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Fri, 16 Feb 2024 12:41:26 +0100 Message-ID: <61cfc73e-e406-4e98-9057-d7843e7694e7@gmx.de> Date: Fri, 16 Feb 2024 13:05:20 +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: [PATCH v8 2/2] lib: checksum: Use aligned accesses for ip_fast_csum and csum_ipv6_magic tests Content-Language: en-US To: Charlie Jenkins , Guenter Roeck Cc: David Laight , Palmer Dabbelt , Andrew Morton , Parisc List , Al Viro , linux-kernel@vger.kernel.org References: <20240214-fix_sparse_errors_checksum_tests-v8-0-36b60e673593@rivosinc.com> <20240214-fix_sparse_errors_checksum_tests-v8-2-36b60e673593@rivosinc.com> <2ec91b11-23c7-4beb-8cef-c68367c8f029@roeck-us.net> <25f108d1-827f-4a18-bee4-4105fbd45974@gmx.de> <6aaa4b89-a967-4b19-b4bf-a1ad5c8e9faa@roeck-us.net> From: Helge Deller Autocrypt: addr=deller@gmx.de; keydata= xsFNBF3Ia3MBEAD3nmWzMgQByYAWnb9cNqspnkb2GLVKzhoH2QD4eRpyDLA/3smlClbeKkWT HLnjgkbPFDmcmCz5V0Wv1mKYRClAHPCIBIJgyICqqUZo2qGmKstUx3pFAiztlXBANpRECgwJ r+8w6mkccOM9GhoPU0vMaD/UVJcJQzvrxVHO8EHS36aUkjKd6cOpdVbCt3qx8cEhCmaFEO6u CL+k5AZQoABbFQEBocZE1/lSYzaHkcHrjn4cQjc3CffXnUVYwlo8EYOtAHgMDC39s9a7S90L 69l6G73lYBD/Br5lnDPlG6dKfGFZZpQ1h8/x+Qz366Ojfq9MuuRJg7ZQpe6foiOtqwKym/zV dVvSdOOc5sHSpfwu5+BVAAyBd6hw4NddlAQUjHSRs3zJ9OfrEx2d3mIfXZ7+pMhZ7qX0Axlq Lq+B5cfLpzkPAgKn11tfXFxP+hcPHIts0bnDz4EEp+HraW+oRCH2m57Y9zhcJTOJaLw4YpTY GRUlF076vZ2Hz/xMEvIJddRGId7UXZgH9a32NDf+BUjWEZvFt1wFSW1r7zb7oGCwZMy2LI/G aHQv/N0NeFMd28z+deyxd0k1CGefHJuJcOJDVtcE1rGQ43aDhWSpXvXKDj42vFD2We6uIo9D 1VNre2+uAxFzqqf026H6cH8hin9Vnx7p3uq3Dka/Y/qmRFnKVQARAQABzRxIZWxnZSBEZWxs ZXIgPGRlbGxlckBnbXguZGU+wsGRBBMBCAA7AhsDBQsJCAcCBhUKCQgLAgQWAgMBAh4BAheA FiEERUSCKCzZENvvPSX4Pl89BKeiRgMFAl3J1zsCGQEACgkQPl89BKeiRgNK7xAAg6kJTPje uBm9PJTUxXaoaLJFXbYdSPfXhqX/BI9Xi2VzhwC2nSmizdFbeobQBTtRIz5LPhjk95t11q0s uP5htzNISPpwxiYZGKrNnXfcPlziI2bUtlz4ke34cLK6MIl1kbS0/kJBxhiXyvyTWk2JmkMi REjR84lCMAoJd1OM9XGFOg94BT5aLlEKFcld9qj7B4UFpma8RbRUpUWdo0omAEgrnhaKJwV8 qt0ULaF/kyP5qbI8iA2PAvIjq73dA4LNKdMFPG7Rw8yITQ1Vi0DlDgDT2RLvKxEQC0o3C6O4 iQq7qamsThLK0JSDRdLDnq6Phv+Yahd7sDMYuk3gIdoyczRkXzncWAYq7XTWl7nZYBVXG1D8 gkdclsnHzEKpTQIzn/rGyZshsjL4pxVUIpw/vdfx8oNRLKj7iduf11g2kFP71e9v2PP94ik3 Xi9oszP+fP770J0B8QM8w745BrcQm41SsILjArK+5mMHrYhM4ZFN7aipK3UXDNs3vjN+t0zi qErzlrxXtsX4J6nqjs/mF9frVkpv7OTAzj7pjFHv0Bu8pRm4AyW6Y5/H6jOup6nkJdP/AFDu 5ImdlA0jhr3iLk9s9WnjBUHyMYu+HD7qR3yhX6uWxg2oB2FWVMRLXbPEt2hRGq09rVQS7DBy dbZgPwou7pD8MTfQhGmDJFKm2jvOwU0EXchrcwEQAOsDQjdtPeaRt8EP2pc8tG+g9eiiX9Sh rX87SLSeKF6uHpEJ3VbhafIU6A7hy7RcIJnQz0hEUdXjH774B8YD3JKnAtfAyuIU2/rOGa/v UN4BY6U6TVIOv9piVQByBthGQh4YHhePSKtPzK9Pv/6rd8H3IWnJK/dXiUDQllkedrENXrZp eLUjhyp94ooo9XqRl44YqlsrSUh+BzW7wqwfmu26UjmAzIZYVCPCq5IjD96QrhLf6naY6En3 ++tqCAWPkqKvWfRdXPOz4GK08uhcBp3jZHTVkcbo5qahVpv8Y8mzOvSIAxnIjb+cklVxjyY9 dVlrhfKiK5L+zA2fWUreVBqLs1SjfHm5OGuQ2qqzVcMYJGH/uisJn22VXB1c48yYyGv2HUN5 lC1JHQUV9734I5cczA2Gfo27nTHy3zANj4hy+s/q1adzvn7hMokU7OehwKrNXafFfwWVK3OG 1dSjWtgIv5KJi1XZk5TV6JlPZSqj4D8pUwIx3KSp0cD7xTEZATRfc47Yc+cyKcXG034tNEAc xZNTR1kMi9njdxc1wzM9T6pspTtA0vuD3ee94Dg+nDrH1As24uwfFLguiILPzpl0kLaPYYgB wumlL2nGcB6RVRRFMiAS5uOTEk+sJ/tRiQwO3K8vmaECaNJRfJC7weH+jww1Dzo0f1TP6rUa fTBRABEBAAHCwXYEGAEIACAWIQRFRIIoLNkQ2+89Jfg+Xz0Ep6JGAwUCXchrcwIbDAAKCRA+ Xz0Ep6JGAxtdEAC54NQMBwjUNqBNCMsh6WrwQwbg9tkJw718QHPw43gKFSxFIYzdBzD/YMPH l+2fFiefvmI4uNDjlyCITGSM+T6b8cA7YAKvZhzJyJSS7pRzsIKGjhk7zADL1+PJei9p9idy RbmFKo0dAL+ac0t/EZULHGPuIiavWLgwYLVoUEBwz86ZtEtVmDmEsj8ryWw75ZIarNDhV74s BdM2ffUJk3+vWe25BPcJiaZkTuFt+xt2CdbvpZv3IPrEkp9GAKof2hHdFCRKMtgxBo8Kao6p Ws/Vv68FusAi94ySuZT3fp1xGWWf5+1jX4ylC//w0Rj85QihTpA2MylORUNFvH0MRJx4mlFk XN6G+5jIIJhG46LUucQ28+VyEDNcGL3tarnkw8ngEhAbnvMJ2RTx8vGh7PssKaGzAUmNNZiG MB4mPKqvDZ02j1wp7vthQcOEg08z1+XHXb8ZZKST7yTVa5P89JymGE8CBGdQaAXnqYK3/yWf FwRDcGV6nxanxZGKEkSHHOm8jHwvQWvPP73pvuPBEPtKGLzbgd7OOcGZWtq2hNC6cRtsRdDx 4TAGMCz4j238m+2mdbdhRh3iBnWT5yPFfnv/2IjFAk+sdix1Mrr+LIDF++kiekeq0yUpDdc4 ExBy2xf6dd+tuFFBp3/VDN4U0UfG4QJ2fg19zE5Z8dS4jGIbLg== In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:YuF9PVuGcuEpBNoBnA5hjOnuz5Bspi64Grxz2iK2S3IkdxDOLtv GCIoagFe46RGCoS+efUsxNyzUihQQFvedTJW87N4RIkC12WFAxCF5Lir2xaisO1CZgCQm0G EoeXSRdQGBscBtRjN86vJD8iSIy+My5vVZ7bFM8y4+xlQG43uQLc2qLpjuzNkr1/lMHZAa6 PnwB1PeWf/kcK+PGdDkWQ== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:RTB83uO8wns=;hiZTewUlieqkNBMyVa449AXBYM6 HdzkyUSoDb/eBmsqzN7SLxRPM72sm3iZzyQbz6IxN0vaqImha6nuQnbR+S7V0++cPK9N/L/4K jtlkTPedTLsFBUD5ax/Wla9tKK343Ir8ApowLkMwdeGrzQXHG4AWAeKrkqngVU7fAfXVbTHI5 RABMhUxvWV6GLqeGNWak6iIGMOjseFrR0fCxAEywtRA02GC/Cs8nQ5YRkpE0xl1iz+iUA/aX8 oFnFcPRodeEWeT5ojaCMJRr0cweZoRrpZMVmznSDke6BUaD9kK4c9nHq/pwzsIPbZiyaw45BK EXXzjptR5csN4fNBjs+Bfcu/91t6MUQUO5jZ8SPkq8PRBozGEj92HNrtw6pNkJ6iIg8Kc6LL2 wPVwHEp7JN0D8J1JmhQpNl1eOZVAhr1JE75o8k1vLZt23QEQzBunKSCkPzuV6pEhGgR3vIDCT 59YCBjLvSISgG5qmBqHY/9lAbjrynkGozWPGqaYgGKIqrkG1RhXvwCVdTARyLU1Xv/gKpNVbE +Nagp2Y/Faurda1lhbkMzTQtUbXi51YLmuF0546r35sqXjkIOlcYuTX3vienWHsvssPG2ozO2 iNb/GK+0hF2eci49SHMtwYKVqjId6USEb1r4Vt1BBw4ur1VVwXagVzSyoq+P0FqSx6covzOO1 fpBL91YgifSzYQgf6yPqWIVRjB4C4iqvWANTkGrDpw3b9v9LeVAVszmpoHf5vlk2wIFYtmJel TjY3I86C7rjAEnvVrM8BxvUBtuC1v4UDV7CTsGW8L+ZG0/R+q8UexA/9WvH+wi3Gm411i+rAb rQBmcHCIVs5qAs9WnRhDCbwFfCUbJs9Q85udohi4ZUrPc= On 2/16/24 07:13, Charlie Jenkins wrote: > On Thu, Feb 15, 2024 at 10:09:42PM -0800, Guenter Roeck wrote: >> On 2/15/24 21:54, Helge Deller wrote: >> [ ... ] >>> >>> Can you please give a pointer to this test code? >>> I'm happy to try it on real hardware. >>> >> You should also see the problem if you use v7 of Charlie's checksum >> unit test fixes. >> >> I submitted the qemu fix (or at least what I think the fix should be) >> a couple of minutes ago. >> >> https://patchwork.kernel.org/project/qemu-devel/patch/20240216053415.21= 63286-1-linux@roeck-us.net/ >> >>>> It is quite easy to show that carry is always set after executing ldd >>>> on an unaligned address. That is also why I know for sure that the >>>> problem is not seen with ldw on unaligned addresses. >>> Interesting. >> >> Ultimately it wasn't surprising, with the unusual carry bit >> implementation on hppa. The upper 8 carry bits were not masked >> correctly when returning from a trap or interrupt. > > Tangential question, but why does Linux need to save and restore the PSW > if that is already handled by the hardware? I am missing something. e.g. for task switching. Helge