#ifndef _ASM_IA64_TLB_H #define _ASM_IA64_TLB_H /* * Based on <asm-generic/tlb.h>. * * Copyright (C) 2002-2003 Hewlett-Packard Co * David Mosberger-Tang <davidm@hpl.hp.com> */ /* * Removing a translation from a page table (including TLB-shootdown) is a four-step * procedure: * * (1) Flush (virtual) caches --- ensures virtual memory is coherent with kernel memory * (this is a no-op on ia64). * (2) Clear the relevant portions of the page-table * (3) Flush the TLBs --- ensures that stale content is gone from CPU TLBs * (4) Release the pages that were freed up in step (2). * * Note that the ordering of these steps is crucial to avoid races on MP machines. * * The Linux kernel defines several platform-specific hooks for TLB-shootdown. When * unmapping a portion of the virtual address space, these hooks are called according to * the following template: * * tlb <- tlb_gather_mmu(mm, full_mm_flush); // start unmap for address space MM * { * for each vma that needs a shootdown do { * tlb_start_vma(tlb, vma); * for each page-table-entry PTE that needs to be removed do { * tlb_remove_tlb_entry(tlb, pte, address); * if (pte refers to a normal page) { * tlb_remove_page(tlb, page); * } * } * tlb_end_vma(tlb, vma); * } * } * tlb_finish_mmu(tlb, start, end); // finish unmap for address space MM */ #include <linux/mm.h> #include <linux/pagemap.h> #include <linux/swap.h> #include <asm/pgalloc.h> #include <asm/processor.h> #include <asm/tlbflush.h> #include <asm/machvec.h> #ifdef CONFIG_SMP # define FREE_PTE_NR 2048 # define tlb_fast_mode(tlb) ((tlb)->nr == ~0U) #else # define FREE_PTE_NR 0 # define tlb_fast_mode(tlb) (1) #endif struct mmu_gather { struct mm_struct *mm; unsigned int nr; /* == ~0U => fast mode */ unsigned char fullmm; /* non-zero means full mm flush */ unsigned char need_flush; /* really unmapped some PTEs? */ unsigned long start_addr; unsigned long end_addr; struct page *pages[FREE_PTE_NR]; }; /* Users of the generic TLB shootdown code must declare this storage space. */ DECLARE_PER_CPU(struct mmu_gather, mmu_gathers); /* * Flush the TLB for address range START to END and, if not in fast mode, release the * freed pages that where gathered up to this point. */ static inline void ia64_tlb_flush_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end) { unsigned int nr; if (!tlb->need_flush) return; tlb->need_flush = 0; if (tlb->fullmm) { /* * Tearing down the entire address space. This happens both as a result * of exit() and execve(). The latter case necessitates the call to * flush_tlb_mm() here. */ flush_tlb_mm(tlb->mm); } else if (unlikely (end - start >= 1024*1024*1024*1024UL || REGION_NUMBER(start) != REGION_NUMBER(end - 1))) { /* * If we flush more than a tera-byte or across regions, we're probably * better off just flushing the entire TLB(s). This should be very rare * and is not worth optimizing for. */ flush_tlb_all(); } else { /* * XXX fix me: flush_tlb_range() should take an mm pointer instead of a * vma pointer. */ struct vm_area_struct vma; vma.vm_mm = tlb->mm; /* flush the address range from the tlb: */ flush_tlb_range(&vma, start, end); /* now flush the virt. page-table area mapping the address range: */ flush_tlb_range(&vma, ia64_thash(start), ia64_thash(end)); } /* lastly, release the freed pages */ nr = tlb->nr; if (!tlb_fast_mode(tlb)) { unsigned long i; tlb->nr = 0; tlb->start_addr = ~0UL; for (i = 0; i < nr; ++i) free_page_and_swap_cache(tlb->pages[i]); } } /* * Return a pointer to an initialized struct mmu_gather. */ static inline struct mmu_gather * tlb_gather_mmu (struct mm_struct *mm, unsigned int full_mm_flush) { struct mmu_gather *tlb = &get_cpu_var(mmu_gathers); tlb->mm = mm; /* * Use fast mode if only 1 CPU is online. * * It would be tempting to turn on fast-mode for full_mm_flush as well. But this * doesn't work because of speculative accesses and software prefetching: the page * table of "mm" may (and usually is) the currently active page table and even * though the kernel won't do any user-space accesses during the TLB shoot down, a * compiler might use speculation or lfetch.fault on what happens to be a valid * user-space address. This in turn could trigger a TLB miss fault (or a VHPT * walk) and re-insert a TLB entry we just removed. Slow mode avoids such * problems. (We could make fast-mode work by switching the current task to a * different "mm" during the shootdown.) --davidm 08/02/2002 */ tlb->nr = (num_online_cpus() == 1) ? ~0U : 0; tlb->fullmm = full_mm_flush; tlb->start_addr = ~0UL; return tlb; } /* * Called at the end of the shootdown operation to free up any resources that were * collected. */ static inline void tlb_finish_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end) { /* * Note: tlb->nr may be 0 at this point, so we can't rely on tlb->start_addr and * tlb->end_addr. */ ia64_tlb_flush_mmu(tlb, start, end); /* keep the page table cache within bounds */ check_pgt_cache(); put_cpu_var(mmu_gathers); } /* * Logically, this routine frees PAGE. On MP machines, the actual freeing of the page * must be delayed until after the TLB has been flushed (see comments at the beginning of * this file). */ static inline void tlb_remove_page (struct mmu_gather *tlb, struct page *page) { tlb->need_flush = 1; if (tlb_fast_mode(tlb)) { free_page_and_swap_cache(page); return; } tlb->pages[tlb->nr++] = page; if (tlb->nr >= FREE_PTE_NR) ia64_tlb_flush_mmu(tlb, tlb->start_addr, tlb->end_addr); } /* * Remove TLB entry for PTE mapped at virtual address ADDRESS. This is called for any * PTE, not just those pointing to (normal) physical memory. */ static inline void __tlb_remove_tlb_entry (struct mmu_gather *tlb, pte_t *ptep, unsigned long address) { if (tlb->start_addr == ~0UL) tlb->start_addr = address; tlb->end_addr = address + PAGE_SIZE; } #define tlb_migrate_finish(mm) platform_tlb_migrate_finish(mm) #define tlb_start_vma(tlb, vma) do { } while (0) #define tlb_end_vma(tlb, vma) do { } while (0) #define tlb_remove_tlb_entry(tlb, ptep, addr) \ do { \ tlb->need_flush = 1; \ __tlb_remove_tlb_entry(tlb, ptep, addr); \ } while (0) #define pte_free_tlb(tlb, ptep) \ do { \ tlb->need_flush = 1; \ __pte_free_tlb(tlb, ptep); \ } while (0) #define pmd_free_tlb(tlb, ptep) \ do { \ tlb->need_flush = 1; \ __pmd_free_tlb(tlb, ptep); \ } while (0) #define pud_free_tlb(tlb, pudp) \ do { \ tlb->need_flush = 1; \ __pud_free_tlb(tlb, pudp); \ } while (0) #endif /* _ASM_IA64_TLB_H */