pgtable.c

  1/*
  2 *  This file contains the routines setting up the linux page tables.
  3 *
  4 * Copyright (C) 2008 Michal Simek
  5 * Copyright (C) 2008 PetaLogix
  6 *
  7 *    Copyright (C) 2007 Xilinx, Inc.  All rights reserved.
  8 *
  9 *  Derived from arch/ppc/mm/pgtable.c:
 10 *    -- paulus
 11 *
 12 *  Derived from arch/ppc/mm/init.c:
 13 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 14 *
 15 *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
 16 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
 17 *    Copyright (C) 1996 Paul Mackerras
 18 *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
 19 *
 20 *  Derived from "arch/i386/mm/init.c"
 21 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 22 *
 23 *  This file is subject to the terms and conditions of the GNU General
 24 *  Public License.  See the file COPYING in the main directory of this
 25 *  archive for more details.
 26 *
 27 */
 28
 29#include <linux/export.h>
 30#include <linux/kernel.h>
 31#include <linux/types.h>
 32#include <linux/vmalloc.h>
 33#include <linux/init.h>
 34#include <linux/mm_types.h>
 35#include <linux/pgtable.h>
 36#include <linux/memblock.h>
 37#include <linux/kallsyms.h>
 38
 39#include <asm/pgalloc.h>
 40#include <linux/io.h>
 41#include <asm/mmu.h>
 42#include <asm/sections.h>
 43#include <asm/fixmap.h>
 44
 45unsigned long ioremap_base;
 46unsigned long ioremap_bot;
 47EXPORT_SYMBOL(ioremap_bot);
 48
 49static void __iomem *__ioremap(phys_addr_t addr, unsigned long size,
 50		unsigned long flags)
 51{
 52	unsigned long v, i;
 53	phys_addr_t p;
 54	int err;
 55
 56	/*
 57	 * Choose an address to map it to.
 58	 * Once the vmalloc system is running, we use it.
 59	 * Before then, we use space going down from ioremap_base
 60	 * (ioremap_bot records where we're up to).
 61	 */
 62	p = addr & PAGE_MASK;
 63	size = PAGE_ALIGN(addr + size) - p;
 64
 65	/*
 66	 * Don't allow anybody to remap normal RAM that we're using.
 67	 * mem_init() sets high_memory so only do the check after that.
 68	 *
 69	 * However, allow remap of rootfs: TBD
 70	 */
 71
 72	if (mem_init_done &&
 73		p >= memory_start && p < virt_to_phys(high_memory) &&
 74		!(p >= __virt_to_phys((phys_addr_t)__bss_stop) &&
 75		p < __virt_to_phys((phys_addr_t)__bss_stop))) {
 76		pr_warn("__ioremap(): phys addr "PTE_FMT" is RAM lr %ps\n",
 77			(unsigned long)p, __builtin_return_address(0));
 78		return NULL;
 79	}
 80
 81	if (size == 0)
 82		return NULL;
 83
 84	/*
 85	 * Is it already mapped? If the whole area is mapped then we're
 86	 * done, otherwise remap it since we want to keep the virt addrs for
 87	 * each request contiguous.
 88	 *
 89	 * We make the assumption here that if the bottom and top
 90	 * of the range we want are mapped then it's mapped to the
 91	 * same virt address (and this is contiguous).
 92	 *  -- Cort
 93	 */
 94
 95	if (mem_init_done) {
 96		struct vm_struct *area;
 97		area = get_vm_area(size, VM_IOREMAP);
 98		if (area == NULL)
 99			return NULL;
100		v = (unsigned long) area->addr;
101	} else {
102		v = (ioremap_bot -= size);
103	}
104
105	if ((flags & _PAGE_PRESENT) == 0)
106		flags |= _PAGE_KERNEL;
107	if (flags & _PAGE_NO_CACHE)
108		flags |= _PAGE_GUARDED;
109
110	err = 0;
111	for (i = 0; i < size && err == 0; i += PAGE_SIZE)
112		err = map_page(v + i, p + i, flags);
113	if (err) {
114		if (mem_init_done)
115			vfree((void *)v);
116		return NULL;
117	}
118
119	return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
120}
121
122void __iomem *ioremap(phys_addr_t addr, unsigned long size)
123{
124	return __ioremap(addr, size, _PAGE_NO_CACHE);
125}
126EXPORT_SYMBOL(ioremap);
127
128void iounmap(volatile void __iomem *addr)
129{
130	if ((__force void *)addr > high_memory &&
131					(unsigned long) addr < ioremap_bot)
132		vfree((void *) (PAGE_MASK & (unsigned long) addr));
133}
134EXPORT_SYMBOL(iounmap);
135
136
137int map_page(unsigned long va, phys_addr_t pa, int flags)
138{
139	p4d_t *p4d;
140	pud_t *pud;
141	pmd_t *pd;
142	pte_t *pg;
143	int err = -ENOMEM;
144
145	/* Use upper 10 bits of VA to index the first level map */
146	p4d = p4d_offset(pgd_offset_k(va), va);
147	pud = pud_offset(p4d, va);
148	pd = pmd_offset(pud, va);
149	/* Use middle 10 bits of VA to index the second-level map */
150	pg = pte_alloc_kernel(pd, va); /* from powerpc - pgtable.c */
151	/* pg = pte_alloc_kernel(&init_mm, pd, va); */
152
153	if (pg != NULL) {
154		err = 0;
155		set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT,
156				__pgprot(flags)));
157		if (unlikely(mem_init_done))
158			_tlbie(va);
159	}
160	return err;
161}
162
163/*
164 * Map in all of physical memory starting at CONFIG_KERNEL_START.
165 */
166void __init mapin_ram(void)
167{
168	unsigned long v, p, s, f;
169
170	v = CONFIG_KERNEL_START;
171	p = memory_start;
172	for (s = 0; s < lowmem_size; s += PAGE_SIZE) {
173		f = _PAGE_PRESENT | _PAGE_ACCESSED |
174				_PAGE_SHARED | _PAGE_HWEXEC;
175		if (!is_kernel_text(v))
176			f |= _PAGE_WRENABLE;
177		else
178			/* On the MicroBlaze, no user access
179			   forces R/W kernel access */
180			f |= _PAGE_USER;
181		map_page(v, p, f);
182		v += PAGE_SIZE;
183		p += PAGE_SIZE;
184	}
185}
186
187/* is x a power of 2? */
188#define is_power_of_2(x)	((x) != 0 && (((x) & ((x) - 1)) == 0))
189
190/* Scan the real Linux page tables and return a PTE pointer for
191 * a virtual address in a context.
192 * Returns true (1) if PTE was found, zero otherwise.  The pointer to
193 * the PTE pointer is unmodified if PTE is not found.
194 */
195static int get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep)
196{
197	pgd_t	*pgd;
198	p4d_t	*p4d;
199	pud_t	*pud;
200	pmd_t	*pmd;
201	pte_t	*pte;
202	int     retval = 0;
203
204	pgd = pgd_offset(mm, addr & PAGE_MASK);
205	if (pgd) {
206		p4d = p4d_offset(pgd, addr & PAGE_MASK);
207		pud = pud_offset(p4d, addr & PAGE_MASK);
208		pmd = pmd_offset(pud, addr & PAGE_MASK);
209		if (pmd_present(*pmd)) {
210			pte = pte_offset_kernel(pmd, addr & PAGE_MASK);
211			if (pte) {
212				retval = 1;
213				*ptep = pte;
214			}
215		}
216	}
217	return retval;
218}
219
220/* Find physical address for this virtual address.  Normally used by
221 * I/O functions, but anyone can call it.
222 */
223unsigned long iopa(unsigned long addr)
224{
225	unsigned long pa;
226
227	pte_t *pte;
228	struct mm_struct *mm;
229
230	/* Allow mapping of user addresses (within the thread)
231	 * for DMA if necessary.
232	 */
233	if (addr < TASK_SIZE)
234		mm = current->mm;
235	else
236		mm = &init_mm;
237
238	pa = 0;
239	if (get_pteptr(mm, addr, &pte))
240		pa = (pte_val(*pte) & PAGE_MASK) | (addr & ~PAGE_MASK);
241
242	return pa;
243}
244
245__ref pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
246{
247	if (mem_init_done)
248		return __pte_alloc_one_kernel(mm);
249	else
250		return memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
251					      MEMBLOCK_LOW_LIMIT,
252					      memory_start + kernel_tlb,
253					      NUMA_NO_NODE);
254}
255
256void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t flags)
257{
258	unsigned long address = __fix_to_virt(idx);
259
260	if (idx >= __end_of_fixed_addresses)
261		BUG();
262
263	map_page(address, phys, pgprot_val(flags));
264}