Revert "bpf: Add support to inline bpf_get_func_ip helper on x86"

This reverts commit 97ee4d20ee.

Following change is adding more complexity to bpf_get_func_ip
helper for kprobe_multi programs, which can't be inlined easily.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220321070113.1449167-2-jolsa@kernel.org

kernel/bpf/verifier.c

@@ -13698,7 +13698,7 @@ patch_map_ops_generic:
 			continue;
 		}
 
-		/* Implement tracing bpf_get_func_ip inline. */
+		/* Implement bpf_get_func_ip inline. */
 		if (prog_type == BPF_PROG_TYPE_TRACING &&
 		    insn->imm == BPF_FUNC_get_func_ip) {
 			/* Load IP address from ctx - 16 */
@@ -13713,25 +13713,6 @@ patch_map_ops_generic:
 			continue;
 		}
 
-#ifdef CONFIG_X86
-		/* Implement kprobe_multi bpf_get_func_ip inline. */
-		if (prog_type == BPF_PROG_TYPE_KPROBE &&
-		    eatype == BPF_TRACE_KPROBE_MULTI &&
-		    insn->imm == BPF_FUNC_get_func_ip) {
-			/* Load IP address from ctx (struct pt_regs) ip */
-			insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1,
-						  offsetof(struct pt_regs, ip));
-
-			new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
-			if (!new_prog)
-				return -ENOMEM;
-
-			env->prog = prog = new_prog;
-			insn      = new_prog->insnsi + i + delta;
-			continue;
-		}
-#endif
-
 patch_call_imm:
 		fn = env->ops->get_func_proto(insn->imm, env->prog);
 		/* all functions that have prototype and verifier allowed

kernel/trace/bpf_trace.c

@@ -1042,7 +1042,6 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
 
 BPF_CALL_1(bpf_get_func_ip_kprobe_multi, struct pt_regs *, regs)
 {
-	/* This helper call is inlined by verifier on x86. */
 	return instruction_pointer(regs);
 }