| Message ID | 20220914123600.927632-1-davemarchevsky@fb.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | [v2,bpf-next,1/2] bpf: Allow ringbuf memory to be used as map key | expand |
On 9/14/22 1:35 PM, Dave Marchevsky wrote: > This patch adds support for the following pattern: > > struct some_data *data = bpf_ringbuf_reserve(&ringbuf, sizeof(struct some_data, 0)); > if (!data) > return; > bpf_map_lookup_elem(&another_map, &data->some_field); > bpf_ringbuf_submit(data); > > Currently the verifier does not consider bpf_ringbuf_reserve's > PTR_TO_MEM | MEM_ALLOC ret type a valid key input to bpf_map_lookup_elem. > Since PTR_TO_MEM is by definition a valid region of memory, it is safe > to use it as a key for lookups. > > Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com> Acked-by: Yonghong Song <yhs@fb.com>
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index c259d734f863..f6e029780698 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5626,6 +5626,7 @@ static const struct bpf_reg_types map_key_value_types = { PTR_TO_PACKET_META, PTR_TO_MAP_KEY, PTR_TO_MAP_VALUE, + PTR_TO_MEM | MEM_ALLOC, }, };
This patch adds support for the following pattern: struct some_data *data = bpf_ringbuf_reserve(&ringbuf, sizeof(struct some_data, 0)); if (!data) return; bpf_map_lookup_elem(&another_map, &data->some_field); bpf_ringbuf_submit(data); Currently the verifier does not consider bpf_ringbuf_reserve's PTR_TO_MEM | MEM_ALLOC ret type a valid key input to bpf_map_lookup_elem. Since PTR_TO_MEM is by definition a valid region of memory, it is safe to use it as a key for lookups. Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com> --- v1->v2: lore.kernel.org/bpf/20220912101106.2765921-1-davemarchevsky@fb.com * Move test changes into separate patch - patch 2 in this series. (Kumar, Yonghong). That patch's changelog enumerates specific changes from v1 * Remove PTR_TO_MEM addition from this patch - patch 1 (Yonghong) * I don't have a usecase for PTR_TO_MEM w/o MEM_ALLOC * Add "if (!data)" error check to example pattern in this patch (Yonghong) * Remove patch 2 from v1's series, which removed map_key_value_types as it was more-or-less duplicate of mem_types * Now that PTR_TO_MEM isn't added here, more differences between map_key_value_types and mem_types, and no usecase for PTR_TO_BUF, so drop for now. kernel/bpf/verifier.c | 1 + 1 file changed, 1 insertion(+)