1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 */
5
6#include <linux/module.h>
7#include <linux/memblock.h>
8#include <linux/mm.h>
9#include <linux/pfn.h>
10#include <asm/page.h>
11#include <asm/sections.h>
12#include <as-layout.h>
13#include <init.h>
14#include <kern.h>
15#include <mem_user.h>
16#include <os.h>
17
18static int physmem_fd = -1;
19
20/* Changed during early boot */
21unsigned long high_physmem;
22EXPORT_SYMBOL(high_physmem);
23
24extern unsigned long long physmem_size;
25
26void __init mem_total_pages(unsigned long physmem, unsigned long iomem,
27 unsigned long highmem)
28{
29 unsigned long phys_pages, highmem_pages;
30 unsigned long iomem_pages, total_pages;
31
32 phys_pages = physmem >> PAGE_SHIFT;
33 iomem_pages = iomem >> PAGE_SHIFT;
34 highmem_pages = highmem >> PAGE_SHIFT;
35
36 total_pages = phys_pages + iomem_pages + highmem_pages;
37
38 max_mapnr = total_pages;
39}
40
41void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
42 int r, int w, int x)
43{
44 __u64 offset;
45 int fd, err;
46
47 fd = phys_mapping(phys, &offset);
48 err = os_map_memory((void *) virt, fd, offset, len, r, w, x);
49 if (err) {
50 if (err == -ENOMEM)
51 printk(KERN_ERR "try increasing the host's "
52 "/proc/sys/vm/max_map_count to <physical "
53 "memory size>/4096\n");
54 panic(fmt: "map_memory(0x%lx, %d, 0x%llx, %ld, %d, %d, %d) failed, "
55 "err = %d\n", virt, fd, offset, len, r, w, x, err);
56 }
57}
58
59/**
60 * setup_physmem() - Setup physical memory for UML
61 * @start: Start address of the physical kernel memory,
62 * i.e start address of the executable image.
63 * @reserve_end: end address of the physical kernel memory.
64 * @len: Length of total physical memory that should be mapped/made
65 * available, in bytes.
66 * @highmem: Number of highmem bytes that should be mapped/made available.
67 *
68 * Creates an unlinked temporary file of size (len + highmem) and memory maps
69 * it on the last executable image address (uml_reserved).
70 *
71 * The offset is needed as the length of the total physical memory
72 * (len + highmem) includes the size of the memory used be the executable image,
73 * but the mapped-to address is the last address of the executable image
74 * (uml_reserved == end address of executable image).
75 *
76 * The memory mapped memory of the temporary file is used as backing memory
77 * of all user space processes/kernel tasks.
78 */
79void __init setup_physmem(unsigned long start, unsigned long reserve_end,
80 unsigned long len, unsigned long long highmem)
81{
82 unsigned long reserve = reserve_end - start;
83 long map_size = len - reserve;
84 int err;
85
86 if(map_size <= 0) {
87 os_warn("Too few physical memory! Needed=%lu, given=%lu\n",
88 reserve, len);
89 exit(1);
90 }
91
92 physmem_fd = create_mem_file(len + highmem);
93
94 err = os_map_memory((void *) reserve_end, physmem_fd, reserve,
95 map_size, 1, 1, 1);
96 if (err < 0) {
97 os_warn("setup_physmem - mapping %ld bytes of memory at 0x%p "
98 "failed - errno = %d\n", map_size,
99 (void *) reserve_end, err);
100 exit(1);
101 }
102
103 /*
104 * Special kludge - This page will be mapped in to userspace processes
105 * from physmem_fd, so it needs to be written out there.
106 */
107 os_seek_file(physmem_fd, __pa(__syscall_stub_start));
108 os_write_file(physmem_fd, __syscall_stub_start, PAGE_SIZE);
109 os_fsync_file(physmem_fd);
110
111 memblock_add(__pa(start), size: len + highmem);
112 memblock_reserve(__pa(start), size: reserve);
113
114 min_low_pfn = PFN_UP(__pa(reserve_end));
115 max_low_pfn = min_low_pfn + (map_size >> PAGE_SHIFT);
116}
117
118int phys_mapping(unsigned long phys, unsigned long long *offset_out)
119{
120 int fd = -1;
121
122 if (phys < physmem_size) {
123 fd = physmem_fd;
124 *offset_out = phys;
125 }
126 else if (phys < __pa(end_iomem)) {
127 struct iomem_region *region = iomem_regions;
128
129 while (region != NULL) {
130 if ((phys >= region->phys) &&
131 (phys < region->phys + region->size)) {
132 fd = region->fd;
133 *offset_out = phys - region->phys;
134 break;
135 }
136 region = region->next;
137 }
138 }
139 else if (phys < __pa(end_iomem) + highmem) {
140 fd = physmem_fd;
141 *offset_out = phys - iomem_size;
142 }
143
144 return fd;
145}
146EXPORT_SYMBOL(phys_mapping);
147
148static int __init uml_mem_setup(char *line, int *add)
149{
150 char *retptr;
151 physmem_size = memparse(ptr: line,retptr: &retptr);
152 return 0;
153}
154__uml_setup("mem=", uml_mem_setup,
155"mem=<Amount of desired ram>\n"
156" This controls how much \"physical\" memory the kernel allocates\n"
157" for the system. The size is specified as a number followed by\n"
158" one of 'k', 'K', 'm', 'M', which have the obvious meanings.\n"
159" This is not related to the amount of memory in the host. It can\n"
160" be more, and the excess, if it's ever used, will just be swapped out.\n"
161" Example: mem=64M\n\n"
162);
163
164extern int __init parse_iomem(char *str, int *add);
165
166__uml_setup("iomem=", parse_iomem,
167"iomem=<name>,<file>\n"
168" Configure <file> as an IO memory region named <name>.\n\n"
169);
170
171/*
172 * This list is constructed in parse_iomem and addresses filled in
173 * setup_iomem, both of which run during early boot. Afterwards, it's
174 * unchanged.
175 */
176struct iomem_region *iomem_regions;
177
178/* Initialized in parse_iomem and unchanged thereafter */
179int iomem_size;
180
181unsigned long find_iomem(char *driver, unsigned long *len_out)
182{
183 struct iomem_region *region = iomem_regions;
184
185 while (region != NULL) {
186 if (!strcmp(region->driver, driver)) {
187 *len_out = region->size;
188 return region->virt;
189 }
190
191 region = region->next;
192 }
193
194 return 0;
195}
196EXPORT_SYMBOL(find_iomem);
197
198static int setup_iomem(void)
199{
200 struct iomem_region *region = iomem_regions;
201 unsigned long iomem_start = high_physmem + PAGE_SIZE;
202 int err;
203
204 while (region != NULL) {
205 err = os_map_memory((void *) iomem_start, region->fd, 0,
206 region->size, 1, 1, 0);
207 if (err)
208 printk(KERN_ERR "Mapping iomem region for driver '%s' "
209 "failed, errno = %d\n", region->driver, -err);
210 else {
211 region->virt = iomem_start;
212 region->phys = __pa(region->virt);
213 }
214
215 iomem_start += region->size + PAGE_SIZE;
216 region = region->next;
217 }
218
219 return 0;
220}
221
222__initcall(setup_iomem);
223

source code of linux/arch/um/kernel/physmem.c