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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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49a7d46a06
This implements smp_cond_load_relaxed() with the slowpath busy loop using the preferred SMT priority pattern. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Acked-by: Waiman Long <longman@redhat.com> [mpe: Make it 64-bit only to fix build errors on 32-bit] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200724131423.1362108-7-npiggin@gmail.com
132 lines
4.2 KiB
C
132 lines
4.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
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*/
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#ifndef _ASM_POWERPC_BARRIER_H
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#define _ASM_POWERPC_BARRIER_H
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#include <asm/asm-const.h>
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#ifndef __ASSEMBLY__
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#include <asm/ppc-opcode.h>
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#endif
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/*
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* Memory barrier.
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* The sync instruction guarantees that all memory accesses initiated
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* by this processor have been performed (with respect to all other
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* mechanisms that access memory). The eieio instruction is a barrier
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* providing an ordering (separately) for (a) cacheable stores and (b)
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* loads and stores to non-cacheable memory (e.g. I/O devices).
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*
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* mb() prevents loads and stores being reordered across this point.
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* rmb() prevents loads being reordered across this point.
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* wmb() prevents stores being reordered across this point.
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*
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* *mb() variants without smp_ prefix must order all types of memory
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* operations with one another. sync is the only instruction sufficient
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* to do this.
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*
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* For the smp_ barriers, ordering is for cacheable memory operations
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* only. We have to use the sync instruction for smp_mb(), since lwsync
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* doesn't order loads with respect to previous stores. Lwsync can be
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* used for smp_rmb() and smp_wmb().
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*
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* However, on CPUs that don't support lwsync, lwsync actually maps to a
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* heavy-weight sync, so smp_wmb() can be a lighter-weight eieio.
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*/
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#define mb() __asm__ __volatile__ ("sync" : : : "memory")
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#define rmb() __asm__ __volatile__ ("sync" : : : "memory")
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#define wmb() __asm__ __volatile__ ("sync" : : : "memory")
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/* The sub-arch has lwsync */
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#if defined(__powerpc64__) || defined(CONFIG_PPC_E500MC)
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# define SMPWMB LWSYNC
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#else
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# define SMPWMB eieio
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#endif
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#define __lwsync() __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory")
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#define dma_rmb() __lwsync()
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#define dma_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
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#define __smp_lwsync() __lwsync()
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#define __smp_mb() mb()
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#define __smp_rmb() __lwsync()
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#define __smp_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
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/*
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* This is a barrier which prevents following instructions from being
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* started until the value of the argument x is known. For example, if
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* x is a variable loaded from memory, this prevents following
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* instructions from being executed until the load has been performed.
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*/
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#define data_barrier(x) \
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asm volatile("twi 0,%0,0; isync" : : "r" (x) : "memory");
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#define __smp_store_release(p, v) \
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do { \
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compiletime_assert_atomic_type(*p); \
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__smp_lwsync(); \
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WRITE_ONCE(*p, v); \
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} while (0)
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#define __smp_load_acquire(p) \
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({ \
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typeof(*p) ___p1 = READ_ONCE(*p); \
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compiletime_assert_atomic_type(*p); \
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__smp_lwsync(); \
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___p1; \
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})
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#ifdef CONFIG_PPC64
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#define smp_cond_load_relaxed(ptr, cond_expr) ({ \
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typeof(ptr) __PTR = (ptr); \
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__unqual_scalar_typeof(*ptr) VAL; \
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VAL = READ_ONCE(*__PTR); \
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if (unlikely(!(cond_expr))) { \
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spin_begin(); \
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do { \
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VAL = READ_ONCE(*__PTR); \
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} while (!(cond_expr)); \
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spin_end(); \
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} \
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(typeof(*ptr))VAL; \
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})
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#endif
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#ifdef CONFIG_PPC_BOOK3S_64
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#define NOSPEC_BARRIER_SLOT nop
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#elif defined(CONFIG_PPC_FSL_BOOK3E)
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#define NOSPEC_BARRIER_SLOT nop; nop
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#endif
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#ifdef CONFIG_PPC_BARRIER_NOSPEC
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/*
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* Prevent execution of subsequent instructions until preceding branches have
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* been fully resolved and are no longer executing speculatively.
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*/
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#define barrier_nospec_asm NOSPEC_BARRIER_FIXUP_SECTION; NOSPEC_BARRIER_SLOT
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// This also acts as a compiler barrier due to the memory clobber.
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#define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "memory")
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#else /* !CONFIG_PPC_BARRIER_NOSPEC */
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#define barrier_nospec_asm
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#define barrier_nospec()
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#endif /* CONFIG_PPC_BARRIER_NOSPEC */
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/*
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* pmem_wmb() ensures that all stores for which the modification
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* are written to persistent storage by preceding dcbfps/dcbstps
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* instructions have updated persistent storage before any data
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* access or data transfer caused by subsequent instructions is
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* initiated.
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*/
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#define pmem_wmb() __asm__ __volatile__(PPC_PHWSYNC ::: "memory")
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#include <asm-generic/barrier.h>
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#endif /* _ASM_POWERPC_BARRIER_H */
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