cregit-Linux how code gets into the kernel

Release 4.10 arch/x86/include/asm/pmem.h

/*
 * Copyright(c) 2015 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */
#ifndef __ASM_X86_PMEM_H__

#define __ASM_X86_PMEM_H__

#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/cpufeature.h>
#include <asm/special_insns.h>

#ifdef CONFIG_ARCH_HAS_PMEM_API
/**
 * arch_memcpy_to_pmem - copy data to persistent memory
 * @dst: destination buffer for the copy
 * @src: source buffer for the copy
 * @n: length of the copy in bytes
 *
 * Copy data to persistent memory media via non-temporal stores so that
 * a subsequent pmem driver flush operation will drain posted write queues.
 */

static inline void arch_memcpy_to_pmem(void *dst, const void *src, size_t n) { int rem; /* * We are copying between two kernel buffers, if * __copy_from_user_inatomic_nocache() returns an error (page * fault) we would have already reported a general protection fault * before the WARN+BUG. */ rem = __copy_from_user_inatomic_nocache(dst, (void __user *) src, n); if (WARN(rem, "%s: fault copying %p <- %p unwritten: %d\n", __func__, dst, src, rem)) BUG(); }

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static inline int arch_memcpy_from_pmem(void *dst, const void *src, size_t n) { return memcpy_mcsafe(dst, src, n); }

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/** * arch_wb_cache_pmem - write back a cache range with CLWB * @vaddr: virtual start address * @size: number of bytes to write back * * Write back a cache range using the CLWB (cache line write back) * instruction. */
static inline void arch_wb_cache_pmem(void *addr, size_t size) { u16 x86_clflush_size = boot_cpu_data.x86_clflush_size; unsigned long clflush_mask = x86_clflush_size - 1; void *vend = addr + size; void *p; for (p = (void *)((unsigned long)addr & ~clflush_mask); p < vend; p += x86_clflush_size) clwb(p); }

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/* * copy_from_iter_nocache() on x86 only uses non-temporal stores for iovec * iterators, so for other types (bvec & kvec) we must do a cache write-back. */
static inline bool __iter_needs_pmem_wb(struct iov_iter *i) { return iter_is_iovec(i) == false; }

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/** * arch_copy_from_iter_pmem - copy data from an iterator to PMEM * @addr: PMEM destination address * @bytes: number of bytes to copy * @i: iterator with source data * * Copy data from the iterator 'i' to the PMEM buffer starting at 'addr'. */
static inline size_t arch_copy_from_iter_pmem(void *addr, size_t bytes, struct iov_iter *i) { size_t len; /* TODO: skip the write-back by always using non-temporal stores */ len = copy_from_iter_nocache(addr, bytes, i); if (__iter_needs_pmem_wb(i)) arch_wb_cache_pmem(addr, bytes); return len; }

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/** * arch_clear_pmem - zero a PMEM memory range * @addr: virtual start address * @size: number of bytes to zero * * Write zeros into the memory range starting at 'addr' for 'size' bytes. */
static inline void arch_clear_pmem(void *addr, size_t size) { memset(addr, 0, size); arch_wb_cache_pmem(addr, size); }

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static inline void arch_invalidate_pmem(void *addr, size_t size) { clflush_cache_range(addr, size); }

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#endif /* CONFIG_ARCH_HAS_PMEM_API */ #endif /* __ASM_X86_PMEM_H__ */

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