#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/config.h>
#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 freed; /* number of pages freed */
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->freed = 0;
tlb->start_addr = ~0UL;
return tlb;
}
/*
* Called at the end of the shootdown operation to free up any resources that were
* collected. The page table lock is still held at this point.
*/
static inline void
tlb_finish_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
unsigned long freed = tlb->freed;
struct mm_struct *mm = tlb->mm;
unsigned long rss = get_mm_counter(mm, rss);
if (rss < freed)
freed = rss;
add_mm_counter(mm, rss, -freed);
/*
* 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();
}
static inline unsigned int
tlb_is_full_mm(struct mmu_gather *tlb)
{
return tlb->fullmm;
}
/*
* 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 */
