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