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authorSteve Capper <steve.capper@linaro.org>2014-03-21 10:55:36 +0000
committerSteve Capper <steve.capper@linaro.org>2014-05-08 13:11:28 +0100
commit5d55b0733703628c42813c8becd23fca3c78488f (patch)
treeca0b93393788e8fa6fc5cf2cd82639cb64d381df
parent2eb3a872067d129b88a0b4fdd03608a7a524a4a6 (diff)
downloadlinux-fast_gup/rfcv5.tar.gz
arm64: mm: Enable RCU fast_gupfast_gup/rfcv5
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. Signed-off-by: Steve Capper <steve.capper@linaro.org>
-rw-r--r--arch/arm64/Kconfig3
-rw-r--r--arch/arm64/include/asm/pgtable.h8
-rw-r--r--arch/arm64/mm/flush.c19
3 files changed, 29 insertions, 1 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 24203903d93..5168949aeea 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -95,6 +95,9 @@ 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 90c811f05a2..126ed77e44d 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -244,7 +244,13 @@ 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)))
diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
index e4193e3adc7..ddf96c1feaa 100644
--- a/arch/arm64/mm/flush.c
+++ b/arch/arm64/mm/flush.c
@@ -103,3 +103,22 @@ 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 */