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4dd3f50af4
Follow-up to kernel commit 6c9059817432 ("bpf: pre-allocate hash map
elements"). Add flags support, so that we can pass in BPF_F_NO_PREALLOC
flag for disallowing preallocation. Update examples accordingly and also
remove the BPF_* map helper macros from them as they were not very useful.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
54 lines
1.4 KiB
C
54 lines
1.4 KiB
C
#include "../../include/bpf_api.h"
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/* Minimal, stand-alone toy map pinning example:
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*
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* clang -target bpf -O2 [...] -o bpf_shared.o -c bpf_shared.c
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* tc filter add dev foo parent 1: bpf obj bpf_shared.o sec egress
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* tc filter add dev foo parent ffff: bpf obj bpf_shared.o sec ingress
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*
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* Both classifier will share the very same map instance in this example,
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* so map content can be accessed from ingress *and* egress side!
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*
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* This example has a pinning of PIN_OBJECT_NS, so it's private and
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* thus shared among various program sections within the object.
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*
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* A setting of PIN_GLOBAL_NS would place it into a global namespace,
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* so that it can be shared among different object files. A setting
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* of PIN_NONE (= 0) means no sharing, so each tc invocation a new map
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* instance is being created.
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*/
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struct bpf_elf_map __section_maps map_sh = {
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.type = BPF_MAP_TYPE_ARRAY,
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.size_key = sizeof(uint32_t),
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.size_value = sizeof(uint32_t),
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.pinning = PIN_OBJECT_NS, /* or PIN_GLOBAL_NS, or PIN_NONE */
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.max_elem = 1,
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};
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__section("egress")
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int emain(struct __sk_buff *skb)
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{
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int key = 0, *val;
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val = map_lookup_elem(&map_sh, &key);
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if (val)
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lock_xadd(val, 1);
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return BPF_H_DEFAULT;
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}
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__section("ingress")
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int imain(struct __sk_buff *skb)
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{
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int key = 0, *val;
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val = map_lookup_elem(&map_sh, &key);
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if (val)
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printt("map val: %d\n", *val);
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return BPF_H_DEFAULT;
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}
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BPF_LICENSE("GPL");
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