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 CFD98C433F5 for ; Tue, 24 May 2022 07:20:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235127AbiEXHU0 (ORCPT ); Tue, 24 May 2022 03:20:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234700AbiEXHU0 (ORCPT ); Tue, 24 May 2022 03:20:26 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9935080227; Tue, 24 May 2022 00:20:25 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 387CF61554; Tue, 24 May 2022 07:20:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BF41EC385AA; Tue, 24 May 2022 07:20:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1653376824; bh=2YWf5LxWQDyQyGJemUCiBxpas8j1IUwZLhuvPzte3HM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=S8zlWKJoM1xCnDH9WqSPWhxWmzwEydonb/vHZc4fHCcpm3Z6HKIjvCRgICxTWICxn MLbPJhboH4pqHkQ3C/Cl6V8u9+LgJsuiQyT2iLWNHsLkhMI+fWKebL6pChLJx/6BWU LIUwLyYk6GlHcjw1nu9Ei3Tj7PCp6sRjBXhfD3EFc/2Nz3npVb5aOG6ZYWcGDan1ga sZcH0LhidrM/i++lVphhY6bzcZaotJr46v6fqOXj/+3Ls8Rg3CrZVzHuLRqK1wSmvy 6+KQEzV9tSvQfm2+dD8R8cyzNYqAz/iy2kDzi7WIfp3FBW+LCKFaTYPO5rif5fuNRb yEbC+p8uVHV+g== Date: Tue, 24 May 2022 10:20:17 +0300 From: Mike Rapoport To: Song Liu Cc: linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-mm@kvack.org, ast@kernel.org, daniel@iogearbox.net, peterz@infradead.org, mcgrof@kernel.org, torvalds@linux-foundation.org, rick.p.edgecombe@intel.com, kernel-team@fb.com Subject: Re: [PATCH v4 bpf-next 3/8] bpf: introduce bpf_arch_text_invalidate for bpf_prog_pack Message-ID: References: <20220520235758.1858153-1-song@kernel.org> <20220520235758.1858153-4-song@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220520235758.1858153-4-song@kernel.org> Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, May 20, 2022 at 04:57:53PM -0700, Song Liu wrote: > Introduce bpf_arch_text_invalidate and use it to fill unused part of the > bpf_prog_pack with illegal instructions when a BPF program is freed. > > Signed-off-by: Song Liu > --- > arch/x86/net/bpf_jit_comp.c | 5 +++++ > include/linux/bpf.h | 1 + > kernel/bpf/core.c | 8 ++++++++ > 3 files changed, 14 insertions(+) > > diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c > index a2b6d197c226..f298b18a9a3d 100644 > --- a/arch/x86/net/bpf_jit_comp.c > +++ b/arch/x86/net/bpf_jit_comp.c > @@ -228,6 +228,11 @@ static void jit_fill_hole(void *area, unsigned int size) > memset(area, 0xcc, size); > } > > +int bpf_arch_text_invalidate(void *dst, size_t len) > +{ > + return IS_ERR_OR_NULL(text_poke_set(dst, 0xcc, len)); > +} > + > struct jit_context { > int cleanup_addr; /* Epilogue code offset */ > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index cc4d5e394031..a9b1875212f6 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -2365,6 +2365,7 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, > void *addr1, void *addr2); > > void *bpf_arch_text_copy(void *dst, void *src, size_t len); > +int bpf_arch_text_invalidate(void *dst, size_t len); > > struct btf_id_set; > bool btf_id_set_contains(const struct btf_id_set *set, u32 id); > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index 2d0c9d4696ad..cacd8684c3c4 100644 > --- a/kernel/bpf/core.c > +++ b/kernel/bpf/core.c > @@ -968,6 +968,9 @@ static void bpf_prog_pack_free(struct bpf_binary_header *hdr) > nbits = BPF_PROG_SIZE_TO_NBITS(hdr->size); > pos = ((unsigned long)hdr - (unsigned long)pack_ptr) >> BPF_PROG_CHUNK_SHIFT; > > + WARN_ONCE(bpf_arch_text_invalidate(hdr, hdr->size), > + "bpf_prog_pack bug: missing bpf_arch_text_invalidate?\n"); Why is this a WARN? What happens if bpf_arch_text_invalidate() is implemented but returns an error? > + > bitmap_clear(pack->bitmap, pos, nbits); > if (bitmap_find_next_zero_area(pack->bitmap, bpf_prog_chunk_count(), 0, > bpf_prog_chunk_count(), 0) == 0) { > @@ -2740,6 +2743,11 @@ void * __weak bpf_arch_text_copy(void *dst, void *src, size_t len) > return ERR_PTR(-ENOTSUPP); > } > > +int __weak bpf_arch_text_invalidate(void *dst, size_t len) > +{ > + return -ENOTSUPP; > +} > + > DEFINE_STATIC_KEY_FALSE(bpf_stats_enabled_key); > EXPORT_SYMBOL(bpf_stats_enabled_key); > > -- > 2.30.2 > > -- Sincerely yours, Mike.