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Subject[PATCH v6 08/18] arm/tlb: Convert to generic mmu_gather
Generic mmu_gather provides everything that ARM needs:

- range tracking
- RCU table free
- VM_EXEC tracking
- VIPT cache flushing

The one notable curiosity is the 'funny' range tracking for classical
ARM in __pte_free_tlb().

Cc: Nick Piggin <npiggin@gmail.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Russell King <linux@armlinux.org.uk>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/arm/include/asm/tlb.h | 254 ++-------------------------------------------
1 file changed, 13 insertions(+), 241 deletions(-)

--- a/arch/arm/include/asm/tlb.h
+++ b/arch/arm/include/asm/tlb.h
@@ -33,270 +33,42 @@
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>

-#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;
- unsigned long range_start;
- unsigned long range_end;
- unsigned int nr;
- unsigned int max;
- struct page **pages;
- struct page *local[MMU_GATHER_BUNDLE];
-};
-
-DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
-
-/*
- * This is unnecessarily complex. There's three ways the TLB shootdown
- * code is used:
- * 1. Unmapping a range of vmas. See zap_page_range(), unmap_region().
- * tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
- * tlb->vma will be non-NULL.
- * 2. Unmapping all vmas. See exit_mmap().
- * tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
- * tlb->vma will be non-NULL. Additionally, page tables will be freed.
- * 3. Unmapping argument pages. See shift_arg_pages().
- * tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
- * tlb->vma will be NULL.
- */
-static inline void tlb_flush(struct mmu_gather *tlb)
-{
- if (tlb->fullmm || !tlb->vma)
- flush_tlb_mm(tlb->mm);
- else if (tlb->range_end > 0) {
- flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end);
- tlb->range_start = TASK_SIZE;
- tlb->range_end = 0;
- }
-}
-
-static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
-{
- if (!tlb->fullmm) {
- if (addr < tlb->range_start)
- tlb->range_start = addr;
- if (addr + PAGE_SIZE > tlb->range_end)
- tlb->range_end = addr + PAGE_SIZE;
- }
-}
-
-static inline void __tlb_alloc_page(struct mmu_gather *tlb)
-{
- unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
-
- if (addr) {
- tlb->pages = (void *)addr;
- tlb->max = PAGE_SIZE / sizeof(struct page *);
- }
-}
-
-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)
-{
- free_pages_and_swap_cache(tlb->pages, tlb->nr);
- tlb->nr = 0;
- if (tlb->pages == tlb->local)
- __tlb_alloc_page(tlb);
-}
-
-static inline void tlb_flush_mmu(struct mmu_gather *tlb)
-{
- tlb_flush_mmu_tlbonly(tlb);
- tlb_flush_mmu_free(tlb);
-}
-
-static inline void
-arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
- unsigned long start, unsigned long end)
-{
- tlb->mm = mm;
- tlb->fullmm = !(start | (end+1));
- tlb->start = start;
- tlb->end = end;
- tlb->vma = NULL;
- tlb->max = ARRAY_SIZE(tlb->local);
- tlb->pages = tlb->local;
- tlb->nr = 0;
- __tlb_alloc_page(tlb);
+#include <asm-generic/tlb.h>

-#ifdef CONFIG_HAVE_RCU_TABLE_FREE
- tlb->batch = NULL;
+#ifndef CONFIG_HAVE_RCU_TABLE_FREE
+#define tlb_remove_table(tlb, entry) tlb_remove_page(tlb, entry)
#endif
-}
-
-static inline void
-arch_tlb_finish_mmu(struct mmu_gather *tlb,
- unsigned long start, unsigned long end, bool force)
-{
- if (force) {
- tlb->range_start = start;
- tlb->range_end = end;
- }
-
- tlb_flush_mmu(tlb);

- /* keep the page table cache within bounds */
- check_pgt_cache();
-
- if (tlb->pages != tlb->local)
- free_pages((unsigned long)tlb->pages, 0);
-}
-
-/*
- * Memorize the range for the TLB flush.
- */
static inline void
-tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr)
-{
- tlb_add_flush(tlb, addr);
-}
-
-#define tlb_remove_huge_tlb_entry(h, tlb, ptep, address) \
- tlb_remove_tlb_entry(tlb, ptep, address)
-/*
- * In the case of tlb vma handling, we can optimise these away in the
- * case where we're doing a full MM flush. When we're doing a munmap,
- * the vmas are adjusted to only cover the region to be torn down.
- */
-static inline void
-tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
-{
- if (!tlb->fullmm) {
- flush_cache_range(vma, vma->vm_start, vma->vm_end);
- tlb->vma = vma;
- tlb->range_start = TASK_SIZE;
- tlb->range_end = 0;
- }
-}
-
-static inline void
-tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
-{
- if (!tlb->fullmm)
- tlb_flush(tlb);
-}
-
-static inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
-{
- tlb->pages[tlb->nr++] = page;
- VM_WARN_ON(tlb->nr > tlb->max);
- if (tlb->nr == tlb->max)
- return true;
- return false;
-}
-
-static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
-{
- if (__tlb_remove_page(tlb, page))
- tlb_flush_mmu(tlb);
-}
-
-static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
- struct page *page, int page_size)
-{
- return __tlb_remove_page(tlb, page);
-}
-
-static inline void tlb_remove_page_size(struct mmu_gather *tlb,
- struct page *page, int page_size)
-{
- return tlb_remove_page(tlb, page);
-}
-
-static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
- unsigned long addr)
+__pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte, unsigned long addr)
{
pgtable_page_dtor(pte);

-#ifdef CONFIG_ARM_LPAE
- tlb_add_flush(tlb, addr);
-#else
+#ifndef CONFIG_ARM_LPAE
/*
* With the classic ARM MMU, a pte page has two corresponding pmd
* entries, each covering 1MB.
*/
- addr &= PMD_MASK;
- tlb_add_flush(tlb, addr + SZ_1M - PAGE_SIZE);
- tlb_add_flush(tlb, addr + SZ_1M);
+ addr = (addr & PMD_MASK) + SZ_1M;
+ __tlb_adjust_range(tlb, addr - PAGE_SIZE, 2 * PAGE_SIZE);
#endif

- tlb_remove_entry(tlb, pte);
-}
-
-static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
- unsigned long addr)
-{
-#ifdef CONFIG_ARM_LPAE
- tlb_add_flush(tlb, addr);
- tlb_remove_entry(tlb, virt_to_page(pmdp));
-#endif
+ tlb_remove_table(tlb, pte);
}

static inline void
-tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr)
+__pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr)
{
- tlb_add_flush(tlb, addr);
-}
-
-#define pte_free_tlb(tlb, ptep, addr) __pte_free_tlb(tlb, ptep, addr)
-#define pmd_free_tlb(tlb, pmdp, addr) __pmd_free_tlb(tlb, pmdp, addr)
-#define pud_free_tlb(tlb, pudp, addr) pud_free((tlb)->mm, pudp)
-
-#define tlb_migrate_finish(mm) do { } while (0)
-
-static inline void tlb_change_page_size(struct mmu_gather *tlb,
- unsigned int page_size)
-{
-}
-
-static inline void tlb_flush_remove_tables(struct mm_struct *mm)
-{
-}
+#ifdef CONFIG_ARM_LPAE
+ struct page *page = virt_to_page(pmdp);

-static inline void tlb_flush_remove_tables_local(void *arg)
-{
+ tlb_remove_table(tlb, page);
+#endif
}

#endif /* CONFIG_MMU */

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