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Diffstat (limited to 'Documentation/networking')
| -rw-r--r-- | Documentation/networking/filter.rst | 47 |
1 files changed, 3 insertions, 44 deletions
diff --git a/Documentation/networking/filter.rst b/Documentation/networking/filter.rst index 83ffcaa5b91a..43ef05b91f98 100644 --- a/Documentation/networking/filter.rst +++ b/Documentation/networking/filter.rst @@ -1232,9 +1232,9 @@ pointer type. The types of pointers describe their base, as follows: Pointer to the value stored in a map element. PTR_TO_MAP_VALUE_OR_NULL Either a pointer to a map value, or NULL; map accesses - (see section 'eBPF maps', below) return this type, - which becomes a PTR_TO_MAP_VALUE when checked != NULL. - Arithmetic on these pointers is forbidden. + (see maps.rst) return this type, which becomes a + a PTR_TO_MAP_VALUE when checked != NULL. Arithmetic on + these pointers is forbidden. PTR_TO_STACK Frame pointer. PTR_TO_PACKET @@ -1402,47 +1402,6 @@ using normal C code as:: which makes such programs easier to write comparing to LD_ABS insn and significantly faster. -eBPF maps ---------- -'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 - ``map_fd = bpf(BPF_MAP_CREATE, union bpf_attr *attr, u32 size)`` - using attr->map_type, attr->key_size, attr->value_size, attr->max_entries - returns process-local file descriptor or negative error - -- lookup key in a given map - ``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 - -- to delete map: close(fd) - Exiting process will delete maps automatically - -userspace programs use this syscall to create/access maps that eBPF programs -are concurrently updating. - -maps can have different types: hash, array, bloom filter, radix-tree, etc. - -The map is defined by: - - - type - - max number of elements - - key size in bytes - - value size in bytes - Pruning ------- The verifier does not actually walk all possible paths through the program. For |