/module.h>
  +#include <linux/export.h>

This commit is only changing the kernel dir; next targets
will probably be mm, fs, the arch dirs, etc.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

Copy the information needed from struct module into a local module list
held within tracepoint.c from within the module coming/going notifier.

This vastly simplifies locking of tracepoint registration /
unregistration, because we don't have to take the module mutex to
register and unregister tracepoints anymore. Steven Rostedt ran into
dependency problems related to modules mutex vs kprobes mutex vs ftrace
mutex vs tracepoint mutex that seems to be hard to fix without removing
this dependency between tracepoint and module mutex. (note: it should be
investigated whether kprobes could benefit of being dissociated from the
modules mutex too.)

This also fixes module handling of tracepoint list iterators, because it
was expecting the list to be sorted by pointer address. Given we have
control on our own list now, it's OK to sort this list which has
tracepoints as its only purpose. The reason why this sorting is required
is to handle the fact that seq files (and any read() operation from
user-space) cannot hold the tracepoint mutex across multiple calls, so
list entries may vanish between calls. With sorting, the tracepoint
iterator becomes usable even if the list don't contain the exact item
pointed to by the iterator anymore.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: NJason Baron <jbaron@redhat.com>
CC: Ingo Molnar <mingo@elte.hu>
CC: Lai Jiangshan <laijs@cn.fujitsu.com>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Link: http://lkml.kernel.org/r/20110810191839.GC8525@KrystalSigned-off-by: NSteven Rostedt <rostedt@goodmis.org>

Userspace wants to manage module parameters with udev rules.
This currently only works for loaded modules, but not for
built-in ones.

To allow access to the built-in modules we need to
re-trigger all module load events that happened before any
userspace was running. We already do the same thing for all
devices, subsystems(buses) and drivers.

This adds the currently missing /sys/module/<name>/uevent files
to all module entries.
Signed-off-by: NKay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (split & trivial fix)

This simplifies the next patch, where we have an attribute on a
builtin module (ie. module == NULL).
Signed-off-by: NKay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (split into 2)

The module loader code allows architectures to hook into the code by
providing a small number of entry points that each arch must implement.
This patch provides __weakly linked generic implementations of these
entry points for architectures that don't need to do anything special.
Signed-off-by: NJonas Bonn <jonas@southpole.se>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

The function is_exported() with its helper function lookup_symbol() are used to
verify if a provided symbol is effectively exported by the kernel or by the
modules. Now that both have their symbols sorted we can replace a linear search
with a binary search which provide a considerably speed-up.

This work was supported by a hardware donation from the CE Linux Forum.
Signed-off-by: NAlessio Igor Bogani <abogani@kernel.org>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Takes advantage of the order and locates symbols using binary search.

This work was supported by a hardware donation from the CE Linux Forum.
Signed-off-by: NAlessio Igor Bogani <abogani@kernel.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Tested-by: NDirk Behme <dirk.behme@googlemail.com>

Instead of having a callback function for each symbol in the kernel,
have a callback for each array of symbols.

This eases the logic when we move to sorted symbols and binary search.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAlessio Igor Bogani <abogani@kernel.org>

Split the unprotect function into a function per section to make
the code more readable and add the missing static declaration.
Signed-off-by: NJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

While debugging I stumbled over two problems in the code that protects module
pages.

First issue is that disabling the protection before freeing init or unload of
a module is not symmetric with the enablement. For instance, if pages are set
to RO the page range from module_core to module_core + core_ro_size is
protected. If a module is unloaded the page range from module_core to
module_core + core_size is set back to RW.
So pages that were not set to RO are also changed to RW.
This is not critical but IMHO it should be symmetric.

Second issue is that while set_memory_rw & set_memory_ro are used for
RO/RW changes only set_memory_nx is involved for NX/X. One would await that
the inverse function is called when the NX protection should be removed,
which is not the case here, unless I'm missing something.
Signed-off-by: NJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Reset mod->init_ro_size to zero after the init part of a module is unloaded.
Otherwise we need to check if module->init is NULL in the unprotect functions
in the next patch.
Signed-off-by: NJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Fix function prototype to be ANSI-C compliant, consistent with other
function prototypes, addressing a sparse warning.
Signed-off-by: NDaniel J Blueman <daniel.blueman@gmail.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Driver modules from the staging directory are marked 'tainted'
by module.c. Subsequently, tainted modules are denied dynamic
debugging. This is unwanted behavior, since staging modules should
be able to use the dynamic debugging mechanism.

Please merge this also into the staging-linus branch.
Signed-off-by: NRoland Vossen <rvossen@broadcom.com>
Acked-by: NJason Baron <jbaron@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>

In an effort to reduce kernel address leaks that might be used to help
target kernel privilege escalation exploits, this patch uses %pK when
displaying addresses in /proc/kallsyms, /proc/modules, and
/sys/module/*/sections/*.

Note that this changes %x to %p, so some legitimately 0 values in
/proc/kallsyms would have changed from 00000000 to "(null)".  To avoid
this, "(null)" is not used when using the "K" format.  Anything that was
already successfully parsing "(null)" in addition to full hex digits
should have no problem with this change.  (Thanks to Joe Perches for the
suggestion.) Due to the %x to %p, "void *" casts are needed since these
addresses are already "unsigned long" everywhere internally, due to their
starting life as ELF section offsets.
Signed-off-by: NKees Cook <kees.cook@canonical.com>
Cc: Eugene Teo <eugene@redhat.com>
Cc: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make the tracepoints more robust, making them solid enough to handle compiler
changes by not relying on anything based on compiler-specific behavior with
respect to structure alignment. Implement an approach proposed by David Miller:
use an array of const pointers to refer to the individual structures, and export
this pointer array through the linker script rather than the structures per se.
It will consume 32 extra bytes per tracepoint (24 for structure padding and 8
for the pointers), but are less likely to break due to compiler changes.

History:

commit 7e066fb8 tracepoints: add DECLARE_TRACE() and DEFINE_TRACE()
added the aligned(32) type and variable attribute to the tracepoint structures
to deal with gcc happily aligning statically defined structures on 32-byte
multiples.

One attempt was to use a 8-byte alignment for tracepoint structures by applying
both the variable and type attribute to tracepoint structures definitions and
declarations. It worked fine with gcc 4.5.1, but broke with gcc 4.4.4 and 4.4.5.

The reason is that the "aligned" attribute only specify the _minimum_ alignment
for a structure, leaving both the compiler and the linker free to align on
larger multiples. Because tracepoint.c expects the structures to be placed as an
array within each section, up-alignment cause NULL-pointer exceptions due to the
extra unexpected padding.

(this patch applies on top of -tip)
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: NDavid S. Miller <davem@davemloft.net>
LKML-Reference: <20110126222622.GA10794@Krystal>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Ingo Molnar <mingo@elte.hu>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The commit:

84e1c6bb
x86: Add RO/NX protection for loadable kernel modules

Broke the function tracer with this output:

------------[ cut here ]------------
WARNING: at kernel/trace/ftrace.c:1014 ftrace_bug+0x114/0x171()
Hardware name: Precision WorkStation 470
Modules linked in: i2c_core(+)
Pid: 86, comm: modprobe Not tainted 2.6.37-rc2+ #68
Call Trace:
 [<ffffffff8104e957>] warn_slowpath_common+0x85/0x9d
 [<ffffffffa00026db>] ? __process_new_adapter+0x7/0x34 [i2c_core]
 [<ffffffffa00026db>] ? __process_new_adapter+0x7/0x34 [i2c_core]
 [<ffffffff8104e989>] warn_slowpath_null+0x1a/0x1c
 [<ffffffff810a9dfe>] ftrace_bug+0x114/0x171
 [<ffffffffa00026db>] ? __process_new_adapter+0x7/0x34 [i2c_core]
 [<ffffffff810aa0db>] ftrace_process_locs+0x1ae/0x274
 [<ffffffffa00026db>] ? __process_new_adapter+0x7/0x34 [i2c_core]
 [<ffffffff810aa29e>] ftrace_module_notify+0x39/0x44
 [<ffffffff814405cf>] notifier_call_chain+0x37/0x63
 [<ffffffff8106e054>] __blocking_notifier_call_chain+0x46/0x5b
 [<ffffffff8106e07d>] blocking_notifier_call_chain+0x14/0x16
 [<ffffffff8107ffde>] sys_init_module+0x73/0x1f3
 [<ffffffff8100acf2>] system_call_fastpath+0x16/0x1b
---[ end trace 2aff4f4ca53ec746 ]---
ftrace faulted on writing [<ffffffffa00026db>]
__process_new_adapter+0x7/0x34 [i2c_core]

The cause was that the module text was set to read only before ftrace
could convert the calls to mcount to nops. Thus, the conversions failed
due to not being able to write to the text locations.

The simple fix is to move setting the module to read only after the
module notifiers are called (where ftrace sets the module mcounts to nops).
Reported-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

This patch is a logical extension of the protection provided by
CONFIG_DEBUG_RODATA to LKMs. The protection is provided by
splitting module_core and module_init into three logical parts
each and setting appropriate page access permissions for each
individual section:

 1. Code: RO+X
 2. RO data: RO+NX
 3. RW data: RW+NX

In order to achieve proper protection, layout_sections() have
been modified to align each of the three parts mentioned above
onto page boundary. Next, the corresponding page access
permissions are set right before successful exit from
load_module(). Further, free_module() and sys_init_module have
been modified to set module_core and module_init as RW+NX right
before calling module_free().

By default, the original section layout and access flags are
preserved. When compiled with CONFIG_DEBUG_SET_MODULE_RONX=y,
the patch will page-align each group of sections to ensure that
each page contains only one type of content and will enforce
RO/NX for each group of pages.

  -v1: Initial proof-of-concept patch.
  -v2: The patch have been re-written to reduce the number of #ifdefs
       and to make it architecture-agnostic. Code formatting has also
       been corrected.
  -v3: Opportunistic RO/NX protection is now unconditional. Section
       page-alignment is enabled when CONFIG_DEBUG_RODATA=y.
  -v4: Removed most macros and improved coding style.
  -v5: Changed page-alignment and RO/NX section size calculation
  -v6: Fixed comments. Restricted RO/NX enforcement to x86 only
  -v7: Introduced CONFIG_DEBUG_SET_MODULE_RONX, added
       calls to set_all_modules_text_rw() and set_all_modules_text_ro()
       in ftrace
  -v8: updated for compatibility with linux 2.6.33-rc5
  -v9: coding style fixes
 -v10: more coding style fixes
 -v11: minor adjustments for -tip
 -v12: minor adjustments for v2.6.35-rc2-tip
 -v13: minor adjustments for v2.6.37-rc1-tip
Signed-off-by: NSiarhei Liakh <sliakh.lkml@gmail.com>
Signed-off-by: NXuxian Jiang <jiang@cs.ncsu.edu>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Reviewed-by: NJames Morris <jmorris@namei.org>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dave Jones <davej@redhat.com>
Cc: Kees Cook <kees.cook@canonical.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <4CE2F914.9070106@free.fr>
[ minor cleanliness edits, -v14: build failure fix ]
Signed-off-by: NIngo Molnar <mingo@elte.hu>

On use of trace_printk() there's a macro that determines if the format
is static or a variable. If it is static, it defaults to __trace_bprintk()
otherwise it uses __trace_printk().

A while ago, Lai Jiangshan added __trace_bprintk(). In that patch, we
discussed a way to allow modules to use it. The difference between
__trace_bprintk() and __trace_printk() is that for faster processing,
just the format and args are stored in the trace instead of running
it through a sprintf function. In order to do this, the format used
by the __trace_bprintk() had to be persistent.

See commit 1ba28e02

The problem comes with trace_bprintk() where the module is unloaded.
The pointer left in the buffer is still pointing to the format.

To solve this issue, the formats in the module were copied into kernel
core. If the same format was used, they would use the same copy (to prevent
memory leak). This all worked well until we tried to merge everything.

At the time this was written, Lai Jiangshan, Frederic Weisbecker,
Ingo Molnar and myself were all touching the same code. When this was
merged, we lost the part of it that was in module.c. This kept out the
copying of the formats and unloading the module could cause bad pointers
left in the ring buffer.

This patch adds back (with updates required for current kernel) the
module code that sets up the necessary pointers.

Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Building with CONFIG_KALLSYMS=n gives following warning:

/mnt/src/linux-git/kernel/module.c: In function ‘post_relocation’:
/mnt/src/linux-git/kernel/module.c:2534:2: warning: passing argument 2 of ‘add_kallsyms’ discards qualifiers from pointer target type
/mnt/src/linux-git/kernel/module.c:2038:13: note: expected ‘struct load_info *’ but argument is of type ‘const struct load_info *’
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

With all the recent module loading cleanups, we've minimized the code
that sits under module_mutex, fixing various deadlocks and making it
possible to do most of the module loading in parallel.

However, that whole conversion totally missed the rather obscure code
that adds a new module to the list for BUG() handling.  That code was
doubly obscure because (a) the code itself lives in lib/bugs.c (for
dubious reasons) and (b) it gets called from the architecture-specific
"module_finalize()" rather than from generic code.

Calling it from arch-specific code makes no sense what-so-ever to begin
with, and is now actively wrong since that code isn't protected by the
module loading lock any more.

So this commit moves the "module_bug_{finalize,cleanup}()" calls away
from the arch-specific code, and into the generic code - and in the
process protects it with the module_mutex so that the list operations
are now safe.

Future fixups:
 - move the module list handling code into kernel/module.c where it
   belongs.
 - get rid of 'module_bug_list' and just use the regular list of modules
   (called 'modules' - imagine that) that we already create and maintain
   for other reasons.
Reported-and-tested-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

base patch to implement 'jump labeling'. Based on a new 'asm goto' inline
assembly gcc mechanism, we can now branch to labels from an 'asm goto'
statment. This allows us to create a 'no-op' fastpath, which can subsequently
be patched with a jump to the slowpath code. This is useful for code which
might be rarely used, but which we'd like to be able to call, if needed.
Tracepoints are the current usecase that these are being implemented for.
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NJason Baron <jbaron@redhat.com>
LKML-Reference: <ee8b3595967989fdaf84e698dc7447d315ce972a.1284733808.git.jbaron@redhat.com>

[ cleaned up some formating ]
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

On my (32-bit x86) machine, sys_init_module() uses 124 bytes of stack
once load_module() is inlined.

This effectively reverts ffb4ba76 which inlined it due to stack
pressure.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

This simply hoists more code out of load_module; we also put the
identification of the extable and dynamic debug table in with the
others in find_module_sections().

We move the taint check to the actual add/remove of the dynamic debug
info: this is certain (find_module_sections is too early).
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: Yehuda Sadeh <yehuda@hq.newdream.net>

Instead of copying and allocating the args and storing it in
load_info, we can just allocate them right before we need them.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Pass the struct load_info into all the other functions in module
loading.  This neatens things and makes them more consistent.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Restore the stub module_remove_modinfo_attrs, remove the now-unused
!CONFIG_SYSFS module_sysfs_init.

Also, rename mod_kobject_remove() to mod_sysfs_teardown() as
it is the logical counterpart to mod_sysfs_setup now.
Reported-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

We change the sysfs functions to take struct load_info, and call
them all in mod_sysfs_setup().

We also clean up the #ifdefs a little.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

layout_and_allocate() does everything up to and including the final
struct module placement inside the allocated module memory.  We have
to store the symbol layout information in our struct load_info though.

This avoids the nasty code we had before where 'mod' pointed first
to the version inside the temporary allocation containing the entire
file, then later was moved to point to the real struct module: now
the main code only ever sees the final module address.

(Includes fix for the Tony Luck-found Linus-diagnosed failure path
 error).
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Andrew had the sole pleasure of tickling this bug in linux-next; when we set
up "info->strtab" it's pointing into the temporary copy of the module.  For
most uses that is fine, but kallsyms keeps a pointer around during module
load (inside mod->strtab).

If we oops for some reason inside a module's init function, kallsyms will use
the mod->strtab pointer into the now-freed temporary module copy.

(Later oopses work fine: after init we overwrite mod->strtab to point to a
 compacted core-only strtab).
Reported-by: NAndrew "Grumpy" Morton <akpm@linux-foundation.org>
Signed-off-by: NRusty "Buggy" Russell <rusty@rustcorp.com.au>
Tested-by: NAndrew "Happy" Morton <akpm@linux-foundation.org>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Simple refactor causes us to lift struct definition to top of file.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

We can't do the find_sec after removing the SHF_ALLOC flags; it won't
find the sections.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>