linux/arch/arm/mm/ioremap.c

338 lines
8.4 KiB
C
Raw Normal View History

/*
* linux/arch/arm/mm/ioremap.c
*
* Re-map IO memory to kernel address space so that we can access it.
*
* (C) Copyright 1995 1996 Linus Torvalds
*
* Hacked for ARM by Phil Blundell <philb@gnu.org>
* Hacked to allow all architectures to build, and various cleanups
* by Russell King
*
* This allows a driver to remap an arbitrary region of bus memory into
* virtual space. One should *only* use readl, writel, memcpy_toio and
* so on with such remapped areas.
*
* Because the ARM only has a 32-bit address space we can't address the
* whole of the (physical) PCI space at once. PCI huge-mode addressing
* allows us to circumvent this restriction by splitting PCI space into
* two 2GB chunks and mapping only one at a time into processor memory.
* We use MMU protection domains to trap any attempt to access the bank
* that is not currently mapped. (This isn't fully implemented yet.)
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <asm/cacheflush.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/sizes.h>
/*
* Used by ioremap() and iounmap() code to mark section-mapped I/O regions
* in vm_struct->flags field.
*/
#define VM_ARM_SECTION_MAPPING 0x80000000
static inline void
remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
unsigned long phys_addr, pgprot_t pgprot)
{
unsigned long end;
address &= ~PMD_MASK;
end = address + size;
if (end > PMD_SIZE)
end = PMD_SIZE;
BUG_ON(address >= end);
do {
if (!pte_none(*pte))
goto bad;
set_pte(pte, pfn_pte(phys_addr >> PAGE_SHIFT, pgprot));
address += PAGE_SIZE;
phys_addr += PAGE_SIZE;
pte++;
} while (address && (address < end));
return;
bad:
printk("remap_area_pte: page already exists\n");
BUG();
}
static inline int
remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
unsigned long phys_addr, unsigned long flags)
{
unsigned long end;
pgprot_t pgprot;
address &= ~PGDIR_MASK;
end = address + size;
if (end > PGDIR_SIZE)
end = PGDIR_SIZE;
phys_addr -= address;
BUG_ON(address >= end);
pgprot = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY | L_PTE_WRITE | flags);
do {
[PATCH] mm: init_mm without ptlock First step in pushing down the page_table_lock. init_mm.page_table_lock has been used throughout the architectures (usually for ioremap): not to serialize kernel address space allocation (that's usually vmlist_lock), but because pud_alloc,pmd_alloc,pte_alloc_kernel expect caller holds it. Reverse that: don't lock or unlock init_mm.page_table_lock in any of the architectures; instead rely on pud_alloc,pmd_alloc,pte_alloc_kernel to take and drop it when allocating a new one, to check lest a racing task already did. Similarly no page_table_lock in vmalloc's map_vm_area. Some temporary ugliness in __pud_alloc and __pmd_alloc: since they also handle user mms, which are converted only by a later patch, for now they have to lock differently according to whether or not it's init_mm. If sources get muddled, there's a danger that an arch source taking init_mm.page_table_lock will be mixed with common source also taking it (or neither take it). So break the rules and make another change, which should break the build for such a mismatch: remove the redundant mm arg from pte_alloc_kernel (ppc64 scrapped its distinct ioremap_mm in 2.6.13). Exceptions: arm26 used pte_alloc_kernel on user mm, now pte_alloc_map; ia64 used pte_alloc_map on init_mm, now pte_alloc_kernel; parisc had bad args to pmd_alloc and pte_alloc_kernel in unused USE_HPPA_IOREMAP code; ppc64 map_io_page forgot to unlock on failure; ppc mmu_mapin_ram and ppc64 im_free took page_table_lock for no good reason. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 01:16:21 +00:00
pte_t * pte = pte_alloc_kernel(pmd, address);
if (!pte)
return -ENOMEM;
remap_area_pte(pte, address, end - address, address + phys_addr, pgprot);
address = (address + PMD_SIZE) & PMD_MASK;
pmd++;
} while (address && (address < end));
return 0;
}
static int
remap_area_pages(unsigned long start, unsigned long pfn,
unsigned long size, unsigned long flags)
{
unsigned long address = start;
unsigned long end = start + size;
unsigned long phys_addr = __pfn_to_phys(pfn);
int err = 0;
pgd_t * dir;
phys_addr -= address;
dir = pgd_offset(&init_mm, address);
BUG_ON(address >= end);
do {
pmd_t *pmd = pmd_alloc(&init_mm, dir, address);
if (!pmd) {
err = -ENOMEM;
break;
}
if (remap_area_pmd(pmd, address, end - address,
phys_addr + address, flags)) {
err = -ENOMEM;
break;
}
address = (address + PGDIR_SIZE) & PGDIR_MASK;
dir++;
} while (address && (address < end));
return err;
}
void __check_kvm_seq(struct mm_struct *mm)
{
unsigned int seq;
do {
seq = init_mm.context.kvm_seq;
memcpy(pgd_offset(mm, VMALLOC_START),
pgd_offset_k(VMALLOC_START),
sizeof(pgd_t) * (pgd_index(VMALLOC_END) -
pgd_index(VMALLOC_START)));
mm->context.kvm_seq = seq;
} while (seq != init_mm.context.kvm_seq);
}
#ifndef CONFIG_SMP
/*
* Section support is unsafe on SMP - If you iounmap and ioremap a region,
* the other CPUs will not see this change until their next context switch.
* Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
* which requires the new ioremap'd region to be referenced, the CPU will
* reference the _old_ region.
*
* Note that get_vm_area() allocates a guard 4K page, so we need to mask
* the size back to 1MB aligned or we will overflow in the loop below.
*/
static void unmap_area_sections(unsigned long virt, unsigned long size)
{
unsigned long addr = virt, end = virt + (size & ~SZ_1M);
pgd_t *pgd;
flush_cache_vunmap(addr, end);
pgd = pgd_offset_k(addr);
do {
pmd_t pmd, *pmdp = pmd_offset(pgd, addr);
pmd = *pmdp;
if (!pmd_none(pmd)) {
/*
* Clear the PMD from the page table, and
* increment the kvm sequence so others
* notice this change.
*
* Note: this is still racy on SMP machines.
*/
pmd_clear(pmdp);
init_mm.context.kvm_seq++;
/*
* Free the page table, if there was one.
*/
if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
pte_free_kernel(pmd_page_kernel(pmd));
}
addr += PGDIR_SIZE;
pgd++;
} while (addr < end);
/*
* Ensure that the active_mm is up to date - we want to
* catch any use-after-iounmap cases.
*/
if (current->active_mm->context.kvm_seq != init_mm.context.kvm_seq)
__check_kvm_seq(current->active_mm);
flush_tlb_kernel_range(virt, end);
}
static int
remap_area_sections(unsigned long virt, unsigned long pfn,
unsigned long size, unsigned long flags)
{
unsigned long prot, addr = virt, end = virt + size;
pgd_t *pgd;
/*
* Remove and free any PTE-based mapping, and
* sync the current kernel mapping.
*/
unmap_area_sections(virt, size);
prot = PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_DOMAIN(DOMAIN_IO) |
(flags & (L_PTE_CACHEABLE | L_PTE_BUFFERABLE));
/*
* ARMv6 and above need XN set to prevent speculative prefetches
* hitting IO.
*/
if (cpu_architecture() >= CPU_ARCH_ARMv6)
prot |= PMD_SECT_XN;
pgd = pgd_offset_k(addr);
do {
pmd_t *pmd = pmd_offset(pgd, addr);
pmd[0] = __pmd(__pfn_to_phys(pfn) | prot);
pfn += SZ_1M >> PAGE_SHIFT;
pmd[1] = __pmd(__pfn_to_phys(pfn) | prot);
pfn += SZ_1M >> PAGE_SHIFT;
flush_pmd_entry(pmd);
addr += PGDIR_SIZE;
pgd++;
} while (addr < end);
return 0;
}
#endif
/*
* Remap an arbitrary physical address space into the kernel virtual
* address space. Needed when the kernel wants to access high addresses
* directly.
*
* NOTE! We need to allow non-page-aligned mappings too: we will obviously
* have to convert them into an offset in a page-aligned mapping, but the
* caller shouldn't need to know that small detail.
*
* 'flags' are the extra L_PTE_ flags that you want to specify for this
* mapping. See include/asm-arm/proc-armv/pgtable.h for more information.
*/
void __iomem *
__ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
unsigned long flags)
{
int err;
unsigned long addr;
struct vm_struct * area;
area = get_vm_area(size, VM_IOREMAP);
if (!area)
return NULL;
addr = (unsigned long)area->addr;
#ifndef CONFIG_SMP
if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
area->flags |= VM_ARM_SECTION_MAPPING;
err = remap_area_sections(addr, pfn, size, flags);
} else
#endif
err = remap_area_pages(addr, pfn, size, flags);
if (err) {
vunmap((void *)addr);
return NULL;
}
flush_cache_vmap(addr, addr + size);
return (void __iomem *) (offset + addr);
}
EXPORT_SYMBOL(__ioremap_pfn);
void __iomem *
__ioremap(unsigned long phys_addr, size_t size, unsigned long flags)
{
unsigned long last_addr;
unsigned long offset = phys_addr & ~PAGE_MASK;
unsigned long pfn = __phys_to_pfn(phys_addr);
/*
* Don't allow wraparound or zero size
*/
last_addr = phys_addr + size - 1;
if (!size || last_addr < phys_addr)
return NULL;
/*
* Page align the mapping size
*/
size = PAGE_ALIGN(last_addr + 1) - phys_addr;
return __ioremap_pfn(pfn, offset, size, flags);
}
EXPORT_SYMBOL(__ioremap);
void __iounmap(void __iomem *addr)
{
struct vm_struct **p, *tmp;
unsigned int section_mapping = 0;
addr = (void __iomem *)(PAGE_MASK & (unsigned long)addr);
/*
* If this is a section based mapping we need to handle it
* specially as the VM subysystem does not know how to handle
* such a beast. We need the lock here b/c we need to clear
* all the mappings before the area can be reclaimed
* by someone else.
*/
write_lock(&vmlist_lock);
for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
if((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
if (tmp->flags & VM_ARM_SECTION_MAPPING) {
*p = tmp->next;
unmap_area_sections((unsigned long)tmp->addr,
tmp->size);
kfree(tmp);
section_mapping = 1;
}
break;
}
}
write_unlock(&vmlist_lock);
if (!section_mapping)
vunmap(addr);
}
EXPORT_SYMBOL(__iounmap);