1 /* 2 * A system pager implementation residing in the same task as a program. 3 * 4 * Copyright (C) 2022, 2023 Paul Boddie <paul@boddie.org.uk> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as 8 * published by the Free Software Foundation; either version 2 of 9 * the License, or (at your option) any later version. 10 * 11 * This program 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 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, 19 * Boston, MA 02110-1301, USA 20 */ 21 22 #include <l4/re/env.h> 23 #include <l4/re/c/dataspace.h> 24 #include <l4/re/c/rm.h> 25 #include <l4/util/util.h> 26 27 #include <ipc/cap_alloc.h> 28 #include <mem/memory_utils.h> 29 #include <systypes/base.h> 30 31 #include <stdio.h> 32 33 #include "dataspace_client.h" 34 #include "internal_pager.h" 35 #include "mapped_region.h" 36 #include "pager_object_server.h" 37 38 39 40 #define DEBUG 0 41 42 43 44 /* A simple system pager also acting as a region mapper. */ 45 46 InternalPager::InternalPager(address_t start, address_t end) 47 : ExecPager(start, end) 48 { 49 } 50 51 ipc_server_default_config_type InternalPager::config() 52 { 53 return config_PagerObject; 54 } 55 56 57 58 /* Close the pager. */ 59 60 void InternalPager::close() 61 { 62 printf("Internal pager closing...\n"); 63 } 64 65 66 67 /* Handle a general exception. */ 68 69 long InternalPager::exception(l4_exc_regs_t regs, l4_snd_fpage_t *region) 70 { 71 (void) region; 72 73 printf("InternalPager::exception(...) -> pfa = %lx, pc = %lx\n", l4_utcb_exc_pfa(®s), l4_utcb_exc_pc(®s)); 74 75 while (1) 76 l4_sleep_forever(); 77 78 return L4_EOK; 79 } 80 81 /* Handle a page fault using any configured regions. */ 82 83 long InternalPager::page_fault(l4_umword_t pfa, l4_umword_t pc, l4_snd_fpage_t *region) 84 { 85 l4_umword_t addr = pfa & ~7UL, flags = pfa & 7; 86 87 #if DEBUG 88 printf("page_fault(%lx, %lx) -> %lx (%lx) -> ", pfa, pc, addr, flags); 89 l4_thread_regs_t *regs = l4_utcb_tcr(); 90 printf("regs = %p\n; regs->user[0] = %lx\n", regs, regs->user[0]); 91 #endif 92 93 /* Obtain a region supporting the fault address. */ 94 95 MemoryArea *r, *parent; 96 long err = _area.find(addr, &r, &parent); 97 98 if (!err) 99 { 100 address_t window_size = L4_PAGESIZE; 101 address_t window_base = trunc(addr, window_size); 102 address_t offset = addr - r->area_start(); 103 address_t page_addr = trunc(addr, L4_PAGESIZE); 104 address_t hot_spot = page_addr - window_base; 105 106 /* Interact with the region's dataspace, specifying a receive window for a 107 map operation. Here, a single page is specified. */ 108 109 client_Dataspace dataspace(r->dataspace()); 110 l4_snd_fpage_t rw_region = {0, l4_fpage(window_base, L4_PAGESHIFT, 0)}; 111 map_flags_t map_flags = map_flags_for_fault(flags); 112 113 #if DEBUG 114 printf("window_base = %lx; window_size = %lx\n", window_base, window_size); 115 printf("region = {%lx, {%lx, %d}}\n", rw_region.snd_base, l4_fpage_memaddr(rw_region.fpage), l4_fpage_size(rw_region.fpage)); 116 printf("map(%lx, %lx, %lx) -> %lx\n", offset, hot_spot, map_flags, r->dataspace()); 117 #endif 118 119 err = dataspace.map(offset, hot_spot, map_flags & r->flags(), &rw_region); 120 121 /* Indicate an unspecified result, since the mapping should have taken 122 place. */ 123 124 *region = {0, l4_fpage_invalid()}; 125 126 return err; 127 } 128 129 printf("not mapped at %lx for pc %lx\n", addr, pc); 130 131 return err; 132 } 133 134 /* Attach a region for provision when page faults occur. This is required in 135 the initialisation of a program by the C library which requires a region 136 mapper. */ 137 138 long InternalPager::attach(address_t *start, address_t size, map_flags_t flags, 139 l4_cap_idx_t ds, address_t offset, 140 unsigned char align) 141 { 142 /* NOTE: The offset apparently indicates the offset within the dataspace of 143 the start of the region. */ 144 145 (void) offset; 146 147 MemoryArea *area; 148 long err = ExecPager::find(start, &size, flags, align, &area); 149 150 if (!err) 151 { 152 MappedRegion r(*start, *start + size, flags & L4RE_DS_F_RIGHTS_MASK, ds); 153 area->add(r); 154 } 155 else 156 ipc_cap_free_um(ds); 157 158 return err; 159 } 160 161 long InternalPager::detach(address_t addr, address_t size, map_flags_t flags, 162 address_t *start, address_t *rsize, l4_cap_idx_t *ds) 163 { 164 (void) size; (void) flags; 165 166 /* Obtain the region supporting the given address. 167 NOTE: All regions within the given range should be detached. */ 168 169 MemoryArea *r, *parent; 170 long err = _area.find(addr, &r, &parent); 171 172 if (!err) 173 { 174 *start = r->area_start(); 175 *rsize = r->area_end() - r->area_start(); 176 *ds = r->dataspace(); 177 parent->remove(*r); 178 } 179 180 return err; 181 } 182 183 long InternalPager::reserve_area(address_t *start, address_t size, 184 map_flags_t flags, unsigned char align) 185 { 186 MemoryArea *area; 187 long err = ExecPager::find(start, &size, flags, align, &area); 188 189 if (!err) 190 { 191 /* Add an object acting like a region but without any associated 192 dataspace. */ 193 194 if (flags & L4RE_RM_F_RESERVED) 195 { 196 ReservedMemoryArea r(*start, *start + size); 197 area->add(r); 198 } 199 200 /* Add an object permitting regions to be added within it. */ 201 202 else 203 { 204 AvailableMemoryArea r(*start, *start + size); 205 area->add(r); 206 } 207 } 208 209 return err; 210 } 211 212 /* vim: tabstop=2 expandtab shiftwidth=2 213 */