From patchwork Tue May 7 16:41:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jiong Wang X-Patchwork-Id: 1096426 X-Patchwork-Delegate: bpf@iogearbox.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 (mailfrom) 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=netronome.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=netronome-com.20150623.gappssmtp.com header.i=@netronome-com.20150623.gappssmtp.com header.b="cd5VhGby"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 44z54N2Z8Gz9sB8 for ; Wed, 8 May 2019 02:42:28 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726369AbfEGQm1 (ORCPT ); Tue, 7 May 2019 12:42:27 -0400 Received: from mail-wm1-f66.google.com ([209.85.128.66]:36415 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726337AbfEGQm1 (ORCPT ); Tue, 7 May 2019 12:42:27 -0400 Received: by mail-wm1-f66.google.com with SMTP id j187so4852068wmj.1 for ; Tue, 07 May 2019 09:42:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netronome-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=ibbhwKSFu7h0i6Chxa22oQdwwgqTaH3G7w5lqVgNsEY=; b=cd5VhGby/NKuAEhK3xO6v4Q1r9lm6oRw53CCiZap5fHlOp+9w8NCPbnfweVB5wrTGD FrlsKZBEkwVqNslqPhLYL3VHYGSrNjLJAmk9XhYupu6zXcZehLFUvw2EabrQSGpeABTX Gqun7QCRYsui3NsoufBYJ4Bk8jkbJ8m26CONlrNuQ75gijF5wEhYvVrjbdxda3woaWDl yqf8/PaMdxak2ofvyc8HQg/NS4lEkGOA8ALcY2lH4Pl+JraPwcaYqqVUcYQkZjoZhkvt Edy2qdF+QyrOuMaWRPwr5lh0cfW8sjg6EVJZN9d3d/brP5pHKRq755xKdkT0YpID5ZWg ru6g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=ibbhwKSFu7h0i6Chxa22oQdwwgqTaH3G7w5lqVgNsEY=; b=sFI62xyEpvQ+7yIC3gr1HsGOydTU+KueDZIjxjcpWtdaDekezM3dhnMXuKczoezwZN oVQmUuR4Ru4/jCCFyYtYSLdnx05+fOQopm7RvOjIyJ+bpC+eieMcTXa6AB82oTOl865o E0kR89z5c+26YrjNsxMdIHy+3SY67bImvIZQDVqyg47okxIfPe7T3ZTvTR1eINeiZmAo 7c5RowmcKbJrDfioFlFfz/vnMLw4KWl4lTqCOr/FeWfxwRzIeqNjo+hsvsK578R+zdrp xwT9jxNyX8Fnbi0ciESPrITD1Ha3QzwaiMB2jDEK+r0QvWpvp2whK5c8ogTnavj+R6Tj 4PTw== X-Gm-Message-State: APjAAAXOF7cXshKShd8JXCZDcNfMULgWc4K43gl7f7ovQ0dUzgmjuWuK WRhZxxQ6sSY4cU0hbMzoHJcp/w== X-Google-Smtp-Source: APXvYqzBHnK1umI+xXbIAlEUpGLzvcM2Mxiy9IA3EN9LgbXQ1crZ6rseGWq2D74gSwcu8U+bLqJOag== X-Received: by 2002:a1c:6342:: with SMTP id x63mr21911958wmb.58.1557247345859; Tue, 07 May 2019 09:42:25 -0700 (PDT) Received: from cbtest28.netronome.com ([217.38.71.146]) by smtp.gmail.com with ESMTPSA id w7sm19034022wmm.16.2019.05.07.09.42.24 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 07 May 2019 09:42:25 -0700 (PDT) From: Jiong Wang To: alexei.starovoitov@gmail.com, daniel@iogearbox.net Cc: oleksandr@natalenko.name, bpf@vger.kernel.org, netdev@vger.kernel.org, oss-drivers@netronome.com, Jiong Wang Subject: [PATCH bpf] nfp: bpf: fix static check error through tightening shift amount adjustment Date: Tue, 7 May 2019 17:41:30 +0100 Message-Id: <1557247291-9686-1-git-send-email-jiong.wang@netronome.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-Id: netdev.vger.kernel.org NFP shift instruction has something special. If shift direction is left then shift amount of 1 to 31 is specified as 32 minus the amount to shift. But no need to do this for indirect shift which has shift amount be 0. Even after we do this subtraction, shift amount 0 will be turned into 32 which will eventually be encoded the same as 0 because only low 5 bits are encoded, but shift amount be 32 will fail the FIELD_PREP check done later on shift mask (0x1f), due to 32 is out of mask range. Such error has been observed when compiling nfp/bpf/jit.c using gcc 8.3 + O3. This issue has started when indirect shift support added after which the incoming shift amount to __emit_shf could be 0, therefore it is at that time shift amount adjustment inside __emit_shf should have been tightened. Fixes: 991f5b3651f6 ("nfp: bpf: support logic indirect shifts (BPF_[L|R]SH | BPF_X)") Reported-by: Oleksandr Natalenko Reported-by: Pablo Cascón Reviewed-by: Jakub Kicinski Signed-off-by: Jiong Wang --- drivers/net/ethernet/netronome/nfp/bpf/jit.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/netronome/nfp/bpf/jit.c b/drivers/net/ethernet/netronome/nfp/bpf/jit.c index f272247..d4bf0e6 100644 --- a/drivers/net/ethernet/netronome/nfp/bpf/jit.c +++ b/drivers/net/ethernet/netronome/nfp/bpf/jit.c @@ -328,7 +328,18 @@ __emit_shf(struct nfp_prog *nfp_prog, u16 dst, enum alu_dst_ab dst_ab, return; } - if (sc == SHF_SC_L_SHF) + /* NFP shift instruction has something special. If shift direction is + * left then shift amount of 1 to 31 is specified as 32 minus the amount + * to shift. + * + * But no need to do this for indirect shift which has shift amount be + * 0. Even after we do this subtraction, shift amount 0 will be turned + * into 32 which will eventually be encoded the same as 0 because only + * low 5 bits are encoded, but shift amount be 32 will fail the + * FIELD_PREP check done later on shift mask (0x1f), due to 32 is out of + * mask range. + */ + if (sc == SHF_SC_L_SHF && shift) shift = 32 - shift; insn = OP_SHF_BASE |