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Hi everyone, I have a strange problem trying to store a map in the map. struct client_inner_map {
__uint(type, BPF_MAP_TYPE_LRU_HASH);
__uint(max_entries, MAX_MAP_ENTRIES);
__type(key, __u16); // dstport
__type(value, struct in6_addr[10]);
} client_inner_map SEC(".maps");
struct client_outer_map {
__uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
__uint(max_entries, MAX_MAP_ENTRIES);
__uint(pinning, LIBBPF_PIN_BY_NAME);
__type(key, __u32); // domain_name id
__array(values, struct client_inner_map);
} client_outer_map SEC(".maps"); definition in my userspace application: func NewClientMap() *ClientMap {
outerMapSpec := &ebpf.MapSpec{
Name: "client_outer_map",
Type: ebpf.HashOfMaps,
KeySize: 4,
ValueSize: 4,
MaxEntries: 1024,
Pinning: ebpf.PinByName,
Contents: make([]ebpf.MapKV, len(config.Params.Services)),
InnerMap: &ebpf.MapSpec{
Name: "client_inner_map",
Type: ebpf.LRUHash,
KeySize: 2,
ValueSize: 160,
MaxEntries: 1,
},
}
return &ClientMap{
outerMapSpec: outerMapSpec,
}
}This has worked completely fine. struct sidlist_data {
__u32 sidlist_size;
struct in6_addr sidlist[10];
};
struct client_inner_map {
__uint(type, BPF_MAP_TYPE_LRU_HASH);
__uint(max_entries, MAX_MAP_ENTRIES);
__type(key, __u16);
__type(value, struct sidlist_data);
} client_inner_map SEC(".maps");
struct client_outer_map {
__uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
__uint(max_entries, MAX_MAP_ENTRIES);
__uint(pinning, LIBBPF_PIN_BY_NAME);
__type(key, __u32);
__array(values, struct client_inner_map);
} client_outer_map SEC(".maps");I am also updating the userspace definition accordingly (change ValueSize to 164). I have investigated the problem and found out that the problem occurs when storing the FD of the inner map in the outer map. Maybe someone sees the problem and can help me... |
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Replies: 1 comment 11 replies
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My guess is that the size of the inner map value isn't Why are you manually crafting the |
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Thank you for your suggestion. I've already tried setting the size of the inner map value to To complete my question here is also the SidListData struct in go: type SidListData struct {
SidlistSize uint32
Sidlist [10]struct{ In6U struct{ U6Addr8 [16]uint8 } }
}As for manually crafting the MapSpec in Go, I'm fairly new to eBPF and have been using bpf2go to generate the code. That's why I haven't read the specifications directly from the ELF file yet. If you have any tips or best practices on how to do that, I would greatly appreciate your advice. |
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Did you write the SidListData by hand or use bpf2go? Try using the generated functions to get access to a ebpf/examples/kprobe/bpf_bpfel.go Line 35 in 5bb4c2f It would also be helpful if you dump the BTF of your compiled code via |
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@jklaiber You can also inspect the resulting map definition in the ELF: I suspect the issue here is you've specified For inspecting BPF ELF contents from Go, see: https://ebpf-go.dev/concepts/loader. (Note: WIP!) |
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@lmb I wrote the SidListData struct by hand. It is also stored correctly in the inner map but I'm not able to store the inner map into the outer map. Here is the BTF dump: |
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@ti-mo I understand that the What confuses me is that everything worked as expected when I was using the |
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@jklaiber Can you see any differences between the MapSpec returned from |
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Did you write the SidListData by hand or use bpf2go?
Try using the generated functions to get access to a
CollectionSpec, that should be what you need:ebpf/examples/kprobe/bpf_bpfel.go
Line 35 in 5bb4c2f
It would also be helpful if you dump the BTF of your compiled code via
bpftool btf dump file ...(IIRC)