Merge tag 'v2.6.25-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds...
[linux-2.6/linux-mips/linux-dm7025.git] / include / asm-ia64 / tlb.h
blob26edcb750f9f28bc37a106c20356e0fbc55b1665
1 #ifndef _ASM_IA64_TLB_H
2 #define _ASM_IA64_TLB_H
3 /*
4 * Based on <asm-generic/tlb.h>.
6 * Copyright (C) 2002-2003 Hewlett-Packard Co
7 * David Mosberger-Tang <davidm@hpl.hp.com>
8 */
9 /*
10 * Removing a translation from a page table (including TLB-shootdown) is a four-step
11 * procedure:
13 * (1) Flush (virtual) caches --- ensures virtual memory is coherent with kernel memory
14 * (this is a no-op on ia64).
15 * (2) Clear the relevant portions of the page-table
16 * (3) Flush the TLBs --- ensures that stale content is gone from CPU TLBs
17 * (4) Release the pages that were freed up in step (2).
19 * Note that the ordering of these steps is crucial to avoid races on MP machines.
21 * The Linux kernel defines several platform-specific hooks for TLB-shootdown. When
22 * unmapping a portion of the virtual address space, these hooks are called according to
23 * the following template:
25 * tlb <- tlb_gather_mmu(mm, full_mm_flush); // start unmap for address space MM
26 * {
27 * for each vma that needs a shootdown do {
28 * tlb_start_vma(tlb, vma);
29 * for each page-table-entry PTE that needs to be removed do {
30 * tlb_remove_tlb_entry(tlb, pte, address);
31 * if (pte refers to a normal page) {
32 * tlb_remove_page(tlb, page);
33 * }
34 * }
35 * tlb_end_vma(tlb, vma);
36 * }
37 * }
38 * tlb_finish_mmu(tlb, start, end); // finish unmap for address space MM
40 #include <linux/mm.h>
41 #include <linux/pagemap.h>
42 #include <linux/swap.h>
44 #include <asm/pgalloc.h>
45 #include <asm/processor.h>
46 #include <asm/tlbflush.h>
47 #include <asm/machvec.h>
49 #ifdef CONFIG_SMP
50 # define FREE_PTE_NR 2048
51 # define tlb_fast_mode(tlb) ((tlb)->nr == ~0U)
52 #else
53 # define FREE_PTE_NR 0
54 # define tlb_fast_mode(tlb) (1)
55 #endif
57 struct mmu_gather {
58 struct mm_struct *mm;
59 unsigned int nr; /* == ~0U => fast mode */
60 unsigned char fullmm; /* non-zero means full mm flush */
61 unsigned char need_flush; /* really unmapped some PTEs? */
62 unsigned long start_addr;
63 unsigned long end_addr;
64 struct page *pages[FREE_PTE_NR];
67 /* Users of the generic TLB shootdown code must declare this storage space. */
68 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
71 * Flush the TLB for address range START to END and, if not in fast mode, release the
72 * freed pages that where gathered up to this point.
74 static inline void
75 ia64_tlb_flush_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
77 unsigned int nr;
79 if (!tlb->need_flush)
80 return;
81 tlb->need_flush = 0;
83 if (tlb->fullmm) {
85 * Tearing down the entire address space. This happens both as a result
86 * of exit() and execve(). The latter case necessitates the call to
87 * flush_tlb_mm() here.
89 flush_tlb_mm(tlb->mm);
90 } else if (unlikely (end - start >= 1024*1024*1024*1024UL
91 || REGION_NUMBER(start) != REGION_NUMBER(end - 1)))
94 * If we flush more than a tera-byte or across regions, we're probably
95 * better off just flushing the entire TLB(s). This should be very rare
96 * and is not worth optimizing for.
98 flush_tlb_all();
99 } else {
101 * XXX fix me: flush_tlb_range() should take an mm pointer instead of a
102 * vma pointer.
104 struct vm_area_struct vma;
106 vma.vm_mm = tlb->mm;
107 /* flush the address range from the tlb: */
108 flush_tlb_range(&vma, start, end);
109 /* now flush the virt. page-table area mapping the address range: */
110 flush_tlb_range(&vma, ia64_thash(start), ia64_thash(end));
113 /* lastly, release the freed pages */
114 nr = tlb->nr;
115 if (!tlb_fast_mode(tlb)) {
116 unsigned long i;
117 tlb->nr = 0;
118 tlb->start_addr = ~0UL;
119 for (i = 0; i < nr; ++i)
120 free_page_and_swap_cache(tlb->pages[i]);
125 * Return a pointer to an initialized struct mmu_gather.
127 static inline struct mmu_gather *
128 tlb_gather_mmu (struct mm_struct *mm, unsigned int full_mm_flush)
130 struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
132 tlb->mm = mm;
134 * Use fast mode if only 1 CPU is online.
136 * It would be tempting to turn on fast-mode for full_mm_flush as well. But this
137 * doesn't work because of speculative accesses and software prefetching: the page
138 * table of "mm" may (and usually is) the currently active page table and even
139 * though the kernel won't do any user-space accesses during the TLB shoot down, a
140 * compiler might use speculation or lfetch.fault on what happens to be a valid
141 * user-space address. This in turn could trigger a TLB miss fault (or a VHPT
142 * walk) and re-insert a TLB entry we just removed. Slow mode avoids such
143 * problems. (We could make fast-mode work by switching the current task to a
144 * different "mm" during the shootdown.) --davidm 08/02/2002
146 tlb->nr = (num_online_cpus() == 1) ? ~0U : 0;
147 tlb->fullmm = full_mm_flush;
148 tlb->start_addr = ~0UL;
149 return tlb;
153 * Called at the end of the shootdown operation to free up any resources that were
154 * collected.
156 static inline void
157 tlb_finish_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
160 * Note: tlb->nr may be 0 at this point, so we can't rely on tlb->start_addr and
161 * tlb->end_addr.
163 ia64_tlb_flush_mmu(tlb, start, end);
165 /* keep the page table cache within bounds */
166 check_pgt_cache();
168 put_cpu_var(mmu_gathers);
172 * Logically, this routine frees PAGE. On MP machines, the actual freeing of the page
173 * must be delayed until after the TLB has been flushed (see comments at the beginning of
174 * this file).
176 static inline void
177 tlb_remove_page (struct mmu_gather *tlb, struct page *page)
179 tlb->need_flush = 1;
181 if (tlb_fast_mode(tlb)) {
182 free_page_and_swap_cache(page);
183 return;
185 tlb->pages[tlb->nr++] = page;
186 if (tlb->nr >= FREE_PTE_NR)
187 ia64_tlb_flush_mmu(tlb, tlb->start_addr, tlb->end_addr);
191 * Remove TLB entry for PTE mapped at virtual address ADDRESS. This is called for any
192 * PTE, not just those pointing to (normal) physical memory.
194 static inline void
195 __tlb_remove_tlb_entry (struct mmu_gather *tlb, pte_t *ptep, unsigned long address)
197 if (tlb->start_addr == ~0UL)
198 tlb->start_addr = address;
199 tlb->end_addr = address + PAGE_SIZE;
202 #define tlb_migrate_finish(mm) platform_tlb_migrate_finish(mm)
204 #define tlb_start_vma(tlb, vma) do { } while (0)
205 #define tlb_end_vma(tlb, vma) do { } while (0)
207 #define tlb_remove_tlb_entry(tlb, ptep, addr) \
208 do { \
209 tlb->need_flush = 1; \
210 __tlb_remove_tlb_entry(tlb, ptep, addr); \
211 } while (0)
213 #define pte_free_tlb(tlb, ptep) \
214 do { \
215 tlb->need_flush = 1; \
216 __pte_free_tlb(tlb, ptep); \
217 } while (0)
219 #define pmd_free_tlb(tlb, ptep) \
220 do { \
221 tlb->need_flush = 1; \
222 __pmd_free_tlb(tlb, ptep); \
223 } while (0)
225 #define pud_free_tlb(tlb, pudp) \
226 do { \
227 tlb->need_flush = 1; \
228 __pud_free_tlb(tlb, pudp); \
229 } while (0)
231 #endif /* _ASM_IA64_TLB_H */