diff options
author | Alexei Starovoitov <ast@plumgrid.com> | 2015-07-20 20:34:18 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2015-07-20 20:52:31 -0700 |
commit | 4e10df9a60d96ced321dd2af71da558c6b750078 (patch) | |
tree | 6a913ab31a28d48de3b3510470320220eb75e6eb /arch/s390/net | |
parent | f3120acc7851bffd1cd15acd044b7fa6fa520e75 (diff) |
bpf: introduce bpf_skb_vlan_push/pop() helpers
Allow eBPF programs attached to TC qdiscs call skb_vlan_push/pop via
helper functions. These functions may change skb->data/hlen which are
cached by some JITs to improve performance of ld_abs/ld_ind instructions.
Therefore JITs need to recognize bpf_skb_vlan_push/pop() calls,
re-compute header len and re-cache skb->data/hlen back into cpu registers.
Note, skb->data/hlen are not directly accessible from the programs,
so any changes to skb->data done either by these helpers or by other
TC actions are safe.
eBPF JIT supported by three architectures:
- arm64 JIT is using bpf_load_pointer() without caching, so it's ok as-is.
- x64 JIT re-caches skb->data/hlen unconditionally after vlan_push/pop calls
(experiments showed that conditional re-caching is slower).
- s390 JIT falls back to interpreter for now when bpf_skb_vlan_push() is present
in the program (re-caching is tbd).
These helpers allow more scalable handling of vlan from the programs.
Instead of creating thousands of vlan netdevs on top of eth0 and attaching
TC+ingress+bpf to all of them, the program can be attached to eth0 directly
and manipulate vlans as necessary.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/s390/net')
-rw-r--r-- | arch/s390/net/bpf_jit_comp.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index fee782acc2ee..79c731e8d178 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -973,6 +973,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i */ const u64 func = (u64)__bpf_call_base + imm; + if (bpf_helper_changes_skb_data((void *)func)) + /* TODO reload skb->data, hlen */ + return -1; + REG_SET_SEEN(BPF_REG_5); jit->seen |= SEEN_FUNC; /* lg %w1,<d(imm)>(%l) */ |