cregit-Linux how code gets into the kernel

Release 4.14 arch/alpha/include/asm/xchg.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ALPHA_CMPXCHG_H
#error Do not include xchg.h directly!
#else
/*
 * xchg/xchg_local and cmpxchg/cmpxchg_local share the same code
 * except that local version do not have the expensive memory barrier.
 * So this file is included twice from asm/cmpxchg.h.
 */

/*
 * Atomic exchange.
 * Since it can be used to implement critical sections
 * it must clobber "memory" (also for interrupts in UP).
 */


static inline unsigned long ____xchg(_u8, volatile char *m, unsigned long val) { unsigned long ret, tmp, addr64; __asm__ __volatile__( " andnot %4,7,%3\n" " insbl %1,%4,%1\n" "1: ldq_l %2,0(%3)\n" " extbl %2,%4,%0\n" " mskbl %2,%4,%2\n" " or %1,%2,%2\n" " stq_c %2,0(%3)\n" " beq %2,2f\n" __ASM__MB ".subsection 2\n" "2: br 1b\n" ".previous" : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64) : "r" ((long)m), "1" (val) : "memory"); return ret; }

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Ivan Kokshaysky33100.00%1100.00%
Total33100.00%1100.00%


static inline unsigned long ____xchg(_u16, volatile short *m, unsigned long val) { unsigned long ret, tmp, addr64; __asm__ __volatile__( " andnot %4,7,%3\n" " inswl %1,%4,%1\n" "1: ldq_l %2,0(%3)\n" " extwl %2,%4,%0\n" " mskwl %2,%4,%2\n" " or %1,%2,%2\n" " stq_c %2,0(%3)\n" " beq %2,2f\n" __ASM__MB ".subsection 2\n" "2: br 1b\n" ".previous" : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64) : "r" ((long)m), "1" (val) : "memory"); return ret; }

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PersonTokensPropCommitsCommitProp
Ivan Kokshaysky33100.00%1100.00%
Total33100.00%1100.00%


static inline unsigned long ____xchg(_u32, volatile int *m, unsigned long val) { unsigned long dummy; __asm__ __volatile__( "1: ldl_l %0,%4\n" " bis $31,%3,%1\n" " stl_c %1,%2\n" " beq %1,2f\n" __ASM__MB ".subsection 2\n" "2: br 1b\n" ".previous" : "=&r" (val), "=&r" (dummy), "=m" (*m) : "rI" (val), "m" (*m) : "memory"); return val; }

Contributors

PersonTokensPropCommitsCommitProp
Ivan Kokshaysky29100.00%1100.00%
Total29100.00%1100.00%


static inline unsigned long ____xchg(_u64, volatile long *m, unsigned long val) { unsigned long dummy; __asm__ __volatile__( "1: ldq_l %0,%4\n" " bis $31,%3,%1\n" " stq_c %1,%2\n" " beq %1,2f\n" __ASM__MB ".subsection 2\n" "2: br 1b\n" ".previous" : "=&r" (val), "=&r" (dummy), "=m" (*m) : "rI" (val), "m" (*m) : "memory"); return val; }

Contributors

PersonTokensPropCommitsCommitProp
Ivan Kokshaysky29100.00%1100.00%
Total29100.00%1100.00%

/* This function doesn't exist, so you'll get a linker error if something tries to do an invalid xchg(). */ extern void __xchg_called_with_bad_pointer(void);
static __always_inline unsigned long ____xchg(, volatile void *ptr, unsigned long x, int size) { switch (size) { case 1: return ____xchg(_u8, ptr, x); case 2: return ____xchg(_u16, ptr, x); case 4: return ____xchg(_u32, ptr, x); case 8: return ____xchg(_u64, ptr, x); } __xchg_called_with_bad_pointer(); return x; }

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Ivan Kokshaysky85100.00%1100.00%
Total85100.00%1100.00%

/* * Atomic compare and exchange. Compare OLD with MEM, if identical, * store NEW in MEM. Return the initial value in MEM. Success is * indicated by comparing RETURN with OLD. * * The memory barrier should be placed in SMP only when we actually * make the change. If we don't change anything (so if the returned * prev is equal to old) then we aren't acquiring anything new and * we don't need any memory barrier as far I can tell. */
static inline unsigned long ____cmpxchg(_u8, volatile char *m, unsigned char old, unsigned char new) { unsigned long prev, tmp, cmp, addr64; __asm__ __volatile__( " andnot %5,7,%4\n" " insbl %1,%5,%1\n" "1: ldq_l %2,0(%4)\n" " extbl %2,%5,%0\n" " cmpeq %0,%6,%3\n" " beq %3,2f\n" " mskbl %2,%5,%2\n" " or %1,%2,%2\n" " stq_c %2,0(%4)\n" " beq %2,3f\n" __ASM__MB "2:\n" ".subsection 2\n" "3: br 1b\n" ".previous" : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64) : "r" ((long)m), "Ir" (old), "1" (new) : "memory"); return prev; }

Contributors

PersonTokensPropCommitsCommitProp
Ivan Kokshaysky39100.00%1100.00%
Total39100.00%1100.00%


static inline unsigned long ____cmpxchg(_u16, volatile short *m, unsigned short old, unsigned short new) { unsigned long prev, tmp, cmp, addr64; __asm__ __volatile__( " andnot %5,7,%4\n" " inswl %1,%5,%1\n" "1: ldq_l %2,0(%4)\n" " extwl %2,%5,%0\n" " cmpeq %0,%6,%3\n" " beq %3,2f\n" " mskwl %2,%5,%2\n" " or %1,%2,%2\n" " stq_c %2,0(%4)\n" " beq %2,3f\n" __ASM__MB "2:\n" ".subsection 2\n" "3: br 1b\n" ".previous" : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64) : "r" ((long)m), "Ir" (old), "1" (new) : "memory"); return prev; }

Contributors

PersonTokensPropCommitsCommitProp
Ivan Kokshaysky39100.00%1100.00%
Total39100.00%1100.00%


static inline unsigned long ____cmpxchg(_u32, volatile int *m, int old, int new) { unsigned long prev, cmp; __asm__ __volatile__( "1: ldl_l %0,%5\n" " cmpeq %0,%3,%1\n" " beq %1,2f\n" " mov %4,%1\n" " stl_c %1,%2\n" " beq %1,3f\n" __ASM__MB "2:\n" ".subsection 2\n" "3: br 1b\n" ".previous" : "=&r"(prev), "=&r"(cmp), "=m"(*m) : "r"((long) old), "r"(new), "m"(*m) : "memory"); return prev; }

Contributors

PersonTokensPropCommitsCommitProp
Ivan Kokshaysky33100.00%1100.00%
Total33100.00%1100.00%


static inline unsigned long ____cmpxchg(_u64, volatile long *m, unsigned long old, unsigned long new) { unsigned long prev, cmp; __asm__ __volatile__( "1: ldq_l %0,%5\n" " cmpeq %0,%3,%1\n" " beq %1,2f\n" " mov %4,%1\n" " stq_c %1,%2\n" " beq %1,3f\n" __ASM__MB "2:\n" ".subsection 2\n" "3: br 1b\n" ".previous" : "=&r"(prev), "=&r"(cmp), "=m"(*m) : "r"((long) old), "r"(new), "m"(*m) : "memory"); return prev; }

Contributors

PersonTokensPropCommitsCommitProp
Ivan Kokshaysky35100.00%1100.00%
Total35100.00%1100.00%

/* This function doesn't exist, so you'll get a linker error if something tries to do an invalid cmpxchg(). */ extern void __cmpxchg_called_with_bad_pointer(void);
static __always_inline unsigned long ____cmpxchg(, volatile void *ptr, unsigned long old, unsigned long new, int size) { switch (size) { case 1: return ____cmpxchg(_u8, ptr, old, new); case 2: return ____cmpxchg(_u16, ptr, old, new); case 4: return ____cmpxchg(_u32, ptr, old, new); case 8: return ____cmpxchg(_u64, ptr, old, new); } __cmpxchg_called_with_bad_pointer(); return old; }

Contributors

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Ivan Kokshaysky97100.00%1100.00%
Total97100.00%1100.00%

#endif

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Ivan Kokshaysky47999.38%133.33%
Paul Gortmaker20.41%133.33%
Greg Kroah-Hartman10.21%133.33%
Total482100.00%3100.00%
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