[PATCH v7 4/5] arm: arm64: introduce pfn_valid_region()

[Jia He]

Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns
where possible") optimized the loop in memmap_init_zone(). But there is
still some room for improvement. E.g. in early_pfn_valid(), we can record
the last returned memblock region. If current pfn and last pfn are in the
same memory region, we needn't do the unnecessary binary searches because
memblock_is_nomap is the same result for whole memory region.

Signed-off-by: Jia He <jia...@hxt-semitech.com>
---
 include/linux/arm96_common.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/include/linux/arm96_common.h b/include/linux/arm96_common.h
index 2f4dea4..bb86bd3 100644
--- a/include/linux/arm96_common.h
+++ b/include/linux/arm96_common.h
@@ -48,5 +48,29 @@ ulong __init_memblock memblock_next_valid_pfn(ulong pfn)
        return PHYS_PFN(regions[early_region_idx].base);
 }
 EXPORT_SYMBOL(memblock_next_valid_pfn);
+
+int pfn_valid_region(ulong pfn)
+{
+       ulong start_pfn, end_pfn;
+       struct memblock_type *type = &memblock.memory;
+       struct memblock_region *regions = type->regions;
+
+       if (early_region_idx != -1) {
+               start_pfn = PFN_DOWN(regions[early_region_idx].base);
+               end_pfn = PFN_DOWN(regions[early_region_idx].base +
+                                       regions[early_region_idx].size);
+
+               if (pfn >= start_pfn && pfn < end_pfn)
+                       return !memblock_is_nomap(
+                                       &regions[early_region_idx]);
+       }
+
+       early_region_idx = memblock_search_pfn_regions(pfn);
+       if (early_region_idx == -1)
+               return false;
+
+       return !memblock_is_nomap(&regions[early_region_idx]);
+}
+EXPORT_SYMBOL(pfn_valid_region);
 #endif /*CONFIG_HAVE_ARCH_PFN_VALID*/
 #endif /*__ARM96_COMMON_H*/
-- 
2.7.4