On 02/09/2020 12:13, David Laight wrote: > From: Colin Ian King >> Sent: 02 September 2020 11:27 >> >> On 14/03/2020 10:23, Rafael J. Wysocki wrote: >>> On Thursday, March 12, 2020 12:13:45 PM CET Colin King wrote: >>>> From: Colin Ian King <colin.king@xxxxxxxxxxxxx> >>>> >>>> Reading ACPI data on ARM64 at a non-aligned offset from >>>> /sys/firmware/acpi/tables/data/BERT will cause a splat because >>>> the data is I/O memory mapped and being read with just a memcpy. >>>> Fix this by introducing an I/O variant of memory_read_from_buffer >>>> and using I/O memory mapped copies instead. > .. >>>> +/** >>>> + * memory_read_from_io_buffer - copy data from a io memory mapped buffer >>>> + * @to: the kernel space buffer to read to >>>> + * @count: the maximum number of bytes to read >>>> + * @ppos: the current position in the buffer >>>> + * @from: the buffer to read from >>>> + * @available: the size of the buffer >>>> + * >>>> + * The memory_read_from_buffer() function reads up to @count bytes from the >>>> + * io memory mappy buffer @from at offset @ppos into the kernel space address >>>> + * starting at @to. >>>> + * >>>> + * On success, the number of bytes read is returned and the offset @ppos is >>>> + * advanced by this number, or negative value is returned on error. >>>> + **/ > > Apart from the return value how is this different from the generic > memcpy_from_io() ? > > David The intention is to be semantically the same as memory_read_from_buffer(), so in that respect quite a bit different from memcpy_fromio() Colin > > - > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK > Registration No: 1397386 (Wales) >
