'maps' is a generic storage of different types for sharing data between kernel and userspace. The maps are accessed from user space via BPF syscall, which has commands: - create a map with given type and attributes fd = bpf(BPF_MAP_CREATE, union bpf_attr *attr, u32 size) returns fd or negative error - lookup key in a given map referenced by fd err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero and stores found elem into value or negative error - create or update key/value pair in a given map err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero or negative error - find and delete element by key in a given map err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key - iterate map elements (based on input key return next_key) err = bpf(BPF_MAP_GET_NEXT_KEY, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->next_key - close(fd) deletes the map
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| @@ -70,6 +70,35 @@ enum bpf_cmd { · 69 unmodified lines | |||
| 70 | * map is deleted when fd is closed | 70 | * map is deleted when fd is closed |
| 71 | */ | 71 | */ |
| 72 | BPF_MAP_CREATE, | 72 | BPF_MAP_CREATE, |
| 73 | |||
| 74 | /* lookup key in a given map | ||
| 75 | * err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size) | ||
| 76 | * Using attr->map_fd, attr->key, attr->value | ||
| 77 | * returns zero and stores found elem into value | ||
| 78 | * or negative error | ||
| 79 | */ | ||
| 80 | BPF_MAP_LOOKUP_ELEM, | ||
| 81 | |||
| 82 | /* create or update key/value pair in a given map | ||
| 83 | * err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size) | ||
| 84 | * Using attr->map_fd, attr->key, attr->value | ||
| 85 | * returns zero or negative error | ||
| 86 | */ | ||
| 87 | BPF_MAP_UPDATE_ELEM, | ||
| 88 | |||
| 89 | /* find and delete elem by key in a given map | ||
| 90 | * err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size) | ||
| 91 | * Using attr->map_fd, attr->key | ||
| 92 | * returns zero or negative error | ||
| 93 | */ | ||
| 94 | BPF_MAP_DELETE_ELEM, | ||
| 95 | |||
| 96 | /* lookup key in a given map and return next key | ||
| 97 | * err = bpf(BPF_MAP_GET_NEXT_KEY, union bpf_attr *attr, u32 size) | ||
| 98 | * Using attr->map_fd, attr->key, attr->next_key | ||
| 99 | * returns zero and stores next key or negative error | ||
| 100 | */ | ||
| 101 | BPF_MAP_GET_NEXT_KEY, | ||
| 73 | }; | 102 | }; |
| 74 | 103 | ||
| 75 | enum bpf_map_type { | 104 | enum bpf_map_type { |
| @@ -83,6 +112,15 @@ union bpf_attr { · 7 unmodified lines | |||
| 83 | __u32 value_size; /* size of value in bytes */ | 112 | __u32 value_size; /* size of value in bytes */ |
| 84 | __u32 max_entries; /* max number of entries in a map */ | 113 | __u32 max_entries; /* max number of entries in a map */ |
| 85 | }; | 114 | }; |
| 115 | |||
| 116 | struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */ | ||
| 117 | __u32 map_fd; | ||
| 118 | __aligned_u64 key; | ||
| 119 | union { | ||
| 120 | __aligned_u64 value; | ||
| 121 | __aligned_u64 next_key; | ||
| 122 | }; | ||
| 123 | }; | ||
| 86 | } __attribute__((aligned(8))); | 124 | } __attribute__((aligned(8))); |
| 87 | 125 | ||
| 88 | #endif /* _UAPI__LINUX_BPF_H__ */ | 126 | #endif /* _UAPI__LINUX_BPF_H__ */ |