From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755163AbcFQEHi (ORCPT ); Fri, 17 Jun 2016 00:07:38 -0400 Received: from mailout4.samsung.com ([203.254.224.34]:35947 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750877AbcFQEHg (ORCPT ); Fri, 17 Jun 2016 00:07:36 -0400 MIME-version: 1.0 Content-type: text/plain; charset=UTF-8 X-AuditID: cbfee68f-f79d26d0000014f6-e0-5763777fbc58 Content-transfer-encoding: 8BIT Message-id: <5763777D.8040601@samsung.com> Date: Fri, 17 Jun 2016 13:07:25 +0900 From: Seung-Woo Kim Reply-to: sw0312.kim@samsung.com User-Agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121011 Thunderbird/16.0.1 To: Jaehoon Chung Cc: ulf.hansson@linaro.org, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, Seung-Woo Kim Subject: Re: [PATCH] mmc: dw_mmc: remove UBSAN warning in dw_mci_setup_bus() References: <1465358840-22826-1-git-send-email-sw0312.kim@samsung.com> <5759633E.7090706@samsung.com> <575A17F5.1050609@samsung.com> <576352CA.3080605@samsung.com> In-reply-to: <576352CA.3080605@samsung.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprOIsWRmVeSWpSXmKPExsWyRsSkULe+PDnc4GejvsWNX22sFpd3zWGz OPK/n9FixuSXbBbH14Y7sHrcubaHzaNvyypGj8+b5AKYo7hsUlJzMstSi/TtErgy7q5ayFiw TLpi8utWtgbG46JdjJwcEgImEtea/jJB2GISF+6tZ+ti5OIQEljBKPFj2zJmmKK5j++zQiRm MUo03/gEluAVEJT4MfkeSxcjBwezgLzEkUvZIGFmAXWJSfMWgZUICTxglPh3lRukhFdAS2JO UzJImEVAVWJL+2ZGEJtNQEdi/5LfrBDlChJXJh5jBykXFQiT2Lk5HSQsAtR5/chENojptRL7 JvaDnSws4CNxrXUyM8RlfxklPvxqZAFJcApoS3T+XQCWkBA4xi5x/0YjK8RiAYlvkw+BnSwh ICux6QDUi5ISB1fcYJnAKD4LyWOzEB6bheSxBYzMqxhFUwuSC4qT0ouM9YoTc4tL89L1kvNz NzEC4+v0v2f9OxjvHrA+xCjAwajEw7tCNDlciDWxrLgy9xCjKdARE5mlRJPzgVGcVxJvaGxm ZGFqYmpsZG5ppiTOu1DqZ7CQQHpiSWp2ampBalF8UWlOavEhRiYOTqkGxlVfZ8YZ3WX5sy1+ 7cuUh8uPbVd+EuB3aE/PSab52wQ89m+LFf6/NnUfg6WxV3LA9Mg+u5WdUcerQ55sOvVhBceu HZlM6tsXavmKilwUvnLoydtdSxsfW3jyLn3A3jKxRXT144OzNDcIaX76l2T31um3MfMzVhmf uJzjb9PkNveWTV96Jsvh9GQlluKMREMt5qLiRADn9RHwqgIAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrCIsWRmVeSWpSXmKPExsVy+t9jQd368uRwgwf/NS1u/Gpjtbi8aw6b xZH//YwWMya/ZLM4vjbcgdXjzrU9bB59W1YxenzeJBfAHNXAaJORmpiSWqSQmpecn5KZl26r 5B0c7xxvamZgqGtoaWGupJCXmJtqq+TiE6DrlpkDtFJJoSwxpxQoFJBYXKykb4dpQmiIm64F TGOErm9IEFyPkQEaSFjDmHF31ULGgmXSFZNft7I1MB4X7WLk5JAQMJGY+/g+K4QtJnHh3nq2 LkYuDiGBWYwSzTc+MYMkeAUEJX5MvsfSxcjBwSwgL3HkUjZImFlAXWLSvEVgJUICDxgl/l3l BinhFdCSmNOUDBJmEVCV2NK+mRHEZhPQkdi/5DcrRLmCxJWJx9hBykUFwiR2bk4HCYsAdV4/ MpENYnqtxL6J/UwgtrCAj8S11snMEJf9ZZT48KuRBSTBKaAt0fl3AfMERsFZSA6dhXDoLCSH LmBkXsUokVqQXFCclJ5rmJdarlecmFtcmpeul5yfu4kRHMPPpHYwHtzlfohRgINRiYd3h3Jy uBBrYllxZe4hRgkOZiURXuMyoBBvSmJlVWpRfnxRaU5q8SFGU6BfJzJLiSbnA9NLXkm8obGJ mZGlkbmhhZGxuZI47+P/68KEBNITS1KzU1MLUotg+pg4OKUaGHd5J33kl24VdLPlm5/cIruX 9xFzqBLf3yzmC+8aheY9uqNzMN/22dVspY/zHi05u8d8Z/CEP7zrnz+w+auy5ev6yolSF8Q4 W28cel6sfK3l790/h/x2SH+ZP23V/sLvqSJRmpurc35WNds2c741f2Vq8ylXyngpT8iddZXr H8SHb5Xcq7dez0yJpTgj0VCLuag4EQCAsc/J9wIAAA== DLP-Filter: Pass X-MTR: 20000000000000000@CPGS X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Jaehoon, On 2016년 06월 17일 10:30, Jaehoon Chung wrote: > Hi Seung-Woo, > > On 06/10/2016 10:29 AM, Seung-Woo Kim wrote: >> Hi Jaehoon, >> >> On 2016년 06월 09일 21:38, Jaehoon Chung wrote: >>> Hi Seung-Woo, >>> >>> On 06/08/2016 01:07 PM, Seung-Woo Kim wrote: >>>> This patch removes following UBSAN warnings in dw_mci_setup_bus(). >>>> The warnings are caused because of shift with more than 31 on 32 >>>> bit variable, so this patch fixes to shift only for less than 32. >>>> >>>> >>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >>>> index 2cc6123..dff045e 100644 >>>> --- a/drivers/mmc/host/dw_mmc.c >>>> +++ b/drivers/mmc/host/dw_mmc.c >>>> @@ -1099,7 +1099,8 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit) >>>> >>>> div = (host->bus_hz != clock) ? DIV_ROUND_UP(div, 2) : 0; >>>> >>>> - if ((clock << div) != slot->__clk_old || force_clkinit) >>>> + if (((div < 32) ? (clock << div) : 0) != slot->__clk_old || >>> >>> Well, we don't expect that clock is 0. >>> if clock is 0, it should be passed to " if (!clock)".. >>> >>> During initializing card, clock is 400KHz or less..I understood what you want to fix. >>> But I taught this is not correct. >> >> It seems slot->__clk_old is not really clock but a kind of value to >> store both clock and div in one variable. And at least, my compiler >> calculates right shift with more than 32 as 0. I am not sure there is >> other proper value for the case. >> >> By the way, in my test environment, clock is calculated as like >> following steps: >> mmc_host mmc0: Bus speed (slot 0) = 200000000Hz (slot req 400000Hz, >> actual 400000HZ div = 250) >> mmc_host mmc0: Bus speed (slot 0) = 200000000Hz (slot req 200000000Hz, >> actual 200000000HZ div = 0) >> mmc_host mmc0: Bus speed (slot 0) = 200000000Hz (slot req 52000000Hz, >> actual 50000000HZ div = 2) >> mmc_host mmc0: Bus speed (slot 0) = 400000000Hz (slot req 52000000Hz, >> actual 50000000HZ div = 4) >> mmc_host mmc0: Bus speed (slot 0) = 400000000Hz (slot req 200000000Hz, >> actual 200000000HZ div = 1) >> >> and only the first case is reported as the warning. If you let me know >> any proper value, then I will fix with the value. > > I think that "clock << div" and__old_clock are used for checking whether clock is changed. > So it doesn't need to rotate with div. > > Could you check the below codes? > > if ((clock != slot->clk_old) || force_clkinit) > ... > > slot->__clk_old = clock; >>From the comment about alignment of slot->__clk_old, it says that "keep the clock with reflecting clock dividor". So to me, it is better also adding slot->__dlv with your suggestion. I will send patch like it, soon. Regards, - Seung-Woo Kim > > Best Regards, > Jaehoon Chung > >> >> Thanks, >> - Seung-Woo Kim >> >> >>> >>> >>>> + force_clkinit) >>>> dev_info(&slot->mmc->class_dev, >>>> "Bus speed (slot %d) = %dHz (slot req %dHz, actual %dHZ div = %d)\n", >>>> slot->id, host->bus_hz, clock, >>>> @@ -1129,7 +1130,7 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit) >>>> mci_send_cmd(slot, sdmmc_cmd_bits, 0); >>>> >>>> /* keep the clock with reflecting clock dividor */ >>>> - slot->__clk_old = clock << div; >>>> + slot->__clk_old = (div < 32) ? (clock << div) : 0; -- Seung-Woo Kim Samsung Software R&D Center --