linux/arch/powerpc/mm/pgtable_32.c
Benjamin Herrenschmidt ea3cc330ac powerpc/mm: Cleanup handling of execute permission
This is an attempt at cleaning up a bit the way we handle execute
permission on powerpc. _PAGE_HWEXEC is gone, _PAGE_EXEC is now only
defined by CPUs that can do something with it, and the myriad of
#ifdef's in the I$/D$ coherency code is reduced to 2 cases that
hopefully should cover everything.

The logic on BookE is a little bit different than what it was though
not by much. Since now, _PAGE_EXEC will be set by the generic code
for executable pages, we need to filter out if they are unclean and
recover it. However, I don't expect the code to be more bloated than
it already was in that area due to that change.

I could boast that this brings proper enforcing of per-page execute
permissions to all BookE and 40x but in fact, we've had that now for
some time as a side effect of my previous rework in that area (and
I didn't even know it :-) We would only enable execute permission if
the page was cache clean and we would only cache clean it if we took
and exec fault. Since we now enforce that the later only work if
VM_EXEC is part of the VMA flags, we de-fact already enforce per-page
execute permissions... Unless I missed something

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2009-08-27 13:12:51 +10:00

420 lines
9.9 KiB
C

/*
* This file contains the routines setting up the linux page tables.
* -- paulus
*
* Derived from arch/ppc/mm/init.c:
* 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
*
* 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/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/highmem.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/fixmap.h>
#include <asm/io.h>
#include "mmu_decl.h"
unsigned long ioremap_base;
unsigned long ioremap_bot;
EXPORT_SYMBOL(ioremap_bot); /* aka VMALLOC_END */
#if defined(CONFIG_6xx) || defined(CONFIG_POWER3)
#define HAVE_BATS 1
#endif
#if defined(CONFIG_FSL_BOOKE)
#define HAVE_TLBCAM 1
#endif
extern char etext[], _stext[];
#ifdef HAVE_BATS
extern phys_addr_t v_mapped_by_bats(unsigned long va);
extern unsigned long p_mapped_by_bats(phys_addr_t pa);
void setbat(int index, unsigned long virt, phys_addr_t phys,
unsigned int size, int flags);
#else /* !HAVE_BATS */
#define v_mapped_by_bats(x) (0UL)
#define p_mapped_by_bats(x) (0UL)
#endif /* HAVE_BATS */
#ifdef HAVE_TLBCAM
extern unsigned int tlbcam_index;
extern phys_addr_t v_mapped_by_tlbcam(unsigned long va);
extern unsigned long p_mapped_by_tlbcam(phys_addr_t pa);
#else /* !HAVE_TLBCAM */
#define v_mapped_by_tlbcam(x) (0UL)
#define p_mapped_by_tlbcam(x) (0UL)
#endif /* HAVE_TLBCAM */
#define PGDIR_ORDER (32 + PGD_T_LOG2 - PGDIR_SHIFT)
pgd_t *pgd_alloc(struct mm_struct *mm)
{
pgd_t *ret;
/* pgdir take page or two with 4K pages and a page fraction otherwise */
#ifndef CONFIG_PPC_4K_PAGES
ret = (pgd_t *)kzalloc(1 << PGDIR_ORDER, GFP_KERNEL);
#else
ret = (pgd_t *)__get_free_pages(GFP_KERNEL|__GFP_ZERO,
PGDIR_ORDER - PAGE_SHIFT);
#endif
return ret;
}
void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
#ifndef CONFIG_PPC_4K_PAGES
kfree((void *)pgd);
#else
free_pages((unsigned long)pgd, PGDIR_ORDER - PAGE_SHIFT);
#endif
}
__init_refok pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
{
pte_t *pte;
extern int mem_init_done;
extern void *early_get_page(void);
if (mem_init_done) {
pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
} else {
pte = (pte_t *)early_get_page();
if (pte)
clear_page(pte);
}
return pte;
}
pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
struct page *ptepage;
#ifdef CONFIG_HIGHPTE
gfp_t flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_REPEAT | __GFP_ZERO;
#else
gfp_t flags = GFP_KERNEL | __GFP_REPEAT | __GFP_ZERO;
#endif
ptepage = alloc_pages(flags, 0);
if (!ptepage)
return NULL;
pgtable_page_ctor(ptepage);
return ptepage;
}
void __iomem *
ioremap(phys_addr_t addr, unsigned long size)
{
return __ioremap_caller(addr, size, _PAGE_NO_CACHE | _PAGE_GUARDED,
__builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap);
void __iomem *
ioremap_flags(phys_addr_t addr, unsigned long size, unsigned long flags)
{
/* writeable implies dirty for kernel addresses */
if (flags & _PAGE_RW)
flags |= _PAGE_DIRTY | _PAGE_HWWRITE;
/* we don't want to let _PAGE_USER and _PAGE_EXEC leak out */
flags &= ~(_PAGE_USER | _PAGE_EXEC);
return __ioremap_caller(addr, size, flags, __builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap_flags);
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_caller(phys_addr_t addr, unsigned long size, unsigned long flags,
void *caller)
{
unsigned long v, i;
phys_addr_t p;
int err;
/* Make sure we have the base flags */
if ((flags & _PAGE_PRESENT) == 0)
flags |= PAGE_KERNEL;
/* Non-cacheable page cannot be coherent */
if (flags & _PAGE_NO_CACHE)
flags &= ~_PAGE_COHERENT;
/*
* Choose an address to map it to.
* Once the vmalloc system is running, we use it.
* Before then, we use space going down from ioremap_base
* (ioremap_bot records where we're up to).
*/
p = addr & PAGE_MASK;
size = PAGE_ALIGN(addr + size) - p;
/*
* If the address lies within the first 16 MB, assume it's in ISA
* memory space
*/
if (p < 16*1024*1024)
p += _ISA_MEM_BASE;
#ifndef CONFIG_CRASH_DUMP
/*
* Don't allow anybody to remap normal RAM that we're using.
* mem_init() sets high_memory so only do the check after that.
*/
if (mem_init_done && (p < virt_to_phys(high_memory))) {
printk("__ioremap(): phys addr 0x%llx is RAM lr %p\n",
(unsigned long long)p, __builtin_return_address(0));
return NULL;
}
#endif
if (size == 0)
return NULL;
/*
* Is it already mapped? Perhaps overlapped by a previous
* BAT mapping. If the whole area is mapped then we're done,
* otherwise remap it since we want to keep the virt addrs for
* each request contiguous.
*
* We make the assumption here that if the bottom and top
* of the range we want are mapped then it's mapped to the
* same virt address (and this is contiguous).
* -- Cort
*/
if ((v = p_mapped_by_bats(p)) /*&& p_mapped_by_bats(p+size-1)*/ )
goto out;
if ((v = p_mapped_by_tlbcam(p)))
goto out;
if (mem_init_done) {
struct vm_struct *area;
area = get_vm_area_caller(size, VM_IOREMAP, caller);
if (area == 0)
return NULL;
v = (unsigned long) area->addr;
} else {
v = (ioremap_bot -= size);
}
/*
* Should check if it is a candidate for a BAT mapping
*/
err = 0;
for (i = 0; i < size && err == 0; i += PAGE_SIZE)
err = map_page(v+i, p+i, flags);
if (err) {
if (mem_init_done)
vunmap((void *)v);
return NULL;
}
out:
return (void __iomem *) (v + ((unsigned long)addr & ~PAGE_MASK));
}
EXPORT_SYMBOL(__ioremap);
void iounmap(volatile void __iomem *addr)
{
/*
* If mapped by BATs then there is nothing to do.
* Calling vfree() generates a benign warning.
*/
if (v_mapped_by_bats((unsigned long)addr)) return;
if (addr > high_memory && (unsigned long) addr < ioremap_bot)
vunmap((void *) (PAGE_MASK & (unsigned long)addr));
}
EXPORT_SYMBOL(iounmap);
int map_page(unsigned long va, phys_addr_t pa, int flags)
{
pmd_t *pd;
pte_t *pg;
int err = -ENOMEM;
/* Use upper 10 bits of VA to index the first level map */
pd = pmd_offset(pud_offset(pgd_offset_k(va), va), va);
/* Use middle 10 bits of VA to index the second-level map */
pg = pte_alloc_kernel(pd, va);
if (pg != 0) {
err = 0;
/* The PTE should never be already set nor present in the
* hash table
*/
BUG_ON((pte_val(*pg) & (_PAGE_PRESENT | _PAGE_HASHPTE)) &&
flags);
set_pte_at(&init_mm, va, pg, pfn_pte(pa >> PAGE_SHIFT,
__pgprot(flags)));
}
return err;
}
/*
* Map in a big chunk of physical memory starting at PAGE_OFFSET.
*/
void __init mapin_ram(void)
{
unsigned long v, s, f;
phys_addr_t p;
int ktext;
s = mmu_mapin_ram();
v = PAGE_OFFSET + s;
p = memstart_addr + s;
for (; s < total_lowmem; s += PAGE_SIZE) {
ktext = ((char *) v >= _stext && (char *) v < etext);
f = ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL;
map_page(v, p, f);
#ifdef CONFIG_PPC_STD_MMU_32
if (ktext)
hash_preload(&init_mm, v, 0, 0x300);
#endif
v += PAGE_SIZE;
p += PAGE_SIZE;
}
}
/* Scan the real Linux page tables and return a PTE pointer for
* a virtual address in a context.
* Returns true (1) if PTE was found, zero otherwise. The pointer to
* the PTE pointer is unmodified if PTE is not found.
*/
int
get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
int retval = 0;
pgd = pgd_offset(mm, addr & PAGE_MASK);
if (pgd) {
pud = pud_offset(pgd, addr & PAGE_MASK);
if (pud && pud_present(*pud)) {
pmd = pmd_offset(pud, addr & PAGE_MASK);
if (pmd_present(*pmd)) {
pte = pte_offset_map(pmd, addr & PAGE_MASK);
if (pte) {
retval = 1;
*ptep = pte;
if (pmdp)
*pmdp = pmd;
/* XXX caller needs to do pte_unmap, yuck */
}
}
}
}
return(retval);
}
#ifdef CONFIG_DEBUG_PAGEALLOC
static int __change_page_attr(struct page *page, pgprot_t prot)
{
pte_t *kpte;
pmd_t *kpmd;
unsigned long address;
BUG_ON(PageHighMem(page));
address = (unsigned long)page_address(page);
if (v_mapped_by_bats(address) || v_mapped_by_tlbcam(address))
return 0;
if (!get_pteptr(&init_mm, address, &kpte, &kpmd))
return -EINVAL;
set_pte_at(&init_mm, address, kpte, mk_pte(page, prot));
wmb();
#ifdef CONFIG_PPC_STD_MMU
flush_hash_pages(0, address, pmd_val(*kpmd), 1);
#else
flush_tlb_page(NULL, address);
#endif
pte_unmap(kpte);
return 0;
}
/*
* Change the page attributes of an page in the linear mapping.
*
* THIS CONFLICTS WITH BAT MAPPINGS, DEBUG USE ONLY
*/
static int change_page_attr(struct page *page, int numpages, pgprot_t prot)
{
int i, err = 0;
unsigned long flags;
local_irq_save(flags);
for (i = 0; i < numpages; i++, page++) {
err = __change_page_attr(page, prot);
if (err)
break;
}
local_irq_restore(flags);
return err;
}
void kernel_map_pages(struct page *page, int numpages, int enable)
{
if (PageHighMem(page))
return;
change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
}
#endif /* CONFIG_DEBUG_PAGEALLOC */
static int fixmaps;
void __set_fixmap (enum fixed_addresses idx, phys_addr_t phys, pgprot_t flags)
{
unsigned long address = __fix_to_virt(idx);
if (idx >= __end_of_fixed_addresses) {
BUG();
return;
}
map_page(address, phys, pgprot_val(flags));
fixmaps++;
}
void __this_fixmap_does_not_exist(void)
{
WARN_ON(1);
}