From patchwork Thu Sep 21 08:02:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gatien CHEVALLIER X-Patchwork-Id: 13394555 X-Patchwork-Delegate: herbert@gondor.apana.org.au 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 0758FE7D0AF for ; Thu, 21 Sep 2023 20:36:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231827AbjIUUgJ (ORCPT ); Thu, 21 Sep 2023 16:36:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232759AbjIUUfo (ORCPT ); Thu, 21 Sep 2023 16:35:44 -0400 Received: from mx07-00178001.pphosted.com (mx07-00178001.pphosted.com [185.132.182.106]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0981897CA; Thu, 21 Sep 2023 10:39:55 -0700 (PDT) Received: from pps.filterd (m0369458.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.17.1.22/8.17.1.22) with ESMTP id 38L4wDok003244; Thu, 21 Sep 2023 10:04:23 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foss.st.com; h= from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding:content-type; s= selector1; bh=DHZkvrsPbLKzcjpy5QIekMLzqwjqX3hQlQ5u65J1ZwU=; b=Ik g2/FyoE5S5MEoPdNYpIF5+vmkH15Wdb3gtypBiinkrzSiBkDWvX7BxnONn2BPMbM mqWmn2wo/AvPB70B7Iec6tRF5UYZgXKylJXKOC3v/a4hJqQZkzqNR2eiCP7DnE2m 1Xfa2yEOi0nlvEd7RwDH5srHh8p/pG3TqZbOUZ/TtH5URbfVPH+u/V6TuPKm/Vlp tjW1NTD2VCE+6t7xhmsa8jW/4vSEqHkols1FX8+Oj6dXl8U8gPYne7yeju9ekHxp WvjaWzgxZHzrbRoRPxoU8NYJ0E5h1bWJ2bvGzeTRP2H4S22C7jW2L0ks93iZ9SyR SzsqOYJsnh3Zl+ZBnXcw== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com (PPS) with ESMTPS id 3t5nx0sbap-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 21 Sep 2023 10:04:23 +0200 (MEST) Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 40D86100058; Thu, 21 Sep 2023 10:04:22 +0200 (CEST) Received: from Webmail-eu.st.com (shfdag1node1.st.com [10.75.129.69]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 37D8C21863D; Thu, 21 Sep 2023 10:04:22 +0200 (CEST) Received: from localhost (10.201.20.32) by SHFDAG1NODE1.st.com (10.75.129.69) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Thu, 21 Sep 2023 10:04:21 +0200 From: Gatien Chevallier To: Olivia Mackall , Herbert Xu , Rob Herring , Krzysztof Kozlowski , Maxime Coquelin , Alexandre Torgue CC: Lionel Debieve , , , , , , Gatien Chevallier Subject: [PATCH v3 5/9] hwrng: stm32 - rework error handling in stm32_rng_read() Date: Thu, 21 Sep 2023 10:02:57 +0200 Message-ID: <20230921080301.253563-6-gatien.chevallier@foss.st.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230921080301.253563-1-gatien.chevallier@foss.st.com> References: <20230921080301.253563-1-gatien.chevallier@foss.st.com> MIME-Version: 1.0 X-Originating-IP: [10.201.20.32] X-ClientProxiedBy: SHFCAS1NODE1.st.com (10.75.129.72) To SHFDAG1NODE1.st.com (10.75.129.69) X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.980,Hydra:6.0.601,FMLib:17.11.176.26 definitions=2023-09-21_06,2023-09-20_01,2023-05-22_02 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Try to conceal seed errors when possible. If, despite the error concealing tries, a seed error is still present, then return an error. A clock error does not compromise the hardware block and data can still be read from RNG_DR. Just warn that the RNG clock is too slow and clear RNG_SR. Signed-off-by: Gatien Chevallier --- Changes in V2: - Use WARN_ONCE instead of WARN_ON as it was buggy drivers/char/hw_random/stm32-rng.c | 53 +++++++++++++++++++++++------- 1 file changed, 41 insertions(+), 12 deletions(-) diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c index adefe8edfd07..9dac177d5286 100644 --- a/drivers/char/hw_random/stm32-rng.c +++ b/drivers/char/hw_random/stm32-rng.c @@ -43,6 +43,8 @@ #define RNG_HTCR 0x10 +#define RNG_NB_RECOVER_TRIES 3 + struct stm32_rng_data { u32 cr; u32 nscr; @@ -162,10 +164,10 @@ static int stm32_rng_conceal_seed_error(struct hwrng *rng) static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) { - struct stm32_rng_private *priv = - container_of(rng, struct stm32_rng_private, rng); + struct stm32_rng_private *priv = container_of(rng, struct stm32_rng_private, rng); + unsigned int i = 0; + int retval = 0, err = 0; u32 sr; - int retval = 0; pm_runtime_get_sync((struct device *) priv->rng.priv); @@ -174,30 +176,57 @@ static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) while (max >= sizeof(u32)) { sr = readl_relaxed(priv->base + RNG_SR); - /* Manage timeout which is based on timer and take */ - /* care of initial delay time when enabling rng */ + /* + * Manage timeout which is based on timer and take + * care of initial delay time when enabling the RNG. + */ if (!sr && wait) { - int err; - err = readl_relaxed_poll_timeout_atomic(priv->base + RNG_SR, sr, sr, 10, 50000); - if (err) + if (err) { dev_err((struct device *)priv->rng.priv, "%s: timeout %x!\n", __func__, sr); + break; + } + } else if (!sr) { + /* The FIFO is being filled up */ + break; } - /* If error detected or data not ready... */ if (sr != RNG_SR_DRDY) { - if (WARN_ONCE(sr & (RNG_SR_SEIS | RNG_SR_CEIS), - "bad RNG status - %x\n", sr)) + if (sr & RNG_SR_SEIS) { + err = stm32_rng_conceal_seed_error(rng); + i++; + if (err && i > RNG_NB_RECOVER_TRIES) { + dev_err((struct device *)priv->rng.priv, + "Couldn't recover from seed error\n"); + return -ENOTRECOVERABLE; + } + + continue; + } + + if (WARN_ONCE((sr & RNG_SR_CEIS), "RNG clock too slow - %x\n", sr)) writel_relaxed(0, priv->base + RNG_SR); - break; } + /* Late seed error case: DR being 0 is an error status */ *(u32 *)data = readl_relaxed(priv->base + RNG_DR); + if (!*(u32 *)data) { + err = stm32_rng_conceal_seed_error(rng); + i++; + if (err && i > RNG_NB_RECOVER_TRIES) { + dev_err((struct device *)priv->rng.priv, + "Couldn't recover from seed error"); + return -ENOTRECOVERABLE; + } + + continue; + } + i = 0; retval += sizeof(u32); data += sizeof(u32); max -= sizeof(u32);