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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2010-10-25 16:10:07 +0200
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2010-10-25 16:10:14 +0200
commit238ec4efeee4461d5cff2ed3e5a15a3ab850959b (patch)
treed9efb4be22cc550c7559c29627a48d66413c645a /arch/s390/include
parent229aebb873e29726b91e076161649cf45154b0bf (diff)
downloadlinux-linaro-android-238ec4efeee4461d5cff2ed3e5a15a3ab850959b.tar.gz
[S390] zero page cache synonyms
If the zero page is mapped to virtual user space addresses that differ only in bit 2^12 or 2^13 we get L1 cache synonyms which can affect performance. Follow the mips model and use multiple zero pages to avoid the synonyms. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include')
-rw-r--r--arch/s390/include/asm/pgtable.h22
1 files changed, 19 insertions, 3 deletions
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 3157441ee1d..22a29457100 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -46,11 +46,27 @@ extern void vmem_map_init(void);
#define update_mmu_cache(vma, address, ptep) do { } while (0)
/*
- * ZERO_PAGE is a global shared page that is always zero: used
+ * ZERO_PAGE is a global shared page that is always zero; used
* for zero-mapped memory areas etc..
*/
-extern char empty_zero_page[PAGE_SIZE];
-#define ZERO_PAGE(vaddr) (virt_to_page(empty_zero_page))
+
+extern unsigned long empty_zero_page;
+extern unsigned long zero_page_mask;
+
+#define ZERO_PAGE(vaddr) \
+ (virt_to_page((void *)(empty_zero_page + \
+ (((unsigned long)(vaddr)) &zero_page_mask))))
+
+#define is_zero_pfn is_zero_pfn
+static inline int is_zero_pfn(unsigned long pfn)
+{
+ extern unsigned long zero_pfn;
+ unsigned long offset_from_zero_pfn = pfn - zero_pfn;
+ return offset_from_zero_pfn <= (zero_page_mask >> PAGE_SHIFT);
+}
+
+#define my_zero_pfn(addr) page_to_pfn(ZERO_PAGE(addr))
+
#endif /* !__ASSEMBLY__ */
/*