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Diffstat (limited to 'kernel/include/asm-generic/tlb.h')
| -rw-r--r-- | kernel/include/asm-generic/tlb.h | 221 |
1 files changed, 221 insertions, 0 deletions
diff --git a/kernel/include/asm-generic/tlb.h b/kernel/include/asm-generic/tlb.h new file mode 100644 index 000000000..db284bff2 --- /dev/null +++ b/kernel/include/asm-generic/tlb.h @@ -0,0 +1,221 @@ +/* include/asm-generic/tlb.h + * + * Generic TLB shootdown code + * + * Copyright 2001 Red Hat, Inc. + * Based on code from mm/memory.c Copyright Linus Torvalds and others. + * + * Copyright 2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +#ifndef _ASM_GENERIC__TLB_H +#define _ASM_GENERIC__TLB_H + +#include <linux/swap.h> +#include <asm/pgalloc.h> +#include <asm/tlbflush.h> + +#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. + * + * 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(). + * + */ +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); + +#endif + +/* + * 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. + */ +#define MMU_GATHER_BUNDLE 8 + +struct mmu_gather_batch { + struct mmu_gather_batch *next; + unsigned int nr; + unsigned int max; + struct page *pages[0]; +}; + +#define MAX_GATHER_BATCH \ + ((PAGE_SIZE - sizeof(struct mmu_gather_batch)) / sizeof(void *)) + +/* + * Limit the maximum number of mmu_gather batches to reduce a risk of soft + * lockups for non-preemptible kernels on huge machines when a lot of memory + * is zapped during unmapping. + * 10K pages freed at once should be safe even without a preemption point. + */ +#define MAX_GATHER_BATCH_COUNT (10000UL/MAX_GATHER_BATCH) + +/* struct mmu_gather is an opaque type used by the mm code for passing around + * any data needed by arch specific code for tlb_remove_page. + */ +struct mmu_gather { + struct mm_struct *mm; +#ifdef CONFIG_HAVE_RCU_TABLE_FREE + struct mmu_table_batch *batch; +#endif + unsigned long start; + unsigned long end; + /* we are in the middle of an operation to clear + * a full mm and can make some optimizations */ + unsigned int fullmm : 1, + /* we have performed an operation which + * requires a complete flush of the tlb */ + need_flush_all : 1; + + struct mmu_gather_batch *active; + struct mmu_gather_batch local; + struct page *__pages[MMU_GATHER_BUNDLE]; + unsigned int batch_count; +}; + +#define HAVE_GENERIC_MMU_GATHER + +void 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 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, + unsigned long end); +int __tlb_remove_page(struct mmu_gather *tlb, struct page *page); + +/* tlb_remove_page + * Similar to __tlb_remove_page but will call tlb_flush_mmu() itself when + * required. + */ +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 void __tlb_adjust_range(struct mmu_gather *tlb, + unsigned long address) +{ + tlb->start = min(tlb->start, address); + tlb->end = max(tlb->end, address + PAGE_SIZE); +} + +static inline void __tlb_reset_range(struct mmu_gather *tlb) +{ + if (tlb->fullmm) { + tlb->start = tlb->end = ~0; + } else { + tlb->start = TASK_SIZE; + tlb->end = 0; + } +} + +/* + * 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. + */ +#ifndef tlb_start_vma +#define tlb_start_vma(tlb, vma) do { } while (0) +#endif + +#define __tlb_end_vma(tlb, vma) \ + do { \ + if (!tlb->fullmm && tlb->end) { \ + tlb_flush(tlb); \ + __tlb_reset_range(tlb); \ + } \ + } while (0) + +#ifndef tlb_end_vma +#define tlb_end_vma __tlb_end_vma +#endif + +#ifndef __tlb_remove_tlb_entry +#define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0) +#endif + +/** + * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation. + * + * Record the fact that pte's were really unmapped by updating the range, + * so we can later optimise away the tlb invalidate. This helps when + * userspace is unmapping already-unmapped pages, which happens quite a lot. + */ +#define tlb_remove_tlb_entry(tlb, ptep, address) \ + do { \ + __tlb_adjust_range(tlb, address); \ + __tlb_remove_tlb_entry(tlb, ptep, address); \ + } while (0) + +/** + * tlb_remove_pmd_tlb_entry - remember a pmd mapping for later tlb invalidation + * This is a nop so far, because only x86 needs it. + */ +#ifndef __tlb_remove_pmd_tlb_entry +#define __tlb_remove_pmd_tlb_entry(tlb, pmdp, address) do {} while (0) +#endif + +#define tlb_remove_pmd_tlb_entry(tlb, pmdp, address) \ + do { \ + __tlb_adjust_range(tlb, address); \ + __tlb_remove_pmd_tlb_entry(tlb, pmdp, address); \ + } while (0) + +#define pte_free_tlb(tlb, ptep, address) \ + do { \ + __tlb_adjust_range(tlb, address); \ + __pte_free_tlb(tlb, ptep, address); \ + } while (0) + +#ifndef __ARCH_HAS_4LEVEL_HACK +#define pud_free_tlb(tlb, pudp, address) \ + do { \ + __tlb_adjust_range(tlb, address); \ + __pud_free_tlb(tlb, pudp, address); \ + } while (0) +#endif + +#define pmd_free_tlb(tlb, pmdp, address) \ + do { \ + __tlb_adjust_range(tlb, address); \ + __pmd_free_tlb(tlb, pmdp, address); \ + } while (0) + +#define tlb_migrate_finish(mm) do {} while (0) + +#endif /* _ASM_GENERIC__TLB_H */ |