1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __UM_FIXMAP_H
3 #define __UM_FIXMAP_H
4
5 #include <asm/processor.h>
6 #include <asm/archparam.h>
7 #include <asm/page.h>
8 #include <linux/threads.h>
9
10 /*
11 * Here we define all the compile-time 'special' virtual
12 * addresses. The point is to have a constant address at
13 * compile time, but to set the physical address only
14 * in the boot process. We allocate these special addresses
15 * from the end of virtual memory (0xfffff000) backwards.
16 * Also this lets us do fail-safe vmalloc(), we
17 * can guarantee that these special addresses and
18 * vmalloc()-ed addresses never overlap.
19 *
20 * these 'compile-time allocated' memory buffers are
21 * fixed-size 4k pages. (or larger if used with an increment
22 * highger than 1) use fixmap_set(idx,phys) to associate
23 * physical memory with fixmap indices.
24 *
25 * TLB entries of such buffers will not be flushed across
26 * task switches.
27 */
28
29 /*
30 * on UP currently we will have no trace of the fixmap mechanizm,
31 * no page table allocations, etc. This might change in the
32 * future, say framebuffers for the console driver(s) could be
33 * fix-mapped?
34 */
35 enum fixed_addresses {
36 __end_of_fixed_addresses
37 };
38
39 extern void __set_fixmap (enum fixed_addresses idx,
40 unsigned long phys, pgprot_t flags);
41
42 /*
43 * used by vmalloc.c.
44 *
45 * Leave one empty page between vmalloc'ed areas and
46 * the start of the fixmap, and leave one page empty
47 * at the top of mem..
48 */
49
50 #define FIXADDR_TOP (TASK_SIZE - 2 * PAGE_SIZE)
51 #define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
52 #define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
53
54 #include <asm-generic/fixmap.h>
55
56 #endif
57
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