Add an optimized mm_zero_struct_page(), so struct page's are zeroed without
calling memset(). We do eight regular stores, thus avoid cost of membar.
Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Reviewed-by: Steven Sistare <steven.sistare@xxxxxxxxxx>
Reviewed-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Reviewed-by: Bob Picco <bob.picco@xxxxxxxxxx>
---
arch/sparc/include/asm/pgtable_64.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index 6fbd931f0570..23ad51ea5340 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -230,6 +230,24 @@ extern unsigned long _PAGE_ALL_SZ_BITS;
extern struct page *mem_map_zero;
#define ZERO_PAGE(vaddr) (mem_map_zero)
+/* This macro must be updated when the size of struct page changes,
+ * so use static assert to enforce the assumed size.
+ */
+#define mm_zero_struct_page(pp) \
+ do { \
+ unsigned long *_pp = (void *)(pp); \
+ \
+ BUILD_BUG_ON(sizeof(struct page) != 64); \
+ _pp[0] = 0; \
+ _pp[1] = 0; \
+ _pp[2] = 0; \
+ _pp[3] = 0; \
+ _pp[4] = 0; \
+ _pp[5] = 0; \
+ _pp[6] = 0; \
+ _pp[7] = 0; \
+ } while (0)
+
/* PFNs are real physical page numbers. However, mem_map only begins to record
* per-page information starting at pfn_base. This is to handle systems where
* the first physical page in the machine is at some huge physical address,
--
2.13.3
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