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/* SPDX-License-Identifier: GPL-2.0
*
* fixmap.h: compile-time virtual memory allocation
*
* Copyright (C) 1998 Ingo Molnar
*
* Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
*/
#ifndef _ASM_FIXMAP_H
#define _ASM_FIXMAP_H
#include <linux/kernel.h>
#include <linux/threads.h>
#include <asm/page.h>
/*
* Here we define all the compile-time 'special' virtual
* addresses. The point is to have a constant address at
* compile time, but to set the physical address only
* in the boot process. We allocate these special addresses
* from the end of P3 backwards.
* Also this lets us do fail-safe vmalloc(), we
* can guarantee that these special addresses and
* vmalloc()-ed addresses never overlap.
*
* these 'compile-time allocated' memory buffers are
* fixed-size 4k pages. (or larger if used with an increment
* highger than 1) use fixmap_set(idx,phys) to associate
* physical memory with fixmap indices.
*
* TLB entries of such buffers will not be flushed across
* task switches.
*/
/*
* on UP currently we will have no trace of the fixmap mechanizm,
* no page table allocations, etc. This might change in the
* future, say framebuffers for the console driver(s) could be
* fix-mapped?
*/
enum fixed_addresses {
/*
* The FIX_CMAP entries are used by kmap_coherent() to get virtual
* addresses which are of a known color, and so their values are
* important. __fix_to_virt(FIX_CMAP_END - n) must give an address
* which is the same color as a page (n<<PAGE_SHIFT).
*/
#define FIX_N_COLOURS 8
FIX_CMAP_BEGIN,
FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * NR_CPUS) - 1,
#ifdef CONFIG_IOREMAP_FIXED
/*
* FIX_IOREMAP entries are useful for mapping physical address
* space before ioremap() is useable, e.g. really early in boot
* before kmalloc() is working.
*/
#define FIX_N_IOREMAPS 32
FIX_IOREMAP_BEGIN,
FIX_IOREMAP_END = FIX_IOREMAP_BEGIN + FIX_N_IOREMAPS - 1,
#endif
__end_of_fixed_addresses
};
extern void __set_fixmap(enum fixed_addresses idx,
unsigned long phys, pgprot_t flags);
extern void __clear_fixmap(enum fixed_addresses idx, pgprot_t flags);
/*
* used by vmalloc.c.
*
* Leave one empty page between vmalloc'ed areas and
* the start of the fixmap, and leave one page empty
* at the top of mem..
*/
#define FIXADDR_TOP (P4SEG - PAGE_SIZE)
#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
#define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
#include <asm-generic/fixmap.h>
#endif
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