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=-15.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, 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 6B23FC47082 for ; Tue, 8 Jun 2021 20:58:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4263C61285 for ; Tue, 8 Jun 2021 20:58:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232404AbhFHVAe (ORCPT ); Tue, 8 Jun 2021 17:00:34 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:58373 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230311AbhFHVAd (ORCPT ); Tue, 8 Jun 2021 17:00:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623185920; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=lZUsgbONkfUzos/C9Av5cRf1otAOa/sTV3ApgVVN1OI=; b=KiSNugb/uJgJi4uJj8jwFzpdjmvtO40cwJae4AHGI2uoZRHKNUaInJvU8M8BMPVHCRUL5/ rpzUH0QdOIRyM0I3gmUUzSkZIO4aHm1BBnlLVGe9M2YmrZVF2PTGG9y4T/RglJmq2eIyun bctvuQAsU4siQCyxf+iCjBS4DOTbZjk= 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-150-T76qJZJuNqy63ucnWwsgMw-1; Tue, 08 Jun 2021 16:58:38 -0400 X-MC-Unique: T76qJZJuNqy63ucnWwsgMw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E0D6B1854E27; Tue, 8 Jun 2021 20:58:36 +0000 (UTC) Received: from krava (unknown [10.40.192.49]) by smtp.corp.redhat.com (Postfix) with SMTP id BCEE8100238C; Tue, 8 Jun 2021 20:58:33 +0000 (UTC) Date: Tue, 8 Jun 2021 22:58:32 +0200 From: Jiri Olsa To: Andrii Nakryiko Cc: Jiri Olsa , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , "Steven Rostedt (VMware)" , Networking , bpf , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Daniel Xu , Viktor Malik Subject: Re: [PATCH 10/19] bpf: Allow to store caller's ip as argument Message-ID: References: <20210605111034.1810858-1-jolsa@kernel.org> <20210605111034.1810858-11-jolsa@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Tue, Jun 08, 2021 at 11:49:31AM -0700, Andrii Nakryiko wrote: > On Sat, Jun 5, 2021 at 4:12 AM Jiri Olsa wrote: > > > > When we will have multiple functions attached to trampoline > > we need to propagate the function's address to the bpf program. > > > > Adding new BPF_TRAMP_F_IP_ARG flag to arch_prepare_bpf_trampoline > > function that will store origin caller's address before function's > > arguments. > > > > Signed-off-by: Jiri Olsa > > --- > > arch/x86/net/bpf_jit_comp.c | 18 ++++++++++++++---- > > include/linux/bpf.h | 5 +++++ > > 2 files changed, 19 insertions(+), 4 deletions(-) > > > > diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c > > index b77e6bd78354..d2425c18272a 100644 > > --- a/arch/x86/net/bpf_jit_comp.c > > +++ b/arch/x86/net/bpf_jit_comp.c > > @@ -1951,7 +1951,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i > > void *orig_call) > > { > > int ret, i, cnt = 0, nr_args = m->nr_args; > > - int stack_size = nr_args * 8; > > + int stack_size = nr_args * 8, ip_arg = 0; > > struct bpf_tramp_progs *fentry = &tprogs[BPF_TRAMP_FENTRY]; > > struct bpf_tramp_progs *fexit = &tprogs[BPF_TRAMP_FEXIT]; > > struct bpf_tramp_progs *fmod_ret = &tprogs[BPF_TRAMP_MODIFY_RETURN]; > > @@ -1975,6 +1975,9 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i > > */ > > orig_call += X86_PATCH_SIZE; > > > > + if (flags & BPF_TRAMP_F_IP_ARG) > > + stack_size += 8; > > + > > nit: move it a bit up where we adjust stack_size for BPF_TRAMP_F_CALL_ORIG flag? ok > > > prog = image; > > > > EMIT1(0x55); /* push rbp */ > > @@ -1982,7 +1985,14 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i > > EMIT4(0x48, 0x83, 0xEC, stack_size); /* sub rsp, stack_size */ > > EMIT1(0x53); /* push rbx */ > > > > - save_regs(m, &prog, nr_args, stack_size); > > + if (flags & BPF_TRAMP_F_IP_ARG) { > > + emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, 8); > > + EMIT4(0x48, 0x83, 0xe8, X86_PATCH_SIZE); /* sub $X86_PATCH_SIZE,%rax*/ > > + emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -stack_size); > > + ip_arg = 8; > > + } > > why not pass flags into save_regs and let it handle this case without > this extra ip_arg adjustment? > > > + > > + save_regs(m, &prog, nr_args, stack_size - ip_arg); > > > > if (flags & BPF_TRAMP_F_CALL_ORIG) { > > /* arg1: mov rdi, im */ > > @@ -2011,7 +2021,7 @@ 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); > > + restore_regs(m, &prog, nr_args, stack_size - ip_arg); > > > > similarly (and symmetrically), pass flags into restore_regs() to > handle that ip_arg transparently? so you mean something like: if (flags & BPF_TRAMP_F_IP_ARG) stack_size -= 8; in both save_regs and restore_regs function, right? jirka > > > if (flags & BPF_TRAMP_F_ORIG_STACK) { > > emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, 8); > > @@ -2052,7 +2062,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i > > } > > > > if (flags & BPF_TRAMP_F_RESTORE_REGS) > > - restore_regs(m, &prog, nr_args, stack_size); > > + restore_regs(m, &prog, nr_args, stack_size - ip_arg); > > > > /* This needs to be done regardless. If there were fmod_ret programs, > > * the return value is only updated on the stack and still needs to be > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > > index 16fc600503fb..6cbf3c81c650 100644 > > --- a/include/linux/bpf.h > > +++ b/include/linux/bpf.h > > @@ -559,6 +559,11 @@ struct btf_func_model { > > */ > > #define BPF_TRAMP_F_ORIG_STACK BIT(3) > > > > +/* First argument is IP address of the caller. Makes sense for fentry/fexit > > + * programs only. > > + */ > > +#define BPF_TRAMP_F_IP_ARG BIT(4) > > + > > /* 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 > > >