path: root/arch/s390/net
diff options
authorAlexei Starovoitov <ast@plumgrid.com>2015-07-20 20:34:18 -0700
committerDavid S. Miller <davem@davemloft.net>2015-07-20 20:52:31 -0700
commit4e10df9a60d96ced321dd2af71da558c6b750078 (patch)
tree6a913ab31a28d48de3b3510470320220eb75e6eb /arch/s390/net
parentf3120acc7851bffd1cd15acd044b7fa6fa520e75 (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')
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;
jit->seen |= SEEN_FUNC;
/* lg %w1,<d(imm)>(%l) */