On Fri, Mar 22, 2019 at 11:37:24PM +1100, Michael Ellerman wrote: > .Lcmp_rest_lt8bytes: > - /* Here we have only less than 8 bytes to compare with. at least s1 > - * Address is aligned with 8 bytes. > - * The next double words are load and shift right with appropriate > - * bits. > + /* > + * Here we have less than 8 bytes to compare. At least s1 is aligned to > + * 8 bytes, but s2 may not be. We must make sure s2 + 8 doesn't cross a
"s2 + 7"? The code is fine though (bgt, not bge). > + * page boundary, otherwise we might read past the end of the buffer and > + * trigger a page fault. We use 4K as the conservative minimum page > + * size. If we detect that case we go to the byte-by-byte loop. > + * > + * Otherwise the next double word is loaded from s1 and s2, and shifted > + * right to compare the appropriate bits. > */ > + clrldi r6,r4,(64-12) // r6 = r4 & 0xfff You can just write rlwinm r6,r4,0,0x0fff if that is clearer? Or do you still want a comment with that :-) > + cmpdi r6,0xff8 > + bgt .Lshort Reviewed-by: Segher Boessenkool <seg...@kernel.crashing.org> Segher
