linux/arch/sparc64/mm/hugetlbpage.c

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/*
* SPARC64 Huge TLB page support.
*
* Copyright (C) 2002, 2003, 2006 David S. Miller (davem@davemloft.net)
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <asm/mman.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
/* Slightly simplified from the non-hugepage variant because by
* definition we don't have to worry about any page coloring stuff
*/
#define VA_EXCLUDE_START (0x0000080000000000UL - (1UL << 32UL))
#define VA_EXCLUDE_END (0xfffff80000000000UL + (1UL << 32UL))
static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *filp,
unsigned long addr,
unsigned long len,
unsigned long pgoff,
unsigned long flags)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct * vma;
unsigned long task_size = TASK_SIZE;
unsigned long start_addr;
if (test_thread_flag(TIF_32BIT))
task_size = STACK_TOP32;
if (unlikely(len >= VA_EXCLUDE_START))
return -ENOMEM;
if (len > mm->cached_hole_size) {
start_addr = addr = mm->free_area_cache;
} else {
start_addr = addr = TASK_UNMAPPED_BASE;
mm->cached_hole_size = 0;
}
task_size -= len;
full_search:
addr = ALIGN(addr, HPAGE_SIZE);
for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
/* At this point: (!vma || addr < vma->vm_end). */
if (addr < VA_EXCLUDE_START &&
(addr + len) >= VA_EXCLUDE_START) {
addr = VA_EXCLUDE_END;
vma = find_vma(mm, VA_EXCLUDE_END);
}
if (unlikely(task_size < addr)) {
if (start_addr != TASK_UNMAPPED_BASE) {
start_addr = addr = TASK_UNMAPPED_BASE;
mm->cached_hole_size = 0;
goto full_search;
}
return -ENOMEM;
}
if (likely(!vma || addr + len <= vma->vm_start)) {
/*
* Remember the place where we stopped the search:
*/
mm->free_area_cache = addr + len;
return addr;
}
if (addr + mm->cached_hole_size < vma->vm_start)
mm->cached_hole_size = vma->vm_start - addr;
addr = ALIGN(vma->vm_end, HPAGE_SIZE);
}
}
static unsigned long
hugetlb_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
const unsigned long len,
const unsigned long pgoff,
const unsigned long flags)
{
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
/* This should only ever run for 32-bit processes. */
BUG_ON(!test_thread_flag(TIF_32BIT));
/* check if free_area_cache is useful for us */
if (len <= mm->cached_hole_size) {
mm->cached_hole_size = 0;
mm->free_area_cache = mm->mmap_base;
}
/* either no address requested or can't fit in requested address hole */
addr = mm->free_area_cache & HPAGE_MASK;
/* make sure it can fit in the remaining address space */
if (likely(addr > len)) {
vma = find_vma(mm, addr-len);
if (!vma || addr <= vma->vm_start) {
/* remember the address as a hint for next time */
return (mm->free_area_cache = addr-len);
}
}
if (unlikely(mm->mmap_base < len))
goto bottomup;
addr = (mm->mmap_base-len) & HPAGE_MASK;
do {
/*
* Lookup failure means no vma is above this address,
* else if new region fits below vma->vm_start,
* return with success:
*/
vma = find_vma(mm, addr);
if (likely(!vma || addr+len <= vma->vm_start)) {
/* remember the address as a hint for next time */
return (mm->free_area_cache = addr);
}
/* remember the largest hole we saw so far */
if (addr + mm->cached_hole_size < vma->vm_start)
mm->cached_hole_size = vma->vm_start - addr;
/* try just below the current vma->vm_start */
addr = (vma->vm_start-len) & HPAGE_MASK;
} while (likely(len < vma->vm_start));
bottomup:
/*
* A failed mmap() very likely causes application failure,
* so fall back to the bottom-up function here. This scenario
* can happen with large stack limits and large mmap()
* allocations.
*/
mm->cached_hole_size = ~0UL;
mm->free_area_cache = TASK_UNMAPPED_BASE;
addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
/*
* Restore the topdown base:
*/
mm->free_area_cache = mm->mmap_base;
mm->cached_hole_size = ~0UL;
return addr;
}
unsigned long
hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long task_size = TASK_SIZE;
if (test_thread_flag(TIF_32BIT))
task_size = STACK_TOP32;
if (len & ~HPAGE_MASK)
return -EINVAL;
if (len > task_size)
return -ENOMEM;
if (flags & MAP_FIXED) {
if (prepare_hugepage_range(addr, len, pgoff))
return -EINVAL;
return addr;
}
if (addr) {
addr = ALIGN(addr, HPAGE_SIZE);
vma = find_vma(mm, addr);
if (task_size - len >= addr &&
(!vma || addr + len <= vma->vm_start))
return addr;
}
if (mm->get_unmapped_area == arch_get_unmapped_area)
return hugetlb_get_unmapped_area_bottomup(file, addr, len,
pgoff, flags);
else
return hugetlb_get_unmapped_area_topdown(file, addr, len,
pgoff, flags);
}
pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte = NULL;
/* We must align the address, because our caller will run
* set_huge_pte_at() on whatever we return, which writes out
* all of the sub-ptes for the hugepage range. So we have
* to give it the first such sub-pte.
*/
addr &= HPAGE_MASK;
pgd = pgd_offset(mm, addr);
pud = pud_alloc(mm, pgd, addr);
if (pud) {
pmd = pmd_alloc(mm, pud, addr);
if (pmd)
pte = pte_alloc_map(mm, pmd, addr);
}
return pte;
}
pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte = NULL;
addr &= HPAGE_MASK;
pgd = pgd_offset(mm, addr);
if (!pgd_none(*pgd)) {
pud = pud_offset(pgd, addr);
if (!pud_none(*pud)) {
pmd = pmd_offset(pud, addr);
if (!pmd_none(*pmd))
pte = pte_offset_map(pmd, addr);
}
}
return pte;
}
[PATCH] shared page table for hugetlb page Following up with the work on shared page table done by Dave McCracken. This set of patch target shared page table for hugetlb memory only. The shared page table is particular useful in the situation of large number of independent processes sharing large shared memory segments. In the normal page case, the amount of memory saved from process' page table is quite significant. For hugetlb, the saving on page table memory is not the primary objective (as hugetlb itself already cuts down page table overhead significantly), instead, the purpose of using shared page table on hugetlb is to allow faster TLB refill and smaller cache pollution upon TLB miss. With PT sharing, pte entries are shared among hundreds of processes, the cache consumption used by all the page table is smaller and in return, application gets much higher cache hit ratio. One other effect is that cache hit ratio with hardware page walker hitting on pte in cache will be higher and this helps to reduce tlb miss latency. These two effects contribute to higher application performance. Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Acked-by: Hugh Dickins <hugh@veritas.com> Cc: Dave McCracken <dmccr@us.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Adam Litke <agl@us.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 07:32:03 +03:00
int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
return 0;
}
void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t entry)
{
int i;
if (!pte_present(*ptep) && pte_present(entry))
mm->context.huge_pte_count++;
addr &= HPAGE_MASK;
for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
set_pte_at(mm, addr, ptep, entry);
ptep++;
addr += PAGE_SIZE;
pte_val(entry) += PAGE_SIZE;
}
}
pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
pte_t *ptep)
{
pte_t entry;
int i;
entry = *ptep;
if (pte_present(entry))
mm->context.huge_pte_count--;
addr &= HPAGE_MASK;
for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
pte_clear(mm, addr, ptep);
addr += PAGE_SIZE;
ptep++;
}
return entry;
}
struct page *follow_huge_addr(struct mm_struct *mm,
unsigned long address, int write)
{
return ERR_PTR(-EINVAL);
}
int pmd_huge(pmd_t pmd)
{
return 0;
}
struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
pmd_t *pmd, int write)
{
return NULL;
}
static void context_reload(void *__data)
{
struct mm_struct *mm = __data;
if (mm == current->mm)
load_secondary_context(mm);
}
void hugetlb_prefault_arch_hook(struct mm_struct *mm)
{
struct tsb_config *tp = &mm->context.tsb_block[MM_TSB_HUGE];
if (likely(tp->tsb != NULL))
return;
tsb_grow(mm, MM_TSB_HUGE, 0);
tsb_context_switch(mm);
smp_tsb_sync(mm);
/* On UltraSPARC-III+ and later, configure the second half of
* the Data-TLB for huge pages.
*/
if (tlb_type == cheetah_plus) {
unsigned long ctx;
spin_lock(&ctx_alloc_lock);
ctx = mm->context.sparc64_ctx_val;
ctx &= ~CTX_PGSZ_MASK;
ctx |= CTX_PGSZ_BASE << CTX_PGSZ0_SHIFT;
ctx |= CTX_PGSZ_HUGE << CTX_PGSZ1_SHIFT;
if (ctx != mm->context.sparc64_ctx_val) {
/* When changing the page size fields, we
* must perform a context flush so that no
* stale entries match. This flush must
* occur with the original context register
* settings.
*/
do_flush_tlb_mm(mm);
/* Reload the context register of all processors
* also executing in this address space.
*/
mm->context.sparc64_ctx_val = ctx;
on_each_cpu(context_reload, mm, 0, 0);
}
spin_unlock(&ctx_alloc_lock);
}
}