On Fri, Oct 22, 2021 at 08:22:35AM -0700, Alexei Starovoitov wrote: > On Fri, Oct 22, 2021 at 4:33 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > > On Thu, Oct 21, 2021 at 04:42:12PM -0700, Alexei Starovoitov wrote: > > > > > Ahh. Right. It's potentially a different offset for every prog. > > > Let's put it into struct jit_context then. > > > > Something like this... > > Yep. Looks nice and clean to me. > > > - poke->tailcall_bypass = image + (addr - poke_off - X86_PATCH_SIZE); > > + poke->tailcall_bypass = ip + (prog - start); > > poke->adj_off = X86_TAIL_CALL_OFFSET; > > - poke->tailcall_target = image + (addr - X86_PATCH_SIZE); > > + poke->tailcall_target = ip + ctx->tail_call_direct_label - X86_PATCH_SIZE; > > This part looks correct too, but this is Daniel's magic. > He'll probably take a look next week when he comes back from PTO. > I don't recall which test exercises this tailcall poking logic. > It's only used with dynamic updates to prog_array. > insmod test_bpf.ko and test_verifier won't go down this path. Please run ./test_progs -t tailcalls from tools/testing/selftests/bpf and make sure that all of the tests are passing in there, especially the tailcall_bpf2bpf* subset. Thanks!
