cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

bit_spinlock.h (2360B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2#ifndef __LINUX_BIT_SPINLOCK_H
      3#define __LINUX_BIT_SPINLOCK_H
      4
      5#include <linux/kernel.h>
      6#include <linux/preempt.h>
      7#include <linux/atomic.h>
      8#include <linux/bug.h>
      9
     10/*
     11 *  bit-based spin_lock()
     12 *
     13 * Don't use this unless you really need to: spin_lock() and spin_unlock()
     14 * are significantly faster.
     15 */
     16static inline void bit_spin_lock(int bitnum, unsigned long *addr)
     17{
     18	/*
     19	 * Assuming the lock is uncontended, this never enters
     20	 * the body of the outer loop. If it is contended, then
     21	 * within the inner loop a non-atomic test is used to
     22	 * busywait with less bus contention for a good time to
     23	 * attempt to acquire the lock bit.
     24	 */
     25	preempt_disable();
     26#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
     27	while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
     28		preempt_enable();
     29		do {
     30			cpu_relax();
     31		} while (test_bit(bitnum, addr));
     32		preempt_disable();
     33	}
     34#endif
     35	__acquire(bitlock);
     36}
     37
     38/*
     39 * Return true if it was acquired
     40 */
     41static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
     42{
     43	preempt_disable();
     44#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
     45	if (unlikely(test_and_set_bit_lock(bitnum, addr))) {
     46		preempt_enable();
     47		return 0;
     48	}
     49#endif
     50	__acquire(bitlock);
     51	return 1;
     52}
     53
     54/*
     55 *  bit-based spin_unlock()
     56 */
     57static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
     58{
     59#ifdef CONFIG_DEBUG_SPINLOCK
     60	BUG_ON(!test_bit(bitnum, addr));
     61#endif
     62#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
     63	clear_bit_unlock(bitnum, addr);
     64#endif
     65	preempt_enable();
     66	__release(bitlock);
     67}
     68
     69/*
     70 *  bit-based spin_unlock()
     71 *  non-atomic version, which can be used eg. if the bit lock itself is
     72 *  protecting the rest of the flags in the word.
     73 */
     74static inline void __bit_spin_unlock(int bitnum, unsigned long *addr)
     75{
     76#ifdef CONFIG_DEBUG_SPINLOCK
     77	BUG_ON(!test_bit(bitnum, addr));
     78#endif
     79#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
     80	__clear_bit_unlock(bitnum, addr);
     81#endif
     82	preempt_enable();
     83	__release(bitlock);
     84}
     85
     86/*
     87 * Return true if the lock is held.
     88 */
     89static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
     90{
     91#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
     92	return test_bit(bitnum, addr);
     93#elif defined CONFIG_PREEMPT_COUNT
     94	return preempt_count();
     95#else
     96	return 1;
     97#endif
     98}
     99
    100#endif /* __LINUX_BIT_SPINLOCK_H */
    101