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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/tools/testing/selftests/bpf/bpf_arena_alloc.h
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/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */

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/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */

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#pragma once

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#include "bpf_arena_common.h"

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#ifndef __round_mask

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#define __round_mask(x, y) ((__typeof__(x))((y)-1))

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#endif

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#ifndef round_up

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#define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)

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#endif

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#ifdef __BPF__

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#define NR_CPUS (sizeof(struct cpumask) * 8)

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static void __arena * __arena page_frag_cur_page[NR_CPUS];

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static int __arena page_frag_cur_offset[NR_CPUS];

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/* Simple page_frag allocator */

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static inline void __arena* bpf_alloc(unsigned int size)

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{

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	__u64 __arena *obj_cnt;

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	__u32 cpu = bpf_get_smp_processor_id();

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	void __arena *page = page_frag_cur_page[cpu];

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	int __arena *cur_offset = &page_frag_cur_offset[cpu];

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	int offset;

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	size = round_up(size, 8);

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	if (size >= PAGE_SIZE - 8)

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		return NULL;

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	if (!page) {

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refill:

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		page = bpf_arena_alloc_pages(&arena, NULL, 1, NUMA_NO_NODE, 0);

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		if (!page)

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			return NULL;

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		cast_kern(page);

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		page_frag_cur_page[cpu] = page;

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		*cur_offset = PAGE_SIZE - 8;

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		obj_cnt = page + PAGE_SIZE - 8;

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		*obj_cnt = 0;

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	} else {

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		cast_kern(page);

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		obj_cnt = page + PAGE_SIZE - 8;

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	}

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	offset = *cur_offset - size;

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	if (offset < 0)

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		goto refill;

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	(*obj_cnt)++;

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	*cur_offset = offset;

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	return page + offset;

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}

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static inline void bpf_free(void __arena *addr)

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{

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	__u64 __arena *obj_cnt;

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	addr = (void __arena *)(((long)addr) & ~(PAGE_SIZE - 1));

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	obj_cnt = addr + PAGE_SIZE - 8;

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	if (--(*obj_cnt) == 0)

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		bpf_arena_free_pages(&arena, addr, 1);

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}

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#else

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static inline void __arena* bpf_alloc(unsigned int size) { return NULL; }

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static inline void bpf_free(void __arena *addr) {}

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#endif

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