| 1 | /* |
| 2 | * Definitions for cpus with variable page sizes. |
| 3 | * |
| 4 | * Copyright (c) 2003 Fabrice Bellard |
| 5 | * |
| 6 | * This library is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU Lesser General Public |
| 8 | * License as published by the Free Software Foundation; either |
| 9 | * version 2.1 of the License, or (at your option) any later version. |
| 10 | * |
| 11 | * This library is distributed in the hope that it will be useful, |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | * Lesser General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU Lesser General Public |
| 17 | * License along with this library; if not, see <http://www.gnu.org/licenses/>. |
| 18 | */ |
| 19 | |
| 20 | #ifndef EXEC_PAGE_VARY_H |
| 21 | #define EXEC_PAGE_VARY_H |
| 22 | |
| 23 | /* |
| 24 | * For system mode, the minimum comes from the number of bits |
| 25 | * required for maximum alignment (6) and the number of bits |
| 26 | * required for TLB_FLAGS_MASK (3). |
| 27 | * |
| 28 | * For user mode, TARGET_PAGE_BITS_VARY is a hack to allow the target |
| 29 | * page size to match the host page size. Mostly, this reduces the |
| 30 | * ordinary target page size to run on a host with 4KiB pages (i.e. x86). |
| 31 | * There is no true minimum required by the implementation, but keep the |
| 32 | * same minimum as for system mode for sanity. |
| 33 | * See linux-user/mmap.c, mmap_h_lt_g and mmap_h_gt_g. |
| 34 | */ |
| 35 | #define TARGET_PAGE_BITS_MIN 9 |
| 36 | |
| 37 | typedef struct { |
| 38 | bool decided; |
| 39 | int bits; |
| 40 | uint64_t mask; |
| 41 | } TargetPageBits; |
| 42 | |
| 43 | /** |
| 44 | * set_preferred_target_page_bits: |
| 45 | * @bits: number of bits needed to represent an address within the page |
| 46 | * |
| 47 | * Set the preferred target page size (the actual target page |
| 48 | * size may be smaller than any given CPU's preference). |
| 49 | * Returns true on success, false on failure (which can only happen |
| 50 | * if this is called after the system has already finalized its |
| 51 | * choice of page size and the requested page size is smaller than that). |
| 52 | */ |
| 53 | bool set_preferred_target_page_bits(int bits); |
| 54 | |
| 55 | /** |
| 56 | * finalize_target_page_bits: |
| 57 | * Commit the final value set by set_preferred_target_page_bits. |
| 58 | */ |
| 59 | void finalize_target_page_bits(void); |
| 60 | |
| 61 | /** |
| 62 | * migration_legacy_page_bits |
| 63 | * |
| 64 | * For migration compatibility with qemu v2.9, prior to the introduction |
| 65 | * of the configuration/target-page-bits section, return the value of |
| 66 | * TARGET_PAGE_BITS that the target had then. |
| 67 | */ |
| 68 | int migration_legacy_page_bits(void); |
| 69 | |
| 70 | #endif /* EXEC_PAGE_VARY_H */ |