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 X-Spam-Level: X-Spam-Status: No, score=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A4729C4743D for ; Sat, 5 Jun 2021 11:11:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8DEF0613AE for ; Sat, 5 Jun 2021 11:11:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230261AbhFELNB convert rfc822-to-8bit (ORCPT ); Sat, 5 Jun 2021 07:13:01 -0400 Received: from us-smtp-delivery-44.mimecast.com ([207.211.30.44]:46671 "EHLO us-smtp-delivery-44.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230252AbhFELNA (ORCPT ); Sat, 5 Jun 2021 07:13:00 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-169-z7izaW1eMC6BLH4upIAvAA-1; Sat, 05 Jun 2021 07:11:09 -0400 X-MC-Unique: z7izaW1eMC6BLH4upIAvAA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 12C90107ACCD; Sat, 5 Jun 2021 11:11:07 +0000 (UTC) Received: from krava.cust.in.nbox.cz (unknown [10.40.192.14]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5281A5272D; Sat, 5 Jun 2021 11:11:04 +0000 (UTC) From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , "Steven Rostedt (VMware)" Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Daniel Xu , Viktor Malik Subject: [PATCH 09/19] bpf, x64: Allow to use caller address from stack Date: Sat, 5 Jun 2021 13:10:24 +0200 Message-Id: <20210605111034.1810858-10-jolsa@kernel.org> In-Reply-To: <20210605111034.1810858-1-jolsa@kernel.org> References: <20210605111034.1810858-1-jolsa@kernel.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jolsa@kernel.org X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kernel.org Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset=WINDOWS-1252 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Currently we call the original function by using the absolute address given at the JIT generation. That's not usable when having trampoline attached to multiple functions. In this case we need to take the return address from the stack. Adding support to retrieve the original function address from the stack by adding new BPF_TRAMP_F_ORIG_STACK flag for arch_prepare_bpf_trampoline function. Signed-off-by: Jiri Olsa --- arch/x86/net/bpf_jit_comp.c | 13 +++++++++---- include/linux/bpf.h | 5 +++++ 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 2a2e290fa5d8..b77e6bd78354 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -2013,10 +2013,15 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i if (flags & BPF_TRAMP_F_CALL_ORIG) { restore_regs(m, &prog, nr_args, stack_size); - /* call original function */ - if (emit_call(&prog, orig_call, prog)) { - ret = -EINVAL; - goto cleanup; + if (flags & BPF_TRAMP_F_ORIG_STACK) { + emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, 8); + EMIT2(0xff, 0xd0); /* call *rax */ + } else { + /* call original function */ + if (emit_call(&prog, orig_call, prog)) { + ret = -EINVAL; + goto cleanup; + } } /* remember return value in a stack for bpf prog to access */ emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -8); diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 86dec5001ae2..16fc600503fb 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -554,6 +554,11 @@ struct btf_func_model { */ #define BPF_TRAMP_F_SKIP_FRAME BIT(2) +/* Get original function from stack instead of from provided direct address. + * Makes sense for fexit programs only. + */ +#define BPF_TRAMP_F_ORIG_STACK BIT(3) + /* Each call __bpf_prog_enter + call bpf_func + call __bpf_prog_exit is ~50 * bytes on x86. Pick a number to fit into BPF_IMAGE_SIZE / 2 */ -- 2.31.1