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linux/arch/powerpc/include/asm/page.h
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

406 lines
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C
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#ifndef _ASM_POWERPC_PAGE_H
#define _ASM_POWERPC_PAGE_H
/*
* Copyright (C) 2001,2005 IBM Corporation.
*
* 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.
*/
#ifndef __ASSEMBLY__
#include <linux/types.h>
#else
#include <asm/types.h>
#endif
#include <asm/asm-compat.h>
#include <asm/kdump.h>
/*
* On regular PPC32 page size is 4K (but we support 4K/16K/64K/256K pages
* on PPC44x). For PPC64 we support either 4K or 64K software
* page size. When using 64K pages however, whether we are really supporting
* 64K pages in HW or not is irrelevant to those definitions.
*/
#if defined(CONFIG_PPC_256K_PAGES)
#define PAGE_SHIFT 18
#elif defined(CONFIG_PPC_64K_PAGES)
#define PAGE_SHIFT 16
#elif defined(CONFIG_PPC_16K_PAGES)
#define PAGE_SHIFT 14
#else
#define PAGE_SHIFT 12
#endif
#define PAGE_SIZE (ASM_CONST(1) << PAGE_SHIFT)
#ifndef __ASSEMBLY__
#ifdef CONFIG_HUGETLB_PAGE
extern unsigned int HPAGE_SHIFT;
#else
#define HPAGE_SHIFT PAGE_SHIFT
#endif
#define HPAGE_SIZE ((1UL) << HPAGE_SHIFT)
#define HPAGE_MASK (~(HPAGE_SIZE - 1))
#define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT)
#define HUGE_MAX_HSTATE (MMU_PAGE_COUNT-1)
#endif
/* We do define AT_SYSINFO_EHDR but don't use the gate mechanism */
#define __HAVE_ARCH_GATE_AREA 1
/*
* Subtle: (1 << PAGE_SHIFT) is an int, not an unsigned long. So if we
* assign PAGE_MASK to a larger type it gets extended the way we want
* (i.e. with 1s in the high bits)
*/
#define PAGE_MASK (~((1 << PAGE_SHIFT) - 1))
/*
* KERNELBASE is the virtual address of the start of the kernel, it's often
* the same as PAGE_OFFSET, but _might not be_.
*
* The kdump dump kernel is one example where KERNELBASE != PAGE_OFFSET.
*
* PAGE_OFFSET is the virtual address of the start of lowmem.
*
* PHYSICAL_START is the physical address of the start of the kernel.
*
* MEMORY_START is the physical address of the start of lowmem.
*
* KERNELBASE, PAGE_OFFSET, and PHYSICAL_START are all configurable on
* ppc32 and based on how they are set we determine MEMORY_START.
*
* For the linear mapping the following equation should be true:
* KERNELBASE - PAGE_OFFSET = PHYSICAL_START - MEMORY_START
*
* Also, KERNELBASE >= PAGE_OFFSET and PHYSICAL_START >= MEMORY_START
*
* There are two was to determine a physical address from a virtual one:
* va = pa + PAGE_OFFSET - MEMORY_START
* va = pa + KERNELBASE - PHYSICAL_START
*
* If you want to know something's offset from the start of the kernel you
* should subtract KERNELBASE.
*
* If you want to test if something's a kernel address, use is_kernel_addr().
*/
#define KERNELBASE ASM_CONST(CONFIG_KERNEL_START)
#define PAGE_OFFSET ASM_CONST(CONFIG_PAGE_OFFSET)
#define LOAD_OFFSET ASM_CONST((CONFIG_KERNEL_START-CONFIG_PHYSICAL_START))
#if defined(CONFIG_NONSTATIC_KERNEL)
#ifndef __ASSEMBLY__
extern phys_addr_t memstart_addr;
extern phys_addr_t kernstart_addr;
#ifdef CONFIG_RELOCATABLE_PPC32
extern long long virt_phys_offset;
#endif
#endif /* __ASSEMBLY__ */
#define PHYSICAL_START kernstart_addr
#else /* !CONFIG_NONSTATIC_KERNEL */
#define PHYSICAL_START ASM_CONST(CONFIG_PHYSICAL_START)
#endif
/* See Description below for VIRT_PHYS_OFFSET */
#ifdef CONFIG_RELOCATABLE_PPC32
#define VIRT_PHYS_OFFSET virt_phys_offset
#else
#define VIRT_PHYS_OFFSET (KERNELBASE - PHYSICAL_START)
#endif
#ifdef CONFIG_PPC64
#define MEMORY_START 0UL
#elif defined(CONFIG_NONSTATIC_KERNEL)
#define MEMORY_START memstart_addr
#else
#define MEMORY_START (PHYSICAL_START + PAGE_OFFSET - KERNELBASE)
#endif
#ifdef CONFIG_FLATMEM
#define ARCH_PFN_OFFSET ((unsigned long)(MEMORY_START >> PAGE_SHIFT))
#define pfn_valid(pfn) ((pfn) >= ARCH_PFN_OFFSET && (pfn) < max_mapnr)
#endif
#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
/*
* On Book-E parts we need __va to parse the device tree and we can't
* determine MEMORY_START until then. However we can determine PHYSICAL_START
* from information at hand (program counter, TLB lookup).
*
* On BookE with RELOCATABLE (RELOCATABLE_PPC32)
*
* With RELOCATABLE_PPC32, we support loading the kernel at any physical
* address without any restriction on the page alignment.
*
* We find the runtime address of _stext and relocate ourselves based on
* the following calculation:
*
* virtual_base = ALIGN_DOWN(KERNELBASE,256M) +
* MODULO(_stext.run,256M)
* and create the following mapping:
*
* ALIGN_DOWN(_stext.run,256M) => ALIGN_DOWN(KERNELBASE,256M)
*
* When we process relocations, we cannot depend on the
* existing equation for the __va()/__pa() translations:
*
* __va(x) = (x) - PHYSICAL_START + KERNELBASE
*
* Where:
* PHYSICAL_START = kernstart_addr = Physical address of _stext
* KERNELBASE = Compiled virtual address of _stext.
*
* This formula holds true iff, kernel load address is TLB page aligned.
*
* In our case, we need to also account for the shift in the kernel Virtual
* address.
*
* E.g.,
*
* Let the kernel be loaded at 64MB and KERNELBASE be 0xc0000000 (same as PAGE_OFFSET).
* In this case, we would be mapping 0 to 0xc0000000, and kernstart_addr = 64M
*
* Now __va(1MB) = (0x100000) - (0x4000000) + 0xc0000000
* = 0xbc100000 , which is wrong.
*
* Rather, it should be : 0xc0000000 + 0x100000 = 0xc0100000
* according to our mapping.
*
* Hence we use the following formula to get the translations right:
*
* __va(x) = (x) - [ PHYSICAL_START - Effective KERNELBASE ]
*
* Where :
* PHYSICAL_START = dynamic load address.(kernstart_addr variable)
* Effective KERNELBASE = virtual_base =
* = ALIGN_DOWN(KERNELBASE,256M) +
* MODULO(PHYSICAL_START,256M)
*
* To make the cost of __va() / __pa() more light weight, we introduce
* a new variable virt_phys_offset, which will hold :
*
* virt_phys_offset = Effective KERNELBASE - PHYSICAL_START
* = ALIGN_DOWN(KERNELBASE,256M) -
* ALIGN_DOWN(PHYSICALSTART,256M)
*
* Hence :
*
* __va(x) = x - PHYSICAL_START + Effective KERNELBASE
* = x + virt_phys_offset
*
* and
* __pa(x) = x + PHYSICAL_START - Effective KERNELBASE
* = x - virt_phys_offset
*
* On non-Book-E PPC64 PAGE_OFFSET and MEMORY_START are constants so use
* the other definitions for __va & __pa.
*/
#ifdef CONFIG_BOOKE
#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) + VIRT_PHYS_OFFSET))
#define __pa(x) ((unsigned long)(x) - VIRT_PHYS_OFFSET)
#else
#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) + PAGE_OFFSET - MEMORY_START))
#define __pa(x) ((unsigned long)(x) - PAGE_OFFSET + MEMORY_START)
#endif
/*
* Unfortunately the PLT is in the BSS in the PPC32 ELF ABI,
* and needs to be executable. This means the whole heap ends
* up being executable.
*/
#define VM_DATA_DEFAULT_FLAGS32 (VM_READ | VM_WRITE | VM_EXEC | \
VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
#define VM_DATA_DEFAULT_FLAGS64 (VM_READ | VM_WRITE | \
VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
#ifdef __powerpc64__
#include <asm/page_64.h>
#else
#include <asm/page_32.h>
#endif
/* align addr on a size boundary - adjust address up/down if needed */
#define _ALIGN_UP(addr,size) (((addr)+((size)-1))&(~((size)-1)))
#define _ALIGN_DOWN(addr,size) ((addr)&(~((size)-1)))
/* align addr on a size boundary - adjust address up if needed */
#define _ALIGN(addr,size) _ALIGN_UP(addr,size)
/*
* Don't compare things with KERNELBASE or PAGE_OFFSET to test for
* "kernelness", use is_kernel_addr() - it should do what you want.
*/
#ifdef CONFIG_PPC_BOOK3E_64
#define is_kernel_addr(x) ((x) >= 0x8000000000000000ul)
#else
#define is_kernel_addr(x) ((x) >= PAGE_OFFSET)
#endif
#ifndef CONFIG_PPC_BOOK3S_64
/*
* Use the top bit of the higher-level page table entries to indicate whether
* the entries we point to contain hugepages. This works because we know that
* the page tables live in kernel space. If we ever decide to support having
* page tables at arbitrary addresses, this breaks and will have to change.
*/
#ifdef CONFIG_PPC64
#define PD_HUGE 0x8000000000000000
#else
#define PD_HUGE 0x80000000
#endif
#endif /* CONFIG_PPC_BOOK3S_64 */
/*
* Some number of bits at the level of the page table that points to
* a hugepte are used to encode the size. This masks those bits.
*/
#define HUGEPD_SHIFT_MASK 0x3f
#ifndef __ASSEMBLY__
#undef STRICT_MM_TYPECHECKS
#ifdef STRICT_MM_TYPECHECKS
/* These are used to make use of C type-checking. */
/* PTE level */
typedef struct { pte_basic_t pte; } pte_t;
#define pte_val(x) ((x).pte)
#define __pte(x) ((pte_t) { (x) })
/* 64k pages additionally define a bigger "real PTE" type that gathers
* the "second half" part of the PTE for pseudo 64k pages
*/
#if defined(CONFIG_PPC_64K_PAGES) && defined(CONFIG_PPC_STD_MMU_64)
typedef struct { pte_t pte; unsigned long hidx; } real_pte_t;
#else
typedef struct { pte_t pte; } real_pte_t;
#endif
/* PMD level */
#ifdef CONFIG_PPC64
typedef struct { unsigned long pmd; } pmd_t;
#define pmd_val(x) ((x).pmd)
#define __pmd(x) ((pmd_t) { (x) })
/* PUD level exusts only on 4k pages */
#ifndef CONFIG_PPC_64K_PAGES
typedef struct { unsigned long pud; } pud_t;
#define pud_val(x) ((x).pud)
#define __pud(x) ((pud_t) { (x) })
#endif /* !CONFIG_PPC_64K_PAGES */
#endif /* CONFIG_PPC64 */
/* PGD level */
typedef struct { unsigned long pgd; } pgd_t;
#define pgd_val(x) ((x).pgd)
#define __pgd(x) ((pgd_t) { (x) })
/* Page protection bits */
typedef struct { unsigned long pgprot; } pgprot_t;
#define pgprot_val(x) ((x).pgprot)
#define __pgprot(x) ((pgprot_t) { (x) })
#else
/*
* .. while these make it easier on the compiler
*/
typedef pte_basic_t pte_t;
#define pte_val(x) (x)
#define __pte(x) (x)
#if defined(CONFIG_PPC_64K_PAGES) && defined(CONFIG_PPC_STD_MMU_64)
typedef struct { pte_t pte; unsigned long hidx; } real_pte_t;
#else
typedef pte_t real_pte_t;
#endif
#ifdef CONFIG_PPC64
typedef unsigned long pmd_t;
#define pmd_val(x) (x)
#define __pmd(x) (x)
#ifndef CONFIG_PPC_64K_PAGES
typedef unsigned long pud_t;
#define pud_val(x) (x)
#define __pud(x) (x)
#endif /* !CONFIG_PPC_64K_PAGES */
#endif /* CONFIG_PPC64 */
typedef unsigned long pgd_t;
#define pgd_val(x) (x)
#define pgprot_val(x) (x)
typedef unsigned long pgprot_t;
#define __pgd(x) (x)
#define __pgprot(x) (x)
#endif
typedef struct { signed long pd; } hugepd_t;
#ifdef CONFIG_HUGETLB_PAGE
#ifdef CONFIG_PPC_BOOK3S_64
static inline int hugepd_ok(hugepd_t hpd)
{
/*
* hugepd pointer, bottom two bits == 00 and next 4 bits
* indicate size of table
*/
return (((hpd.pd & 0x3) == 0x0) && ((hpd.pd & HUGEPD_SHIFT_MASK) != 0));
}
#else
static inline int hugepd_ok(hugepd_t hpd)
{
return (hpd.pd > 0);
}
#endif
#define is_hugepd(pdep) (hugepd_ok(*((hugepd_t *)(pdep))))
int pgd_huge(pgd_t pgd);
#else /* CONFIG_HUGETLB_PAGE */
#define is_hugepd(pdep) 0
#define pgd_huge(pgd) 0
#endif /* CONFIG_HUGETLB_PAGE */
struct page;
extern void clear_user_page(void *page, unsigned long vaddr, struct page *pg);
extern void copy_user_page(void *to, void *from, unsigned long vaddr,
struct page *p);
extern int page_is_ram(unsigned long pfn);
extern int devmem_is_allowed(unsigned long pfn);
#ifdef CONFIG_PPC_SMLPAR
void arch_free_page(struct page *page, int order);
#define HAVE_ARCH_FREE_PAGE
#endif
struct vm_area_struct;
#ifdef CONFIG_PPC_64K_PAGES
typedef pte_t *pgtable_t;
#else
typedef struct page *pgtable_t;
#endif
#include <asm-generic/memory_model.h>
#endif /* __ASSEMBLY__ */
#endif /* _ASM_POWERPC_PAGE_H */
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