| b.liu | e958203 | 2025-04-17 19:18:16 +0800 | [diff] [blame^] | 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 |