linux/arch/mn10300/mm/init.c
Mark Salter 5a226c6f5c MN10300: Map userspace atomic op regs as a vmalloc page
The AM34 processor has an atomic operation that's the equivalent of LL/SC on
other architectures.  However, rather than being done through a pair of
instructions, it's driven by writing to a pair of memory-mapped CPU control
registers.

One set of these registers (AARU/ADRU/ASRU) is available for use by userspace,
but for userspace to access them a PTE must be set up to cover the region.
This is done by dedicating the first vmalloc region page to this purpose,
setting the permissions on its PTE such that userspace can access the page.

glibc is hardcoded to expect the registers to be there.

The way atomic ops are done through these registers is straightforward:

 (1) Write the address of the word you wish to access into AARU.  This causes
     the CPU to go and fetch that word and load it into ADRU.  The status bits
     are also cleared in ASRU.

 (2) The current data value is read from the ADRU register and modified.

 (3) To alter the data in RAM, the revised data is written back to the ADRU
     register, which causes the CPU to attempt to write it back.

 (4) The ASRU.RW flag (ASRU read watch), ASRU.LW flag (bus lock watch),
     ASRU.IW (interrupt watch) and the ASRU.BW (bus error watch) flags then
     must be checked to confirm that the operation wasn't aborted.  If any of
     the watches have been set to true, the operation was aborted.

Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2010-10-27 17:28:56 +01:00

180 lines
4.9 KiB
C

/* MN10300 Memory management initialisation
*
* Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Modified by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, 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/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/initrd.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/bootmem.h>
#include <linux/gfp.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/dma.h>
#include <asm/tlb.h>
#include <asm/sections.h>
DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
unsigned long highstart_pfn, highend_pfn;
#ifdef CONFIG_MN10300_HAS_ATOMIC_OPS_UNIT
static struct vm_struct user_iomap_vm;
#endif
/*
* set up paging
*/
void __init paging_init(void)
{
unsigned long zones_size[MAX_NR_ZONES] = {0,};
pte_t *ppte;
int loop;
/* main kernel space -> RAM mapping is handled as 1:1 transparent by
* the MMU */
memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
memset(kernel_vmalloc_ptes, 0, sizeof(kernel_vmalloc_ptes));
/* load the VMALLOC area PTE table addresses into the kernel PGD */
ppte = kernel_vmalloc_ptes;
for (loop = VMALLOC_START / (PAGE_SIZE * PTRS_PER_PTE);
loop < VMALLOC_END / (PAGE_SIZE * PTRS_PER_PTE);
loop++
) {
set_pgd(swapper_pg_dir + loop, __pgd(__pa(ppte) | _PAGE_TABLE));
ppte += PAGE_SIZE / sizeof(pte_t);
}
/* declare the sizes of the RAM zones (only use the normal zone) */
zones_size[ZONE_NORMAL] =
contig_page_data.bdata->node_low_pfn -
contig_page_data.bdata->node_min_pfn;
/* pass the memory from the bootmem allocator to the main allocator */
free_area_init(zones_size);
#ifdef CONFIG_MN10300_HAS_ATOMIC_OPS_UNIT
/* The Atomic Operation Unit registers need to be mapped to userspace
* for all processes. The following uses vm_area_register_early() to
* reserve the first page of the vmalloc area and sets the pte for that
* page.
*
* glibc hardcodes this virtual mapping, so we're pretty much stuck with
* it from now on.
*/
user_iomap_vm.flags = VM_USERMAP;
user_iomap_vm.size = 1 << PAGE_SHIFT;
vm_area_register_early(&user_iomap_vm, PAGE_SIZE);
ppte = kernel_vmalloc_ptes;
set_pte(ppte, pfn_pte(USER_ATOMIC_OPS_PAGE_ADDR >> PAGE_SHIFT,
PAGE_USERIO));
#endif
local_flush_tlb_all();
}
/*
* transfer all the memory from the bootmem allocator to the runtime allocator
*/
void __init mem_init(void)
{
int codesize, reservedpages, datasize, initsize;
int tmp;
BUG_ON(!mem_map);
#define START_PFN (contig_page_data.bdata->node_min_pfn)
#define MAX_LOW_PFN (contig_page_data.bdata->node_low_pfn)
max_mapnr = num_physpages = MAX_LOW_PFN - START_PFN;
high_memory = (void *) __va(MAX_LOW_PFN * PAGE_SIZE);
/* clear the zero-page */
memset(empty_zero_page, 0, PAGE_SIZE);
/* this will put all low memory onto the freelists */
totalram_pages += free_all_bootmem();
reservedpages = 0;
for (tmp = 0; tmp < num_physpages; tmp++)
if (PageReserved(&mem_map[tmp]))
reservedpages++;
codesize = (unsigned long) &_etext - (unsigned long) &_stext;
datasize = (unsigned long) &_edata - (unsigned long) &_etext;
initsize = (unsigned long) &__init_end - (unsigned long) &__init_begin;
printk(KERN_INFO
"Memory: %luk/%luk available"
" (%dk kernel code, %dk reserved, %dk data, %dk init,"
" %ldk highmem)\n",
nr_free_pages() << (PAGE_SHIFT - 10),
max_mapnr << (PAGE_SHIFT - 10),
codesize >> 10,
reservedpages << (PAGE_SHIFT - 10),
datasize >> 10,
initsize >> 10,
totalhigh_pages << (PAGE_SHIFT - 10));
}
/*
*
*/
void free_init_pages(char *what, unsigned long begin, unsigned long end)
{
unsigned long addr;
for (addr = begin; addr < end; addr += PAGE_SIZE) {
ClearPageReserved(virt_to_page(addr));
init_page_count(virt_to_page(addr));
memset((void *) addr, 0xcc, PAGE_SIZE);
free_page(addr);
totalram_pages++;
}
printk(KERN_INFO "Freeing %s: %ldk freed\n", what, (end - begin) >> 10);
}
/*
* recycle memory containing stuff only required for initialisation
*/
void free_initmem(void)
{
free_init_pages("unused kernel memory",
(unsigned long) &__init_begin,
(unsigned long) &__init_end);
}
/*
* dispose of the memory on which the initial ramdisk resided
*/
#ifdef CONFIG_BLK_DEV_INITRD
void free_initrd_mem(unsigned long start, unsigned long end)
{
free_init_pages("initrd memory", start, end);
}
#endif