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linux-next/arch/powerpc/mm/pgtable_64.c
Aneesh Kumar K.V 5c1f6ee9a3 powerpc: Reduce PTE table memory wastage
We allocate one page for the last level of linux page table. With THP and
large page size of 16MB, that would mean we are wasting large part
of that page. To map 16MB area, we only need a PTE space of 2K with 64K
page size. This patch reduce the space wastage by sharing the page
allocated for the last level of linux page table with multiple pmd
entries. We call these smaller chunks PTE page fragments and allocated
page, PTE page.

In order to support systems which doesn't have 64K HPTE support, we also
add another 2K to PTE page fragment. The second half of the PTE fragments
is used for storing slot and secondary bit information of an HPTE. With this
we now have a 4K PTE fragment.

We use a simple approach to share the PTE page. On allocation, we bump the
PTE page refcount to 16 and share the PTE page with the next 16 pte alloc
request. This should help in the node locality of the PTE page fragment,
assuming that the immediate pte alloc request will mostly come from the
same NUMA node. We don't try to reuse the freed PTE page fragment. Hence
we could be waisting some space.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-04-30 16:00:07 +10:00

458 lines
11 KiB
C

/*
* This file contains ioremap and related functions for 64-bit machines.
*
* Derived from arch/ppc64/mm/init.c
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
*
* Modifications by Paul Mackerras (PowerMac) (paulus@samba.org)
* and Cort Dougan (PReP) (cort@cs.nmt.edu)
* Copyright (C) 1996 Paul Mackerras
*
* Derived from "arch/i386/mm/init.c"
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*
* Dave Engebretsen <engebret@us.ibm.com>
* Rework for PPC64 port.
*
* 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.
*
*/
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/export.h>
#include <linux/types.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/stddef.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/memblock.h>
#include <linux/slab.h>
#include <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/prom.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/smp.h>
#include <asm/machdep.h>
#include <asm/tlb.h>
#include <asm/processor.h>
#include <asm/cputable.h>
#include <asm/sections.h>
#include <asm/firmware.h>
#include "mmu_decl.h"
/* Some sanity checking */
#if TASK_SIZE_USER64 > PGTABLE_RANGE
#error TASK_SIZE_USER64 exceeds pagetable range
#endif
#ifdef CONFIG_PPC_STD_MMU_64
#if TASK_SIZE_USER64 > (1UL << (ESID_BITS + SID_SHIFT))
#error TASK_SIZE_USER64 exceeds user VSID range
#endif
#endif
unsigned long ioremap_bot = IOREMAP_BASE;
#ifdef CONFIG_PPC_MMU_NOHASH
static void *early_alloc_pgtable(unsigned long size)
{
void *pt;
if (init_bootmem_done)
pt = __alloc_bootmem(size, size, __pa(MAX_DMA_ADDRESS));
else
pt = __va(memblock_alloc_base(size, size,
__pa(MAX_DMA_ADDRESS)));
memset(pt, 0, size);
return pt;
}
#endif /* CONFIG_PPC_MMU_NOHASH */
/*
* map_kernel_page currently only called by __ioremap
* map_kernel_page adds an entry to the ioremap page table
* and adds an entry to the HPT, possibly bolting it
*/
int map_kernel_page(unsigned long ea, unsigned long pa, int flags)
{
pgd_t *pgdp;
pud_t *pudp;
pmd_t *pmdp;
pte_t *ptep;
if (slab_is_available()) {
pgdp = pgd_offset_k(ea);
pudp = pud_alloc(&init_mm, pgdp, ea);
if (!pudp)
return -ENOMEM;
pmdp = pmd_alloc(&init_mm, pudp, ea);
if (!pmdp)
return -ENOMEM;
ptep = pte_alloc_kernel(pmdp, ea);
if (!ptep)
return -ENOMEM;
set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT,
__pgprot(flags)));
} else {
#ifdef CONFIG_PPC_MMU_NOHASH
/* Warning ! This will blow up if bootmem is not initialized
* which our ppc64 code is keen to do that, we'll need to
* fix it and/or be more careful
*/
pgdp = pgd_offset_k(ea);
#ifdef PUD_TABLE_SIZE
if (pgd_none(*pgdp)) {
pudp = early_alloc_pgtable(PUD_TABLE_SIZE);
BUG_ON(pudp == NULL);
pgd_populate(&init_mm, pgdp, pudp);
}
#endif /* PUD_TABLE_SIZE */
pudp = pud_offset(pgdp, ea);
if (pud_none(*pudp)) {
pmdp = early_alloc_pgtable(PMD_TABLE_SIZE);
BUG_ON(pmdp == NULL);
pud_populate(&init_mm, pudp, pmdp);
}
pmdp = pmd_offset(pudp, ea);
if (!pmd_present(*pmdp)) {
ptep = early_alloc_pgtable(PAGE_SIZE);
BUG_ON(ptep == NULL);
pmd_populate_kernel(&init_mm, pmdp, ptep);
}
ptep = pte_offset_kernel(pmdp, ea);
set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT,
__pgprot(flags)));
#else /* CONFIG_PPC_MMU_NOHASH */
/*
* If the mm subsystem is not fully up, we cannot create a
* linux page table entry for this mapping. Simply bolt an
* entry in the hardware page table.
*
*/
if (htab_bolt_mapping(ea, ea + PAGE_SIZE, pa, flags,
mmu_io_psize, mmu_kernel_ssize)) {
printk(KERN_ERR "Failed to do bolted mapping IO "
"memory at %016lx !\n", pa);
return -ENOMEM;
}
#endif /* !CONFIG_PPC_MMU_NOHASH */
}
return 0;
}
/**
* __ioremap_at - Low level function to establish the page tables
* for an IO mapping
*/
void __iomem * __ioremap_at(phys_addr_t pa, void *ea, unsigned long size,
unsigned long flags)
{
unsigned long i;
/* Make sure we have the base flags */
if ((flags & _PAGE_PRESENT) == 0)
flags |= pgprot_val(PAGE_KERNEL);
/* Non-cacheable page cannot be coherent */
if (flags & _PAGE_NO_CACHE)
flags &= ~_PAGE_COHERENT;
/* We don't support the 4K PFN hack with ioremap */
if (flags & _PAGE_4K_PFN)
return NULL;
WARN_ON(pa & ~PAGE_MASK);
WARN_ON(((unsigned long)ea) & ~PAGE_MASK);
WARN_ON(size & ~PAGE_MASK);
for (i = 0; i < size; i += PAGE_SIZE)
if (map_kernel_page((unsigned long)ea+i, pa+i, flags))
return NULL;
return (void __iomem *)ea;
}
/**
* __iounmap_from - Low level function to tear down the page tables
* for an IO mapping. This is used for mappings that
* are manipulated manually, like partial unmapping of
* PCI IOs or ISA space.
*/
void __iounmap_at(void *ea, unsigned long size)
{
WARN_ON(((unsigned long)ea) & ~PAGE_MASK);
WARN_ON(size & ~PAGE_MASK);
unmap_kernel_range((unsigned long)ea, size);
}
void __iomem * __ioremap_caller(phys_addr_t addr, unsigned long size,
unsigned long flags, void *caller)
{
phys_addr_t paligned;
void __iomem *ret;
/*
* Choose an address to map it to.
* Once the imalloc system is running, we use it.
* Before that, we map using addresses going
* up from ioremap_bot. imalloc will use
* the addresses from ioremap_bot through
* IMALLOC_END
*
*/
paligned = addr & PAGE_MASK;
size = PAGE_ALIGN(addr + size) - paligned;
if ((size == 0) || (paligned == 0))
return NULL;
if (mem_init_done) {
struct vm_struct *area;
area = __get_vm_area_caller(size, VM_IOREMAP,
ioremap_bot, IOREMAP_END,
caller);
if (area == NULL)
return NULL;
area->phys_addr = paligned;
ret = __ioremap_at(paligned, area->addr, size, flags);
if (!ret)
vunmap(area->addr);
} else {
ret = __ioremap_at(paligned, (void *)ioremap_bot, size, flags);
if (ret)
ioremap_bot += size;
}
if (ret)
ret += addr & ~PAGE_MASK;
return ret;
}
void __iomem * __ioremap(phys_addr_t addr, unsigned long size,
unsigned long flags)
{
return __ioremap_caller(addr, size, flags, __builtin_return_address(0));
}
void __iomem * ioremap(phys_addr_t addr, unsigned long size)
{
unsigned long flags = _PAGE_NO_CACHE | _PAGE_GUARDED;
void *caller = __builtin_return_address(0);
if (ppc_md.ioremap)
return ppc_md.ioremap(addr, size, flags, caller);
return __ioremap_caller(addr, size, flags, caller);
}
void __iomem * ioremap_wc(phys_addr_t addr, unsigned long size)
{
unsigned long flags = _PAGE_NO_CACHE;
void *caller = __builtin_return_address(0);
if (ppc_md.ioremap)
return ppc_md.ioremap(addr, size, flags, caller);
return __ioremap_caller(addr, size, flags, caller);
}
void __iomem * ioremap_prot(phys_addr_t addr, unsigned long size,
unsigned long flags)
{
void *caller = __builtin_return_address(0);
/* writeable implies dirty for kernel addresses */
if (flags & _PAGE_RW)
flags |= _PAGE_DIRTY;
/* we don't want to let _PAGE_USER and _PAGE_EXEC leak out */
flags &= ~(_PAGE_USER | _PAGE_EXEC);
#ifdef _PAGE_BAP_SR
/* _PAGE_USER contains _PAGE_BAP_SR on BookE using the new PTE format
* which means that we just cleared supervisor access... oops ;-) This
* restores it
*/
flags |= _PAGE_BAP_SR;
#endif
if (ppc_md.ioremap)
return ppc_md.ioremap(addr, size, flags, caller);
return __ioremap_caller(addr, size, flags, caller);
}
/*
* Unmap an IO region and remove it from imalloc'd list.
* Access to IO memory should be serialized by driver.
*/
void __iounmap(volatile void __iomem *token)
{
void *addr;
if (!mem_init_done)
return;
addr = (void *) ((unsigned long __force)
PCI_FIX_ADDR(token) & PAGE_MASK);
if ((unsigned long)addr < ioremap_bot) {
printk(KERN_WARNING "Attempt to iounmap early bolted mapping"
" at 0x%p\n", addr);
return;
}
vunmap(addr);
}
void iounmap(volatile void __iomem *token)
{
if (ppc_md.iounmap)
ppc_md.iounmap(token);
else
__iounmap(token);
}
EXPORT_SYMBOL(ioremap);
EXPORT_SYMBOL(ioremap_wc);
EXPORT_SYMBOL(ioremap_prot);
EXPORT_SYMBOL(__ioremap);
EXPORT_SYMBOL(__ioremap_at);
EXPORT_SYMBOL(iounmap);
EXPORT_SYMBOL(__iounmap);
EXPORT_SYMBOL(__iounmap_at);
#ifdef CONFIG_PPC_64K_PAGES
static pte_t *get_from_cache(struct mm_struct *mm)
{
void *pte_frag, *ret;
spin_lock(&mm->page_table_lock);
ret = mm->context.pte_frag;
if (ret) {
pte_frag = ret + PTE_FRAG_SIZE;
/*
* If we have taken up all the fragments mark PTE page NULL
*/
if (((unsigned long)pte_frag & ~PAGE_MASK) == 0)
pte_frag = NULL;
mm->context.pte_frag = pte_frag;
}
spin_unlock(&mm->page_table_lock);
return (pte_t *)ret;
}
static pte_t *__alloc_for_cache(struct mm_struct *mm, int kernel)
{
void *ret = NULL;
struct page *page = alloc_page(GFP_KERNEL | __GFP_NOTRACK |
__GFP_REPEAT | __GFP_ZERO);
if (!page)
return NULL;
ret = page_address(page);
spin_lock(&mm->page_table_lock);
/*
* If we find pgtable_page set, we return
* the allocated page with single fragement
* count.
*/
if (likely(!mm->context.pte_frag)) {
atomic_set(&page->_count, PTE_FRAG_NR);
mm->context.pte_frag = ret + PTE_FRAG_SIZE;
}
spin_unlock(&mm->page_table_lock);
if (!kernel)
pgtable_page_ctor(page);
return (pte_t *)ret;
}
pte_t *page_table_alloc(struct mm_struct *mm, unsigned long vmaddr, int kernel)
{
pte_t *pte;
pte = get_from_cache(mm);
if (pte)
return pte;
return __alloc_for_cache(mm, kernel);
}
void page_table_free(struct mm_struct *mm, unsigned long *table, int kernel)
{
struct page *page = virt_to_page(table);
if (put_page_testzero(page)) {
if (!kernel)
pgtable_page_dtor(page);
free_hot_cold_page(page, 0);
}
}
#ifdef CONFIG_SMP
static void page_table_free_rcu(void *table)
{
struct page *page = virt_to_page(table);
if (put_page_testzero(page)) {
pgtable_page_dtor(page);
free_hot_cold_page(page, 0);
}
}
void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int shift)
{
unsigned long pgf = (unsigned long)table;
BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
pgf |= shift;
tlb_remove_table(tlb, (void *)pgf);
}
void __tlb_remove_table(void *_table)
{
void *table = (void *)((unsigned long)_table & ~MAX_PGTABLE_INDEX_SIZE);
unsigned shift = (unsigned long)_table & MAX_PGTABLE_INDEX_SIZE;
if (!shift)
/* PTE page needs special handling */
page_table_free_rcu(table);
else {
BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
kmem_cache_free(PGT_CACHE(shift), table);
}
}
#else
void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int shift)
{
if (!shift) {
/* PTE page needs special handling */
struct page *page = virt_to_page(table);
if (put_page_testzero(page)) {
pgtable_page_dtor(page);
free_hot_cold_page(page, 0);
}
} else {
BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
kmem_cache_free(PGT_CACHE(shift), table);
}
}
#endif
#endif /* CONFIG_PPC_64K_PAGES */