On x86_64-efi (at least) regions seem to be added from top down. The mm code will merge a new region with an existing region that comes immediately before the new region. This allows larger allocations to be satisfied that would otherwise be the case.
On powerpc-ieee1275, however, regions are added from bottom up. So if we add 3x 32MB regions, we can still only satisfy a 32MB allocation, rather than the 96MB allocation we might otherwise be able to satisfy. * Define 'post_size' as being bytes lost to the end of an allocation due to being given weird sizes from firmware that are not multiples of GRUB_MM_ALIGN. * Allow merging of regions immediately _after_ existing regions, not just before. As with the other approach, we create an allocated block to represent the new space and the pass it to grub_free() to get the metadata right. Signed-off-by: Daniel Axtens <d...@axtens.net> --- grub-core/kern/mm.c | 55 +++++++++++++++++++++++++-------------- include/grub/mm_private.h | 15 +++++++++++ 2 files changed, 51 insertions(+), 19 deletions(-) diff --git a/grub-core/kern/mm.c b/grub-core/kern/mm.c index c070afc621f8..835ed8a8f6f9 100644 --- a/grub-core/kern/mm.c +++ b/grub-core/kern/mm.c @@ -129,25 +129,41 @@ grub_mm_init_region (void *addr, grub_size_t size) size = ((grub_addr_t) -0x1000) - (grub_addr_t) addr; for (p = &grub_mm_base, q = *p; q; p = &(q->next), q = *p) - if ((grub_uint8_t *) addr + size + q->pre_size == (grub_uint8_t *) q) - { - r = (grub_mm_region_t) ALIGN_UP ((grub_addr_t) addr, GRUB_MM_ALIGN); - *r = *q; - r->pre_size += size; - - if (r->pre_size >> GRUB_MM_ALIGN_LOG2) - { - h = (grub_mm_header_t) (r + 1); - h->size = (r->pre_size >> GRUB_MM_ALIGN_LOG2); - h->magic = GRUB_MM_ALLOC_MAGIC; - r->size += h->size << GRUB_MM_ALIGN_LOG2; - r->pre_size &= (GRUB_MM_ALIGN - 1); - *p = r; - grub_free (h + 1); - } - *p = r; - return; - } + { + /* Does this region come _before_ an existing region? */ + if ((grub_uint8_t *) addr + size + q->pre_size == (grub_uint8_t *) q) + { + r = (grub_mm_region_t) ALIGN_UP ((grub_addr_t) addr, GRUB_MM_ALIGN); + *r = *q; + r->pre_size += size; + + if (r->pre_size >> GRUB_MM_ALIGN_LOG2) + { + h = (grub_mm_header_t) (r + 1); + h->size = (r->pre_size >> GRUB_MM_ALIGN_LOG2); + h->magic = GRUB_MM_ALLOC_MAGIC; + r->size += h->size << GRUB_MM_ALIGN_LOG2; + r->pre_size &= (GRUB_MM_ALIGN - 1); + *p = r; + grub_free (h + 1); + } + *p = r; + return; + } + + /* Does this region come _after_ an existing region? */ + if ((grub_uint8_t *)q + sizeof(*q) + q->size + q->post_size == + (grub_uint8_t *) addr) + { + h = (grub_mm_header_t) ((grub_uint8_t *)addr - q->post_size); + h->size = (size + q->post_size) >> GRUB_MM_ALIGN_LOG2; + h->magic = GRUB_MM_ALLOC_MAGIC; + q->size += h->size << GRUB_MM_ALIGN_LOG2; + q->post_size = (q->post_size + size) & (GRUB_MM_ALIGN - 1); + grub_free (h + 1); + return; + } + } /* Allocate a region from the head. */ r = (grub_mm_region_t) ALIGN_UP ((grub_addr_t) addr, GRUB_MM_ALIGN); @@ -166,6 +182,7 @@ grub_mm_init_region (void *addr, grub_size_t size) r->first = h; r->pre_size = (grub_addr_t) r - (grub_addr_t) addr; r->size = (h->size << GRUB_MM_ALIGN_LOG2); + r->post_size = size - r->size; /* Find where to insert this region. Put a smaller one before bigger ones, to prevent fragmentation. */ diff --git a/include/grub/mm_private.h b/include/grub/mm_private.h index 533b47173e18..0effbc45a668 100644 --- a/include/grub/mm_private.h +++ b/include/grub/mm_private.h @@ -74,8 +74,23 @@ typedef struct grub_mm_region */ grub_size_t pre_size; + /* Likewise, the post-size is the number of bytes we wasted at the end + of the allocation because it wasn't a multiple of GRUB_MM_ALIGN + */ + grub_size_t post_size; + /* How many bytes are in this region? (free and allocated) */ grub_size_t size; + + /* pad to a multiple of cell size */ +#if GRUB_CPU_SIZEOF_VOID_P == 4 + char padding[4+4+4]; +#elif GRUB_CPU_SIZEOF_VOID_P == 8 + char padding[8+8+8]; +#else +# error "unknown word size" +#endif + } *grub_mm_region_t; -- 2.30.2 _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel