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Alexei Starovoitovanakryiko
Alexei Starovoitov
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anakryiko
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selftests/bpf: Add bpf_arena_htab test.
bpf_arena_htab.h - hash table implemented as bpf program Signed-off-by: Alexei Starovoitov <[email protected]> Signed-off-by: Andrii Nakryiko <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
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‎tools/testing/selftests/bpf/DENYLIST.aarch64‎

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@@ -11,3 +11,4 @@ fill_link_info/kretprobe_multi_link_info # bpf_program__attach_kprobe_mu
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fill_link_info/kprobe_multi_invalid_ubuff # bpf_program__attach_kprobe_multi_opts unexpected error: -95
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missed/kprobe_recursion # missed_kprobe_recursion__attach unexpected error: -95 (errno 95)
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verifier_arena # JIT does not support arena
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arena_htab # JIT does not support arena

‎tools/testing/selftests/bpf/DENYLIST.s390x‎

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@@ -5,3 +5,4 @@ get_stack_raw_tp # user_stack corrupted user stack
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stacktrace_build_id # compare_map_keys stackid_hmap vs. stackmap err -2 errno 2 (?)
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verifier_iterating_callbacks
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verifier_arena # JIT does not support arena
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arena_htab # JIT does not support arena

‎tools/testing/selftests/bpf/bpf_arena_htab.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 <errno.h>
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#include "bpf_arena_alloc.h"
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#include "bpf_arena_list.h"
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struct htab_bucket {
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struct arena_list_head head;
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};
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typedef struct htab_bucket __arena htab_bucket_t;
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struct htab {
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htab_bucket_t *buckets;
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int n_buckets;
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};
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typedef struct htab __arena htab_t;
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static inline htab_bucket_t *__select_bucket(htab_t *htab, __u32 hash)
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{
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htab_bucket_t *b = htab->buckets;
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cast_kern(b);
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return &b[hash & (htab->n_buckets - 1)];
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}
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static inline arena_list_head_t *select_bucket(htab_t *htab, __u32 hash)
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{
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return &__select_bucket(htab, hash)->head;
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}
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struct hashtab_elem {
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int hash;
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int key;
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int value;
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struct arena_list_node hash_node;
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};
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typedef struct hashtab_elem __arena hashtab_elem_t;
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static hashtab_elem_t *lookup_elem_raw(arena_list_head_t *head, __u32 hash, int key)
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{
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hashtab_elem_t *l;
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list_for_each_entry(l, head, hash_node)
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if (l->hash == hash && l->key == key)
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return l;
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return NULL;
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}
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static int htab_hash(int key)
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{
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return key;
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}
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__weak int htab_lookup_elem(htab_t *htab __arg_arena, int key)
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{
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hashtab_elem_t *l_old;
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arena_list_head_t *head;
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cast_kern(htab);
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head = select_bucket(htab, key);
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l_old = lookup_elem_raw(head, htab_hash(key), key);
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if (l_old)
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return l_old->value;
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return 0;
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}
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__weak int htab_update_elem(htab_t *htab __arg_arena, int key, int value)
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{
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hashtab_elem_t *l_new = NULL, *l_old;
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arena_list_head_t *head;
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cast_kern(htab);
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head = select_bucket(htab, key);
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l_old = lookup_elem_raw(head, htab_hash(key), key);
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l_new = bpf_alloc(sizeof(*l_new));
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if (!l_new)
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return -ENOMEM;
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l_new->key = key;
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l_new->hash = htab_hash(key);
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l_new->value = value;
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list_add_head(&l_new->hash_node, head);
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if (l_old) {
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list_del(&l_old->hash_node);
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bpf_free(l_old);
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}
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return 0;
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}
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void htab_init(htab_t *htab)
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{
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void __arena *buckets = bpf_arena_alloc_pages(&arena, NULL, 2, NUMA_NO_NODE, 0);
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cast_user(buckets);
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htab->buckets = buckets;
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htab->n_buckets = 2 * PAGE_SIZE / sizeof(struct htab_bucket);
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}

‎tools/testing/selftests/bpf/prog_tests/arena_htab.c‎

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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
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#include <test_progs.h>
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#include <sys/mman.h>
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#include <network_helpers.h>
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#include "arena_htab_asm.skel.h"
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#include "arena_htab.skel.h"
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#define PAGE_SIZE 4096
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#include "bpf_arena_htab.h"
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static void test_arena_htab_common(struct htab *htab)
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{
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int i;
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printf("htab %p buckets %p n_buckets %d\n", htab, htab->buckets, htab->n_buckets);
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ASSERT_OK_PTR(htab->buckets, "htab->buckets shouldn't be NULL");
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for (i = 0; htab->buckets && i < 16; i += 4) {
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/*
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* Walk htab buckets and link lists since all pointers are correct,
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* though they were written by bpf program.
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*/
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int val = htab_lookup_elem(htab, i);
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ASSERT_EQ(i, val, "key == value");
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}
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}
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static void test_arena_htab_llvm(void)
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{
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LIBBPF_OPTS(bpf_test_run_opts, opts);
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struct arena_htab *skel;
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struct htab *htab;
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size_t arena_sz;
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void *area;
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int ret;
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skel = arena_htab__open_and_load();
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if (!ASSERT_OK_PTR(skel, "arena_htab__open_and_load"))
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return;
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area = bpf_map__initial_value(skel->maps.arena, &arena_sz);
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/* fault-in a page with pgoff == 0 as sanity check */
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*(volatile int *)area = 0x55aa;
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/* bpf prog will allocate more pages */
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ret = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.arena_htab_llvm), &opts);
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ASSERT_OK(ret, "ret");
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ASSERT_OK(opts.retval, "retval");
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if (skel->bss->skip) {
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printf("%s:SKIP:compiler doesn't support arena_cast\n", __func__);
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test__skip();
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goto out;
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}
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htab = skel->bss->htab_for_user;
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test_arena_htab_common(htab);
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out:
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arena_htab__destroy(skel);
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}
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static void test_arena_htab_asm(void)
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{
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LIBBPF_OPTS(bpf_test_run_opts, opts);
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struct arena_htab_asm *skel;
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struct htab *htab;
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int ret;
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skel = arena_htab_asm__open_and_load();
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if (!ASSERT_OK_PTR(skel, "arena_htab_asm__open_and_load"))
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return;
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ret = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.arena_htab_asm), &opts);
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ASSERT_OK(ret, "ret");
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ASSERT_OK(opts.retval, "retval");
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htab = skel->bss->htab_for_user;
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test_arena_htab_common(htab);
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arena_htab_asm__destroy(skel);
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}
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void test_arena_htab(void)
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{
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if (test__start_subtest("arena_htab_llvm"))
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test_arena_htab_llvm();
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if (test__start_subtest("arena_htab_asm"))
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test_arena_htab_asm();
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}

‎tools/testing/selftests/bpf/progs/arena_htab.c‎

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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
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#include <vmlinux.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include <bpf/bpf_core_read.h>
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#include "bpf_experimental.h"
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struct {
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__uint(type, BPF_MAP_TYPE_ARENA);
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__uint(map_flags, BPF_F_MMAPABLE);
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__uint(max_entries, 100); /* number of pages */
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} arena SEC(".maps");
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#include "bpf_arena_htab.h"
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void __arena *htab_for_user;
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bool skip = false;
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int zero = 0;
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SEC("syscall")
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int arena_htab_llvm(void *ctx)
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{
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#if defined(__BPF_FEATURE_ARENA_CAST) || defined(BPF_ARENA_FORCE_ASM)
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struct htab __arena *htab;
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__u64 i;
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htab = bpf_alloc(sizeof(*htab));
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cast_kern(htab);
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htab_init(htab);
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/* first run. No old elems in the table */
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for (i = zero; i < 1000; i++)
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htab_update_elem(htab, i, i);
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/* should replace all elems with new ones */
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for (i = zero; i < 1000; i++)
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htab_update_elem(htab, i, i);
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cast_user(htab);
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htab_for_user = htab;
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#else
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skip = true;
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#endif
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return 0;
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}
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char _license[] SEC("license") = "GPL";

‎tools/testing/selftests/bpf/progs/arena_htab_asm.c‎

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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
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#define BPF_ARENA_FORCE_ASM
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#define arena_htab_llvm arena_htab_asm
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#include "arena_htab.c"

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