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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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1159517253
Optimized version that make use of the l.lwa and l.swa atomic instruction pair. Most openrisc cores provide these instructions now, if not available emulation is provided. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> [shorne@gmail.com: remove OPENRISC_HAVE_INST_LWA_SWA config suggesed by Alan Cox https://lkml.org/lkml/2014/7/23/666] [shorne@gmail.com: fixed unused calculated value compiler warning in define cmpxchg] Signed-off-by: Stafford Horne <shorne@gmail.com>
84 lines
1.8 KiB
C
84 lines
1.8 KiB
C
/*
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* Copyright (C) 2014 Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
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*
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* This file is licensed under the terms of the GNU General Public License
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* version 2. This program is licensed "as is" without any warranty of any
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* kind, whether express or implied.
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*/
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#ifndef __ASM_OPENRISC_CMPXCHG_H
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#define __ASM_OPENRISC_CMPXCHG_H
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#include <linux/types.h>
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/*
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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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*/
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extern void __cmpxchg_called_with_bad_pointer(void);
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#define __HAVE_ARCH_CMPXCHG 1
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static inline unsigned long
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__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
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{
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if (size != 4) {
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__cmpxchg_called_with_bad_pointer();
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return old;
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}
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__asm__ __volatile__(
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"1: l.lwa %0, 0(%1) \n"
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" l.sfeq %0, %2 \n"
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" l.bnf 2f \n"
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" l.nop \n"
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" l.swa 0(%1), %3 \n"
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" l.bnf 1b \n"
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" l.nop \n"
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"2: \n"
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: "=&r"(old)
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: "r"(ptr), "r"(old), "r"(new)
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: "cc", "memory");
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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))) __cmpxchg((ptr), \
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(unsigned long)(o), \
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(unsigned long)(n), \
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sizeof(*(ptr))); \
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})
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/*
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* This function doesn't exist, so you'll get a linker error if
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* something tries to do an invalidly-sized xchg().
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*/
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extern void __xchg_called_with_bad_pointer(void);
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static inline unsigned long __xchg(unsigned long val, volatile void *ptr,
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int size)
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{
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if (size != 4) {
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__xchg_called_with_bad_pointer();
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return val;
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}
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__asm__ __volatile__(
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"1: l.lwa %0, 0(%1) \n"
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" l.swa 0(%1), %2 \n"
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" l.bnf 1b \n"
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" l.nop \n"
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: "=&r"(val)
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: "r"(ptr), "r"(val)
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: "cc", "memory");
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return val;
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}
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#define xchg(ptr, with) \
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((typeof(*(ptr)))__xchg((unsigned long)(with), (ptr), sizeof(*(ptr))))
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#endif /* __ASM_OPENRISC_CMPXCHG_H */
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