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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 E57D4C47094 for ; Mon, 7 Jun 2021 11:28:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CB24D610C7 for ; Mon, 7 Jun 2021 11:28:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231469AbhFGL3v (ORCPT ); Mon, 7 Jun 2021 07:29:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40970 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231342AbhFGL3o (ORCPT ); Mon, 7 Jun 2021 07:29:44 -0400 Received: from ssl.serverraum.org (ssl.serverraum.org [IPv6:2a01:4f8:151:8464::1:2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CDF2FC061766 for ; Mon, 7 Jun 2021 04:27:52 -0700 (PDT) Received: from mwalle01.fritz.box (ip4d17858c.dynamic.kabel-deutschland.de [77.23.133.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by ssl.serverraum.org (Postfix) with ESMTPSA id 152B72224D; Mon, 7 Jun 2021 13:27:51 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1623065271; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=aPLr0bC6c5jU5r1OPXE3alwU7oqwB2zXRdHsI9UOrv8=; b=AboVC3dj7CIGi8nFLXtsf/q32kzUPsv48V3gRuSSqv2/RF1+2Gr+8+vdtMDW0r9Axiikcs 0rNmV2UjZtxk9lj/Z1jlz846NR2Q13LzcOno9fPAhmJz/J2fHlAjsftnB2ySQpVNlT7HsL R9U+kL3TvhncKlq9qi1Uk2dSYDtLAAo= From: Michael Walle To: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Tudor Ambarus , Michael Walle , Pratyush Yadav , Miquel Raynal , Richard Weinberger , Vignesh Raghavendra Subject: [PATCH v6 3/4] mtd: spi-nor: otp: return -EROFS if region is read-only Date: Mon, 7 Jun 2021 13:27:43 +0200 Message-Id: <20210607112744.21587-4-michael@walle.cc> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210607112744.21587-1-michael@walle.cc> References: <20210607112744.21587-1-michael@walle.cc> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org SPI NOR flashes will just ignore program commands if the OTP region is locked. Thus, a user might not notice that the intended write didn't end up in the flash. Return -EROFS to the user in this case. From what I can tell, chips/cfi_cmdset_0001.c also return this error code. One could optimize spi_nor_mtd_otp_range_is_locked() to read the status register only once and not for every OTP region, but for that we would need some more invasive changes. Given that this is one-time-programmable memory and the normal access mode is reading, we just live with the small overhead. By moving the code around a bit, we can just check the length before calling spi_nor_mtd_otp_range_is_locked() and avoid an underflow there if a len is 0. This way we don't need to take the lock either. We also skip the "*retlen = 0" assignment, mtdcore already takes care of that for us. Fixes: 069089acf88b ("mtd: spi-nor: add OTP support") Signed-off-by: Michael Walle Reviewed-by: Pratyush Yadav Reviewed-by: Tudor Ambarus --- drivers/mtd/spi-nor/otp.c | 41 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 38 insertions(+), 3 deletions(-) diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c index 3898ed67ba1c..89fe52e3851a 100644 --- a/drivers/mtd/spi-nor/otp.c +++ b/drivers/mtd/spi-nor/otp.c @@ -249,6 +249,29 @@ static int spi_nor_mtd_otp_info(struct mtd_info *mtd, size_t len, return ret; } +static int spi_nor_mtd_otp_range_is_locked(struct spi_nor *nor, loff_t ofs, + size_t len) +{ + const struct spi_nor_otp_ops *ops = nor->params->otp.ops; + unsigned int region; + int locked; + + /* + * If any of the affected OTP regions are locked the entire range is + * considered locked. + */ + for (region = spi_nor_otp_offset_to_region(nor, ofs); + region <= spi_nor_otp_offset_to_region(nor, ofs + len - 1); + region++) { + locked = ops->is_locked(nor, region); + /* take the branch it is locked or in case of an error */ + if (locked) + return locked; + } + + return 0; +} + static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs, size_t total_len, size_t *retlen, const u8 *buf, bool is_write) @@ -264,14 +287,26 @@ static int spi_nor_mtd_otp_read_write(struct mtd_info *mtd, loff_t ofs, if (ofs < 0 || ofs >= spi_nor_otp_size(nor)) return 0; + /* don't access beyond the end */ + total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs); + + if (!total_len) + return 0; + ret = spi_nor_lock_and_prep(nor); if (ret) return ret; - /* don't access beyond the end */ - total_len = min_t(size_t, total_len, spi_nor_otp_size(nor) - ofs); + if (is_write) { + ret = spi_nor_mtd_otp_range_is_locked(nor, ofs, total_len); + if (ret < 0) { + goto out; + } else if (ret) { + ret = -EROFS; + goto out; + } + } - *retlen = 0; while (total_len) { /* * The OTP regions are mapped into a contiguous area starting -- 2.20.1