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/*
* arch/arm/mm/highmem.c -- ARM highmem support
*
* Author: Nicolas Pitre
* Created: september 8, 2008
* Copyright: Marvell Semiconductors Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/highmem.h>
#include <linux/interrupt.h>
#include <asm/fixmap.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include "mm.h"
void *kmap(struct page *page)
{
might_sleep();
if (!PageHighMem(page))
return page_address(page);
return kmap_high(page);
}
EXPORT_SYMBOL(kmap);
void kunmap(struct page *page)
{
BUG_ON(in_interrupt());
if (!PageHighMem(page))
return;
kunmap_high(page);
}
EXPORT_SYMBOL(kunmap);
void *kmap_atomic(struct page *page, enum km_type type)
{
unsigned int idx;
unsigned long vaddr;
void *kmap;
pagefault_disable();
if (!PageHighMem(page))
return page_address(page);
debug_kmap_atomic(type);
#ifdef CONFIG_DEBUG_HIGHMEM
/*
* There is no cache coherency issue when non VIVT, so force the
* dedicated kmap usage for better debugging purposes in that case.
*/
if (!cache_is_vivt())
kmap = NULL;
else
#endif
kmap = kmap_high_get(page);
if (kmap)
return kmap;
idx = type + KM_TYPE_NR * smp_processor_id();
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
#ifdef CONFIG_DEBUG_HIGHMEM
/*
* With debugging enabled, kunmap_atomic forces that entry to 0.
* Make sure it was indeed properly unmapped.
*/
BUG_ON(!pte_none(*(TOP_PTE(vaddr))));
#endif
set_pte_ext(TOP_PTE(vaddr), mk_pte(page, kmap_prot), 0);
/*
* When debugging is off, kunmap_atomic leaves the previous mapping
* in place, so this TLB flush ensures the TLB is updated with the
* new mapping.
*/
local_flush_tlb_kernel_page(vaddr);
return (void *)vaddr;
}
EXPORT_SYMBOL(kmap_atomic);
void kunmap_atomic(void *kvaddr, enum km_type type)
{
unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
unsigned int idx = type + KM_TYPE_NR * smp_processor_id();
if (kvaddr >= (void *)FIXADDR_START) {
if (cache_is_vivt())
__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
#ifdef CONFIG_DEBUG_HIGHMEM
BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
set_pte_ext(TOP_PTE(vaddr), __pte(0), 0);
local_flush_tlb_kernel_page(vaddr);
#else
(void) idx; /* to kill a warning */
#endif
} else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
/* this address was obtained through kmap_high_get() */
kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
}
pagefault_enable();
}
EXPORT_SYMBOL(kunmap_atomic);
void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
{
unsigned int idx;
unsigned long vaddr;
pagefault_disable();
idx = type + KM_TYPE_NR * smp_processor_id();
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
#ifdef CONFIG_DEBUG_HIGHMEM
BUG_ON(!pte_none(*(TOP_PTE(vaddr))));
#endif
set_pte_ext(TOP_PTE(vaddr), pfn_pte(pfn, kmap_prot), 0);
local_flush_tlb_kernel_page(vaddr);
return (void *)vaddr;
}
struct page *kmap_atomic_to_page(const void *ptr)
{
unsigned long vaddr = (unsigned long)ptr;
pte_t *pte;
if (vaddr < FIXADDR_START)
return virt_to_page(ptr);
pte = TOP_PTE(vaddr);
return pte_page(*pte);
}
#ifdef CONFIG_CPU_CACHE_VIPT
#include <linux/percpu.h>
/*
* The VIVT cache of a highmem page is always flushed before the page
* is unmapped. Hence unmapped highmem pages need no cache maintenance
* in that case.
*
* However unmapped pages may still be cached with a VIPT cache, and
* it is not possible to perform cache maintenance on them using physical
* addresses unfortunately. So we have no choice but to set up a temporary
* virtual mapping for that purpose.
*
* Yet this VIPT cache maintenance may be triggered from DMA support
* functions which are possibly called from interrupt context. As we don't
* want to keep interrupt disabled all the time when such maintenance is
* taking place, we therefore allow for some reentrancy by preserving and
* restoring the previous fixmap entry before the interrupted context is
* resumed. If the reentrancy depth is 0 then there is no need to restore
* the previous fixmap, and leaving the current one in place allow it to
* be reused the next time without a TLB flush (common with DMA).
*/
static DEFINE_PER_CPU(int, kmap_high_l1_vipt_depth);
void *kmap_high_l1_vipt(struct page *page, pte_t *saved_pte)
{
unsigned int idx, cpu = smp_processor_id();
int *depth = &per_cpu(kmap_high_l1_vipt_depth, cpu);
unsigned long vaddr, flags;
pte_t pte, *ptep;
idx = KM_L1_CACHE + KM_TYPE_NR * cpu;
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
ptep = TOP_PTE(vaddr);
pte = mk_pte(page, kmap_prot);
if (!in_interrupt())
preempt_disable();
raw_local_irq_save(flags);
(*depth)++;
if (pte_val(*ptep) == pte_val(pte)) {
*saved_pte = pte;
} else {
*saved_pte = *ptep;
set_pte_ext(ptep, pte, 0);
local_flush_tlb_kernel_page(vaddr);
}
raw_local_irq_restore(flags);
return (void *)vaddr;
}
void kunmap_high_l1_vipt(struct page *page, pte_t saved_pte)
{
unsigned int idx, cpu = smp_processor_id();
int *depth = &per_cpu(kmap_high_l1_vipt_depth, cpu);
unsigned long vaddr, flags;
pte_t pte, *ptep;
idx = KM_L1_CACHE + KM_TYPE_NR * cpu;
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
ptep = TOP_PTE(vaddr);
pte = mk_pte(page, kmap_prot);
BUG_ON(pte_val(*ptep) != pte_val(pte));
BUG_ON(*depth <= 0);
raw_local_irq_save(flags);
(*depth)--;
if (*depth != 0 && pte_val(pte) != pte_val(saved_pte)) {
set_pte_ext(ptep, saved_pte, 0);
local_flush_tlb_kernel_page(vaddr);
}
raw_local_irq_restore(flags);
if (!in_interrupt())
preempt_enable();
}
#endif /* CONFIG_CPU_CACHE_VIPT */
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