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authorAlexander Lobakin2022-04-12 21:59:16 +0000
committerJens Axboe2022-04-12 16:31:38 -0600
commitb97687527be85a55e12804c98745c5619eadcc32 (patch)
treeea4de3c755a03a0f0e9dc001529da1ddc90bdefa /sound/virtio
parent868e6139c5212e7d9de8332806aacfeafb349320 (diff)
asm-generic: fix __get_unaligned_be48() on 32 bit platforms
While testing the new macros for working with 48 bit containers, I faced a weird problem: 32 + 16: 0x2ef6e8da 0x79e60000 48: 0xffffe8da + 0x79e60000 All the bits starting from the 32nd were getting 1d in 9/10 cases. The debug showed: p[0]: 0x00002e0000000000 p[1]: 0x00002ef600000000 p[2]: 0xffffffffe8000000 p[3]: 0xffffffffe8da0000 p[4]: 0xffffffffe8da7900 p[5]: 0xffffffffe8da79e6 that the value becomes a garbage after the third OR, i.e. on `p[2] << 24`. When the 31st bit is 1 and there's no explicit cast to an unsigned, it's being considered as a signed int and getting sign-extended on OR, so `e8000000` becomes `ffffffffe8000000` and messes up the result. Cast the @p[2] to u64 as well to avoid this. Now: 32 + 16: 0x7ef6a490 0xddc10000 48: 0x7ef6a490 + 0xddc10000 p[0]: 0x00007e0000000000 p[1]: 0x00007ef600000000 p[2]: 0x00007ef6a4000000 p[3]: 0x00007ef6a4900000 p[4]: 0x00007ef6a490dd00 p[5]: 0x00007ef6a490ddc1 Fixes: c2ea5fcf53d5 ("asm-generic: introduce be48 unaligned accessors") Signed-off-by: Alexander Lobakin <alobakin@pm.me> Link: https://lore.kernel.org/r/20220412215220.75677-1-alobakin@pm.me Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'sound/virtio')
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