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c4b2c0c5f6
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>
37 lines
921 B
C
37 lines
921 B
C
#ifndef _LINUX_JUMP_LABEL_RATELIMIT_H
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#define _LINUX_JUMP_LABEL_RATELIMIT_H
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#include <linux/jump_label.h>
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#include <linux/workqueue.h>
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#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
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struct static_key_deferred {
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struct static_key key;
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unsigned long timeout;
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struct delayed_work work;
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};
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#endif
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#ifdef HAVE_JUMP_LABEL
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extern void static_key_slow_dec_deferred(struct static_key_deferred *key);
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extern void
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jump_label_rate_limit(struct static_key_deferred *key, unsigned long rl);
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#else /* !HAVE_JUMP_LABEL */
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struct static_key_deferred {
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struct static_key key;
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};
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static inline void static_key_slow_dec_deferred(struct static_key_deferred *key)
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{
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STATIC_KEY_CHECK_USE();
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static_key_slow_dec(&key->key);
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}
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static inline void
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jump_label_rate_limit(struct static_key_deferred *key,
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unsigned long rl)
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{
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STATIC_KEY_CHECK_USE();
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}
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#endif /* HAVE_JUMP_LABEL */
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#endif /* _LINUX_JUMP_LABEL_RATELIMIT_H */
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