linux-sg2042/init
Hannes Frederic Sowa c4b2c0c5f6 static_key: WARN on usage before jump_label_init was called
Usage of the static key primitives to toggle a branch must not be used
before jump_label_init() is called from init/main.c. jump_label_init
reorganizes and wires up the jump_entries so usage before that could
have unforeseen consequences.

Following primitives are now checked for correct use:
* static_key_slow_inc
* static_key_slow_dec
* static_key_slow_dec_deferred
* jump_label_rate_limit

The x86 architecture already checks this by testing if the default_nop
was already replaced with an optimal nop or with a branch instruction. It
will panic then. Other architectures don't check for this.

Because we need to relax this check for the x86 arch to allow code to
transition from default_nop to the enabled state and other architectures
did not check for this at all this patch introduces checking on the
static_key primitives in a non-arch dependent manner.

All checked functions are considered slow-path so the additional check
does no harm to performance.

The warnings are best observed with earlyprintk.

Based on a patch from Andi Kleen.

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19 19:45:35 -04:00
..
Kconfig Merge branch 'slab/next' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux 2013-09-15 07:15:06 -04:00
Makefile init_task: Replace CONFIG_HAVE_GENERIC_INIT_TASK 2012-05-05 13:00:46 +02:00
calibrate.c kernel: delete __cpuinit usage from all core kernel files 2013-07-14 19:36:59 -04:00
do_mounts.c initmpfs: use initramfs if rootfstype= or root= specified 2013-09-11 15:59:38 -07:00
do_mounts.h md: move lots of #include lines out of .h files and into .c 2009-03-31 14:33:13 +11:00
do_mounts_initrd.c usermodehelper: split remaining calls to call_usermodehelper_fns() 2013-04-30 17:04:06 -07:00
do_mounts_md.c init: disable sparse checking of the mount.o source files 2012-05-31 17:49:27 -07:00
do_mounts_rd.c init: disable sparse checking of the mount.o source files 2012-05-31 17:49:27 -07:00
init_task.c sched/rt: Move rt specific bits into new header file 2013-02-07 20:51:08 +01:00
initramfs.c init, block: try to load default elevator module early during boot 2013-01-18 14:05:56 -08:00
main.c static_key: WARN on usage before jump_label_init was called 2013-10-19 19:45:35 -04:00
noinitramfs.c init: mark __user address space on string literals 2010-10-26 16:52:15 -07:00
version.c proc: Split the namespace stuff out into linux/proc_ns.h 2013-05-01 17:29:39 -04:00