From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Thu, 15 Aug 2024 08:57:48 +0200 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1seUQe-009nAV-2X for lore@lore.pengutronix.de; Thu, 15 Aug 2024 08:57:48 +0200 Received: from bombadil.infradead.org ([2607:7c80:54:3::133]) by metis.whiteo.stw.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1seUQe-00036q-4q for lore@pengutronix.de; Thu, 15 Aug 2024 08:57:48 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=4w9A1e49OAky2UduftNU4DjMseY8ZAEzQuyU+bo3Hcw=; b=VgzNCL4WdFNl1IoUgNXvws+xkV if1htnHdHAFT9Ypi3t0DgaTZD53xVUDkCnKxi4BZ8/fezuKRlXwXKBJ0qhKwR2Kp8zibHH2hR2aVb bVDhUH0bGNxDybh+5FJhjVPWE57LavKBYKqaUNiyVVNckCPgW2J1UMNK93Qwv2nW/ITmaO6/yLc08 aEscObT6ECKbWn6QQd/nsf95jBOrZ927bCEEBfjSfsp7SL0JiUXv0mMNZqwleP/keGy1/iUGb1BYY P+DvVPO4vXtuy6xtaNAT65FUaI/I1pL+PRnc8blgYaPpOwg+z1y5WjJ3+S+0I80Zx2g0nH6vsLKrN pEdvhJAg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1seUQE-00000009D5x-3W5o; Thu, 15 Aug 2024 06:57:22 +0000 Received: from metis.whiteo.stw.pengutronix.de ([2a0a:edc0:2:b01:1d::104]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1seUQB-00000009D4g-2q0C for barebox@lists.infradead.org; Thu, 15 Aug 2024 06:57:21 +0000 Received: from ptz.office.stw.pengutronix.de ([2a0a:edc0:0:900:1d::77] helo=[127.0.0.1]) by metis.whiteo.stw.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1seUQA-0002y7-Ct; Thu, 15 Aug 2024 08:57:18 +0200 Message-ID: Date: Thu, 15 Aug 2024 08:57:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Tomas Marek , Sascha Hauer Cc: barebox@lists.infradead.org References: <20240814092424.39878-1-a.fatoum@pengutronix.de> <20240814092424.39878-5-a.fatoum@pengutronix.de> Content-Language: en-US From: Ahmad Fatoum In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240814_235719_752198_21A5C752 X-CRM114-Status: GOOD ( 21.60 ) X-BeenThere: barebox@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:3::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.whiteo.stw.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-5.2 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE, T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH 5/6] i2c: efi: avoid 64-bit division X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.whiteo.stw.pengutronix.de) Hello Tomas, On 15.08.24 07:53, Tomas Marek wrote: > Hello Ahmad, > > Thanks for maintenance of the Barebox EFI. > > On Wed, Aug 14, 2024 at 11:24:23AM +0200, Ahmad Fatoum wrote: >> I2C message length is 16 bit, so doing a 64-bit division is overkill. >> Let's remove the cast and just rely on the usual integer promotion >> to 32-bit. >> >> Cc: Tomas Marek >> Signed-off-by: Ahmad Fatoum >> --- >> drivers/i2c/busses/i2c-efi.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/i2c/busses/i2c-efi.c b/drivers/i2c/busses/i2c-efi.c >> index 5f6cc0eed28e..a666a28fab51 100644 >> --- a/drivers/i2c/busses/i2c-efi.c >> +++ b/drivers/i2c/busses/i2c-efi.c >> @@ -114,7 +114,7 @@ static unsigned int efi_i2c_msg_op_cnt(const struct efi_i2c_priv *i2c_priv, >> >> max_len = efi_i2c_max_len(i2c_priv, msg); >> >> - return ((u64)msg->len + max_len - 1) / max_len; >> + return (msg->len + max_len - 1) / max_len; > > The issue here is that max_len, which represents the MaximumReceiveBytes > or MaximumTransmitBytes in EFI I2C capabilities, is 32-bit. In some EFI > implementations (including the one I use), the EFI I2C MaximumReceiveBytes > and MaximumTransmitBytes are set to the maximum value (0xFFFFFFFF). This > causes msg->len + max_len - 1 to overflow, leading to an incorrect number > of returned operations. To address this, the msg->len is extended to 64 bits. Thanks for the info. See the patch I just Cc'd you on. @Sascha, can you drop this one patch again? Thanks, Ahmad > > Best regards > > Tomas > >> } >> >> static unsigned int efi_i2c_req_op_cnt( >> -- >> 2.39.2 >> > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |