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authorSteve Capper <steve.capper@linaro.org>2014-03-21 10:55:36 +0000
committerSteve Capper <steve.capper@linaro.org>2014-03-26 09:33:49 +0000
commitce076a3b56c2e011bf860124e2dd43eba34afa65 (patch)
tree49f96986255eb09c9771e897d49feae67e9859c5
parent4a31becf6d669e6d71f72442eb5f64f834aa483a (diff)
downloadlinux-fast_gup/general.tar.gz
arm64: mm: Enable RCU fast_gupfast_gup/general
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.h4
-rw-r--r--arch/arm64/mm/flush.c19
3 files changed, 26 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6185f95108f..9f5a81a6ea1 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -86,6 +86,9 @@ config GENERIC_CSUM
config GENERIC_CALIBRATE_DELAY
def_bool y
+config HAVE_RCU_GUP
+ def_bool y
+
config ZONE_DMA32
def_bool y
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index aa3917c8b62..0e148ae4249 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -245,6 +245,10 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define pmd_trans_huge(pmd) (pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT))
#define pmd_trans_splitting(pmd) (pmd_val(pmd) & PMD_SECT_SPLITTING)
+#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
#define PMD_BIT_FUNC(fn,op) \
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 */