diff options
| author | Kumar Kartikeya Dwivedi <memxor@gmail.com> | 2023-02-25 16:40:09 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-03-01 10:24:33 -0800 |
| commit | 9db44fdd8105da00669d425acab887c668df75f6 (patch) | |
| tree | 9215fabe2595aa084f2707d653dca82f4937fe80 /include | |
| parent | 65334e64a493c6a0976de7ad56bf8b7a9ff04b4a (diff) | |
| download | linux-9db44fdd8105da00669d425acab887c668df75f6.tar.gz linux-9db44fdd8105da00669d425acab887c668df75f6.tar.bz2 linux-9db44fdd8105da00669d425acab887c668df75f6.zip | |
bpf: Support kptrs in local storage maps
Enable support for kptrs in local storage maps by wiring up the freeing
of these kptrs from map value. Freeing of bpf_local_storage_map is only
delayed in case there are special fields, therefore bpf_selem_free_*
path can also only dereference smap safely in that case. This is
recorded using a bool utilizing a hole in bpF_local_storage_elem. It
could have been tagged in the pointer value smap using the lowest bit
(since alignment > 1), but since there was already a hole I went with
the simpler option. Only the map structure freeing is delayed using RCU
barriers, as the buckets aren't used when selem is being freed, so they
can be freed once all readers of the bucket lists can no longer access
it.
Cc: Martin KaFai Lau <martin.lau@kernel.org>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230225154010.391965-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/bpf_local_storage.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/bpf_local_storage.h b/include/linux/bpf_local_storage.h index 6d37a40cd90e..0fe92986412b 100644 --- a/include/linux/bpf_local_storage.h +++ b/include/linux/bpf_local_storage.h @@ -74,6 +74,12 @@ struct bpf_local_storage_elem { struct hlist_node snode; /* Linked to bpf_local_storage */ struct bpf_local_storage __rcu *local_storage; struct rcu_head rcu; + bool can_use_smap; /* Is it safe to access smap in bpf_selem_free_* RCU + * callbacks? bpf_local_storage_map_free only + * executes rcu_barrier when there are special + * fields, this field remembers that to ensure we + * don't access already freed smap in sdata. + */ /* 8 bytes hole */ /* The data is stored in another cacheline to minimize * the number of cachelines access during a cache hit. |