From patchwork Fri Nov 29 22:16:39 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: George Spelvin X-Patchwork-Id: 1263264 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=sdf.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48qPj95VJHz9sSN for ; Sun, 29 Mar 2020 03:45:17 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727766AbgC1QpI (ORCPT ); Sat, 28 Mar 2020 12:45:08 -0400 Received: from mx.sdf.org ([205.166.94.20]:49937 "EHLO mx.sdf.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727829AbgC1Qno (ORCPT ); Sat, 28 Mar 2020 12:43:44 -0400 Received: from sdf.org (IDENT:lkml@sdf.lonestar.org [205.166.94.16]) by mx.sdf.org (8.15.2/8.14.5) with ESMTPS id 02SGhPra027632 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits) verified NO); Sat, 28 Mar 2020 16:43:25 GMT Received: (from lkml@localhost) by sdf.org (8.15.2/8.12.8/Submit) id 02SGhPH7029961; Sat, 28 Mar 2020 16:43:25 GMT Message-Id: <202003281643.02SGhPH7029961@sdf.org> From: George Spelvin Date: Fri, 29 Nov 2019 17:16:39 -0500 Subject: [RFC PATCH v1 47/50] kernel/bpf/core.c: Use get_random_max32() To: linux-kernel@vger.kernel.org, lkml@sdf.org Cc: Daniel Borkmann , Alexei Starovoitov , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , bpf@vger.kernel.org, netdev@vger.kernel.org Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Smaller, faster, and a smidge more uniform than %. Signed-off-by: George Spelvin Cc: Daniel Borkmann Cc: Alexei Starovoitov Cc: Martin KaFai Lau Cc: Song Liu Cc: Yonghong Song Cc: Andrii Nakryiko Cc: bpf@vger.kernel.org Cc: netdev@vger.kernel.org Acked-by: Alexei Starovoitov --- kernel/bpf/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index af6b738cf435c..61713a7f73d85 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -874,7 +874,7 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, hdr->pages = pages; hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)), PAGE_SIZE - sizeof(*hdr)); - start = (get_random_int() % hole) & ~(alignment - 1); + start = get_random_max32(hole) & ~(alignment - 1); /* Leave a random number of instructions before BPF code. */ *image_ptr = &hdr->image[start]; @@ -947,7 +947,7 @@ static int bpf_jit_blind_insn(const struct bpf_insn *from, bool emit_zext) { struct bpf_insn *to = to_buff; - u32 imm_rnd = get_random_int(); + u32 imm_rnd = get_random_u32(); s16 off; BUILD_BUG_ON(BPF_REG_AX + 1 != MAX_BPF_JIT_REG);