The bpf_get_local_storage() helper function is used to get a pointer to the bpf local storage from a bpf program. It takes a pointer to a storage map and flags as arguments. Right now it accepts only cgroup storage maps, and flags argument has to be 0. Further it can be extended to support other types of local storage: e.g. thread local storage etc.
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| @@ -2095,6 +2095,24 @@ union bpf_attr { · 2094 unmodified lines | |||
| 2095 | * Return | 2095 | * Return |
| 2096 | * A 64-bit integer containing the current cgroup id based | 2096 | * A 64-bit integer containing the current cgroup id based |
| 2097 | * on the cgroup within which the current task is running. | 2097 | * on the cgroup within which the current task is running. |
| 2098 | * | ||
| 2099 | * void* get_local_storage(void *map, u64 flags) | ||
| 2100 | * Description | ||
| 2101 | * Get the pointer to the local storage area. | ||
| 2102 | * The type and the size of the local storage is defined | ||
| 2103 | * by the *map* argument. | ||
| 2104 | * The *flags* meaning is specific for each map type, | ||
| 2105 | * and has to be 0 for cgroup local storage. | ||
| 2106 | * | ||
| 2107 | * Depending on the bpf program type, a local storage area | ||
| 2108 | * can be shared between multiple instances of the bpf program, | ||
| 2109 | * running simultaneously. | ||
| 2110 | * | ||
| 2111 | * A user should care about the synchronization by himself. | ||
| 2112 | * For example, by using the BPF_STX_XADD instruction to alter | ||
| 2113 | * the shared data. | ||
| 2114 | * Return | ||
| 2115 | * Pointer to the local storage area. | ||
| 2098 | */ | 2116 | */ |
| 2099 | #define __BPF_FUNC_MAPPER(FN) \ | 2117 | #define __BPF_FUNC_MAPPER(FN) \ |
| 2100 | FN(unspec), \ | 2118 | FN(unspec), \ |
| @@ -2177,7 +2195,8 @@ union bpf_attr { · 76 unmodified lines | |||
| 2177 | FN(rc_repeat), \ | 2195 | FN(rc_repeat), \ |
| 2178 | FN(rc_keydown), \ | 2196 | FN(rc_keydown), \ |
| 2179 | FN(skb_cgroup_id), \ | 2197 | FN(skb_cgroup_id), \ |
| 2180 | FN(get_current_cgroup_id), | 2198 | FN(get_current_cgroup_id), \ |
| 2199 | FN(get_local_storage), | ||
| 2181 | 2200 | ||
| 2182 | /* integer value in 'imm' field of BPF_CALL instruction selects which helper | 2201 | /* integer value in 'imm' field of BPF_CALL instruction selects which helper |
| 2183 | * function eBPF program intends to call | 2202 | * function eBPF program intends to call |