bpf: add support for bpf_call to interpreter

though bpf_call is still the same call instruction and
calling convention 'bpf to bpf' and 'bpf to helper' is the same
the interpreter has to oparate on 'struct bpf_insn *'.
To distinguish these two cases add a kernel internal opcode and
mark call insns with it.
This opcode is seen by interpreter only. JITs will never see it.
Also add tiny bit of debug code to aid interpreter debugging.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 5feb441d3dd9..f26e6da1007b 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -58,6 +58,9 @@ struct bpf_prog_aux;
 /* unused opcode to mark special call to bpf_tail_call() helper */
 #define BPF_TAIL_CALL	0xf0
 
+/* unused opcode to mark call to interpreter with arguments */
+#define BPF_CALL_ARGS	0xe0
+
 /* As per nm, we expose JITed images as text (code) section for
  * kallsyms. That way, tools like perf can find it to match
  * addresses.
@@ -710,6 +713,9 @@ bool sk_filter_charge(struct sock *sk, struct sk_filter *fp);
 void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
 
 u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
+#define __bpf_call_base_args \
+	((u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)) \
+	 __bpf_call_base)
 
 struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog);
 void bpf_jit_compile(struct bpf_prog *prog);