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-rw-r--r--include/asm-generic/tlb.h120
1 files changed, 72 insertions, 48 deletions
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 2b10036fefd0..f391f6b500b4 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -56,6 +56,15 @@
* Defaults to flushing at tlb_end_vma() to reset the range; helps when
* there's large holes between the VMAs.
*
+ * - tlb_remove_table()
+ *
+ * tlb_remove_table() is the basic primitive to free page-table directories
+ * (__p*_free_tlb()). In it's most primitive form it is an alias for
+ * tlb_remove_page() below, for when page directories are pages and have no
+ * additional constraints.
+ *
+ * See also MMU_GATHER_TABLE_FREE and MMU_GATHER_RCU_TABLE_FREE.
+ *
* - tlb_remove_page() / __tlb_remove_page()
* - tlb_remove_page_size() / __tlb_remove_page_size()
*
@@ -121,65 +130,53 @@
*
* Additionally there are a few opt-in features:
*
- * HAVE_MMU_GATHER_PAGE_SIZE
+ * MMU_GATHER_PAGE_SIZE
*
* This ensures we call tlb_flush() every time tlb_change_page_size() actually
* changes the size and provides mmu_gather::page_size to tlb_flush().
*
- * HAVE_RCU_TABLE_FREE
+ * This might be useful if your architecture has size specific TLB
+ * invalidation instructions.
+ *
+ * MMU_GATHER_TABLE_FREE
*
* This provides tlb_remove_table(), to be used instead of tlb_remove_page()
- * for page directores (__p*_free_tlb()). This provides separate freeing of
- * the page-table pages themselves in a semi-RCU fashion (see comment below).
- * Useful if your architecture doesn't use IPIs for remote TLB invalidates
- * and therefore doesn't naturally serialize with software page-table walkers.
+ * for page directores (__p*_free_tlb()).
+ *
+ * Useful if your architecture has non-page page directories.
*
* When used, an architecture is expected to provide __tlb_remove_table()
* which does the actual freeing of these pages.
*
- * HAVE_RCU_TABLE_NO_INVALIDATE
+ * MMU_GATHER_RCU_TABLE_FREE
*
- * This makes HAVE_RCU_TABLE_FREE avoid calling tlb_flush_mmu_tlbonly() before
- * freeing the page-table pages. This can be avoided if you use
- * HAVE_RCU_TABLE_FREE and your architecture does _NOT_ use the Linux
- * page-tables natively.
+ * Like MMU_GATHER_TABLE_FREE, and adds semi-RCU semantics to the free (see
+ * comment below).
+ *
+ * Useful if your architecture doesn't use IPIs for remote TLB invalidates
+ * and therefore doesn't naturally serialize with software page-table walkers.
*
* MMU_GATHER_NO_RANGE
*
* Use this if your architecture lacks an efficient flush_tlb_range().
- */
-
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
-/*
- * Semi RCU freeing of the page directories.
- *
- * This is needed by some architectures to implement software pagetable walkers.
*
- * gup_fast() and other software pagetable walkers do a lockless page-table
- * walk and therefore needs some synchronization with the freeing of the page
- * directories. The chosen means to accomplish that is by disabling IRQs over
- * the walk.
+ * MMU_GATHER_NO_GATHER
*
- * Architectures that use IPIs to flush TLBs will then automagically DTRT,
- * since we unlink the page, flush TLBs, free the page. Since the disabling of
- * IRQs delays the completion of the TLB flush we can never observe an already
- * freed page.
- *
- * Architectures that do not have this (PPC) need to delay the freeing by some
- * other means, this is that means.
- *
- * What we do is batch the freed directory pages (tables) and RCU free them.
- * We use the sched RCU variant, as that guarantees that IRQ/preempt disabling
- * holds off grace periods.
- *
- * However, in order to batch these pages we need to allocate storage, this
- * allocation is deep inside the MM code and can thus easily fail on memory
- * pressure. To guarantee progress we fall back to single table freeing, see
- * the implementation of tlb_remove_table_one().
+ * If the option is set the mmu_gather will not track individual pages for
+ * delayed page free anymore. A platform that enables the option needs to
+ * provide its own implementation of the __tlb_remove_page_size() function to
+ * free pages.
*
+ * This is useful if your architecture already flushes TLB entries in the
+ * various ptep_get_and_clear() functions.
*/
+
+#ifdef CONFIG_MMU_GATHER_TABLE_FREE
+
struct mmu_table_batch {
+#ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE
struct rcu_head rcu;
+#endif
unsigned int nr;
void *tables[0];
};
@@ -189,9 +186,35 @@ struct mmu_table_batch {
extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
+#else /* !CONFIG_MMU_GATHER_HAVE_TABLE_FREE */
+
+/*
+ * Without MMU_GATHER_TABLE_FREE the architecture is assumed to have page based
+ * page directories and we can use the normal page batching to free them.
+ */
+#define tlb_remove_table(tlb, page) tlb_remove_page((tlb), (page))
+
+#endif /* CONFIG_MMU_GATHER_TABLE_FREE */
+
+#ifdef CONFIG_MMU_GATHER_RCU_TABLE_FREE
+/*
+ * This allows an architecture that does not use the linux page-tables for
+ * hardware to skip the TLBI when freeing page tables.
+ */
+#ifndef tlb_needs_table_invalidate
+#define tlb_needs_table_invalidate() (true)
#endif
-#ifndef CONFIG_HAVE_MMU_GATHER_NO_GATHER
+#else
+
+#ifdef tlb_needs_table_invalidate
+#error tlb_needs_table_invalidate() requires MMU_GATHER_RCU_TABLE_FREE
+#endif
+
+#endif /* CONFIG_MMU_GATHER_RCU_TABLE_FREE */
+
+
+#ifndef CONFIG_MMU_GATHER_NO_GATHER
/*
* If we can't allocate a page to make a big batch of page pointers
* to work on, then just handle a few from the on-stack structure.
@@ -227,7 +250,7 @@ extern bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page,
struct mmu_gather {
struct mm_struct *mm;
-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+#ifdef CONFIG_MMU_GATHER_TABLE_FREE
struct mmu_table_batch *batch;
#endif
@@ -266,22 +289,18 @@ struct mmu_gather {
unsigned int batch_count;
-#ifndef CONFIG_HAVE_MMU_GATHER_NO_GATHER
+#ifndef CONFIG_MMU_GATHER_NO_GATHER
struct mmu_gather_batch *active;
struct mmu_gather_batch local;
struct page *__pages[MMU_GATHER_BUNDLE];
-#ifdef CONFIG_HAVE_MMU_GATHER_PAGE_SIZE
+#ifdef CONFIG_MMU_GATHER_PAGE_SIZE
unsigned int page_size;
#endif
#endif
};
-void arch_tlb_gather_mmu(struct mmu_gather *tlb,
- struct mm_struct *mm, unsigned long start, unsigned long end);
void tlb_flush_mmu(struct mmu_gather *tlb);
-void arch_tlb_finish_mmu(struct mmu_gather *tlb,
- unsigned long start, unsigned long end, bool force);
static inline void __tlb_adjust_range(struct mmu_gather *tlb,
unsigned long address,
@@ -394,7 +413,12 @@ tlb_update_vma_flags(struct mmu_gather *tlb, struct vm_area_struct *vma) { }
static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
{
- if (!tlb->end)
+ /*
+ * Anything calling __tlb_adjust_range() also sets at least one of
+ * these bits.
+ */
+ if (!(tlb->freed_tables || tlb->cleared_ptes || tlb->cleared_pmds ||
+ tlb->cleared_puds || tlb->cleared_p4ds))
return;
tlb_flush(tlb);
@@ -426,7 +450,7 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
static inline void tlb_change_page_size(struct mmu_gather *tlb,
unsigned int page_size)
{
-#ifdef CONFIG_HAVE_MMU_GATHER_PAGE_SIZE
+#ifdef CONFIG_MMU_GATHER_PAGE_SIZE
if (tlb->page_size && tlb->page_size != page_size) {
if (!tlb->fullmm && !tlb->need_flush_all)
tlb_flush_mmu(tlb);