Ram Pai <linuxram@xxxxxxxxxx> writes: > Rearrange 64K PTE bits to free up bits 3, 4, 5 and 6 > in the 64K backed HPTE pages. This along with the earlier > patch will entirely free up the four bits from 64K PTE. > The bit numbers are big-endian as defined in the ISA3.0 > > This patch does the following change to 64K PTE backed > by 64K HPTE. > > H_PAGE_F_SECOND (S) which occupied bit 4 moves to the > second part of the pte to bit 60. > H_PAGE_F_GIX (G,I,X) which occupied bit 5, 6 and 7 also > moves to the second part of the pte to bit 61, > 62, 63, 64 respectively > > since bit 7 is now freed up, we move H_PAGE_BUSY (B) from > bit 9 to bit 7. > > The second part of the PTE will hold > (H_PAGE_F_SECOND|H_PAGE_F_GIX) at bit 60,61,62,63. > NOTE: None of the bits in the secondary PTE were not used > by 64k-HPTE backed PTE. > > Before the patch, the 64K HPTE backed 64k PTE format was > as follows > > 0 1 2 3 4 5 6 7 8 9 10...........................63 > : : : : : : : : : : : : > v v v v v v v v v v v v > > ,-,-,-,-,--,--,--,--,-,-,-,-,-,------------------,-,-,-, > |x|x|x| |S |G |I |X |x|B| |x|x|................|x|x|x|x| <- primary pte > '_'_'_'_'__'__'__'__'_'_'_'_'_'________________'_'_'_'_' > | | | | | | | | | | | | |..................| | | | | <- secondary pte > '_'_'_'_'__'__'__'__'_'_'_'_'__________________'_'_'_'_' > > After the patch, the 64k HPTE backed 64k PTE format is > as follows > > 0 1 2 3 4 5 6 7 8 9 10...........................63 > : : : : : : : : : : : : > v v v v v v v v v v v v > > ,-,-,-,-,--,--,--,--,-,-,-,-,-,------------------,-,-,-, > |x|x|x| | | | |B |x| | |x|x|................|.|.|.|.| <- primary pte > '_'_'_'_'__'__'__'__'_'_'_'_'_'________________'_'_'_'_' > | | | | | | | | | | | | |..................|S|G|I|X| <- secondary pte > '_'_'_'_'__'__'__'__'_'_'_'_'__________________'_'_'_'_' > > The above PTE changes is applicable to hugetlbpages aswell. > > The patch does the following code changes: > > a) moves the H_PAGE_F_SECOND and H_PAGE_F_GIX to 4k PTE > header since it is no more needed b the 64k PTEs. > b) abstracts out __real_pte() and __rpte_to_hidx() so the > caller need not know the bit location of the slot. > c) moves the slot bits the secondary pte. > Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> With changes suggested for the first patch. > Signed-off-by: Ram Pai <linuxram@xxxxxxxxxx> > --- -aneesh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
