On Fri, 21 Dec 2018 10:05:04 +0100, Bard liao wrote: > > > On 12/20/2018 11:07 PM, Pierre-Louis Bossart wrote: > > > >>>>> + snd_sof_dsp_block_write(sdev, offset, > >>>>> + (void *)block + sizeof(*block), > >>>>> + block->size); > >>>>> + > >>>>> + /* next block */ > >>>>> + block = (void *)block + sizeof(*block) + block->size; > >>>> This may lead to an unaligned access. > >>> Did you mean we should double check the block->size to > >>> prevent access to an invalid address? > >> You need two types of checks for the given data: > >> - The bounce check of block->size; > >> We need to avoid out-of-bounce access. > > s/bounce/bounds ? > >> > >> - Alignment of block->size; > >> For some non-x86 platforms, the access to an unaligned address might > >> be illegal. > > > > Maybe I am missing something but I don't see any sort of explicit > > restriction on alignment in the SOF tools. it looks implicit based > > on address offsets and bases. > > Maybe get_unaligned() is good enough to avoid unaligned access? That's another option, but you'd need to put everywhere. An alternative is to just copy the data on a new block header on the stack temporarily and refer it. Or simply assuring the alignment by checking block->size as Pierre suggested... Takashi > > > > > Liam, do you see any negative side effects if we enforce a 32-bit > > alignment for all blocks (which essentially means all block sizes > > are multiple of 4)? we can try and experiment but it's better if we > > have an agreement on the design. > > > > > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
