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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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3226aad81a
This completes the xchg implementation for sh architecture. Note: The llsc variant is tricky since this only supports 4 byte atomics, the existing implementation of 1 byte xchg is wrong: we need to do a 4 byte cmpxchg and retry if any bytes changed meanwhile. Write this in C for clarity. Suggested-by: Rich Felker <dalias@libc.org> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
72 lines
1.7 KiB
C
72 lines
1.7 KiB
C
#ifndef __ASM_SH_CMPXCHG_H
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#define __ASM_SH_CMPXCHG_H
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/*
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* Atomic operations that C can't guarantee us. Useful for
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* resource counting etc..
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*/
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#include <linux/compiler.h>
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#include <linux/types.h>
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#if defined(CONFIG_GUSA_RB)
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#include <asm/cmpxchg-grb.h>
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#elif defined(CONFIG_CPU_SH4A)
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#include <asm/cmpxchg-llsc.h>
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#else
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#include <asm/cmpxchg-irq.h>
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#endif
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extern void __xchg_called_with_bad_pointer(void);
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#define __xchg(ptr, x, size) \
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({ \
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unsigned long __xchg__res; \
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volatile void *__xchg_ptr = (ptr); \
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switch (size) { \
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case 4: \
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__xchg__res = xchg_u32(__xchg_ptr, x); \
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break; \
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case 2: \
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__xchg__res = xchg_u16(__xchg_ptr, x); \
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break; \
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case 1: \
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__xchg__res = xchg_u8(__xchg_ptr, x); \
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break; \
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default: \
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__xchg_called_with_bad_pointer(); \
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__xchg__res = x; \
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break; \
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} \
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\
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__xchg__res; \
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})
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#define xchg(ptr,x) \
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((__typeof__(*(ptr)))__xchg((ptr),(unsigned long)(x), sizeof(*(ptr))))
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/* This function doesn't exist, so you'll get a linker error
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* if something tries to do an invalid cmpxchg(). */
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extern void __cmpxchg_called_with_bad_pointer(void);
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static inline unsigned long __cmpxchg(volatile void * ptr, unsigned long old,
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unsigned long new, int size)
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{
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switch (size) {
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case 4:
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return __cmpxchg_u32(ptr, old, new);
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}
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__cmpxchg_called_with_bad_pointer();
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return old;
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}
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#define cmpxchg(ptr,o,n) \
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({ \
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__typeof__(*(ptr)) _o_ = (o); \
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__typeof__(*(ptr)) _n_ = (n); \
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(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \
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(unsigned long)_n_, sizeof(*(ptr))); \
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})
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#endif /* __ASM_SH_CMPXCHG_H */
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