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linux/arch/powerpc/mm/init_32.c
Becky Bruce 41151e77a4 powerpc: Hugetlb for BookE 
Enable hugepages on Freescale BookE processors.  This allows the kernel to
use huge TLB entries to map pages, which can greatly reduce the number of
TLB misses and the amount of TLB thrashing experienced by applications with
large memory footprints.  Care should be taken when using this on FSL
processors, as the number of large TLB entries supported by the core is low
(16-64) on current processors.

The supported set of hugepage sizes include 4m, 16m, 64m, 256m, and 1g.
Page sizes larger than the max zone size are called "gigantic" pages and
must be allocated on the command line (and cannot be deallocated).

This is currently only fully implemented for Freescale 32-bit BookE
processors, but there is some infrastructure in the code for
64-bit BooKE.

Signed-off-by: Becky Bruce <beckyb@kernel.crashing.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2011-09-20 09:19:40 +10:00

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/*
* PowerPC version
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
*
* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
* and Cort Dougan (PReP) (cort@cs.nmt.edu)
* Copyright (C) 1996 Paul Mackerras
* PPC44x/36-bit changes by Matt Porter (mporter@mvista.com)
*
* Derived from "arch/i386/mm/init.c"
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*
* 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/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/highmem.h>
#include <linux/initrd.h>
#include <linux/pagemap.h>
#include <linux/memblock.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/hugetlb.h>
#include <asm/pgalloc.h>
#include <asm/prom.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/smp.h>
#include <asm/machdep.h>
#include <asm/btext.h>
#include <asm/tlb.h>
#include <asm/sections.h>
#include <asm/system.h>
#include <asm/hugetlb.h>
#include "mmu_decl.h"
#if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
/* The amount of lowmem must be within 0xF0000000 - KERNELBASE. */
#if (CONFIG_LOWMEM_SIZE > (0xF0000000 - PAGE_OFFSET))
#error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_START_KERNEL"
#endif
#endif
#define MAX_LOW_MEM CONFIG_LOWMEM_SIZE
phys_addr_t total_memory;
phys_addr_t total_lowmem;
phys_addr_t memstart_addr = (phys_addr_t)~0ull;
EXPORT_SYMBOL(memstart_addr);
phys_addr_t kernstart_addr;
EXPORT_SYMBOL(kernstart_addr);
phys_addr_t lowmem_end_addr;
int boot_mapsize;
#ifdef CONFIG_PPC_PMAC
unsigned long agp_special_page;
EXPORT_SYMBOL(agp_special_page);
#endif
void MMU_init(void);
/* XXX should be in current.h -- paulus */
extern struct task_struct *current_set[NR_CPUS];
/*
* this tells the system to map all of ram with the segregs
* (i.e. page tables) instead of the bats.
* -- Cort
*/
int __map_without_bats;
int __map_without_ltlbs;
/*
* This tells the system to allow ioremapping memory marked as reserved.
*/
int __allow_ioremap_reserved;
/* max amount of low RAM to map in */
unsigned long __max_low_memory = MAX_LOW_MEM;
/*
* Check for command-line options that affect what MMU_init will do.
*/
void MMU_setup(void)
{
/* Check for nobats option (used in mapin_ram). */
if (strstr(cmd_line, "nobats")) {
__map_without_bats = 1;
}
if (strstr(cmd_line, "noltlbs")) {
__map_without_ltlbs = 1;
}
#ifdef CONFIG_DEBUG_PAGEALLOC
__map_without_bats = 1;
__map_without_ltlbs = 1;
#endif
}
/*
* MMU_init sets up the basic memory mappings for the kernel,
* including both RAM and possibly some I/O regions,
* and sets up the page tables and the MMU hardware ready to go.
*/
void __init MMU_init(void)
{
if (ppc_md.progress)
ppc_md.progress("MMU:enter", 0x111);
/* parse args from command line */
MMU_setup();
/*
* Reserve gigantic pages for hugetlb. This MUST occur before
* lowmem_end_addr is initialized below.
*/
reserve_hugetlb_gpages();
if (memblock.memory.cnt > 1) {
#ifndef CONFIG_WII
memblock.memory.cnt = 1;
memblock_analyze();
printk(KERN_WARNING "Only using first contiguous memory region");
#else
wii_memory_fixups();
#endif
}
total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
lowmem_end_addr = memstart_addr + total_lowmem;
#ifdef CONFIG_FSL_BOOKE
/* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
* entries, so we need to adjust lowmem to match the amount we can map
* in the fixed entries */
adjust_total_lowmem();
#endif /* CONFIG_FSL_BOOKE */
if (total_lowmem > __max_low_memory) {
total_lowmem = __max_low_memory;
lowmem_end_addr = memstart_addr + total_lowmem;
#ifndef CONFIG_HIGHMEM
total_memory = total_lowmem;
memblock_enforce_memory_limit(total_lowmem);
memblock_analyze();
#endif /* CONFIG_HIGHMEM */
}
/* Initialize the MMU hardware */
if (ppc_md.progress)
ppc_md.progress("MMU:hw init", 0x300);
MMU_init_hw();
/* Map in all of RAM starting at KERNELBASE */
if (ppc_md.progress)
ppc_md.progress("MMU:mapin", 0x301);
mapin_ram();
/* Initialize early top-down ioremap allocator */
ioremap_bot = IOREMAP_TOP;
/* Map in I/O resources */
if (ppc_md.progress)
ppc_md.progress("MMU:setio", 0x302);
if (ppc_md.progress)
ppc_md.progress("MMU:exit", 0x211);
/* From now on, btext is no longer BAT mapped if it was at all */
#ifdef CONFIG_BOOTX_TEXT
btext_unmap();
#endif
/* Shortly after that, the entire linear mapping will be available */
memblock_set_current_limit(lowmem_end_addr);
}
/* This is only called until mem_init is done. */
void __init *early_get_page(void)
{
if (init_bootmem_done)
return alloc_bootmem_pages(PAGE_SIZE);
else
return __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
}
#ifdef CONFIG_8xx /* No 8xx specific .c file to put that in ... */
void setup_initial_memory_limit(phys_addr_t first_memblock_base,
phys_addr_t first_memblock_size)
{
/* We don't currently support the first MEMBLOCK not mapping 0
* physical on those processors
*/
BUG_ON(first_memblock_base != 0);
/* 8xx can only access 8MB at the moment */
memblock_set_current_limit(min_t(u64, first_memblock_size, 0x00800000));
}
#endif /* CONFIG_8xx */
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