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authorSteve Capper <steve.capper@linaro.org>2013-11-20 15:27:14 +0000
committerSteve Capper <steve.capper@linaro.org>2014-08-11 13:28:34 +0100
commite802048cec008cc69ba73606d13ec036219cdb8d (patch)
treed1db86f1e91ca45b644066d6816b09b0774077df
parent9d615287c114062af1f72895f0f1f3fd2080da4f (diff)
downloadlinux-e802048cec008cc69ba73606d13ec036219cdb8d.tar.gz
arm: mm: Enable HAVE_RCU_TABLE_FREE logic
In order to implement fast_get_user_pages we need to ensure that the page table walker is protected from page table pages being freed from under it. This patch enables HAVE_RCU_TABLE_FREE, any page table pages belonging to address spaces with multiple users will be call_rcu_sched freed. Meaning that disabling interrupts will block the free and protect the fast gup page walker. Signed-off-by: Steve Capper <steve.capper@linaro.org>
-rw-r--r--arch/arm/Kconfig1
-rw-r--r--arch/arm/include/asm/tlb.h38
2 files changed, 37 insertions, 2 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 290f02ee015..4cb4735c5c0 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -60,6 +60,7 @@ config ARM
select HAVE_PERF_EVENTS
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
+ select HAVE_RCU_TABLE_FREE if (SMP && CPU_V7)
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_UID16
diff --git a/arch/arm/include/asm/tlb.h b/arch/arm/include/asm/tlb.h
index f1a0dace3ef..3cadb726ec8 100644
--- a/arch/arm/include/asm/tlb.h
+++ b/arch/arm/include/asm/tlb.h
@@ -35,12 +35,39 @@
#define MMU_GATHER_BUNDLE 8
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+static inline void __tlb_remove_table(void *_table)
+{
+ free_page_and_swap_cache((struct page *)_table);
+}
+
+struct mmu_table_batch {
+ struct rcu_head rcu;
+ unsigned int nr;
+ void *tables[0];
+};
+
+#define MAX_TABLE_BATCH \
+ ((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
+
+extern void tlb_table_flush(struct mmu_gather *tlb);
+extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
+
+#define tlb_remove_entry(tlb, entry) tlb_remove_table(tlb, entry)
+#else
+#define tlb_remove_entry(tlb, entry) tlb_remove_page(tlb, entry)
+#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
+
/*
* TLB handling. This allows us to remove pages from the page
* tables, and efficiently handle the TLB issues.
*/
struct mmu_gather {
struct mm_struct *mm;
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+ struct mmu_table_batch *batch;
+ unsigned int need_flush;
+#endif
unsigned int fullmm;
struct vm_area_struct *vma;
unsigned long start, end;
@@ -101,6 +128,9 @@ static inline void __tlb_alloc_page(struct mmu_gather *tlb)
static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
{
tlb_flush(tlb);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+ tlb_table_flush(tlb);
+#endif
}
static inline void tlb_flush_mmu_free(struct mmu_gather *tlb)
@@ -129,6 +159,10 @@ tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start
tlb->pages = tlb->local;
tlb->nr = 0;
__tlb_alloc_page(tlb);
+
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+ tlb->batch = NULL;
+#endif
}
static inline void
@@ -205,7 +239,7 @@ static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
tlb_add_flush(tlb, addr + SZ_1M);
#endif
- tlb_remove_page(tlb, pte);
+ tlb_remove_entry(tlb, pte);
}
static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
@@ -213,7 +247,7 @@ static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
{
#ifdef CONFIG_ARM_LPAE
tlb_add_flush(tlb, addr);
- tlb_remove_page(tlb, virt_to_page(pmdp));
+ tlb_remove_entry(tlb, virt_to_page(pmdp));
#endif
}