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Wed, 30 Oct 2024 04:08:12 -0700 (PDT) Received: from [10.176.68.61] ([192.19.176.250]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7205793189esm8950018b3a.58.2024.10.30.04.08.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Oct 2024 04:08:11 -0700 (PDT) Message-ID: <467fd994-01f0-4057-964c-4184a23e59c4@broadcom.com> Date: Wed, 30 Oct 2024 12:08:07 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: incorrect shift and mask operation in drivers/net/wireless/broadcom/brcm80211/brcmsmac/phy/phy_n.c To: "Colin King (gmail)" , "linux-wireless@vger.kernel.org" , brcm80211@lists.linux.dev, brcm80211-dev-list.pdl@broadcom.com Cc: "linux-kernel@vger.kernel.org" , Dmitry Antipov References: <9c02683d-c688-4e39-913e-6b20b3bd76a0@gmail.com> Content-Language: en-US From: Arend van Spriel Autocrypt: addr=arend.vanspriel@broadcom.com; keydata= xsFNBGP96SABEACfErEjSRi7TA1ttHYaUM3GuirbgqrNvQ41UJs1ag1T0TeyINqG+s6aFuO8 evRHRnyAqTjMQoo4tkfy21XQX/OsBlgvMeNzfs6jnVwlCVrhqPkX5g5GaXJnO3c4AvXHyWik SOd8nOIwt9MNfGn99tkRAmmsLaMiVLzYfg+n3kNDsqgylcSahbd+gVMq+32q8QA+L1B9tAkM UccmSXuhilER70gFMJeM9ZQwD/WPOQ2jHpd0hDVoQsTbBxZZnr2GSjSNr7r5ilGV7a3uaRUU HLWPOuGUngSktUTpjwgGYZ87Edp+BpxO62h0aKMyjzWNTkt6UVnMPOwvb70hNA2v58Pt4kHh 8ApHky6IepI6SOCcMpUEHQuoKxTMw/pzmlb4A8PY//Xu/SJF8xpkpWPVcQxNTqkjbpazOUw3 12u4EK1lzwH7wjnhM3Fs5aNBgyg+STS1VWIwoXJ7Q2Z51odh0XecsjL8EkHbp9qHdRvZQmMu Ns8lBPBkzpS7y2Q6Sp7DcRvDfQQxPrE2sKxKLZVGcRYAD90r7NANryRA/i+785MSPUNSTWK3 MGZ3Xv3fY7phISvYAklVn/tYRh88Zthf6iDuq86m5mr+qOO8s1JnCz6uxd/SSWLVOWov9Gx3 uClOYpVsUSu3utTta3XVcKVMWG/M+dWkbdt2KES2cv4P5twxyQARAQABzS9BcmVuZCB2YW4g U3ByaWVsIDxhcmVuZC52YW5zcHJpZWxAYnJvYWRjb20uY29tPsLBhwQTAQgAMRYhBLX1Z69w T4l/vfdb0pZ6NOIYA/1RBQJj/ek9AhsDBAsJCAcFFQgJCgsFFgIDAQAACgkQlno04hgD/VGw 8A//VEoGTamfCks+a12yFtT1d/GjDdf3i9agKMk3esn08JwjJ96x9OFFl2vFaQCSiefeXITR K4T/yT+n/IXntVWT3pOBfb343cAPjpaZvBMh8p32z3CuV1H0Y+753HX7gdWTEojGWaWmKkZh w3nGoRZQEeAcwcF3gMNwsM5Gemj7aInIhRLUeoKh/0yV85lNE1D7JkyNheQ+v91DWVj5/a9X 7kiL18fH1iC9kvP3lq5VE54okpGqUj5KE5pmHNFBp7HZO3EXFAd3Zxm9ol5ic9tggY0oET28 ucARi1wXLD/oCf1R9sAoWfSTnvOcJjG+kUwK7T+ZHTF8YZ4GAT3k5EwZ2Mk3+Rt62R81gzRF A6+zsewqdymbpwgyPDKcJ8YUHbqvspMQnPTmXNk+7p7fXReVPOYFtzzfBGSCByIkh1bB45jO +TM5ZbMmhsUbqA0dFT5JMHjJIaGmcw21ocgBcLsJ730fbLP/L08udgWHywPoq7Ja7lj5W0io ZDLz5uQ6CEER6wzD07vZwSl/NokljVexnOrwbR3wIhdr6B0Hc/0Bh7T8gpeM+QcK6EwJBG7A xCHLEacOuKo4jinf94YQrOEMnOmvucuQRm9CIwZrQ69Mg6rLn32pA4cK4XWQN1N3wQXnRUnb MTymLAoxE4MInhDVsZCtIDFxMVvBUgZiZZszN33OwU0EY/3pIgEQAN35Ii1Hn90ghm/qlvz/ L+wFi3PTQ90V6UKPv5Q5hq+1BtLA6aj2qmdFBO9lgO9AbzHo8Eizrgtxp41GkKTgHuYChijI kdhTVPm+Pv44N/3uHUeFhN3wQ3sTs1ZT/0HhwXt8JvjqbhvtNmoGosZvpUCTwiyM1VBF/ICT ltzFmXd5z7sEuDyZcz9Q1t1Bb2cmbhp3eIgLmVA4Lc9ZS3sK1UMgSDwaR4KYBhF0OKMC1OH8 M5jfcPHR8OLTLIM/Thw0YIUiYfj6lWwWkb82qa4IQvIEmz0LwvHkaLU1TCXbehO0pLWB9HnK r3nofx5oMfhu+cMa5C6g3fBB8Z43mDi2m/xM6p5c3q/EybOxBzhujeKN7smBTlkvAdwQfvuD jKr9lvrC2oKIjcsO+MxSGY4zRU0WKr4KD720PV2DCn54ZcOxOkOGR624d5bhDbjw1l2r+89V WLRLirBZn7VmWHSdfq5Xl9CyHT1uY6X9FRr3sWde9kA/C7Z2tqy0MevXAz+MtavOJb9XDUlI 7Bm0OPe5BTIuhtLvVZiW4ivT2LJOpkokLy2K852u32Z1QlOYjsbimf77avcrLBplvms0D7j6 OaKOq503UKfcSZo3lF70J5UtJfXy64noI4oyVNl1b+egkV2iSXifTGGzOjt50/efgm1bKNkX iCVOYt9sGTrVhiX1ABEBAAHCwXYEGAEIACAWIQS19WevcE+Jf733W9KWejTiGAP9UQUCY/3p PgIbDAAKCRCWejTiGAP9UaC/EACZvViKrMkFooyACGaukqIo/s94sGuqxj308NbZ4g5jgy/T +lYBzlurnFmIbJESFOEq0MBZorozDGk+/p8pfAh4S868i1HFeLivVIujkcL6unG1UYEnnJI9 uSwUbEqgA8vwdUPEGewYkPH6AaQoh1DdYGOleQqDq1Mo62xu+bKstYHpArzT2islvLdrBtjD MEzYThskDgDUk/aGPgtPlU9mB7IiBnQcqbS/V5f01ZicI1esy9ywnlWdZCHy36uTUfacshpz LsTCSKICXRotA0p6ZiCQloW7uRH28JFDBEbIOgAcuXGojqYx5vSM6o+03W9UjKkBGYFCqjIy Ku843p86Ky4JBs5dAXN7msLGLhAhtiVx8ymeoLGMoYoxqIoqVNaovvH9y1ZHGqS/IYXWf+jE H4MX7ucv4N8RcsoMGzXyi4UbBjxgljAhTYs+c5YOkbXfkRqXQeECOuQ4prsc6/zxGJf7MlPy NKowQLrlMBGXT4NnRNV0+yHmusXPOPIqQCKEtbWSx9s2slQxmXukPYvLnuRJqkPkvrTgjn5d eSE0Dkhni4292/Nn/TnZf5mxCNWH1p3dz/vrT6EIYk2GSJgCLoTkCcqaM6+5E4IwgYOq3UYu AAgeEbPV1QeTVAPrntrLb0t0U5vdwG7Xl40baV9OydTv7ghjYZU349w1d5mdxg== In-Reply-To: <9c02683d-c688-4e39-913e-6b20b3bd76a0@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 10/15/2024 1:02 AM, Colin King (gmail) wrote: > Hi, > > Static analysis on drivers/net/wireless/broadcom/brcm80211/brcmsmac/phy/ > phy_n.c has found an issue with a mask and shift operation in function > wlc_phy_rxcal_radio_setup_nphy() as follows: > > lines 26326-26330: > >         offtune_val = >                 (pi->tx_rx_cal_radio_saveregs >                  [2] & 0xF0) >> 8; >         offtune_val = >                 (offtune_val <= 0x7) ? 0xF : 0; > > and similar in lines 26376-26381 too. > > The issue is that the expression pi->tx_rx_cal_radio_saveregs[2] & 0xF0 > when shifted 8 places right is always zero, so this looks like a mistake > since some value value between 0..0xf is expected in the second statement. > > Since pi->tx_rx_cal_radio_saveregs[2] is a u16 value the expression > could plausible be: > >     (pi->tx_rx_cal_radio_saveregs[2] & 0xf0) >> 4 > or >     (pi->tx_rx_cal_radio_saveregs[2] & 0xf00) >> 8 > > I don't have knowledge of the hardware so I'm not sure what a suitable > fix is. Thanks, Colin That looks pretty redundant indeed. I look into the history of it, but ended up in an old end-of-life development tree and the code was pretty much the same. It is one of the finer dark arts of our phy/radio development team I guess ;-) I see that Dmitry Antipov submitted a patch to address this. Again thanks for reporting. Regards, Arend