cregit-Linux how code gets into the kernel

Release 4.14 arch/metag/include/asm/spinlock_lnkget.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_SPINLOCK_LNKGET_H

#define __ASM_SPINLOCK_LNKGET_H

/*
 * None of these asm statements clobber memory as LNKSET writes around
 * the cache so the memory it modifies cannot safely be read by any means
 * other than these accessors.
 */


static inline int arch_spin_is_locked(arch_spinlock_t *lock) { int ret; asm volatile ("LNKGETD %0, [%1]\n" "TST %0, #1\n" "MOV %0, #1\n" "XORZ %0, %0, %0\n" : "=&d" (ret) : "da" (&lock->lock) : "cc"); return ret; }

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static inline void arch_spin_lock(arch_spinlock_t *lock) { int tmp; asm volatile ("1: LNKGETD %0,[%1]\n" " TST %0, #1\n" " ADD %0, %0, #1\n" " LNKSETDZ [%1], %0\n" " BNZ 1b\n" " DEFR %0, TXSTAT\n" " ANDT %0, %0, #HI(0x3f000000)\n" " CMPT %0, #HI(0x02000000)\n" " BNZ 1b\n" : "=&d" (tmp) : "da" (&lock->lock) : "cc"); smp_mb(); }

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/* Returns 0 if failed to acquire lock */
static inline int arch_spin_trylock(arch_spinlock_t *lock) { int tmp; asm volatile (" LNKGETD %0,[%1]\n" " TST %0, #1\n" " ADD %0, %0, #1\n" " LNKSETDZ [%1], %0\n" " BNZ 1f\n" " DEFR %0, TXSTAT\n" " ANDT %0, %0, #HI(0x3f000000)\n" " CMPT %0, #HI(0x02000000)\n" " MOV %0, #1\n" "1: XORNZ %0, %0, %0\n" : "=&d" (tmp) : "da" (&lock->lock) : "cc"); smp_mb(); return tmp; }

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static inline void arch_spin_unlock(arch_spinlock_t *lock) { smp_mb(); asm volatile (" SETD [%0], %1\n" : : "da" (&lock->lock), "da" (0) : "memory"); }

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/* * RWLOCKS * * * Write locks are easy - we just set bit 31. When unlocking, we can * just write zero since the lock is exclusively held. */
static inline void arch_write_lock(arch_rwlock_t *rw) { int tmp; asm volatile ("1: LNKGETD %0,[%1]\n" " CMP %0, #0\n" " ADD %0, %0, %2\n" " LNKSETDZ [%1], %0\n" " BNZ 1b\n" " DEFR %0, TXSTAT\n" " ANDT %0, %0, #HI(0x3f000000)\n" " CMPT %0, #HI(0x02000000)\n" " BNZ 1b\n" : "=&d" (tmp) : "da" (&rw->lock), "bd" (0x80000000) : "cc"); smp_mb(); }

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static inline int arch_write_trylock(arch_rwlock_t *rw) { int tmp; asm volatile (" LNKGETD %0,[%1]\n" " CMP %0, #0\n" " ADD %0, %0, %2\n" " LNKSETDZ [%1], %0\n" " BNZ 1f\n" " DEFR %0, TXSTAT\n" " ANDT %0, %0, #HI(0x3f000000)\n" " CMPT %0, #HI(0x02000000)\n" " MOV %0,#1\n" "1: XORNZ %0, %0, %0\n" : "=&d" (tmp) : "da" (&rw->lock), "bd" (0x80000000) : "cc"); smp_mb(); return tmp; }

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static inline void arch_write_unlock(arch_rwlock_t *rw) { smp_mb(); asm volatile (" SETD [%0], %1\n" : : "da" (&rw->lock), "da" (0) : "memory"); }

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/* write_can_lock - would write_trylock() succeed? */
static inline int arch_write_can_lock(arch_rwlock_t *rw) { int ret; asm volatile ("LNKGETD %0, [%1]\n" "CMP %0, #0\n" "MOV %0, #1\n" "XORNZ %0, %0, %0\n" : "=&d" (ret) : "da" (&rw->lock) : "cc"); return ret; }

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/* * Read locks are a bit more hairy: * - Exclusively load the lock value. * - Increment it. * - Store new lock value if positive, and we still own this location. * If the value is negative, we've already failed. * - If we failed to store the value, we want a negative result. * - If we failed, try again. * Unlocking is similarly hairy. We may have multiple read locks * currently active. However, we know we won't have any write * locks. */
static inline void arch_read_lock(arch_rwlock_t *rw) { int tmp; asm volatile ("1: LNKGETD %0,[%1]\n" " ADDS %0, %0, #1\n" " LNKSETDPL [%1], %0\n" " BMI 1b\n" " DEFR %0, TXSTAT\n" " ANDT %0, %0, #HI(0x3f000000)\n" " CMPT %0, #HI(0x02000000)\n" " BNZ 1b\n" : "=&d" (tmp) : "da" (&rw->lock) : "cc"); smp_mb(); }

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static inline void arch_read_unlock(arch_rwlock_t *rw) { int tmp; smp_mb(); asm volatile ("1: LNKGETD %0,[%1]\n" " SUB %0, %0, #1\n" " LNKSETD [%1], %0\n" " DEFR %0, TXSTAT\n" " ANDT %0, %0, #HI(0x3f000000)\n" " CMPT %0, #HI(0x02000000)\n" " BNZ 1b\n" : "=&d" (tmp) : "da" (&rw->lock) : "cc", "memory"); }

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static inline int arch_read_trylock(arch_rwlock_t *rw) { int tmp; asm volatile (" LNKGETD %0,[%1]\n" " ADDS %0, %0, #1\n" " LNKSETDPL [%1], %0\n" " BMI 1f\n" " DEFR %0, TXSTAT\n" " ANDT %0, %0, #HI(0x3f000000)\n" " CMPT %0, #HI(0x02000000)\n" " MOV %0,#1\n" " BZ 2f\n" "1: MOV %0,#0\n" "2:\n" : "=&d" (tmp) : "da" (&rw->lock) : "cc"); smp_mb(); return tmp; }

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/* read_can_lock - would read_trylock() succeed? */
static inline int arch_read_can_lock(arch_rwlock_t *rw) { int tmp; asm volatile ("LNKGETD %0, [%1]\n" "CMP %0, %2\n" "MOV %0, #1\n" "XORZ %0, %0, %0\n" : "=&d" (tmp) : "da" (&rw->lock), "bd" (0x80000000) : "cc"); return tmp; }

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#define arch_read_lock_flags(lock, flags) arch_read_lock(lock) #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) #define arch_spin_relax(lock) cpu_relax() #define arch_read_relax(lock) cpu_relax() #define arch_write_relax(lock) cpu_relax() #endif /* __ASM_SPINLOCK_LNKGET_H */

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