linux-kernel - [PATCH bpf-next 1/2] Revert "bpf: Add support to inline bpf_get_func

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Date:   Mon, 21 Mar 2022 08:01:12 +0100
From:   Jiri Olsa <jolsa@...nel.org>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        lkml <linux-kernel@...r.kernel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH bpf-next 1/2] Revert "bpf: Add support to inline bpf_get_func_ip helper on x86"

This reverts commit 97ee4d20ee67eb462581a7af01442de6586e390b.

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@...nel.org>
---
 kernel/bpf/verifier.c    | 21 +--------------------
 kernel/trace/bpf_trace.c |  1 -
 2 files changed, 1 insertion(+), 21 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0287176bfe9a..cf92f9c01556 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -13678,7 +13678,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
 			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 */
@@ -13693,25 +13693,6 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
 			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
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 9a7b6be655e4..52c2998e1dc3 100644
--- a/kernel/trace/bpf_trace.c
+++ b/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);
 }
 
-- 
2.35.1