From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9464BECAAD3 for ; Fri, 9 Sep 2022 10:14:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230107AbiIIKOD (ORCPT ); Fri, 9 Sep 2022 06:14:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36604 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230262AbiIIKN7 (ORCPT ); Fri, 9 Sep 2022 06:13:59 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C468B113C46 for ; Fri, 9 Sep 2022 03:13:50 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 1E772CE227E for ; Fri, 9 Sep 2022 10:13:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CAB75C433D7; Fri, 9 Sep 2022 10:13:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662718427; bh=NeD9J+hlFmOiZztf/4mgtbH/WlCig7osqOQURM0sWqU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oP/KrUAHJJ95FYjktAvVUGywqZU1J752y4639I85CvUoaStZ42B7wMaDmZjw1rwtb MMefjrzkOiT7lhryHe1AvEGrcNW+DWF2+pqdTmFUEpMDMDoo6U8dv56/6aFmIbhk9t KPwzj3fjVn1BAThG1pJjDmmqjEDq410iiB7XEg6/xI2QYL9soqEM+TtHIf6wSyZgru 0VwsanQ2pqfgDl/O/MlWLeRara6Rmy2RbTCHtu13trmytEI9q5QROGDk+9tNMtHIFb Xcd4jYYIQ1XpiIkykAcH6NZ6DkXsrf7ufFTK6I4gxSMNYPB08htYok1RYhsqVBLeYP cDjN3/ZtekOlw== From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , "Masami Hiramatsu (Google)" , Peter Zijlstra , Martynas Pumputis Subject: [PATCHv3 bpf-next 5/6] bpf: Return value in kprobe get_func_ip only for entry address Date: Fri, 9 Sep 2022 12:12:44 +0200 Message-Id: <20220909101245.347173-6-jolsa@kernel.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220909101245.347173-1-jolsa@kernel.org> References: <20220909101245.347173-1-jolsa@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Changing return value of kprobe's version of bpf_get_func_ip to return zero if the attach address is not on the function's entry point. For kprobes attached in the middle of the function we can't easily get to the function address especially now with the CONFIG_X86_KERNEL_IBT support. If user cares about current IP for kprobes attached within the function body, they can get it with PT_REGS_IP(ctx). Suggested-by: Andrii Nakryiko Signed-off-by: Jiri Olsa --- kernel/trace/bpf_trace.c | 11 ++++++++++- tools/testing/selftests/bpf/progs/get_func_ip_test.c | 4 ++-- 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index bcada91b0b3b..027abc38faab 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1029,8 +1029,17 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_tracing = { BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs) { struct kprobe *kp = kprobe_running(); + uintptr_t addr; - return kp ? (uintptr_t)kp->addr : 0; + if (!kp || !(kp->flags & KPROBE_FLAG_ON_FUNC_ENTRY)) + return 0; + + addr = (uintptr_t)kp->addr; +#ifdef CONFIG_X86_KERNEL_IBT + if (is_endbr(*((u32 *) addr - 1))) + addr -= ENDBR_INSN_SIZE; +#endif + return addr; } static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = { diff --git a/tools/testing/selftests/bpf/progs/get_func_ip_test.c b/tools/testing/selftests/bpf/progs/get_func_ip_test.c index a587aeca5ae0..6db70757bc8b 100644 --- a/tools/testing/selftests/bpf/progs/get_func_ip_test.c +++ b/tools/testing/selftests/bpf/progs/get_func_ip_test.c @@ -69,7 +69,7 @@ int test6(struct pt_regs *ctx) { __u64 addr = bpf_get_func_ip(ctx); - test6_result = (const void *) addr == &bpf_fentry_test6 + 5; + test6_result = (const void *) addr == 0; return 0; } @@ -79,6 +79,6 @@ int test7(struct pt_regs *ctx) { __u64 addr = bpf_get_func_ip(ctx); - test7_result = (const void *) addr == &bpf_fentry_test7 + 5; + test7_result = (const void *) addr == 0; return 0; } -- 2.37.3