84 lines
2.2 KiB
C
84 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* highmem.c: virtual kernel memory mappings for high memory
|
|
*
|
|
* PowerPC version, stolen from the i386 version.
|
|
*
|
|
* Used in CONFIG_HIGHMEM systems for memory pages which
|
|
* are not addressable by direct kernel virtual addresses.
|
|
*
|
|
* Copyright (C) 1999 Gerhard Wichert, Siemens AG
|
|
* Gerhard.Wichert@pdb.siemens.de
|
|
*
|
|
*
|
|
* Redesigned the x86 32-bit VM architecture to deal with
|
|
* up to 16 Terrabyte physical memory. With current x86 CPUs
|
|
* we now support up to 64 Gigabytes physical RAM.
|
|
*
|
|
* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
|
|
*
|
|
* Reworked for PowerPC by various contributors. Moved from
|
|
* highmem.h by Benjamin Herrenschmidt (c) 2009 IBM Corp.
|
|
*/
|
|
|
|
#include <linux/highmem.h>
|
|
#include <linux/module.h>
|
|
|
|
/*
|
|
* The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
|
|
* gives a more generic (and caching) interface. But kmap_atomic can
|
|
* be used in IRQ contexts, so in some (very limited) cases we need
|
|
* it.
|
|
*/
|
|
void *kmap_atomic_prot(struct page *page, pgprot_t prot)
|
|
{
|
|
unsigned long vaddr;
|
|
int idx, type;
|
|
|
|
preempt_disable();
|
|
pagefault_disable();
|
|
if (!PageHighMem(page))
|
|
return page_address(page);
|
|
|
|
type = kmap_atomic_idx_push();
|
|
idx = type + KM_TYPE_NR*smp_processor_id();
|
|
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
|
|
WARN_ON(IS_ENABLED(CONFIG_DEBUG_HIGHMEM) && !pte_none(*(kmap_pte - idx)));
|
|
__set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot), 1);
|
|
local_flush_tlb_page(NULL, vaddr);
|
|
|
|
return (void*) vaddr;
|
|
}
|
|
EXPORT_SYMBOL(kmap_atomic_prot);
|
|
|
|
void __kunmap_atomic(void *kvaddr)
|
|
{
|
|
unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
|
|
|
|
if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
|
|
pagefault_enable();
|
|
preempt_enable();
|
|
return;
|
|
}
|
|
|
|
if (IS_ENABLED(CONFIG_DEBUG_HIGHMEM)) {
|
|
int type = kmap_atomic_idx();
|
|
unsigned int idx;
|
|
|
|
idx = type + KM_TYPE_NR * smp_processor_id();
|
|
WARN_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
|
|
|
|
/*
|
|
* force other mappings to Oops if they'll try to access
|
|
* this pte without first remap it
|
|
*/
|
|
pte_clear(&init_mm, vaddr, kmap_pte-idx);
|
|
local_flush_tlb_page(NULL, vaddr);
|
|
}
|
|
|
|
kmap_atomic_idx_pop();
|
|
pagefault_enable();
|
|
preempt_enable();
|
|
}
|
|
EXPORT_SYMBOL(__kunmap_atomic);
|