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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.
131 lines
3.1 KiB
C
131 lines
3.1 KiB
C
#ifndef _ASM_GENERIC_RWSEM_H
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#define _ASM_GENERIC_RWSEM_H
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#ifndef _LINUX_RWSEM_H
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#error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead."
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#endif
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#ifdef __KERNEL__
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/*
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* R/W semaphores originally for PPC using the stuff in lib/rwsem.c.
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* Adapted largely from include/asm-i386/rwsem.h
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* by Paul Mackerras <paulus@samba.org>.
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*/
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/*
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* the semaphore definition
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*/
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#ifdef CONFIG_64BIT
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# define RWSEM_ACTIVE_MASK 0xffffffffL
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#else
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# define RWSEM_ACTIVE_MASK 0x0000ffffL
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#endif
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#define RWSEM_UNLOCKED_VALUE 0x00000000L
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#define RWSEM_ACTIVE_BIAS 0x00000001L
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#define RWSEM_WAITING_BIAS (-RWSEM_ACTIVE_MASK-1)
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#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
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#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
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/*
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* lock for reading
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*/
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static inline void __down_read(struct rw_semaphore *sem)
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{
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if (unlikely(atomic_long_inc_return_acquire((atomic_long_t *)&sem->count) <= 0))
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rwsem_down_read_failed(sem);
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}
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static inline int __down_read_trylock(struct rw_semaphore *sem)
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{
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long tmp;
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while ((tmp = atomic_long_read(&sem->count)) >= 0) {
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if (tmp == atomic_long_cmpxchg_acquire(&sem->count, tmp,
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tmp + RWSEM_ACTIVE_READ_BIAS)) {
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return 1;
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}
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}
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return 0;
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}
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/*
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* lock for writing
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*/
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static inline void __down_write(struct rw_semaphore *sem)
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{
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long tmp;
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tmp = atomic_long_add_return_acquire(RWSEM_ACTIVE_WRITE_BIAS,
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(atomic_long_t *)&sem->count);
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if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
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rwsem_down_write_failed(sem);
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}
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static inline int __down_write_killable(struct rw_semaphore *sem)
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{
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long tmp;
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tmp = atomic_long_add_return_acquire(RWSEM_ACTIVE_WRITE_BIAS,
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(atomic_long_t *)&sem->count);
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if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
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if (IS_ERR(rwsem_down_write_failed_killable(sem)))
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return -EINTR;
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return 0;
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}
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static inline int __down_write_trylock(struct rw_semaphore *sem)
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{
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long tmp;
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tmp = atomic_long_cmpxchg_acquire(&sem->count, RWSEM_UNLOCKED_VALUE,
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RWSEM_ACTIVE_WRITE_BIAS);
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return tmp == RWSEM_UNLOCKED_VALUE;
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}
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/*
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* unlock after reading
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*/
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static inline void __up_read(struct rw_semaphore *sem)
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{
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long tmp;
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tmp = atomic_long_dec_return_release((atomic_long_t *)&sem->count);
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if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0))
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rwsem_wake(sem);
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}
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/*
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* unlock after writing
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*/
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static inline void __up_write(struct rw_semaphore *sem)
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{
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if (unlikely(atomic_long_sub_return_release(RWSEM_ACTIVE_WRITE_BIAS,
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(atomic_long_t *)&sem->count) < 0))
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rwsem_wake(sem);
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}
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/*
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* downgrade write lock to read lock
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*/
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static inline void __downgrade_write(struct rw_semaphore *sem)
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{
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long tmp;
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/*
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* When downgrading from exclusive to shared ownership,
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* anything inside the write-locked region cannot leak
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* into the read side. In contrast, anything in the
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* read-locked region is ok to be re-ordered into the
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* write side. As such, rely on RELEASE semantics.
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*/
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tmp = atomic_long_add_return_release(-RWSEM_WAITING_BIAS,
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(atomic_long_t *)&sem->count);
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if (tmp < 0)
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rwsem_downgrade_wake(sem);
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}
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#endif /* __KERNEL__ */
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#endif /* _ASM_GENERIC_RWSEM_H */
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