xref: /openbmc/linux/arch/um/kernel/physmem.c (revision 3848d470)
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 
18 static int physmem_fd = -1;
19 
20 /* Changed during early boot */
21 unsigned long high_physmem;
22 EXPORT_SYMBOL(high_physmem);
23 
24 extern unsigned long long physmem_size;
25 
mem_total_pages(unsigned long physmem,unsigned long iomem,unsigned long highmem)26 void __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 
map_memory(unsigned long virt,unsigned long phys,unsigned long len,int r,int w,int x)41 void 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("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  */
setup_physmem(unsigned long start,unsigned long reserve_end,unsigned long len,unsigned long long highmem)79 void __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), len + highmem);
112 	memblock_reserve(__pa(start), reserve);
113 
114 	min_low_pfn = PFN_UP(__pa(reserve_end));
115 	max_low_pfn = min_low_pfn + (map_size >> PAGE_SHIFT);
116 }
117 
phys_mapping(unsigned long phys,unsigned long long * offset_out)118 int 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 }
146 EXPORT_SYMBOL(phys_mapping);
147 
uml_mem_setup(char * line,int * add)148 static int __init uml_mem_setup(char *line, int *add)
149 {
150 	char *retptr;
151 	physmem_size = memparse(line,&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 
164 extern 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  */
176 struct iomem_region *iomem_regions;
177 
178 /* Initialized in parse_iomem and unchanged thereafter */
179 int iomem_size;
180 
find_iomem(char * driver,unsigned long * len_out)181 unsigned 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 }
196 EXPORT_SYMBOL(find_iomem);
197 
setup_iomem(void)198 static 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