forked from Qortal/Brooklyn
2a709f28fa
* 0day explit mitigation * Memory corruption prevention * Privilege escalation prevention * Buffer over flow prevention * File System corruption defense * Thread escape prevention This may very well be the most intensive inclusion to BrooklynR. This will not be part of an x86 suite nor it will be released as tool kit. The security core toolkit will remain part of kernel base.
89 lines
2.8 KiB
C
89 lines
2.8 KiB
C
/*
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* include/asm-generic/mutex-dec.h
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*
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* Generic implementation of the mutex fastpath, based on atomic
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* decrement/increment.
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*/
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#ifndef _ASM_GENERIC_MUTEX_DEC_H
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#define _ASM_GENERIC_MUTEX_DEC_H
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/**
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* __mutex_fastpath_lock - try to take the lock by moving the count
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* from 1 to a 0 value
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* @count: pointer of type atomic_t
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* @fail_fn: function to call if the original value was not 1
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*
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* Change the count from 1 to a value lower than 1, and call <fail_fn> if
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* it wasn't 1 originally. This function MUST leave the value lower than
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* 1 even when the "1" assertion wasn't true.
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*/
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static inline void
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__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
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{
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if (unlikely(atomic_dec_return_acquire(count) < 0))
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fail_fn(count);
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}
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/**
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* __mutex_fastpath_lock_retval - try to take the lock by moving the count
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* from 1 to a 0 value
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* @count: pointer of type atomic_t
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*
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* Change the count from 1 to a value lower than 1. This function returns 0
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* if the fastpath succeeds, or -1 otherwise.
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*/
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static inline int
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__mutex_fastpath_lock_retval(atomic_t *count)
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{
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if (unlikely(atomic_dec_return_acquire(count) < 0))
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return -1;
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return 0;
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}
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/**
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* __mutex_fastpath_unlock - try to promote the count from 0 to 1
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* @count: pointer of type atomic_t
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* @fail_fn: function to call if the original value was not 0
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*
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* Try to promote the count from 0 to 1. If it wasn't 0, call <fail_fn>.
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* In the failure case, this function is allowed to either set the value to
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* 1, or to set it to a value lower than 1.
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*
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* If the implementation sets it to a value of lower than 1, then the
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* __mutex_slowpath_needs_to_unlock() macro needs to return 1, it needs
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* to return 0 otherwise.
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*/
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static inline void
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__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
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{
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if (unlikely(atomic_inc_return_release(count) <= 0))
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fail_fn(count);
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}
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#define __mutex_slowpath_needs_to_unlock() 1
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/**
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* __mutex_fastpath_trylock - try to acquire the mutex, without waiting
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*
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* @count: pointer of type atomic_t
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* @fail_fn: fallback function
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*
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* Change the count from 1 to a value lower than 1, and return 0 (failure)
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* if it wasn't 1 originally, or return 1 (success) otherwise. This function
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* MUST leave the value lower than 1 even when the "1" assertion wasn't true.
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* Additionally, if the value was < 0 originally, this function must not leave
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* it to 0 on failure.
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*
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* If the architecture has no effective trylock variant, it should call the
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* <fail_fn> spinlock-based trylock variant unconditionally.
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*/
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static inline int
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__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
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{
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if (likely(atomic_read(count) == 1 && atomic_cmpxchg_acquire(count, 1, 0) == 1))
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return 1;
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return 0;
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}
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#endif
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