highmem.c
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/*
* High memory support for Xtensa architecture
*
* This file is subject to the terms and conditions of the GNU General
* Public License. See the file "COPYING" in the main directory of
* this archive for more details.
*
* Copyright (C) 2014 Cadence Design Systems Inc.
*/
#include <linux/export.h>
#include <linux/highmem.h>
#include <asm/tlbflush.h>
static pte_t *kmap_pte;
#if DCACHE_WAY_SIZE > PAGE_SIZE
unsigned int last_pkmap_nr_arr[DCACHE_N_COLORS];
wait_queue_head_t pkmap_map_wait_arr[DCACHE_N_COLORS];
static void __init kmap_waitqueues_init(void)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE(pkmap_map_wait_arr); ++i)
init_waitqueue_head(pkmap_map_wait_arr + i);
}
#else
static inline void kmap_waitqueues_init(void)
{
}
#endif
static inline enum fixed_addresses kmap_idx(int type, unsigned long color)
{
return (type + KM_TYPE_NR * smp_processor_id()) * DCACHE_N_COLORS +
color;
}
void *kmap_atomic(struct page *page)
{
enum fixed_addresses idx;
unsigned long vaddr;
preempt_disable();
pagefault_disable();
if (!PageHighMem(page))
return page_address(page);
idx = kmap_idx(kmap_atomic_idx_push(),
DCACHE_ALIAS(page_to_phys(page)));
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
#ifdef CONFIG_DEBUG_HIGHMEM
BUG_ON(!pte_none(*(kmap_pte + idx)));
#endif
set_pte(kmap_pte + idx, mk_pte(page, PAGE_KERNEL_EXEC));
return (void *)vaddr;
}
EXPORT_SYMBOL(kmap_atomic);
void __kunmap_atomic(void *kvaddr)
{
if (kvaddr >= (void *)FIXADDR_START &&
kvaddr < (void *)FIXADDR_TOP) {
int idx = kmap_idx(kmap_atomic_idx(),
DCACHE_ALIAS((unsigned long)kvaddr));
/*
* Force other mappings to Oops if they'll try to access this
* pte without first remap it. Keeping stale mappings around
* is a bad idea also, in case the page changes cacheability
* attributes or becomes a protected page in a hypervisor.
*/
pte_clear(&init_mm, kvaddr, kmap_pte + idx);
local_flush_tlb_kernel_range((unsigned long)kvaddr,
(unsigned long)kvaddr + PAGE_SIZE);
kmap_atomic_idx_pop();
}
pagefault_enable();
preempt_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);
void __init kmap_init(void)
{
unsigned long kmap_vstart;
/* cache the first kmap pte */
kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
kmap_waitqueues_init();
}