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authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>2013-04-28 09:37:30 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-04-30 15:59:56 +1000
commite2b3d202d1dba8f3546ed28224ce485bc50010be (patch)
tree7062737220b109cb1312ae9a6220761dd23e3ed5 /arch/powerpc/include
parentcf9427b85e90bb1ff90e2397ff419691d983c68b (diff)
powerpc: Switch 16GB and 16MB explicit hugepages to a different page table format
We will be switching PMD_SHIFT to 24 bits to facilitate THP impmenetation. With PMD_SHIFT set to 24, we now have 16MB huge pages allocated at PGD level. That means with 32 bit process we cannot allocate normal pages at all, because we cover the entire address space with one pgd entry. Fix this by switching to a new page table format for hugepages. With the new page table format for 16GB and 16MB hugepages we won't allocate hugepage directory. Instead we encode the PTE information directly at the directory level. This forces 16MB hugepage at PMD level. This will also make the page take walk much simpler later when we add the THP support. With the new table format we have 4 cases for pgds and pmds: (1) invalid (all zeroes) (2) pointer to next table, as normal; bottom 6 bits == 0 (3) leaf pte for huge page, bottom two bits != 00 (4) hugepd pointer, bottom two bits == 00, next 4 bits indicate size of table Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/include')
-rw-r--r--arch/powerpc/include/asm/page.h2
-rw-r--r--arch/powerpc/include/asm/pgtable.h2
2 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 652719ccd2e..711e83a79e3 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -373,8 +373,10 @@ static inline int hugepd_ok(hugepd_t hpd)
#endif
#define is_hugepd(pdep) (hugepd_ok(*((hugepd_t *)(pdep))))
+int pgd_huge(pgd_t pgd);
#else /* CONFIG_HUGETLB_PAGE */
#define is_hugepd(pdep) 0
+#define pgd_huge(pgd) 0
#endif /* CONFIG_HUGETLB_PAGE */
struct page;
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index 4b52726e01c..7aeb9555f6e 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -218,6 +218,8 @@ extern void update_mmu_cache(struct vm_area_struct *, unsigned long, pte_t *);
extern int gup_hugepd(hugepd_t *hugepd, unsigned pdshift, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr);
+extern int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
+ unsigned long end, int write, struct page **pages, int *nr);
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */