57 lines
1.6 KiB
C
57 lines
1.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __UM_FIXMAP_H
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#define __UM_FIXMAP_H
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#include <asm/processor.h>
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#include <asm/archparam.h>
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#include <asm/page.h>
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#include <linux/threads.h>
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/*
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* Here we define all the compile-time 'special' virtual
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* addresses. The point is to have a constant address at
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* compile time, but to set the physical address only
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* in the boot process. We allocate these special addresses
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* from the end of virtual memory (0xfffff000) backwards.
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* Also this lets us do fail-safe vmalloc(), we
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* can guarantee that these special addresses and
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* vmalloc()-ed addresses never overlap.
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*
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* these 'compile-time allocated' memory buffers are
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* fixed-size 4k pages. (or larger if used with an increment
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* highger than 1) use fixmap_set(idx,phys) to associate
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* physical memory with fixmap indices.
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*
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* TLB entries of such buffers will not be flushed across
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* task switches.
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*/
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/*
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* on UP currently we will have no trace of the fixmap mechanizm,
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* no page table allocations, etc. This might change in the
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* future, say framebuffers for the console driver(s) could be
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* fix-mapped?
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*/
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enum fixed_addresses {
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__end_of_fixed_addresses
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};
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extern void __set_fixmap (enum fixed_addresses idx,
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unsigned long phys, pgprot_t flags);
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/*
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* used by vmalloc.c.
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*
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* Leave one empty page between vmalloc'ed areas and
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* the start of the fixmap, and leave one page empty
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* at the top of mem..
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*/
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#define FIXADDR_TOP (TASK_SIZE - 2 * PAGE_SIZE)
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#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
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#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
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#include <asm-generic/fixmap.h>
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#endif
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