aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorSteve Capper <steve.capper@linaro.org>2014-03-21 10:55:36 +0000
committerSteve Capper <steve.capper@linaro.org>2014-08-11 13:28:35 +0100
commitcb7413c65e80bd4e56759ca99f010be0e526f6f4 (patch)
tree06255646d08ddd5940e2dbf6b38c4dc4e9fd26a0
parentd6f9fff293f3cd8b4433bc8df7f5a5fc3238cdde (diff)
downloadlinux-cb7413c65e80bd4e56759ca99f010be0e526f6f4.tar.gz
arm64: mm: Enable RCU fast_gup
Activate the RCU fast_gup for ARM64. We also need to force THP splits to broadcast an IPI s.t. we block in the fast_gup page walker. As THP splits are comparatively rare, this should not lead to a noticeable performance degradation. Some pre-requisite functions pud_write and pud_page are also added. Signed-off-by: Steve Capper <steve.capper@linaro.org>
-rw-r--r--arch/arm64/Kconfig3
-rw-r--r--arch/arm64/include/asm/pgtable.h11
-rw-r--r--arch/arm64/mm/flush.c19
3 files changed, 32 insertions, 1 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e03b47cae2b..8d3ad8dec05 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -103,6 +103,9 @@ config GENERIC_CALIBRATE_DELAY
config ZONE_DMA
def_bool y
+config HAVE_RCU_GUP
+ def_bool y
+
config ARCH_DMA_ADDR_T_64BIT
def_bool y
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index e0ccceb317d..62510f7ca20 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -237,7 +237,13 @@ static inline pmd_t pte_pmd(pte_t pte)
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define pmd_trans_huge(pmd) (pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT))
#define pmd_trans_splitting(pmd) pte_special(pmd_pte(pmd))
-#endif
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH
+struct vm_area_struct;
+void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
+ pmd_t *pmdp);
+#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#define pmd_young(pmd) pte_young(pmd_pte(pmd))
#define pmd_wrprotect(pmd) pte_pmd(pte_wrprotect(pmd_pte(pmd)))
@@ -258,6 +264,7 @@ static inline pmd_t pte_pmd(pte_t pte)
#define mk_pmd(page,prot) pfn_pmd(page_to_pfn(page),prot)
#define pmd_page(pmd) pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
+#define pud_write(pud) pmd_write(__pmd(pud_val(pud)))
#define pud_pfn(pud) (((pud_val(pud) & PUD_MASK) & PHYS_MASK) >> PAGE_SHIFT)
#define set_pmd_at(mm, addr, pmdp, pmd) set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd))
@@ -345,6 +352,8 @@ static inline pmd_t *pud_page_vaddr(pud_t pud)
return __va(pud_val(pud) & PHYS_MASK & (s32)PAGE_MASK);
}
+#define pud_page(pud) pmd_page(__pmd(pud_val(pud)))
+
#endif /* CONFIG_ARM64_64K_PAGES */
/* to find an entry in a page-table-directory */
diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
index 0d64089d28b..a177b703aa3 100644
--- a/arch/arm64/mm/flush.c
+++ b/arch/arm64/mm/flush.c
@@ -104,3 +104,22 @@ EXPORT_SYMBOL(flush_dcache_page);
*/
EXPORT_SYMBOL(flush_cache_all);
EXPORT_SYMBOL(flush_icache_range);
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+static void thp_splitting_flush_sync(void *arg)
+{
+}
+
+void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
+ pmd_t *pmdp)
+{
+ pmd_t pmd = pmd_mksplitting(*pmdp);
+ VM_BUG_ON(address & ~PMD_MASK);
+ set_pmd_at(vma->vm_mm, address, pmdp, pmd);
+
+ /* dummy IPI to serialise against fast_gup */
+ smp_call_function(thp_splitting_flush_sync, NULL, 1);
+}
+#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */